A Composite Approach to Study Drought Tolerance in Tall Fescue

Tall fescue is a cool-season perennial grass grown in the temperate regions of the world. The forage-purpose tall fescue belongs under two distinct morphotypes, the Continental and the Mediterranean. Drought is the single most constrain for tall fescue cultivation in the southern Great Plains. Enhancing drought tolerance is the key strategy for improving persistence of Continental fescue in the region. A suitable drought screening protocol was developed in our program. A transcriptome profiling between water-stress tolerant and susceptible genotypes unraveled the genetic regulatory mechanism of water-stress responses. A total of 199,399 contigs were assembled with an average length of 585 bp. Significantly differentially expressed reference transcripts (RTs, 2986) were identified and 1048 of them could be annotated into functional groups. In total 175 RTs were reported for various stress-related functions and 65 of them were encoded kinase proteins and 40 each were encoded transposons and transporter proteins. Summer dormancy is an important drought adaptation trait, which can improve persistence of the Mediterranean fescue. Screening experiments suggested that physiological traits, i.e., stomatal conductance, can be used to discriminate summer dormancy. Multi-factor transcriptome sequencing has been conducted using leaf, root and crown tissues from genotypes of both morphotypes to understand and identify the genetic mechanism of summer dormancy. A de novo assembly assembled 710,125,152 bp sequences into contigs. A total of 1,031,513 RTs were identified in 583,736 contigs. Differential transcriptional responses were documented among the genotypes, tissue types and three time points. Further exploration to pin down the background mechanism is undergoing.