Research advances in molecular mechanisms regulating heat tolerance in cool-season turfgrasses

Cool-season turfgrasses widely used on golf courses, athletic fields, and other landscapes are environmentally and economically important, but they are functionally and aesthetically damaged under prolonged exposure to high temperatures because of their sensitivity to heat stress. Because the consequences of climate change include elevated global temperatures, it is necessary to understand mechanisms underlying heat tolerance in cool-season turfgrasses to improve heat tolerance and maintain high-quality turf during the summer, when heat stress is most severe. This paper identifies major metabolic pathways associated with genes differentially expressed in heat-tolerant cultivars or species of different turfgrasses by overviewing research from studies using comparative transcriptomics, proteomics, and biotechnological approaches and provides insight into progress toward elucidating the genetic and molecular factors regulating heat tolerance in cool-season turfgrasses. Key molecular factors and genes associated with heat tolerance in cool-season turfgrasses include those in the following cellular and metabolic processes or pathways: (1) cell cycle and DNA synthesis, replication, stability, and binding factors; (2) heat shock proteins for stress protection and protease enzymes controlling protein degradation or turnover; (3) carbohydrate metabolism for chloroplast development, chlorophyll degradation enzymes regulating the stay-green phenotype, photochemical efficiency, carboxylation, and cytochrome respiratory activities; (4) activation of antioxidant metabolism for oxidation protection; (5) modulation of lipid saturation and composition to maintain cellular membrane integrity; and (6) upregulation of secondary metabolism for stress defense. Understanding how these regulatory mechanisms cohesively operate during heat stress will facilitate the development of cool-season turfgrass germplasm with greater heat tolerance through breeding and biotechnological methods.