Characterization Of QRC10-2,a Major Cold Tolerant QTL From Dongxiang Wild Rice

Rice(Oryza sativa L.)is one of the world's major food crops.In recent years,the world's climate change has been abnormal,and low-temperature chilling has become one of the most important factors that threaten the stability of rice production.Therefore,improving the cold-tolerance traits of rice and the selection of cold-tolerant cultivars are of great significance to ensure food safety.1.In this study,the subcellular localization of the gene qRC10-2 which found that GFP fluorescence is almost entirely localized on the cell membrane,but there was no GFP fluorescence signal detected in other regions,which confirms that the qRC10-2 expression product is mainly located on the cell membrane.2.qRC10-2+ in Dongxiang wild rice was transformed into the cold-sensitive material indica R6547 by Agrobacterium to overexpress qRC10-2+.At the same time,we interference with qRC10-2-in rice indica R6547 and qRC10-2+ in japonica Nipponbare.The results have shown that the survival rate of the interfered qRC10-2+ gene plants in japonica Nipponbare after cold treatment is significantly reduced.However,after overexpression of qRC10-2+ gene in Dongxiang wild rice in indica R6547,the survival rate of transgenic plants after cold treatment was significantly increased.Therefore,the cold-tolerance gene qRC10-2+ has cold tolerance at rice seedling stage,while the gene qRC10-2-has no cold-tolerance function.3.The function of qRC10-2 is involved in pectin metabolism,and pectin is one of the main components of plant cell wall.Before cold treatment,the pectin content of indica R6547 transformed with qRC10-2+(OR-qRC10-2+)T2 pure lines was significantly higher than that of indica R6547.The pectin content of japonica Nipponbare interfered with qRC10-2+(IJ-qRC10-2+)T2 pure lines was significantly lower than that of japonica Nipponbare,indicating that the qRC10-2+ gene could increase the pectin content of plants before being subjected to cold stress.The pectin content in the roots increased the cold tolerance of OR-qRC10-2+ plants.After cold treatment,the pectin content of UK-qRC10-2+ T2 pure lines was still significantly higher than that of indica R6547,which further indicated that qRC10-2+ could still promote pectin synthesis in rice roots after being subjected to cold stress.The synthesis of pectin increased the cold tolerance of transgenic plants,but the interference of qRC10-2+ gene in IJ-qRC10-2+ plants could not increase the pectin content in the cell wall,and the cold tolerance of the transgenic plants was reduced.4.The transcriptome expression profiles of transgenic plants were analyzed to study the differentially expressed genes of qRC10-2.Most of the qRC10-2 transgenic lines were found to be up-regulated or down-regulated in metabolic pathways,stress responses,and biological systems.Transcription factors such as MYB,WRKY,and NAC were significantly up-regulated or down-regulated after cold stress treatment,and the expression of WRKY transcription factor enhanced plant cold tolerance and participate in the ABA response.This study provided experimental basis for further revealing the molecular mechanism and regulation pathway of cold tolerance at rice seedling stage.The cloning of qRC10-2 functional genes provided new genetic resources for cold-resistant rice varieties.