Differential modulation of photosynthesis, signaling, and transcriptional regulation between tolerant and sensitive tomato genotypes under cold stress

Experiment description: The wild species Solanum habrochaites is more cold-tolerant than the cultivated tomato (S. lycopersicum). To explore the mechanisms responsible for cold tolerance in S. habrochaites, one cold-tolerant line (LA3969) was identified from S. habrochaites LA1777 introgression lines (ILs). The differences in physiology and global gene expression between cold-tolerant (LA1777 and LA3969) and -sensitive (LA4024) genotypes under cold stress were further investigated. The two tolerant genotypes exhibited less severe membrane damage, higher peroxidase activity, lower ascorbate peroxidase activity, and a slightly higher reactive oxygen species (ROS) accumulation. Transcriptome analysis identified 296 genes differentially expressed between tolerant and sensitive genotypes under cold stress. More transcripts categorized into response to stress , biosynthetic process , signal transduction , and transcription , were up-regulated in the two tolerant genotypes. However, more biological processes were significantly repressed in LA4024, such as auxin homeostasis, oxidation reduction, calcium ion homeostasis, and regulation of hormone levels. The two tolerant genotypes showed less repression of many photosynthesis-related genes, and maintained higher PSII activities than the sensitive one. Many transcripts involved in ROS homeostasis, hormone metabolism and signaling pathways, and calcium regulation were modulated between tolerant and sensitive genotypes. ROS, calcium, and hormones as signaling molecules may play critical roles in regulating gene expression in response to cold stress. Moreover, the expression of various transcription factors, post-translational proteins, and metabolic enzymes were also specifically modulated. These special modifications may play important roles in conferring cold tolerance in tomato. These results not only provide new insights into the molecular mechanisms of cold tolerance in tomato, but also provide potential candidate genes for genetic improvement.

Author: Hui Liu

Contact: Zhibiao Ye (zbye@mail.hzau.edu.cn), Huazhong Agricultural University