Molecular Responses to Salinity Stress in Poa pratensis L. by Subtractive Hybridization Analysis.

Salinity stress in turfgrasses is a limiting factor for productivity and persistence when grown on marginal lands and where low quality irrigation water is used.  Selection for salt tolerance is underway in many breeding programs.  However, the molecular mechanisms of plant response to salinity stress have not been widely investigated in turfgrasses, especially in the genus Poa.  To evaluate the responses of Poa pratensis L. to salt stress, RNA from control and treated plants was subjected to subtractive suppression hybridization analysis in order to identify differentially expressed genes.    Several NPGS accessions and cultivar checks  were germinated from seed and grown in a greenhouse in silica sand, and  the mature plants were submersed in nutrient solution containing sodium and calcium salts (ECw=18dS/m), twice a week for three weeks.  Following salt treatment, root and shoot tissue was collected from each plant and total RNA was extracted for the gene expression analysis.  The sampled germplasms exhibited a range of visual salinity stress symptoms, with a few being particularly robust.  Subtractive hybridization analysis is underway comparing these against the salt-sensitive accessions.  This method has revealed several abiotic stress-related genes as well as a few novel sequences in other studies involving turfgrasses such as Lolium.  The identification of similar candidate genes in this study will elucidate genetic mechanisms by which Poa pratensis L. responds to salinity stress.