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Isack Mathew
African Centre for Crop Improvement, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Pietermaritzburg Private Bag X01, Scottsville 3209, South Africa

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Short Biography

Isack Mathew is a Post-Doctoral Research Fellow in Plant Breeding at the African Centre for Crop Improvement (ACCI), University of KwaZulu-Natal in South Africa.

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Journal article
Published: 29 July 2021 in Sustainability
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Pearl millet (Pennisetum glaucum) is a staple food crop in Burkina Faso that is widely grown in the Sahelian and Sudano-Sahelian zones, characterised by poor soil conditions and erratic rainfall, and high temperatures. The objective of this study was to document farmers’ perceptions of the prevailing constraints affecting pearl millet production and related approaches to manage the parasitic weeds S. hermonthica. The study was conducted in the Sahel, Sudano-Sahelian zones in the North, North Central, West Central, Central Plateau, and South Central of Burkina Faso. Data were collected through a structured questionnaire and focus group discussions involving 492 participant farmers. Recurrent drought, S. hermonthica infestation, shortage of labour, lack of fertilisers, lack of cash, and the use of low-yielding varieties were the main challenges hindering pearl millet production in the study areas. The majority of the respondents (40%) ranked S. hermonthica infestation as the primary constraint affecting pearl millet production. Respondent farmers reported yield losses of up to 80% due to S. hermonthica infestation. 61.4% of the respondents in the study areas had achieved a mean pearl millet yields of <1 t/ha. Poor access and the high cost of introduced seed, and a lack of farmers preferred traits in the existing introduced pearl millet varieties were the main reasons for their low adoption, as reported by 32% of respondents. S. hermonthica management options in pearl millet production fields included moisture conservation using terraces, manual hoeing, hand weeding, use of microplots locally referred to as ‘zaï’, crop rotation and mulching. These management techniques were ineffective because they do not suppress the below ground S. hermonthica seed, and they are difficult to implement. Integrated management practices employing breeding for S. hermonthica resistant varieties with the aforementioned control measures could offer a sustainable solution for S. hermonthica management and improved pearl millet productivity in Burkina Faso.

ACS Style

Armel Rouamba; Hussein Shimelis; Inoussa Drabo; Mark Laing; Prakash Gangashetty; Isack Mathew; Emmanuel Mrema; Admire Shayanowako. Constraints to Pearl Millet (Pennisetum glaucum) Production and Farmers’ Approaches to Striga hermonthica Management in Burkina Faso. Sustainability 2021, 13, 8460 .

AMA Style

Armel Rouamba, Hussein Shimelis, Inoussa Drabo, Mark Laing, Prakash Gangashetty, Isack Mathew, Emmanuel Mrema, Admire Shayanowako. Constraints to Pearl Millet (Pennisetum glaucum) Production and Farmers’ Approaches to Striga hermonthica Management in Burkina Faso. Sustainability. 2021; 13 (15):8460.

Chicago/Turabian Style

Armel Rouamba; Hussein Shimelis; Inoussa Drabo; Mark Laing; Prakash Gangashetty; Isack Mathew; Emmanuel Mrema; Admire Shayanowako. 2021. "Constraints to Pearl Millet (Pennisetum glaucum) Production and Farmers’ Approaches to Striga hermonthica Management in Burkina Faso." Sustainability 13, no. 15: 8460.

Journal article
Published: 18 June 2021 in Journal of Food Composition and Analysis
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Bambara groundnut (Vigna subterranea (L.) Verdc) has the potential to address food insecurity in sub-Saharan Africa. However, a lack of cultivars with improved nutritional quality hinders its potential. This study evaluated nutritional content in the grain of 19 Bambara groundnut lines. The nutritional content of the lines varied significantly (p < 0.05) with lines Mix, Tiganecuru, and Pong-Br-UNK exhibiting the highest means for starch protein and fat contents, respectively. The first principal component (PC) accounted for 21.9 % of the variation and was strongly correlated with K (which contributed 20.1 %), ash (19.5 %), NDF (16.4 %) and ADF (14.8 %). The second PC explained 16.1 % of the variation and was significantly correlated to magnesium (19.7 %), starch (17.3 %) and protein (10.7 %). This is essential to select superior lines for developing Bambara groundnut breeding populations for improving nutrition in SSA. The negative correlations between some of the nutrient such as NDF and ash, NDF and K, and Mg and Mn would be a challenge for simultaneous selection to breed nutritious Bambara groundnut lines. Further, analyses of anti-nutrient chemicals is recommended.

ACS Style

Nokuthula Cherry Hlanga; Albert Thembinkosi Modi; Isack Mathew. Evaluating Nutritional Content Among Bambara Groundnut Lines. Journal of Food Composition and Analysis 2021, 102, 104053 .

AMA Style

Nokuthula Cherry Hlanga, Albert Thembinkosi Modi, Isack Mathew. Evaluating Nutritional Content Among Bambara Groundnut Lines. Journal of Food Composition and Analysis. 2021; 102 ():104053.

Chicago/Turabian Style

Nokuthula Cherry Hlanga; Albert Thembinkosi Modi; Isack Mathew. 2021. "Evaluating Nutritional Content Among Bambara Groundnut Lines." Journal of Food Composition and Analysis 102, no. : 104053.

Journal article
Published: 22 February 2021 in Agronomy
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Rice (Oryza species) is a commercial crop worldwide. Across Africa, the potential yield and quality of rice is diminished by a lack of high performance, locally adapted varieties, and the impact of rice yellow mottle virus (RYMV). The objective of this study was to assess the performance of a diverse collection of rice germplasm for RYMV resistance and agronomic traits, and to select promising lines for breeding for Tanzanian conditions. Fifty-four rice genotypes were field evaluated in two important rice production sites (Ifakara and Mkindo) in Tanzania, which are recognized as RYMV hotspots, using a 6 × 9 alpha lattice design with two replications. There was significant (p < 0.05) genotypic variation for agronomic traits and RYMV susceptibility in the tested germplasm. Seven genotypes with moderate to high RYMV resistance were identified, including Salama M-57, SSD1, IRAT 256, Salama M-55, Mwangaza, Lunyuki, and Salama M-19, which were identified as new sources of resistance genes. Positive and significant correlations were detected between grain yield and number of panicles per plant (NPP), panicle length (PL), number of grains per panicle (NGP), percentage-filled grains (PFG), and thousand-grain weight (TGW), which are useful traits for simultaneous selection for rice yield improvement. A principal component analysis allocated five principal components, accounting for 79.88% of the total variation present in the assessed germplasm collection. Traits that contributed most to variability included NPP, number of tillers/plant (NT), PL, grain yield (GY), and days to 50% flowering (DFL). The genotypes Rangimbili, Gigante, and SARO possess complementary agronomic traits and RYMV resistance, and can be recommended for further evaluation, genetic analysis, and breeding.

ACS Style

William Suvi; Hussein Shimelis; Mark Laing; Isack Mathew; Admire Shayanowako. Variation among Tanzania Rice Germplasm Collections Based on Agronomic Traits and Resistance to Rice Yellow Mottle Virus. Agronomy 2021, 11, 391 .

AMA Style

William Suvi, Hussein Shimelis, Mark Laing, Isack Mathew, Admire Shayanowako. Variation among Tanzania Rice Germplasm Collections Based on Agronomic Traits and Resistance to Rice Yellow Mottle Virus. Agronomy. 2021; 11 (2):391.

Chicago/Turabian Style

William Suvi; Hussein Shimelis; Mark Laing; Isack Mathew; Admire Shayanowako. 2021. "Variation among Tanzania Rice Germplasm Collections Based on Agronomic Traits and Resistance to Rice Yellow Mottle Virus." Agronomy 11, no. 2: 391.

Research article
Published: 12 February 2021 in Acta Agriculturae Scandinavica, Section B — Soil & Plant Science
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Genotype-by-environment interaction (GEI) analysis is fundamental in crop improvement programmes to guide selection and for recommendation of high performing and stable genotypes for breeding or production. The objectives of this study were to quantify the GEI effects and determine grain yield stability among diverse pigeonpea genotypes to select candidate lines for breeding in Malawi. Eighty-one pigeonpea genotypes were tested under six environments using a 9 × 9 alpha-lattice design with two replications. Data collected were subjected to additive main effects and multiplicative interaction (AMMI) analysis and genotype plus genotype-by-environment interaction (GGE) biplot analysis. Genotype, environment, and genotype × environment interaction (GEI) accounted for 16.4, 33.5, and 49.6%, respectively, of the total variation for grain yield. The test environments were delineated into three mega-environments, based on site and seasonal variability. The AMMI and GGE analyses indicated that the top-yielding and stable genotypes across the test environments were MWPLR 24, ICEAP 01155, MWPLR 14, TZA 5582, and MWPLR 4. The selected genotypes are recommended as parental lines for grain yield improvement in Malawi or similar agro-ecologies.

ACS Style

Esnart Nyirenda Yohane; Hussein Shimelis; Mark Laing; Isack Mathew; Admire Shayanowako. Genotype-by-environment interaction and stability analyses of grain yield in pigeonpea [Cajanus cajan (L.) Millspaugh]. Acta Agriculturae Scandinavica, Section B — Soil & Plant Science 2021, 1 -11.

AMA Style

Esnart Nyirenda Yohane, Hussein Shimelis, Mark Laing, Isack Mathew, Admire Shayanowako. Genotype-by-environment interaction and stability analyses of grain yield in pigeonpea [Cajanus cajan (L.) Millspaugh]. Acta Agriculturae Scandinavica, Section B — Soil & Plant Science. 2021; ():1-11.

Chicago/Turabian Style

Esnart Nyirenda Yohane; Hussein Shimelis; Mark Laing; Isack Mathew; Admire Shayanowako. 2021. "Genotype-by-environment interaction and stability analyses of grain yield in pigeonpea [Cajanus cajan (L.) Millspaugh]." Acta Agriculturae Scandinavica, Section B — Soil & Plant Science , no. : 1-11.

Research article
Published: 28 December 2020 in PLOS ONE
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Russian wheat aphid (RWA; Diuraphis noxia Kurdjumov) resistance on the 1D chromosome of wheat has been the subject of intensive research. Conversely, the deployment of the Dn4 derived RWA resistant varieties diminished in recent years due to the overcoming of the resistance it imparts in the United States of America. However, this resistance has not been deployed in South Africa despite reports that Dn4 containing genotypes exhibited varying levels of resistance against the South African RWA biotypes. It is possible that there may be certain genetic differences within breeding lines or cultivars that influence the expression of resistance. The aim of this study was to identify single nucleotide polymorphism (SNP) markers associated with resistance to South African RWA biotypes. A panel of thirty-two wheat lines were phenotyped for RWA resistance using four South African RWA biotypes and a total of 181 samples were genotyped using the Illumina 9K SNP wheat chip. A genome wide association study using 7598 polymorphic SNPs showed that the population was clustered into two distinct subpopulations. Twenty-seven marker trait associations (MTA) were identified with an average linkage disequilibrium of 0.38 at 10 Mbp. Four of these markers were highly significant and three correlated with previously reported quantitative trait loci linked to RWA resistance in wheat. Twenty putative genes were annotated using the IWGSC RefSeq, three of which are linked to plant defence responses. This study identified novel chromosomal regions that contribute to RWA resistance and contributes to unravelling the complex genetics that control RWA resistance in wheat.

ACS Style

Lavinia Kisten; Vicki L. Tolmay; Isack Mathew; Scott L. Sydenham; Eduard Venter. Genome-wide association analysis of Russian wheat aphid (Diuraphis noxia) resistance in Dn4 derived wheat lines evaluated in South Africa. PLOS ONE 2020, 15, e0244455 .

AMA Style

Lavinia Kisten, Vicki L. Tolmay, Isack Mathew, Scott L. Sydenham, Eduard Venter. Genome-wide association analysis of Russian wheat aphid (Diuraphis noxia) resistance in Dn4 derived wheat lines evaluated in South Africa. PLOS ONE. 2020; 15 (12):e0244455.

Chicago/Turabian Style

Lavinia Kisten; Vicki L. Tolmay; Isack Mathew; Scott L. Sydenham; Eduard Venter. 2020. "Genome-wide association analysis of Russian wheat aphid (Diuraphis noxia) resistance in Dn4 derived wheat lines evaluated in South Africa." PLOS ONE 15, no. 12: e0244455.

Journal article
Published: 23 December 2020 in Agronomy
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Selecting genetically diverse and complementary parental lines and superior crosses are pre-requisites in developing improved cultivars. The objectives of this study were to determine the combining ability effects and gene action conditioning rice yellow mottle virus disease (RYMVD) resistance and agronomic traits in rice (Oryza sativa L.). Ten parental lines and their 45 F2 progenies were field evaluated in three locations using a 5 × 11 alpha lattice design with two replications. The genotype × site interaction effects were significant (p < 0.05) for the number of tillers (NT), number of panicles per plant (NPP), number of grains per panicle (NGP), percentage of filled grains (PFG), thousand grain weight (TGW), RYMVD resistance and grain yield (GY). The analysis of general and specific combining ability (GCA and SCA) indicated involvement of both additive and non-additive gene action governing inheritance of traits. High GCA/SCA ratio estimate revealed additive genetic effect was predominant. Parental lines Mwangaza, Lunyuki, Salama M-57, Salama M-19, IRAT 256 and Salama M-55, which had negative GCA effects for RYMVD, and families such as SARO 5 × Salama M-55, IRAT 245 × Rangimbili, Rangimbili × Gigante and Rangimbili × Mwangaza, which had negative SCA effects for RYMVD, were selected for RYMV resistance breeding. The crosses Rangimbili × Gigante, Gigante × Salama M-19 and Rangimbili × Salama M-55 were selected due to their desirable SCA effects for GY. The predominance of additive gene effects for agronomic traits and RYMVD resistance in the present breeding populations suggested that rice improvement could be achieved through gene introgression using recurrent selection.

ACS Style

William Titus Suvi; Hussein Shimelis; Mark Laing; Isack Mathew; Admire I. T. Shayanowako. Determining the Combining Ability and Gene Action for Rice Yellow Mottle Virus Disease Resistance and Agronomic Traits in Rice (Oryza sativa L.). Agronomy 2020, 11, 12 .

AMA Style

William Titus Suvi, Hussein Shimelis, Mark Laing, Isack Mathew, Admire I. T. Shayanowako. Determining the Combining Ability and Gene Action for Rice Yellow Mottle Virus Disease Resistance and Agronomic Traits in Rice (Oryza sativa L.). Agronomy. 2020; 11 (1):12.

Chicago/Turabian Style

William Titus Suvi; Hussein Shimelis; Mark Laing; Isack Mathew; Admire I. T. Shayanowako. 2020. "Determining the Combining Ability and Gene Action for Rice Yellow Mottle Virus Disease Resistance and Agronomic Traits in Rice (Oryza sativa L.)." Agronomy 11, no. 1: 12.

Drought stress
Published: 24 November 2020 in Journal of Agronomy and Crop Science
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Genetic variation is fundamental for plant breeding programmes. Exploiting the genetic variation of wheat for biomass allocation, yield and yield‐related traits enhances breeding for drought tolerance. The aim of this study was to evaluate genetic variation and to select best individuals among 180 M3 mutant families of wheat developed through EMS mutagenesis based on better biomass allocation to root systems, desirable agronomic traits and high yield potential under greenhouse and field environment evaluations with drought‐stressed and non‐stressed conditions. Experiments were conducted using a randomized complete block design with two replications. Days to 50% heading (DTH), days to 90% maturity (DTM), plant height (PH), number of productive tillers (PTN), shoot biomass (SB), root biomass (RB), total biomass (TB), root–shoot ratio (RSR), spike length (SL), spikelet per spike (SPS), one thousand seed weight (TSW) and grain yield (GY) were collected. Mutant families showed significant genotypic (p < .05) variation for yield and biomass traits, whereas genotype × environment × water regime interaction effects were significant (p < .05) for DTM, SB, TB, TSW and GY. Superior families designated as 52, 159, 103, 126 and 145 were selected for improved drought tolerance and high biomass allocation to roots.

ACS Style

Boluwatife M. OlaOlorun; Hussein A. Shimelis; Isack Mathew. Variability and selection among mutant families of wheat for biomass allocation, yield and yield‐related traits under drought‐stressed and non‐stressed conditions. Journal of Agronomy and Crop Science 2020, 207, 404 -421.

AMA Style

Boluwatife M. OlaOlorun, Hussein A. Shimelis, Isack Mathew. Variability and selection among mutant families of wheat for biomass allocation, yield and yield‐related traits under drought‐stressed and non‐stressed conditions. Journal of Agronomy and Crop Science. 2020; 207 (3):404-421.

Chicago/Turabian Style

Boluwatife M. OlaOlorun; Hussein A. Shimelis; Isack Mathew. 2020. "Variability and selection among mutant families of wheat for biomass allocation, yield and yield‐related traits under drought‐stressed and non‐stressed conditions." Journal of Agronomy and Crop Science 207, no. 3: 404-421.

Journal article
Published: 30 October 2020 in Agronomy
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Pigeonpea (Cajanus cajan [L,] Millspaugh) is an important source of grain protein for low-income countries such as Malawi. Knowledge of the genetic diversity in pigeonpea is essential for an effective breeding program. The study objective was to assess the genetic diversity among diverse pigeonpea accessions to select complementary and unique genotypes for breeding. Eighty-one pigeonpea accessions were evaluated in six environments in Malawi using a 9 × 9 alpha-lattice design with two replications. The cross-tabulation analysis revealed a significant genotype variation on plant growth, flower, and seed traits. The combined analysis of variance identified genotypes MWPLR 14, ICEAP 01170, ICEAP 871091, and ICEAP 01285 as early maturing varieties, while Kachangu, MWPLR 16, TZA 5582, No. 40, and MWPLR 14 were identified as high-yielding genotypes. The correlation analysis revealed a significant positive correlation between grain yield and a hundred seed weight (HSWT) (r = 0.50, p < 0.01), suggesting the usefulness of this trait for selection. The nonlinear principal component analysis identified grain yield (GDY), days to 50% flowering (DTF), days to 75% maturity (DTM), number of pods per plant (NPP), number of racemes per plant (NRP), 100 seed weight (HSWT), leaf hairiness (LH), and number of seeds per pod (NSP) as the most discriminated traits among the test genotypes. The cluster analysis using morphological traits delineated the accessions into three clusters. The selected high-yielding and early-maturing genotypes may be recommended as parental lines for breeding and grain yield improvement in Malawi or similar agro-ecologies.

ACS Style

Esnart Nyirenda Yohane; Hussein Shimelis; Mark Laing; Isack Mathew; Admire Shayanowako. Phenotypic Divergence Analysis in Pigeonpea [Cajanus cajan (L.) Millspaugh] Germplasm Accessions. Agronomy 2020, 10, 1682 .

AMA Style

Esnart Nyirenda Yohane, Hussein Shimelis, Mark Laing, Isack Mathew, Admire Shayanowako. Phenotypic Divergence Analysis in Pigeonpea [Cajanus cajan (L.) Millspaugh] Germplasm Accessions. Agronomy. 2020; 10 (11):1682.

Chicago/Turabian Style

Esnart Nyirenda Yohane; Hussein Shimelis; Mark Laing; Isack Mathew; Admire Shayanowako. 2020. "Phenotypic Divergence Analysis in Pigeonpea [Cajanus cajan (L.) Millspaugh] Germplasm Accessions." Agronomy 10, no. 11: 1682.

Journal article
Published: 05 October 2020 in Journal of Crop Improvement
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ACS Style

Yared Belete; Hussein Shimelis; Mark Laing; Isack Mathew. Genetic diversity and population structure of bread wheat genotypes determined via phenotypic and SSR marker analyses under drought-stress conditions. Journal of Crop Improvement 2020, 35, 303 -325.

AMA Style

Yared Belete, Hussein Shimelis, Mark Laing, Isack Mathew. Genetic diversity and population structure of bread wheat genotypes determined via phenotypic and SSR marker analyses under drought-stress conditions. Journal of Crop Improvement. 2020; 35 (3):303-325.

Chicago/Turabian Style

Yared Belete; Hussein Shimelis; Mark Laing; Isack Mathew. 2020. "Genetic diversity and population structure of bread wheat genotypes determined via phenotypic and SSR marker analyses under drought-stress conditions." Journal of Crop Improvement 35, no. 3: 303-325.

Original paper
Published: 03 October 2020 in Cereal Research Communications
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Genetic gains in wheat yield have stagnated over the years due to genetic drift. There is a need to create new genetic variation for yield using various methods including ethyl methanesulphonate (EMS). The use of EMS mutagenesis is limited by variations in lethality, efficiency and effectiveness, which confound to selection. The objective of this study was to evaluate morphological variation in wheat after EMS mutagenesis. Wheat genotype LM43 was subjected to EMS mutagenesis under the following conditions: 0.1% v/v for 1 h at 25 °C, 0.1% v/v for 1 h at 30 °C and 0.7% v/v for 1.5 h at 25 °C. Some mutant plants in M1 had significantly (p < 0.05) higher spikelets per spike and kernels per spike. The number of tillers and kernels per spike increased significantly at M2 generation. EMS treatment with 0.1% v/v for 1 h at 30 °C was the most effective and efficient with the lowest biological damage. Macro-mutations were observed in spike, peduncle, awn and flag leaf morphology. The study identified early generation mutants that could be exploited for improving drought tolerance, yield and biomass, or for genetic analysis to identify quantitative trait loci in wheat.

ACS Style

Boluwatife M. OlaOlorun; Hussein Shimelis; Mark Laing; Isack Mathew. Morphological variations of wheat (Triticum aestivum L. em. Thell.) under variable ethyl methanesulphonate mutagenesis. Cereal Research Communications 2020, 49, 301 -310.

AMA Style

Boluwatife M. OlaOlorun, Hussein Shimelis, Mark Laing, Isack Mathew. Morphological variations of wheat (Triticum aestivum L. em. Thell.) under variable ethyl methanesulphonate mutagenesis. Cereal Research Communications. 2020; 49 (2):301-310.

Chicago/Turabian Style

Boluwatife M. OlaOlorun; Hussein Shimelis; Mark Laing; Isack Mathew. 2020. "Morphological variations of wheat (Triticum aestivum L. em. Thell.) under variable ethyl methanesulphonate mutagenesis." Cereal Research Communications 49, no. 2: 301-310.

Journal article
Published: 18 September 2020 in BMC Genetics
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Background Productivity of cowpea [Vigna unguiculata(L.)Walp] in sub-Sahara Africa is curtailed by a lack of farmer-preferred and improved cultivars and modern production technologies. The objectives of the study were to determine the extent of genetic diversity present among a collection of cowpea accessions from Zambia and Malawi using phenotypic traits and single nucleotide polymorphism (SNP) markers and, to select distinct and complementary parental lines for cultivar development. One hundred cowpea genotypes were evaluated for agronomic traits in two selected sites in Zambia, using a 10 × 10 alpha lattice design with two replications. Ninety-four of the test genotypes were profiled with 14,116 SNP markers. Results Number of pods plant− 1(NPP), pod length (PDL), and number of seeds pod− 1(NSP), were significantly (p < 0.05) affected by genotype × environment interaction effects. Genotypes such as CP411, CP421, CP645, CP732, Chimponongo, and MS1–8–1-4 exhibited higher grain yield of > 1200 kg/ha with excellent performance in yield components such as NSP, PDL, HSW and GYD. Grain yield had significant (p < 0.05) associations with NPP (r = 0.50), NSP (r = 0.46) and PDL (r = 0.42) useful for simultaneous selection for yield improvement in cowpea. The SNP markers revealed gene diversity and polymorphic information content of 0.22 and 0.17, respectively, showing that the tested cowpea accessions were genetically diverse. Test genotypes were classified into four genetic groups irrespective of source of collection allowing selection and subsequent crosses to develop breeding populations for cultivar development. Conclusions Genotypes Bubebe, CP411, CP421, CP645, Chimponogo and MS1–8–1-4 were identified to be the most genetically divergent and high yielding making them ideal parental lines for breeding. This study provided a baseline information and identified promising cowpea genetic resources for effective breeding and systematic conservation.

ACS Style

Nelia Nkhoma; Hussein Shimelis; Mark D. Laing; Admire Shayanowako; Isack Mathew. Assessing the genetic diversity of cowpea [Vigna unguiculata (L.) Walp.] germplasm collections using phenotypic traits and SNP markers. BMC Genetics 2020, 21, 1 -16.

AMA Style

Nelia Nkhoma, Hussein Shimelis, Mark D. Laing, Admire Shayanowako, Isack Mathew. Assessing the genetic diversity of cowpea [Vigna unguiculata (L.) Walp.] germplasm collections using phenotypic traits and SNP markers. BMC Genetics. 2020; 21 (1):1-16.

Chicago/Turabian Style

Nelia Nkhoma; Hussein Shimelis; Mark D. Laing; Admire Shayanowako; Isack Mathew. 2020. "Assessing the genetic diversity of cowpea [Vigna unguiculata (L.) Walp.] germplasm collections using phenotypic traits and SNP markers." BMC Genetics 21, no. 1: 1-16.

Preprint content
Published: 13 August 2020
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Background: Productivity of cowpea [Vigna unguiculata (L.) Walp] in sub-Sahara Africa is curtailed by a lack of farmer-preferred and improved cultivars and modern production technologies. The objectives of the study were to determine the extent of genetic diversity present among a collection of cowpea accessions from Zambia and Malawi using phenotypic traits and single nucleotide polymorphism (SNP) markers and, to select distinct and complementary parental lines for cultivar development. One hundred cowpea genotypes were evaluated for agronomic traits in two selected sites in Zambia, using a 10×10 alpha lattice design with two replications. Ninety-four of the test genotypes were profiled with 14,116 SNP markers. Results: Number of pods plant-1 (NPP), pod length (PDL), and number of seeds pod-1 (NSP), were significantly (p 1200 kg/ha with excellent performance in yield components such as NSP, PDL, HSW and GYD. Grain yield had significant (p (r=0.50), NSP (r=0.46) and PDL (r=0.42) useful for simultaneous selection for yield improvement in cowpea. The SNP markers revealed gene diversity and polymorphic information content of 0.22 and 0.17, respectively, showing that the tested cowpea accessions were genetically diverse. Test genotypes were classified into four genetic groups irrespective of source of collection allowing selection and subsequent crosses to develop breeding populations for cultivar development. Conclusions: Genotypes Bubebe, CP411, CP421, CP645, Chimponogo and MS1-8-1-4 were identified to be the most genetically divergent and high yielding making them ideal parental lines for breeding. This study provided a baseline information and identified promising cowpea genetic resources for effective breeding and systematic conservation.

ACS Style

Nelia Nkhoma; Hussein Shimelis; Mark Laing; Admire Shayanowako; Isack Mathew. Assessing the genetic diversity of cowpea [Vigna unguiculata (L.) Walp.] germplasm collections using phenotypic traits and SNP markers. 2020, 1 .

AMA Style

Nelia Nkhoma, Hussein Shimelis, Mark Laing, Admire Shayanowako, Isack Mathew. Assessing the genetic diversity of cowpea [Vigna unguiculata (L.) Walp.] germplasm collections using phenotypic traits and SNP markers. . 2020; ():1.

Chicago/Turabian Style

Nelia Nkhoma; Hussein Shimelis; Mark Laing; Admire Shayanowako; Isack Mathew. 2020. "Assessing the genetic diversity of cowpea [Vigna unguiculata (L.) Walp.] germplasm collections using phenotypic traits and SNP markers." , no. : 1.

Articles
Published: 01 June 2020 in Acta Agriculturae Scandinavica, Section B — Soil & Plant Science
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Drought is a major factor threatening crop production worldwide. Developing wheat varieties that are adapted to drought prone environments is a sustainable strategy to improve wheat production and productivity. The aim of this study was to evaluate and select bread wheat genotypes for yield and yield components, and for stability under drought stress and non-stress conditions. One hundred and twenty genotypes were evaluated at five test sites in the 2018/19 cropping season using a 10 x 12 alpha lattice design with two replicates. The level of drought stress was imposed using different sowing dates (early planting representing non-stressed, while late planting as drought stressed conditions) following the onset of the main rain at each site. Grain yield and yield components were recorded, and drought indices were calculated for each genotype. Among the drought tolerance indices, GMP, MP, HM, STI and YI were found to be the most suitable for predicting drought tolerance because they had significant and positive correlations with yield under drought stress and non-stress conditions. Rank sum analysis identified the most drought tolerant genotypes as ‘YS-34', ‘YS-85' and ‘YS-82’. The selected wheat genotypes are useful genetic resources for future drought tolerance breeding programmes in Ethiopia or similar agro-ecologies.

ACS Style

Yared Semahegn; Hussein Shimelis; Mark Laing; Isack Mathew. Evaluation of bread wheat (Triticum aestivum L.) genotypes for yield and related traits under drought stress conditions. Acta Agriculturae Scandinavica, Section B — Soil & Plant Science 2020, 70, 474 -484.

AMA Style

Yared Semahegn, Hussein Shimelis, Mark Laing, Isack Mathew. Evaluation of bread wheat (Triticum aestivum L.) genotypes for yield and related traits under drought stress conditions. Acta Agriculturae Scandinavica, Section B — Soil & Plant Science. 2020; 70 (6):474-484.

Chicago/Turabian Style

Yared Semahegn; Hussein Shimelis; Mark Laing; Isack Mathew. 2020. "Evaluation of bread wheat (Triticum aestivum L.) genotypes for yield and related traits under drought stress conditions." Acta Agriculturae Scandinavica, Section B — Soil & Plant Science 70, no. 6: 474-484.

Preprint content
Published: 26 May 2020
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Background Productivity of cowpea [Vigna unguiculata (L.) Walp] in sub-Sahara Africa is curtailed by a lack of farmer-preferred and improved cultivars and modern production technologies. The objectives of the study were to determine the extent of genetic diversity present among a collection of cowpea accessions from Zambia and Malawi using phenotypic traits and single nucleotide polymorphism (SNP) markers and, to select distinct and complementary parental lines for cultivar development. One hundred cowpea genotypes were evaluated for agronomic traits in two selected sites in Zambia, using a 10 × 10 alpha lattice design with two replications. Ninety-four of the test genotypes were profiled with 14,116 SNP markers. Results Number of pods plant− 1 (NPP), pod length (PDL), and number of seeds pod− 1 (NSP), were significantly (p < 0.05) affected by genotype × environment interaction effects. Genotypes such as CP411, CP421, CP645, CP732, Chimponongo, and MS1-8-1-4 exhibited higher grain yield of > 1200 kg/ha with excellent performance in yield components such as NSP, PDL, HSW and GYD. Grain yield had significant (p < 0.05) associations with NPP (r = 0.50), NSP (r = 0.46) and PDL (r = 0.42) useful for simultaneous selection for yield improvement in cowpea. The SNP markers revealed gene diversity and polymorphic information content of 0.22 and 0.17, respectively, showing that the tested cowpea accessions were genetically diverse. Test genotypes were classified into four genetic groups irrespective of source of collection allowing selection and subsequent crosses to develop breeding populations for cultivar development. Conclusions Genotypes Bubebe, CP411, CP421, CP645, Chimponogo and MS1-8-1-4 were identified to be the most genetically divergent and high yielding making them ideal parental lines for breeding. This study provided a baseline information and identified promising cowpea genetic resources for effective breeding and systematic conservation.

ACS Style

Nelia Nkhoma; Hussein Shimelis; Mark Laing; Admire Shayanowako; Isack Mathew. Assessing the genetic diversity of cowpea [Vigna unguiculata (L.) Walp.] germplasm collections using phenotypic traits and SNP markers. 2020, 1 .

AMA Style

Nelia Nkhoma, Hussein Shimelis, Mark Laing, Admire Shayanowako, Isack Mathew. Assessing the genetic diversity of cowpea [Vigna unguiculata (L.) Walp.] germplasm collections using phenotypic traits and SNP markers. . 2020; ():1.

Chicago/Turabian Style

Nelia Nkhoma; Hussein Shimelis; Mark Laing; Admire Shayanowako; Isack Mathew. 2020. "Assessing the genetic diversity of cowpea [Vigna unguiculata (L.) Walp.] germplasm collections using phenotypic traits and SNP markers." , no. : 1.

Online first articles
Published: 26 May 2020 in South African Journal of Plant and Soil
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Systematic genetic profiling of the genetic pool is fundamental to select desirable parents for conventional and genomic-assisted breeding. The objective of this study was to assess genetic variation and population structure in a diverse population of sorghum accessions collected from various regions of Ethiopia. Using single nucleotide polymorphism (SNP) markers, potential breeding parents were then selected. In all, 342 sorghum accessions were genotyped using diversity array technology sequence-derived 5060 SNPs with > 5% minor allele frequency. Population structure, clustering, PCA, and analysis of molecular variance (AMOVA) were conducted to deduce variability within the germplasm. The AMOVA results revealed a higher percentage (58.8%) of variation among the populations followed by variation within accessions (40.4%). Polymorphic information content (PIC) values ranged from 0.184 for accessions collected from the Somali to 0.260 for the Oromia and Southern Nations, Nationalities, and Peoples (SNNP) regions. Higher genetic variation was detected among sorghum collections from Oromia followed by those of the SNNP region. The selected SNP markers were the most powerful in discriminating the tested sorghum accessions. Population structure analysis revealed the presence of two main distinct genetic clusters in which accessions were grouped based on area of collection. The present findings indicated abundant genetic variability among Ethiopian sorghum accessions, confirming that they will be useful for breeding, germplasm conservation and genomic selection.

ACS Style

Girma Mengistu; Hussein Shimelis; Mark Laing; Dagnachew Lule; Ermias Assefa; Isack Mathew. Genetic diversity assessment of sorghum (Sorghum bicolor (L.) Moench) landraces using SNP markers. South African Journal of Plant and Soil 2020, 37, 220 -226.

AMA Style

Girma Mengistu, Hussein Shimelis, Mark Laing, Dagnachew Lule, Ermias Assefa, Isack Mathew. Genetic diversity assessment of sorghum (Sorghum bicolor (L.) Moench) landraces using SNP markers. South African Journal of Plant and Soil. 2020; 37 (3):220-226.

Chicago/Turabian Style

Girma Mengistu; Hussein Shimelis; Mark Laing; Dagnachew Lule; Ermias Assefa; Isack Mathew. 2020. "Genetic diversity assessment of sorghum (Sorghum bicolor (L.) Moench) landraces using SNP markers." South African Journal of Plant and Soil 37, no. 3: 220-226.

Journal article
Published: 19 May 2020 in Crop Protection
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The fall armyworm (FAW) (Spodoptera frugiperda J.E. Smith) is a major cause of crop loss and food insecurity in sub-Saharan Africa. There is a need to identify maize genetic resources with FAW resistance for breeding. The objectives of this study were to screen two sets of diverse maize germplasm and to select genotypes with FAW resistance and desirable yield-related traits. Set I and Set II, containing 60 and 253 maize genotypes, respectively, were selected based on their agronomic potential and adaptability for screening in FAW infested areas in Zambia. Highly significant differences (P < 0.001) were detected among the test genotypes for FAW-leaf damage (FLD) and FAW cob damage (FCD) and agronomic traits. The lowest FLD and FCD were 8.87% and 5.36%, recorded in genotypes CML304-B and CML442, respectively. Five principal components (PCs) accounted for ≥80% of the total variation showing that key traits included reduced anthesis-silking interval (ASI), plant height, FLD and FCD, desirable ear aspect and grain yield. Some genotypes, such as Pool 16 and ZM7114 from Set I, and CZL1310c, CML444-B, CZL15220 and TL1512847 from Set II had low mean FCD and FLD, showing that they were potential sources of FAW resistance. Grain yield was negatively correlated with mean FLD (r = −0.18, p < 0.05), and FCD (r = −0.15, p < 0.05). Promising maize genotypes including CZL1310c, CML444-B, CZL15220, TL1512847 and CML491 were selected for their low mean FLD, FCD, earliness to flowering and high grain yield potential. These genotypes will be useful in developing tropical and sub-tropical maize breeding populations with partial FAW resistance and yield gains.

ACS Style

Chapwa Kasoma; Hussein Shimelis; Mark Laing; Admire I.T. Shayanowako; Isack Mathew. Screening of inbred lines of tropical maize for resistance to fall armyworm, and for yield and yield-related traits. Crop Protection 2020, 136, 105218 .

AMA Style

Chapwa Kasoma, Hussein Shimelis, Mark Laing, Admire I.T. Shayanowako, Isack Mathew. Screening of inbred lines of tropical maize for resistance to fall armyworm, and for yield and yield-related traits. Crop Protection. 2020; 136 ():105218.

Chicago/Turabian Style

Chapwa Kasoma; Hussein Shimelis; Mark Laing; Admire I.T. Shayanowako; Isack Mathew. 2020. "Screening of inbred lines of tropical maize for resistance to fall armyworm, and for yield and yield-related traits." Crop Protection 136, no. : 105218.

Article
Published: 06 May 2020 in Euphytica
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Agronomic performance of maize is subject to genotype-by-environment interaction (GEI), necessitating multi-environment evaluation to identify superior genotypes. The objectives of this study were to evaluate the adaptation range of hybrids developed from crossing tropical with temperate maize lines for improving yield stability and select hybrids with broad and specific adaptation in five sites across South Africa and Zimbabwe. One hundred and seventeen genotypes were evaluated using a 9 × 13 alpha lattice design with two replications. The additive main effects and multiplicative interaction (AMMI) analysis showed that effects of genotypes (G), environments (E) and their interaction (GEI) on grain yield were significant (p ≤ 0.001). The G and GEI effects accounted for 36.67% of the total variation. Hybrids 18C2542 (mean grain yield 6.12 t/ha), SC727 (7.05 t/ha), SC410 (5.16 t/ha), and 18C2572 (7.55 t/ha) were identified as superior for Potchefstroom, Panmure, Rattray Arnold Research Stations and the AU-DRS mega-environment, respectively. Hybrids 18C2550 (mean grain yield 7.24 t/ha), 18C2578 (7.42 t/ha), 18C2538 (7.12 t/ha) and 18C2546 (7.39 t/ha) exhibited high grain yield and broad stability.t The Africa University (AU) site in Zimbabwe and Dundee Research Station (DRS) in South Africa were clustered in one mega-environment, indicating that they were correlated. The study reveals that hybrids generated from temperate × tropical inbred lines could be useful for replacing currently used poor performing commercial hybrids. The hybrids 18C2545, 18C2577, 18C2578, 18C2546, 18C2550, 18C2579, 18C2535 and 18C2572 exhibited superiority over commercial hybrids and were recommended for further yield tests and cultivar replacement.

ACS Style

Malven Mushayi; Hussein Shimelis; John Derera; Admire I. T. Shayanowako; Isack Mathew. Multi-environmental evaluation of maize hybrids developed from tropical and temperate lines. Euphytica 2020, 216, 1 -14.

AMA Style

Malven Mushayi, Hussein Shimelis, John Derera, Admire I. T. Shayanowako, Isack Mathew. Multi-environmental evaluation of maize hybrids developed from tropical and temperate lines. Euphytica. 2020; 216 (5):1-14.

Chicago/Turabian Style

Malven Mushayi; Hussein Shimelis; John Derera; Admire I. T. Shayanowako; Isack Mathew. 2020. "Multi-environmental evaluation of maize hybrids developed from tropical and temperate lines." Euphytica 216, no. 5: 1-14.

Research article
Published: 04 December 2019 in PLOS ONE
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Genome wide association studies (GWAS) are important in discerning the genetic architecture of complex traits such as biomass allocation for improving drought tolerance and carbon sequestration potential of wheat. The objectives of this study were to deduce the population structure and marker-trait association for biomass traits in wheat under drought-stressed and non-stressed conditions. A 100-wheat (Triticum aestivum L.) genotype panel was phenotyped for days to heading (DTH), days to maturity (DTM), shoot biomass (SB), root biomass (RB), root to shoot ratio (RS) and grain yield (GY). The panel was sequenced using 15,600 single nucleotide polymorphism (SNPs) markers and subjected to genetic analysis using the compressed mixed linear model (CMLM) at false discovery rate (FDR < 0.05). Population structure analysis revealed six sub-clusters with high membership ancestry coefficient of ≤0.65 to their assigned sub-clusters. A total of 75 significant marker-trait associations (MTAs) were identified with a linkage disequilibrium threshold of 0.38 at 5cM. Thirty-seven of the MTAs were detected under drought-stressed condition and 48% were on the B genome, where most quantitative trait loci (QTLs) for RB, SB and GY were previously identified. There were seven pleiotropic markers for RB and SB that may facilitate simultaneous selection. Thirty-seven putative candidate genes were mined by gene annotation on the IWGSC RefSeq 1.1. The significant MTAs observed in this study will be useful in devising strategies for marker-assisted breeding for simultaneous improvement of drought tolerance and to enhance C sequestration capacity of wheat.

ACS Style

Isack Mathew; Hussein Shimelis; Admire Isaac Tichafa Shayanowako; Mark Laing; Vincent Chaplot. Genome-wide association study of drought tolerance and biomass allocation in wheat. PLOS ONE 2019, 14, e0225383 .

AMA Style

Isack Mathew, Hussein Shimelis, Admire Isaac Tichafa Shayanowako, Mark Laing, Vincent Chaplot. Genome-wide association study of drought tolerance and biomass allocation in wheat. PLOS ONE. 2019; 14 (12):e0225383.

Chicago/Turabian Style

Isack Mathew; Hussein Shimelis; Admire Isaac Tichafa Shayanowako; Mark Laing; Vincent Chaplot. 2019. "Genome-wide association study of drought tolerance and biomass allocation in wheat." PLOS ONE 14, no. 12: e0225383.

Review
Published: 28 November 2019 in Journal of Crop Improvement
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Reliable and effective hybridization methods are required in self-pollinating crops for genetic analysis, recurrent selection and large-scale production of hybrid seed. The objective of this review was to document the different methodologies available for hybrid seed production in predominantly self-pollinating crops. Various methods have been used for hybrid seed production, each with its own advantages and limitations. To obtain a limited quantity of hybrid seed, mechanical emasculation combined with hand pollination remain the most widely used technique. However, these methods are labor-intensive and expensive when a continuous supply of large quantities of hybrid seed is required. Genetic male-sterility systems provide opportunities for large-scale hybrid seed production. However, the occurrence of natural male sterility is rare, and when available, it may not always provide compatible combinations with desirable agronomic attributes. Temporal male sterility can be achieved by the application of chemical hybridizing agents (CHAs), which render the pollen non-viable but maintain female fertility. CHAs hold promise for hybrid seed production because they are easy to use, particularly for field crops that are predominantly self-fertilizing. The cost and variable response of different crops and genotypes to various concentrations of CHAs present technical challenges for their widespread adoption. The choice of crossing method in each breeding program is influenced by the amount of seed required, crop species, level of technical expertise required, availability of cytoplasmic male-sterile lines and access to cheap and effective CHAs. This review provides guidance to plant breeders and seed producers in selecting a suitable crossing method for hybrid seed production in self-pollinating crops.

ACS Style

Muhammad Ahmad Yahaya; Hussein Shimelis; Mark Laing; Mohammed Sagir Mohammed; Isack Mathew. Methodologies for hybridization in predominantly self-pollinating crops: a review. Journal of Crop Improvement 2019, 34, 268 -289.

AMA Style

Muhammad Ahmad Yahaya, Hussein Shimelis, Mark Laing, Mohammed Sagir Mohammed, Isack Mathew. Methodologies for hybridization in predominantly self-pollinating crops: a review. Journal of Crop Improvement. 2019; 34 (2):268-289.

Chicago/Turabian Style

Muhammad Ahmad Yahaya; Hussein Shimelis; Mark Laing; Mohammed Sagir Mohammed; Isack Mathew. 2019. "Methodologies for hybridization in predominantly self-pollinating crops: a review." Journal of Crop Improvement 34, no. 2: 268-289.

Articles
Published: 30 September 2019 in Acta Agriculturae Scandinavica, Section B — Soil & Plant Science
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Genetic diversity is a pre-requisite for rice (Oryza sativa L.) breeding and population development. Hence, the objective of this study was to assess the genetic diversity and population structure of 54 rice accessions using 14 polymorphic simple sequence repeats (SSR) markers to select unique parents for breeding. Data analysis was based on marker and population genetic parameters. The mean polymorphic information content (PIC) was 0.61 suggesting high polymorphisms for the selected SSR markers among the rice accessions. The population structure revealed a narrow genetic base with only two major sub-populations. Analysis of molecular variance revealed that only 30% of the variation was attributed to population differences while 47% and 23% were due to variation among individuals within populations and within individual variation, respectively. The genetic distance and identity among genotypes varied from 0.083 to 1.834 and 0.159 to 0.921, respectively. Dendrogram grouped the genotypes into three clusters with wide variation among the accessions. The study established the existence of considerable genetic diversity among the tested 54 accessions. The selected genetic resources will be useful resources for rice breeding in Tanzania or other African countries.

ACS Style

William Titus Suvi; Hussein Shimelis; Mark Laing; Isack Mathew; Admire Isaac Tichafa Shayanowako. Assessment of the genetic diversity and population structure of rice genotypes using SSR markers. Acta Agriculturae Scandinavica, Section B — Soil & Plant Science 2019, 70, 76 -86.

AMA Style

William Titus Suvi, Hussein Shimelis, Mark Laing, Isack Mathew, Admire Isaac Tichafa Shayanowako. Assessment of the genetic diversity and population structure of rice genotypes using SSR markers. Acta Agriculturae Scandinavica, Section B — Soil & Plant Science. 2019; 70 (1):76-86.

Chicago/Turabian Style

William Titus Suvi; Hussein Shimelis; Mark Laing; Isack Mathew; Admire Isaac Tichafa Shayanowako. 2019. "Assessment of the genetic diversity and population structure of rice genotypes using SSR markers." Acta Agriculturae Scandinavica, Section B — Soil & Plant Science 70, no. 1: 76-86.