Genetic mapping of candidate loci for water-deficit stress-induced proline accumulation in bread wheat (Triticum aestivum)

Proline is an important metabolite that plays an adaptive role in plants under water-deficit stress. Understanding the genetic basis of water-deficit-induced proline accumulation remains elusive in crop plants, especially in wheat. Here, we investigated proline accumulation under control and water-deficit conditions using a diversity panel which comprises of 150 bread wheat cultivars. Water-deficit stress significantly increased proline accumulation than well-water treated plants. Water-deficit-induced proline variability was dissected using genome-wide association studies that identified significant marker-trait associations, especially on 1A and 1B chromosomes. Population structure analysis revealed the cultivars originated from Europe were associated with higher proline content. Further, linkage disequilibrium analysis identified minor allele of haplotypes, and single markers were linked with higher proline accumulation under water-deficit conditions. The identified candidate genes were mostly involved in ATP and ADP binding, protein and oligopeptide transporter activity and also found in defence response, carbohydrate and fatty acid biosynthetic processes. Next, an in silico transcript analysis found higher expression of candidate genes in shoot/leaves under water-deficit stress conditions. Overall, the key genomic regions controlling water deficit-induced proline accumulation can be utilized in improving plant adaptation to drought.