Analysis of transcriptomic and metabolomic differences revealed the mechanism underlying the tobacco response to low-temperature

Low-temperature is one of the main natural adversities in tobacco leaf planting. Tobacco is very sensitive to low-temperature. To understand the underlying the response mechanism of tobacco to low-temperature stress, the physiology, biochemistry, transcription and metabolism at the seedling stage under low-temperature stress were investigated. The results showed that compared with the control, the leaves were thinner, wilted and yellow, the chlorophyll content was reduced, and the chloroplasts were damaged to some extent by low-temperature stress. Compared with the control group, a total of 8262 differentially expressed genes (DEGs) were detected in the group under low-temperature stress, of which 4513 were up-regulated and 3749 were down-regulated. GO and KEGG enrichment analyses showed that low-temperature had significant effects on the antioxidant activity, hormone response and photosynthetic pathway of tobacco cells. Furthermore, 560 differentially expressed transcription factors were screened, including AP2/ERF-ERF (60), WRKY (36), bHLH (31), NAC (29), MYB (28), and C2H2 (26) families. There were 110 differentially abundant metabolites detected, of which 62 were up-regulated and 48 down-regulated. The differentially abundant metabolites were mainly concentrated in metabolism and synthesis related pathways, such as carbon metabolism, glucose metabolism, amino acid metabolism and flavonoid synthesis and metabolism. This combined omics analysis revealed that the plant hormone transduction pathway, starch and sucrose metabolism pathway, flavonoid synthesis pathway, photosynthetic pathway and related transcription factor regulatory genes played an important role in the response of tobacco seedlings to low-temperature stress.