Functional analysis of MaRHD3 a predicted salt responsive gene from Musa acuminata CV. Berangan in Arabidopsis thaliana / Wong Gwo Rong

• Main Author: Wong, Gwo Rong
• Format: Thesis
• Published: 2019
• Subjects: QH426 Genetics; QR Microbiology
• Online Access: http://studentsrepo.um.edu.my/11858/1/Wong_Gwo_Rong.pdf; http://studentsrepo.um.edu.my/11858/2/Wong_Gwo_Rong.pdf; http://studentsrepo.um.edu.my/11858/

Regulation of gene expression via microRNA (miRNAs) highly influences the response of plants to abiotic stresses. In this study, expression profiling of 12 salt-responsive miRNAs and their 14 corresponding targets predicted from salt responsive banana transcriptome were validated by RT-qPCR. Among the predicted miRNA and corresponding targets, 10 miRNAs showed down-regulation and 9 miRNA-targets showed up-regulation in salt as predicted from RNAseq data. The up-regulation of these miRNA-targets indicate the involvement of these genes in banana salinity stress response mechanisms. Functional analysis of one candidate stress responsive mRNA, a target of miRNA mac-miR157m, was based on the constitutive expression of a banana cDNA, MaRHD3 in Arabidopsis. Transgenic Arabidopsis plants expressing MaRHD3 had roots with enhanced branching and more root hairs when challenged with drought stress. The MaRHD3 plants had higher biomass accumulation (2.6-fold), higher relative water content (2.4-fold), higher chlorophyll content (2.5-fold) and an increase in activity of reactive oxygen species (ROS) scavenging enzymes; SOD (1.6-fold), CAT (4-fold), GR (3-fold), POD (1.74-fold) and APX (1.9-fold) with reduced transpiration rates compared to control plants. The analysis of oxidative damage indicated lower cell membrane damage in transgenic lines compared to control plants. These findings, together with data showing higher expression of ABF-3 (6.8-fold) and higher levels of ABA in drought-stressed transgenic MaRHD3 expressing plants, support the involvement of the ABA signal pathway and ROS scavenging enzyme systems in MaRHD3 mediated drought tolerance. Keywords: