Pinpointing genomic loci for drought-induced proline and hydrogen peroxide accumulation in bread wheat under field conditions

BACKGROUND: Proline (Pro) and hydrogen peroxide (H(2)O(2)) play a critical role in plants during drought adaptation. Genetic mapping for drought-induced Pro and H(2)O(2) production under field conditions is very limited in crop plants since their phenotyping with large populations is labor-intensive. A genome-wide association study (GWAS) of a diversity panel comprised of 184 bread wheat cultivars grown in natural field (control) and rain-out shelter (drought) environments was performed to identify candidate loci and genes regulating Pro and H(2)O(2) accumulation induced by drought. RESULTS: The GWAS identified top significant marker-trait associations (MTAs) on 1A and 2A chromosomes, respectively for Pro and H(2)O(2) in response to drought. Similarly, MTAs for stress tolerance index (STI) of Pro and H(2)O(2) were identified on 5B and 1B chromosomes, respectively. Total 143 significant MTAs were identified including 36 and 71 were linked to drought and 2 and 34 were linked to STI for Pro and H(2)O(2,) respectively. Next, linkage disequilibrium analysis revealed minor alleles of significant single-markers and haplotypes were associated with higher Pro and H(2)O(2) accumulation under drought. Several putative candidate genes for Pro and H(2)O(2) content encode proteins with kinase, transporter or protein-binding activities. CONCLUSIONS: The identified genetic factors associated with Pro and H(2)O(2) biosynthesis underlying drought adaptation lay a fundamental basis for functional studies and future marker-assisted breeding programs. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12870-022-03943-9.