Uncovering natural variation in TdBCAT genes and phenotypic variation under drought in durum wheat.

Drought severely limits wheat productivity, highlighting the need for tolerant genetic resources. Targeted allele mining and high-throughput phenotyping (HTP) were combined to assess natural variation in TdBCAT genes and drought response in 38 durum wheat genotypes. A cost-effective strategy integrating next-generation sequencing and Kompetitive Allele Specific PCR (KASP) genotyping identified 27 single nucleotide polymorphisms (SNPs) and 10 haplotypes across TdBCAT-A and TdBCAT-B, mainly in promoter regions. Under controlled drought, RGB imaging and the digital biovolume ratio (DBR) classified SSD 195, SSD 269, SSD 322, SSD 343, SSD 409, SSD 416, SSD 441, and Svevo as the best-performing genotypes, with SSD 195 and SSD 441 showing the greatest stability. Integrating genotypic and phenotypic data identified TdBCAT haplotype combinations associated with improved drought performance and valuable landraces for pre-breeding. This integrated approach efficiently characterized haplotypic diversity and identified drought-adaptive germplasm, providing valuable resources for pre-breeding and the sustainable selection of durum wheat under water-limited conditions.