Integrated transcriptomics and metabolomics analysis to characterize cold stress responses in Phaseolus vulgaris L.

Cold tolerance of crop plants influences survival and productivity under low-temperature conditions. Elucidation of molecular mechanisms underlying low temperature tolerance could be helpful in breeding. In this study, based on transcriptome and metabolomic analysis, we successfully identified a number of candidate genes and metabolites involved in key biological pathways during cold stress response. During cold stress, a total of 22335 differentially expressed genes were detected in each group (093Cvs120C, 093Tvs120T, 093Cvs093T, 120Cvs120T), of which 12978 were up-regulated and 9357 were down-regulated. A total of 18,166 metabolites were detected and 7,670 metabolites were annotated, among which 654 were secondary metabolites with significant differences. Under cold stress, the petC gene in both common bean cultivars was down-regulated, which led to the decrease of photosynthetic efficiency. Transcriptome and metabolome results under cold stress showed that the synthesis pathways of various unsaturated fatty acids including alpha-linolenic acid were significantly up-regulated and their contents were enriched. In addition, leukotriene-A4 hydrolase in the catabolic pathway of 120 arachidonic acid was inhibited under cold stress. Furthermore, the content of arachidonic acid was increased. A variety of amino acids in both 093 and 120 were enriched under cold stress, which was beneficial to the resistance of bean to osmotic stress caused by cold stress. However, in addition to a few amino acids that were enriched together, 093 was mainly positively charged and 120 was negatively charged among the amino acids that were enriched differently. This is an interesting phenomenon that needs to be further studied. In addition, under cold stress, we found that genes in multiple metabolic pathways, including ABA, GA, JA and other hormone metabolism pathways, were differentially expressed in 093 and 120. Overall design: Transcriptome analysis was conducted on cold-tolerant common bean variety 120 and cold-sensitive common bean variety 093. 120C and 093C were the control group under non-cold stress, and 120T and 093T were the 4? cold stress groups. The specific test conditions are:Sow the seeds in a pot with an inner diameter of 10cm. Sow 6 pots for each variety, one treatment for each 3 pots, and 4 seeds for each pot. After sowing, place the seeds on the culture rack (12h light and 12h darkness every day) for culture. The cold treatment group was then moved to an incubator at 4 °C (12h daily light, 12h dark) for a period of 3 days. The true leaves of the plants were selected for sampling. All leaf samples were immediately frozen in liquid nitrogen and stored at -80°C.