Chlorophyll-associated genes and SSR markers linked to genetic
variations in heat tolerance of perennial ryegrass
Abstract
Identification of genetic diversity in heat tolerance and associated
markers is of great importance for improving heat tolerance in
cool-season grass species. In this study, 98 accessions of perennial
ryegrass (Lolium perenne L.) were subjected to heat stress (35/30 ℃,
day/night) or optimal growth temperature (25/20 ℃) for 24 d in growth
chambers. Overall heat tolerance of those accessions was ranked by
principal component analysis (PCA) based on eight growth and
physiological traits. Among these traits, chlorophyll (Chl) content had
the highest correlation coefficient (0.864) with the PCA ranking of heat
tolerance, indicating it was the most closely linked parameter to heat
tolerance. And expressions of four Chl catabolic genes (CCGs) were
negatively correlated with PCA ranking of heat. Furthermore, simple
sequence repeat (SSR) markers were identified that significantly
associated with Chl content and other heat tolerance-related traits.
Together, the result highlighted the importance of Chl catabolism in
heat tolerance of cool-season grasses. Chl content, heat-associated CCG
genes and their associated SSR markers could be used as reliable trait
or molecular markers in the breeding program of perennial ryegrass
toward better heat tolerance.