Genetic variations of HvP5CS1 and their association with drought tolerance related traits in barley (Hordeum vulgare L.)

Delta-1-pyrroline-5-carboxylate synthase gene1 (P5CS1) is the key gene involved in the biosynthesis of
proline and is significantly induced by drought stress. The exploration of genetic variation in HvP5CS1
may facilitate a better understanding of the mechanism of drought adaptation in barley. In the current
study, 41 polymorphisms including 16 single nucleotide polymorphisms (SNPs) and 25 insertions/
deletions (indels) were detected in HvP5CS1 among 287 barley (Hordeum vulgare L.) accessions
collected worldwide, with 13 distinct haplotypes identified in the barley collection. Five polymorphisms
in HvP5CS1 were significantly (P < 0.001) associated with drought tolerance related traits in barley. The
phenotypic variation of a given trait explained by each associated polymorphism ranged from 4.43%
to 9.81%. Two sequence variations that were significantly (P < 0.0001) associated with grain yield
had marginally significant positive Tajima’s D values in the sliding window, so they might have been
selected for environmental adaptation. Meanwhile, two haplotypes HvP5CS1_H1 and HvP5CS1_H4,
which contained desired alleles of the two variations mentioned above, were significantly (P < 0.001)
associated with drought tolerance related traits, and explained 5.00~11.89% of the phenotypic
variations. These variations associated with drought tolerance related traits can be used as potential
markers for improving drought tolerance in barley.