The banana salt stress transcriptome: large and small RNA expression in stressed banana

Banana (Musa spp.) is the most widely consumed fruit worldwide, and a staple food for millions of people in developing countries. Global production however is hampered by pathogens and by suboptimal cultivation environments and, as with other crops, is likely to be adversely affected by climate change. Our research group is using high salt as a means to study gene expression in response to abiotic stress in roots of the local banana cultivar 'Berangan' (AAA genome). Examination of both total RNA and small RNA expression can help to develop a clearer picture of the stress related responses in banana on a genome-wide scale. We constructed libraries from stressed and control banana roots and then characterized these by high-throughput Next Generation Sequencing, followed by transcriptome assembly and expression analysis. From comparisons with published sequence data from other NaCl-stressed plant species, we have identified several new gene candidates involved in the root salt stress response. These include many stress-related miRNA and their predicted targets, including new targets of known miRNA in addition to novel miRNA sequences present in the banana A and B genomes with some being unique to each genome. Our data also indicate that siRNA expression patterns change in response to salt stress, and thus provide new insights into the response of the banana 'small RNAome' to stress that may help in crop improvement.