Sorghum is an important staple food crop in drought prone areas of Sub-Saharan Africa, which is characterized by erratic rainfall with poor distribution. Sorghum is a drought-tolerant crop by nature with reasonable yield compared to other cereal crops, but such abiotic stress adversely affects the productivity. Some sorghum varieties maintain green functional leaves under post-anthesis drought stress referred to as stay-green, which makes it an important crop for food and nutritional security. Notwithstanding, it is difficult to maintain consistency of tolerance over time due to climate change, which is caused by human activities. Drought in sorghum is addressed by several approaches, for instance, breeding drought-tolerant sorghum using conventional and molecular technologies. The challenge with conventional methods is that they depend on phenotyping stay-green, which is complex in sorghum, as it is constituted by multiple genes and environmental effects. Marker assisted selection, which involves the use of DNA molecular markers to map QTL associated with stay-green, has been useful to supplement stay-green improvement in sorghum. It involves QTL mapping associated with the stay-green trait for introgression into the senescent sorghum varieties through marker-assisted backcrossing by comparing with phenotypic field data. Therefore, this review discusses mechanisms of drought tolerance in sorghum focusing on physiological, morphological, and biochemical traits. In addition, the review discusses the application of marker-assisted selection techniques, including marker-assisted backcrossing, QTL mapping, and QTL pyramiding for addressing post-flowering drought in sorghum.

In cucurbits, CmWIP1 is a master gene controlling sex determination. To bring new insight in the function of CmWIP1, we investigated two Arabidopsis WIP transcription factors, AtWIP1/TT1 and AtWIP2/NTT. Using an inducible system we showed that WIPs are powerful inhibitor of growth and inducer of cell death. Using ChIP-seq and RNA-seq we revealed that most of the up-regulated genes bound by WIPs display a W-box motif, associated with stress signaling. In contrast, the down-regulated genes contain a GAGA motif, a known target of polycomb repressive complex. To validate the role of WIP proteins in inhibition of growth, we expressed AtWIP1/TT1 in carpel primordia and obtained male flowers, mimicking CmWIP1 function in melon. Using other promoters, we further demonstrated that WIPs can trigger growth arrest of both vegetative and reproductive organs. Our data supports an evolutionary conserved role of WIPs in recruiting gene networks controlling growth and adaptation to stress.

Sorghum is an important food crop for people in drought-prone areas of the world. The production in Tanzania has been ≤1 t ha⁻¹ for a decade. The study was conducted in Iramba, Ikungi, and Kongwa districts to identify factors influencing the sorghum production, adoption rate, and strategies to address drought in Tanzania. The study involved 240 respondents for individual interviews and focus group discussions. Thirty respondents participated in individual interviews while ten farmers participated in the focus group discussion per village. Our study found that birds, poor soil fertility, and drought were the major constraints across the study districts. Drought tolerance, high yield, and early maturity were the most preferred traits by farmers across the study areas. Farmers addressed drought stress in sorghum by practicing early planting early maturing varieties in November and using drought-tolerant varieties. However, most farmers failed to name the diseases and pests affecting sorghum. This study highlights basic information for plant breeders to incorporate traits preferred by farmers in breeding programs when developing new sorghum varieties for sustainable production. The study shows the importance of involving farmers to identify the problems and solutions of sorghum production to increase the adoption rate.

Sorghum is a major staple food crop for the people in semi-arid areas of Africa and Asia. Post-flowering drought is a global constraint of sorghum production. The study aimed to improve stay-green (STG) characteristics of farmer-preferred sorghum varieties in Tanzania using marker-assisted backcrossing. A total of 752 individuals representing five BC₂F₁ populations and their parents were genotyped using previously reported KASP markers linked with STG 3A and STG 3B quantitative trait loci (QTL). In the BC₂F₁ populations, the maximum number of individuals with heterozygous alleles were observed in S35*Pato background (37) whereas only seven individuals derived from the B35*Wahi parents’ background contained heterozygous alleles. Of the 30 single nucleotide polymorphism (SNP) markers, favourable alleles were observed at 18 loci in BC₂F₁ populations. In the BC₂F₁ generation, the highest (0.127 kg/panicle) grain yield was observed in the B35*NACO Mtama 1 background population. The genotypic analysis revealed the presence of favourable alleles in homozygous conditions at markers loci associated with STG 3A and STG 3B QTLs in BC₂F₃ populations, suggesting successful introgression of STG QTLs from the donor parents to the recurrent parents. Across water irrigation regimes, the highest (0.068 kg/panicle) mean grain weight was observed in the genotype NA316C. Therefore, our study demonstrated the utility of marker-assisted backcrossing for drought tolerance improvement of locally adapted sorghum varieties in Africa.

In angiosperms, sex determination leads to development of unisexual flowers. In Cucumis melo, development of unisexual male flowers results from the expression of the sex determination gene, CmWIP1, in carpel primordia. To bring new insight on the molecular mechanisms through which CmWIP1 leads to carpel abortion in male flowers, we used the yeast two-hybrid approach to look for CmWIP1-interacting proteins. We found that CmWIP1 physically interacts with an S2 bZIP transcription factor, CmbZIP48. We further determined the region mediating the interaction and showed that it involves the N-terminal part of CmWIP1. Using laser capture microdissection coupled with quantitative real-time gene expression analysis, we demonstrated that CmWIP1 and CmbZIP48 share a similar spatiotemporal expression pattern, providing the plant organ context for the CmWIP1-CmbZIP48 protein interaction. Using sex transition mutants, we demonstrated that the expression of the male promoting gene CmWIP1 correlates with the expression of CmbZIP48. Altogether, our data support a model in which the coexpression and the physical interaction of CmWIP1 and CmbZIP48 trigger carpel primordia abortion, leading to the development of unisexual male flowers.