Transcript responses to drought in Kentucky bluegrass (Poa pratensis L.) germplasm varying in their tolerance to drought stress

Abstract For the cool-season turfgrass Kentucky bluegrass, improving germplasm for drought tolerance is an increasingly important priority. Although genetic mechanisms behind drought tolerance have been characterized for model and agronomic plant species, the critical genes, gene families, and transcript isoforms important in Kentucky bluegrass are unclear. Using an RNAseq approach across three germplasm sources that differ in their regrowth, relative water content, and turf quality under drought stress, we have identified transcript isoforms exhibiting a shared response of all three germplasm sources to drought stress and transcript isoforms exhibiting a tolerance response where the more drought-tolerant germplasm sources exhibited higher transcript differences compared to the drought-susceptible cultivar Midnight. Annotation and transcript profile groupings both identified abundant chaperone gene families with protein folding and protective functions, such as heat shock proteins, DNAj, and late embryogenesis abundant genes. Transcript isoforms within these gene families were tolerance related and known to respond to abscisic acid. Two dehydrin genes, RAB15 and HVA1, were induced in several more drought-tolerant germplasm sources and show promise as candidate genes for selection.