摘要
The molecular mechanisms underlying genetic variations in heat tolerance,one of the important turfgrass traits,for fine fescue are not well-understood.In the present study,our objective was to identify molecular constituents and metabolic interactions involved in heat tolerance in two genotypes of hard fescue(Festuca trachyphylla)contrasting in heat tolerance by comparative transcriptomics and gene comparison network analysis.Two cultivars of hard fescue,'Reliant IV'(heat-tolerant),and'Predator'(heat-sensitive),were subjected to heat stress temperature at 35/30℃(day/night)or maintained at optimal temperature at 22/18℃(day/night)(non-stress control)for 21 d.At 14 and 21 d of heat stress,'Reliant IV'maintained significantly higher photochemical efficiency(F_(v)/F_(m)),chlorophyll(Chl)content,and lower cell membrane electrolyte leakage(EL)compared to'Predator',suggesting its superiority in heat tolerance.Comparative transcriptomic profiles,gene functional enrichment analysis,and weighted gene comparison network analysis revealed central hub genes(BBE22 and ALPLD)and their connecting genes involved in secondary metabolism for biosynthesis of oxylipins(LOX1 and LOX3),phenolic compounds(PAL2),and dhurrin(C79A1 and C71E1).These genes were up-regulated in heat-tolerant'Reliant IV'under heat stress but not in heat-sensitive'Predator',while a majority of heat-regulated genes involved in primary metabolism responded similarly to heat stress in both cultivars.Those unique genes in the secondary metabolic pathways enriched in only the heat-tolerant cultivar could be critical for mediating the protection of hard fescue against heat stress and are potentially useful as candidate genes or molecular markers for augmenting heat tolerance in other temperate species of grass.
基金
The authors wish to thank the National Institute of Food and Agriculture,USDA,Specialty Crop Research Initiative for funding(award number 2017-51181-27222).
