Abstract
Methyl jasmonate (MeJA) plays a role in improving plant stress tolerance. The molecular mechanisms associated with heat tolerance mediated by MeJA are not fully understood in perennial grass species. The study was designed to explore transcriptomic mechanisms underlying heat tolerance by exogenous MeJA in perennial ryegrass (Lolium perenne L.) using RNA-seq. Transcriptomic profiling was performed on plants under normal temperature (CK), high temperature for 12 h (H), MeJA pretreatment (T), MeJA pretreatment + H (T-H), respectively. The analysis of differentially expressed genes (DEGs) showed that H resulted in the most DEGs and T had the least, compared with CK. Among them, the DEGs related to the response to oxygen-containing compound was higher in CKvsH, while many genes related to photosynthetic system were down-regulated. The DEGs related to plastid components was higher in CKvsT. GO and KEGG analysis showed that exogenous application of MeJA enriched photosynthesis related pathways under heat stress. Exogenous MeJA significantly increased the expression of genes involved in chlorophyll (Chl) biosynthesis and antioxidant metabolism, and decreased the expression of Chl degradation genes, as well as the expression of heat shock transcription factor - heat shock protein (HSF-HSP) network under heat stress. The results indicated that exogenous application of MeJA improved the heat tolerance of perennial ryegrass by mediating expression of genes in different pathways, such as Chl biosynthesis and degradation, antioxidant enzyme system, HSF-HSP network and JAs biosynthesis.
Highlights
Perennial ryegrass (Lolium perenne L.) is a widely cultivated cool-season grass species in temperate regions
Exogenous Methyl jasmonate (MeJA) increased the expression of genes involved in chlorophyll biosynthesis (CHLH, HEMB, chelatase I-subunit (CHLI)) and decreased chlorophyll degradation genes (SGR, pheophorbide hydrolase (PPH)), which contributed to stay green of plant leaf under heat stress
Superoxidation metabolism was significantly enriched in HvsT-H, and gene expression analysis showed that MeJA application enhanced the expression of antioxidant genes (SODCP, APX2), which alleviated oxidative damage
Summary
Perennial ryegrass (Lolium perenne L.) is a widely cultivated cool-season grass species in temperate regions. This species has high nutritive values and herbage yield, making it a suitable grass for forage production, while its fast establishment and good traffic tolerance are desirable for turfgrass uses [1, 2]. A number of physiological parameters, such as photochemical efficiency, photosynthetic rate, Nie et al BMC Plant Biology (2022) 22:68 water use efficiency, and chlorophyll (Chl) content are often used as indicators for heat stress tolerance [6,7,8]. Leaf senescence, characterized by loss of Chl, is a hallmark of damage induced by heat stress among cool-season grass species. Heat induced leaf senescence involves key physiological changes in perennial grass species
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