Molecular Characterization of Heat-responsive Genes Associated with Heat Tolerance in Bentgrass Species.

The objectives of this study were to characterize the expression of three heat-responsive genes: Hsp16, Hsp70, cysteine protease identified using subtractive suppression hybridization analysis in thermal Agrostis scabra L. and to determine how the expression of these gene/proteins is related to heat tolerance in creeping bentgrass. Three full length cDNAs, encoding AsCP1, AsHsp16 and AsHsp70 were isolated. Enhanced expressions of three genes are observed in the roots of all tested genotypes of thermal A. scabra and creeping bentgrass exposed to high temperature (35^oC). Northern blot, semi-quantitative RT-PCR and western blot analysis revealed that the expression level of two genes encoding heat shock proteins (AsHsp16 and AsHsp70) and the gene encoding cysteine proteases controlling protein degradation (AsCP1) was positively and negatively correlated with the level of heat tolerance, respectively, in both bentgrass species. Our results demonstrated the importance of HSP16 and HSP70 and proteases in regulating plant tolerance to heat stress, and also suggest that these heat-responsive genes may be useful as a molecular marker to select for heat-tolerant cool-season grass germplasm.