Genomic regions of durum wheat involved in water productivity

Abstract

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. These 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 germplasm 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. These loci were tagged by Kompetitive Allele Specific PCR (KASP) markers. Screening by KASP of a third independent germplasm validation panel tested across moisture stressed sites confirmed that these loci explained 34% of the variation for grain yield at 65% accuracy. These are the first ever reported markers truly ready for deployment by molecular breeding to convert moisture into yield in durum wheat.

Performance and Stability Analysis of Selected Durum Wheat Genotypes Differing in Their Kernel Characteristics

“…Bolenga is a Spanish cultivar that has been described previously as salt sensitive and susceptible to leaf rust [ 42 , 43 ]. It was selected from the ICARDA global panel of durum wheat [ 36 ] based on promising GY observed in preliminary field trials under drought conditions [ 44 ]. Bolenga performed exceptionally under different conditions in Jordan and was considered a winning genotype in 10 out of 15 environments.…”

“…In this study, eight durum wheat genotypes were selected. These included Um Qais (synonymous with Omrabi5 (Jori-C69/Hourani), a Jordanian registered cultivar developed by ICARDA; Norsi, a durum wheat landrace collected in Jordan that was chosen for its high TKW and unique kernel-related characteristics [ 29 ]; two Spanish elite cultivars (entry 335 (Boabdil) and entry 336 (Bolenga) were selected from the ICARDA global panel of durum [ 36 , 44 ]; UC1113 Yr36+Gpc-B1 , a high-yielding line carrying the Yr36 and Gpc - B1 alleles, was also included. This line was developed at UC-Davis (Davis, CA, USA) and obtained from the USDA-ARS national small grains collection (PI 638741); Finally, three durum wheat recombinant inbred lines (RILs) were selected from a F7-RIL population derived from a cross between Norsi and UC1113 Yr36+Gpc-B1 .…”