Kehel, Z. | bioRxiv Science

bioRxiv2023

Genomic regions of durum wheat involved in water productivity.

Durum wheat is a staple food of the Mediterranean Basin, mostly cultivated under rainfed conditions. As such, the crop is often exposed to moisture stress. Therefore, the identification of genetic factors controlling the capacity of genotypes to convert moisture into grain yield (i.e. water productivity) is quintessential to stabilize production despite climatic variations. A global panel of 384 accessions was tested across eighteen Mediterranean environments (Morocco, Lebanon, and Jordan) representing a vast range of moisture levels. The accessions were assigned to water responsiveness classes, with genotypes Responsive to Low Moisture reaching an average + 1.5 kg ha-1 mm-1 advantage. Genome wide association studies (GWAS) revealed that six loci explained the majority of this variation. A second validation panel tested under moisture stress confirmed that carrying the positive allele at three loci on chromosomes 1B, 2A and 7B generated an average water productivity gain of + 2.2 kg ha-1 mm-1. Interestingly, loci on chromosome 2A is novel. The three loci were tagged by Kompetitive Allele Specific PCR (KASP) markers, and these were used to screen a third independent validation panel composed by elites tested across moisture stressed sites. The three KASP combined predicted up to 34% of the variation for grain yield at 65% accuracy. These loci are now ready for molecular pyramiding and transfer across cultivars to improve the moisture conversion of durum wheat. HighlightLoci controlling drought tolerance were identified using a solid strategy, involving 3 different panels. Those loci associated enables higher water productivity and grain yield.

plant biology↗

bioRxiv2021

Genetic diversity, distribution and domestication history of the neglected GGAtAt genepool of wheat

Wheat yields are stagnating around the world and new sources of genes for resistance or tolerances to abiotic traits are required. In this context, the tetraploid wheat wild relatives are among the key candidates for wheat improvement. Despite of its potential huge value for wheat breeding, the tetraploid GGAtAt genepool is largely neglected. Understanding the population structure, native distribution range, intraspecific variation of the entire tetraploid GGAtAt genepool and its domestication history would further its use for wheat improvement. We report the first comprehensive survey of genomic and cytogenetic diversity sampling the full breadth and depth of the tetraploid GGAtAt genepool. We show that the extant GGAtAt genepool consists of three distinct lineages. We provide detailed insights into the cytogenetic composition of GGAtAt wheats, revealed group-, and population-specific markers and show that chromosomal rearrangements play an important role in intraspecific diversity of T. araraticum. We discuss the origin and domestication history of the GGAtAt lineages in the context of state-of-the-art archaeobotanical finds. We shed new light on the complex evolutionary history of the GGAtAt wheat genepool. We provide the basis for an increased use of the GGAtAt wheat genepool for wheat improvement. The findings have implications for our understanding of the origins of agriculture in southwest Asia.

evolutionary biology↗