Association of Candidate Genes With Submergence Response in Perennial Ryegrass.

Perennial ryegrass is a popular cool-season grass species due to its high quality for forage and turf. The objective of this study was to identify associations of candidate genes with growth and physiological traits to submergence stress and recovery after de-submergence in a global collection of 94 perennial ryegrass accessions. Accessions varied largely in leaf color, plant height (HT), leaf fresh weight (LFW), leaf dry weight (LDW), and chlorophyll fluorescence (Fv/Fm) at 7 days of submergence and in HT, LFW and LDW at 7 days of recovery in two experiments. Among 26 candidate genes tested by various models, single nucleotide polymorphisms (SNPs) in 10 genes showed significant associations with traits including 16 associations for control, 10 for submergence, and 8 for recovery. Under submergence, encoding sucrose:sucrose 1-fructosyltransferase and encoding gibberellin 20-oxidase were associated with LFW and LDW, and encoding 1-aminocyclopropane-1-carboxylic acid oxidase was associated with LFW. Associations between and HT, encoding fructan:fructan 6G-fructosyltransferase and Fv/Fm, encoding catalase and HT were also detected under submergence stress. Upon de-submergence, , and encoding plasma membrane intrinsic protein type 1 were associated with LFW or LDW, while encoding C-repeat binding factor were associated with HT. Nine significant SNPs in , and resulted in amino acid changes with five substitutions found in under submergence or recovery. The results indicated that allelic diversity in genes involved in carbohydrate and antioxidant metabolism, ethylene and gibberellin biosynthesis, and transcript factor could contribute to growth variations in perennial ryegrass under submergence stress and recovery after de-submergence.