GENOME WIDE ASSOCIATION STUDY FOR DROUGHT ADAPTIVE TRAITS IN DURUM WHEAT

A better understanding of the genetic basis of the plastic response of plants to drought will be instrumental to optimize management practices and breeding strategies in wheat. This study investigated a number of proxy traits i nfluencing the adaptive response to drought stress (NDVI and IRT by UAV and tractor, leaf and spike waxiness, leaf angle and leaf rolling) using a GWAS panel of 280 elite durum wheat accessions that were field - evaluated at Maricopa Agricultural Center, USA , under full irrigation and progressive drought stress. A genetic characterization of the durum panel was carried out using the Illumina iSelect wheat 90K SNP assay and a Genome Wide Association Study (GWAS) was performed using Mixed Linear Model (MLM) i n Tassel in order to identify the genetic intervals harboring loci controlling the investigated traits. For epicuticular leaf and spike waxiness, highly significant QTLs were detected for both traits (chromosomes 1B, 2A, 5B) while others were associated on ly to one of the two traits (chr. 1AS, 2AS and 7BL for ear waxiness, 6BS and 4BS for leaf waxiness). GWAS analysis pointed out other significant regions controlling leaf angle in chr. 1AL, 1BS, 3AS, 5AS, 5BL and 6BL chromosomes, two major QTLs in chr. 5BL and 6BS for leaf rolling and four in chr. 1AL, 5BL, 6BS and 7BL for SPAD. As to NDVI and IRT collected in different times and phenological phases, different results were obtained with the drone and tractor-mounted camera. Common QTLs were detected with both methods on chr.2BS, 5AL, 7AS and 7AL for NDVI. Additional QTLs were identified in chr. 1AL and 4BL for NDVI and in chr. 2AL and 5AS for IRT trait with tractor-mounted sensors.