De novo assembly of mulberry (Morus alba L.) transcriptome and identification of candidate unigenes related to salt stress responses

Abstract

Mulberry (Morus alba L.) is a kind of plant with strong adaptation to drought, salt stress, water logging, and other environmental stresses. However, there is little knowledge on the molecular mechanism involved in its response and resistance to environmental stresses, including salt stress. In this study, a total of 101589 unigenes were obtained from 24 Morus salinity subtranscriptomes using Illumina RNA-sequencing technology, and led to 34.72% of the assembled reads being matched to known transcripts. The number of down-regulated DEGs (differentially expressed genes) under salt stress is more than that of up-regulated DEGs, and these down-regulated DEGs enriched in the process related to stress response by GO and KEGG enrichment analysis. It is notable that some genes showed diverse response patterns against salt stress in genotype- and tissue-dependent manners. The DEGs involved in signal transduction and transcription regulation were found to be more enriched in low-salt-tolerant genotypes and the majority of these responsive genes showed decreased transcript abundance, which may result in low tolerance of low-salt-tolerant genotypes. The results of this study will advance our understanding of the salt response in Morus and provide the basis for further genetic improvement of salt tolerance in Morus and other plants.