Genetic Mechanisms of Winter Survival in Perennial Ryegrass.

Perennial ryegrass (Lolium perenne L.) is a widely cultivated cool-season grass species. However, perennial ryegrass is susceptible to extreme cold temperatures, which limits expanding the use of this grass in temperate zones. Genetic mechanisms of winter hardiness in perennial grasses are not well understood, owing to the quantitative trait of winter hardiness as well as the complex genetic nature and genomes of most popular perennial grasses. The objective of this study was to identify candidate genes significantly associated with winter survival and spring regrowth in a global collection of 192 perennial ryegrass accessions. Winter survival (WS), percentage of canopy green cover (CGC), chlorophyll index (Chl), and normalized difference vegetation index (NDVI) were evaluated for all accessions in two locations in Indiana. Accessions significantly differed in these parameters. After controlling population structure, significant associations were discovered between C-repeat binding factor LpCBF1b and WS as well as between LpLEA3 encoding a late embryogenesis abundant group 3 protein with CGC and Chl. One pair of adjacent single nucleotide polymorphisms (SNPs) in LpLEA3 and one SNP in LpCBF1b resulted in amino acid change. The results demonstrated that allelic variation in LpLEA3 and LpCBF1b were closely related to winter survival and spring regrowth in perennial ryegrass.