Combined Analysis of Transcriptome and Metabolome Reveals the Heat Stress Resistance of Dongxiang Wild Rice at Seedling Stage.

Rice is sensitive to high temperatures at the seedling stage. In the present study, a combined analysis of transcriptome and metabolome was performed on a heat-resistant accession, DY80, from Dongxiang wild rice and a heat-sensitive variety, R974, under heat stress at the seedling stage. The results of the transcriptome and metabolome analyses were verified through qRT-PCR and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) analysis. We found that there were 1817 and 561 differentially expressed genes (DEGs) unique in DY80 and R974 under heat stress, respectively. The elite genes for the heat stress involved in Dongxiang wild rice may include upregulated genes in the pathway of unfolded protein binding; downregulated genes in the pathways of chlorophyll biosynthetic process, and cysteine and methionine metabolism; and photosystem I, photosystem II, and unchanged genes in the pathways of the anchored component of the plasma membrane, cell wall biogenesis, and photosynthesis-antenna proteins. Moreover, a total of 301 and 28 metabolites were identified as unique in DY80 and R974 after heat treatment, respectively. Further analyses showed that malic acid, stearic acid, and L-threonine might be causal metabolites, contributing to strong heat resistance in Dongxiang wild rice. These findings provide new insights into the mechanisms of heat resistance in rice.