Faye, J. M. | Search bioRxiv

bioRxiv2021

Quantitative and population genomics suggest a broad role of staygreen loci in the drought adaptation of sorghum

O_LIDrought is a major constraint on plant productivity globally. Sorghum (Sorghum bicolor) landraces have evolved in drought-prone regions, but the genetics of their adaptation is not yet understood. Loci underlying stay-green post-flowering drought tolerance (Stg), have been identified in a temperate breeding line, but their role in drought adaptation of tropical sorghum is to be elucidated. C_LIO_LIWe phenotyped 590 diverse sorghum accessions from West Africa under field-based managed drought stress, pre-flowering (WS1) and post-flowering (WS2) over several years and conducted genome-wide association studies (GWAS). C_LIO_LIBroad-sense heritability for grain and biomass yield components was high (33-92%) across environments. There was a significant correlation between stress tolerance index (STI) for grain weight across WS1 and WS2. GWAS revealed that SbZfl1 and SbCN12, orthologs of maize flowering genes, likely underlie flowering time variation under these conditions. GWAS further identified associations (n = 134) for STI and drought effects on yield components, including 16 putative pleiotropic associations. Thirty of the associations colocalized with Stg1-4 loci and had large effects. Seven lead associations, including some within Stg1, overlapped with positive selection outliers. C_LIO_LIOur findings reveal natural genetic variation for drought tolerance-related traits, and suggest a broad role of Stg loci in drought adaptation of sorghum. C_LI

plant biology↗

bioRxiv2020

A Genomics Resource for Genetics, Physiology, and Breeding of West African Sorghum

Local landrace and breeding germplasm is a useful source of genetic diversity for regional and global crop improvement initiatives. Sorghum (Sorghum bicolor L. Moench) in West Africa has diversified across a mosaic of cultures and end-uses, and along steep precipitation and photoperiod gradients. To facilitate germplasm utilization, a West African sorghum association panel (WASAP) of 756 accessions from national breeding programs of Niger, Mali, Senegal, and Togo was assembled and characterized. Genotyping-by-sequencing was used to generate 159,101 high-quality biallelic SNPs, with 43% in intergenic regions and 13% in genic regions. High genetic diversity was observed within the WASAP ({pi} = 0.00045), only slightly less than in a global diversity panel ({pi} = 0.00055). Linkage disequilibrium decayed to background level (r2 < 0.1) by ~50 kb in the WASAP. Genome-wide diversity was structured both by botanical type, and by populations within botanical type, with eight ancestral populations identified. Most populations were distributed across multiple countries, suggesting several potential common gene pools across the national programs. Genome-wide association studies of days to flowering and plant height revealed eight and three significant quantitative trait loci (QTL), respectively, with major height QTL at canonical height loci Dw3 and SbHT7.1. Colocalization of two of eight major flowering time QTL with flowering genes previously described in US germplasm (Ma6 and SbCN8) suggests that photoperiodic flowering in WA sorghum is conditioned by both known and novel genes. This genomic resource provides a foundation for genomics-enabled breeding of climate-resilient varieties in West Africa.

genomics↗