SUMMARY: The phenotypic analysis of root system growth is important to inform efforts to enhance plant resource acquisition from soils; however, root phenotyping remains challenging because of the opacity of soil, requiring systems that facilitate root system visibility and image acquisition. Previously reported systems require costly or bespoke materials not available in most countries, where breeders need tools to select varieties best adapted to local soils and field conditions. Here, we report an affordable soil‐based growth (rhizobox) and imaging system to phenotype root development in glasshouses or shelters. All components of the system are made from locally available commodity components, facilitating the adoption of this affordable technology in low‐income countries. The rhizobox is large enough (approximately 6000 cm2 of visible soil) to avoid restricting vertical root system growth for most if not all of the life cycle, yet light enough (approximately 21 kg when filled with soil) for routine handling. Support structures and an imaging station, with five cameras covering the whole soil surface, complement the rhizoboxes. Images are acquired via the Phenotiki sensor interface, collected, stitched and analysed. Root system architecture (RSA) parameters are quantified without intervention. The RSAs of a dicot species (Cicer arietinum, chickpea) and a monocot species (Hordeum vulgare, barley), exhibiting contrasting root systems, were analysed. Insights into root system dynamics during vegetative and reproductive stages of the chickpea life cycle were obtained. This affordable system is relevant for efforts in Ethiopia and other low‐ and middle‐income countries to enhance crop yields and climate resilience sustainably.
Chickpea is a nutrition-rich, cropping-system friendly, climate-resilient, and low-cost production crop. It has large economic potential in the sub-Saharan Africa (SSA) region, where it currently accounts for only approximately half a million hectares of the approximately 12 million hectares of total chickpea production land worldwide. This review highlights the opportunities for promoting chickpea production and marketing to tap the vast economic potential in SSA. The region can potentially produce chickpea on approximately 10 million hectares, possibly doubling the global production, and the region could become one of the highest consumption geographies of this healthy crop. Chickpea could easily be integrated into existing cropping systems including rice-fallows and cereal monocropping systems. Successful cases studies of the crop in the region are highlighted. The region could tap into the potential at scale through intervention in the agricultural policy environment and development and promotion of improved chickpea production technologies supported by well-organized extension services and sustainable seed systems. These interventions could be complemented with value addition and product quality improvementsÍ for SSA chickpea to benefit from high-value markets.
26 June 2023 in Proceedings of the National Academy of Sciences
Understanding the origins of variation in agricultural pathogens is of fundamental interest and practical importance, especially for diseases that threaten food security. Fusarium oxysporum is among the most important of soil-borne pathogens, with a global distribution and an extensive host range. The pathogen is considered to be asexual, with horizontal transfer of chromosomes providing an analog of assortment by meiotic recombination. Here, we challenge those assumptions based on the results of population genomic analyses, describing the pathogen’s diversity and inferring its origins and functional consequences in the context of a single, long-standing agricultural system. We identify simultaneously low nucleotide distance among strains, and unexpectedly high levels of genetic and genomic variability. We determine that these features arise from a combination of genome-scale recombination, best explained by widespread sexual reproduction, and presence–absence variation consistent with chromosomal rearrangement. Pangenome analyses document an accessory genome more than twice the size of the core genome, with contrasting evolutionary dynamics. The core genome is stable, with low diversity and high genetic differentiation across geographic space, while the accessory genome is paradoxically more diverse and unstable but with lower genetic differentiation and hallmarks of contemporary gene flow at local scales. We suggest a model in which episodic sexual reproduction generates haplotypes that are selected and then maintained through clone-like dynamics, followed by contemporary genomic rearrangements that reassort the accessory genome among sympatric strains. Taken together, these processes contribute unique genome content, including reassortment of virulence determinants that may explain observed variation in pathogenic potential.
21 January 2022 in Agrosystems, Geosciences & Environment
Chickpea (Cicer arietinum L.) is an economically important crop grown by nearly one million Ethiopian smallholder farmers. The crop is often considered as “stress‐loving,” but moisture stress at flowering and grain filling stages could be detrimental. Yield of chickpea is commonly affected by terminal drought stress in the rainfed production system in Ethiopia. The lack of proper field‐screening methods has hindered the development of drought‐tolerant varieties. This study demonstrates a simple and practical field‐level screening method for drought tolerance traits in the conventional breeding programs. A field experiment was conducted using 28 elite chickpea cultivars during the 2018–2019 main cropping season to study their response to moisture regimes of varying drought intensities. We used yield and its components as proxy parameters of screening to select tolerant cultivars. The study revealed significant variation among the cultivars in their response to different moisture regimes. The kabuli cultivars were found more sensitive compared with the desi types. Yield penalty exceeded 70% under severe drought. Conversely, cultivars tested under mild and severe stress drought showed average yield gain of 22 and 48%, respectively, relative to the irrigated treatment. Overall, over 50% yield gain can be obtained in drought‐affected rainfed production areas in Ethiopia using supplemental irrigation during pod setting to grain filling stages. For post‐rainy‐season crops relying on residual soil moisture, such as chickpea, breeding for shorter duration and resilient cultivars are reliable management approaches to minimize drought‐caused yield losses.
Chickpea (Cicer arietinum L.) is a cheap source of protein and rich in minerals for people living in developing countries. In order to assess the existing molecular genetic diversity and determine population structures in selected Ethiopian chickpea germplasm accessions (118), a set of 46 simple sequence repeat (SSR) markers equally distributed on the chickpea genome were genotyped. A total of 572 alleles were detected from 46 SSR markers, and the number of alleles per locus varied from 2 (ICCM0289) to 28 (TA22). The average number of alleles per locus, polymorphism information content, and expected heterozygosity were 12, 0.684, and 0.699, respectively. Phylogenetic analysis grouped the 118 chickpea genotypes from diverse sources into three evolutionary and/or biological groups (improved desi, improved kabuli, and landraces). The population structure analysis revealed six sub-populations from 118 chickpea genotypes studied. AMOVA revealed that 57%, 29%, and 14% of the total genetic variations were observed among individuals, within populations, and among populations. The insights into the genetic diversity at molecular levels in the Ethiopian germplasm lines can be used for designing conservation strategies as well as the diverse germplasm lines identified in this study can be used for trait dissection and trait improvement.