Transcriptome Analysis of Salt-Stressed Perennial Ryegrass.

The development of turfgrass cultivars that can tolerate salinity while maintaining safe, acceptable quality would result in a community and industry more accepting of voluntary utilization of alternative water sources.  However, current breeding efforts have been slow and the mechanism for salinity tolerance is not fully understood. Previous research in rice indicates that genes responsible for salinity tolerance are expressed in the first few hours of salinity stress. The goal of this project is to study gene expression of salinity tolerant and susceptible perennial ryegrass clones by sequencing the transcriptome of salt-stressed and non-stressed leaves. Two genotypes, S1 – salt tolerant and B-salt sensitive, were selected based on a previous salinity tolerance screening. These genotypes were vegetatively propagated into three replicates and grown under control and salinity stress conditions in a greenhouse. Leaf tissue was cut and immediately flash frozen in liquid nitrogen. RNA was extracted using RNAeasy Plant Mini Kit and libraries were constructed using TruSeq RNA Sample Preparation Kit v2 by Illumina Inc. Samples were then run on a MiSeq benchtop sequencer. Two thousand two hundred and ninety-six genes were differentially expressed in the salt tolerant genotype compared to 314 expressed only in the salt sensitive genotype when genotypes were exposed to salt. The majority of the genes that were strongly upregulated in the salt tolerant genotype under salinity stress where in the dehydrin (or LEA [Late Embryogenesis Abundant]) family of genes including drought acclimating dehydrin WZY2, Dehydrin DHN3, and LEA proteins, which are considered to participate in protecting cellular components from dehydration in response to drought, salt or cold tolerance.  We are hopeful that this project will bring us closer to identifying mechanisms involved with salinity tolerance and potentially identify sequence variation that can be used in the future for genomic selection in perennial ryegrass.