Abstract:

To study coexpression network of Luffa cylindrica（L.）Roem under low temperature and weak light stress，weighted gene co-expression network analysis was introduced. WGCNA to screen out the core genes that respond to low temperature and weak light. Based on 15 transcript sequencing samples of common Luffa treated with low temperature and weak light，phenotypic matrix was created with low temperature and weak light samples as processing traits，and 29 module were clustered，among which 13 module were correlated with low temperature and weak light treatment traits. The three module with the highest positive correlation were predicted and 108 transcription factors were obtained，among which the top three types were ERF（18），MYB（10）and NAC（10）. According to the enrichment of KEGG pathway，the three module are involved in peroxisome，plant hormone signal transduction，photosynthesis and MAPK signal pathway，respectively. Three core genes were screened from the module according to topological overlap matrix（TOM），module member-ship（MM）and connectivity（K.in），and identified as ATPβ，G6PDH and PER5 by protein homology analysis. The analysis of up-expression and down-expression differentially expressed genes （DEG）of the three core genes showed that 93.97% of down-expression genes of G6PDH were down-regulated in the downstream genes，and the up-expression expression of G6PDH gene induced by low temperature and weak light might inhibit the expression of downstream associated genes. The promoters of the three core genes had elements such as low temperature response，methyl jasmonate response，gibberellin response and light response. The co-expression networks of the three core genes predicted ERF transcription.

Key words: WGCNA, seeding of luffa, low temperature and weak light stress, RNA-Seq, gene co-expression modules