Studying the Transcriptome Profiling of Banana Plantlets Exposed to Water Stress and the Alteration in Their Major Bioprocesses

Abstract

Water shortage has been one of the major problems that limit the production yield of banana. The molecular mechanisms by which banana plants thrive in drought are not completely understood. This study aimed to reveal the major bioprocesses affected by water shortage in banana plantlet using a transcriptomic analysis approach. In vitro shoot cultures of banana (Musa acuminata) cv Barangan Merah were established on water stress treatments with the addition of polyethylene glycol (PEG) in the culture medium. Banana plantlets generated from water stressed shoots from the control (BK), low 2.5% PEG), medium (7.5% PEG) and high (10% PEG) levels were utilized as the resource for total RNA samples. Four cDNA libraries were constructed and sequenced using the Illumina MiSeq TM 2000 platform. Transcriptome data analysis was conducted. From a pool of four transcriptome libraries, each consisting of about 3,500,000 paired-end raw reads, 147,811 contigs were assembled, from which 129,701 contigs were annotated with SwissProt reference and Musa acuminata gene model. A total of 101,406 high quality and non-redundant contigs were obtained for differential expressed genes (DEG) analyses. Gene ontology was performed using DAVID, followed by pathway prediction using KEGG. Statistical analysis identified 1,744 genes as DEGs under PEG treatment in which 1,046 genes (67%) of them were mapped to the reference genomes. These DEGs were distributed in 26 functional clusters. There were eight major biological processes that were highly affected by the drought stress in banana, including photosynthesis, cellular redox balance, cellular components stability, cellular energy preservation, metal ion homeostasis, hormonal-activated signaling pathways, organ development, and production of transcription factors (TFs). There 47 genes encoded for TFs were identified including five families that are typical for stressresponsive genes families (MYB, WRKY, bZIP, ABF, DRE), also auxin-and ethylene-activated TFs and WUSCHELrelated homeobox. Fifteen DEGs were selected for qRT-PCR validation and their expression results were confirmed.