Comparative transcriptome sequencing analysis and functional identification of a NAM-2-like gene in jute (Corchorus capsularis L.).

Jute (Corchorus capsularis L.) is one of the most important sources of natural fibre. Drought is among the main factors affecting the production of jute. It is essential for drought tolerance improvement to discover the genes associated with jute development during drought stress. In this study, we analyzed the transcriptome of jute under drought stress and identified new genes involved in drought stress response. In total, 120,219 transcripts with an average length of 764 bp were obtained, these transcripts included 94,246 unigenes (average length, 622 bp). Differentially expressed genes (DEGs) were discovered in drought stress (1329), among which 903 genes showed up-regulated expression, while 426 genes showed down-regulated expression. GO enrichment analyses indicated most of the enriched biological pathways were biosynthesis pathways of organic ring compounds and cellular nitrogen compounds. KEGG enrichment analyses indicated 573 DEGs were involved in 157 metabolic pathways. RT-qPCR experiments indicated that the expression trends were consistent with the results of the high-throughput sequencing. Over-expression of no apical meristem (NAM) -2-like gene increased drought tolerance and knockdown plants were drought sensitive. It has expression peaks after 6 h of drought stress and regulate 3-ketoacyl-CoA synthase gene expression. Yeast-2-Hybrid assays validated the physical interaction between NAM-2-like protein and KCS. The results provide relatively comprehensive information regarding genes and metabolic pathways that lays the foundation for the breeding of drought-resistant varieties, and represent the first identification of NAM-2-like gene and provides new insight into the regulatory network of drought tolerance in Corchorus capsularis L.

Overexpression of CcNAC1 gene promotes early flowering and enhances drought tolerance of jute (Corchorus capsularis L.).

Drought is the main factor that significantly affects plant growth and has devastating effects on crop production of jute. NAC (NAM, ATAF, and CUC2) transcription factors (TFs) are a large gene family in plants that have been shown to play many important roles in regulating developmental processes and abiotic stress resistance. In this study, a NAC transcription factor, CcNAC1, was cloned and characterized its function in jute. RT-qPCR analysis showed that CcNAC1 expression peaks after 8 h of drought stress. CcNAC1 overexpression and knockdown plants were created by Agrobacterium-mediated genetic transformation. PCR and southern hybridization results indicate that the CcNAC1 gene was integrated into the genome of jute. Overexpression of the CcNAC1 gene sped up the plant growth, promoted early flowering, and increased drought tolerance compared to the control plants. 3-Ketoacyl-CoA synthase (KCS) gene expression level increased significantly in the CcNAC1-overexpression plants and decreased in knockdown plants, which showed that CcNAC1 transcription factor regulated KCS gene expression. Yeast-2-Hybrid (Y2H) assays validated the physical interaction between CcNAC1 and KCS. The results provide relatively comprehensive information on the molecular mechanisms of CcNAC1 gene underlying the regulation of plant growth and drought stress resistance, and indicate that CcNAC1 acts as a positive regulator in drought tolerance in jute (Corchorus capsularis L.).