Transcriptome analysis reveals MYB and WRKY transcription factors involved in banana (Musa paradisiaca AA) magnesium deficiency

The banana development was inhibited under the long-term magnesium deficiency (MD) stress, resulting in the leaf chlorosis. MYB108 and WRKY75 are involved in regulating the growth and development of banana leaves and roots under long-term MD. Magnesium deficiency (MD) causes plant growth inhibition, ageing acceleration, yield reduction and quality decline of banana (Musa paradisiaca AA), but the molecular regulatory mechanisms underlying the changes in response to long-term MD conditions remain unknown. In this study, a long-term MD experiment was performed with banana seedlings at the four-leaf stage. Compared to those in the control group, the growth of leaves and roots of seedlings in the long-term MD treatment experimental groups was inhibited, and the Mg content and chlorophyll contents were decreased. Leaves and roots of seedlings from the control and experimental groups were subsequently collected for RNA sequencing to identify the genes that respond to long-term MD. More than 50 million reads were identified from each sample, resulting in the detection of 3500 and 948 differentially expressed genes (DEGs) in the leaves and roots, respectively. MYB and WRKY transcription factors (TFs) involved in plant stress responses were selected for further analysis, and 102 MYB and 149 WRKY TFs were differentially expressed. Furthermore, two highly differentially expressed candidate genes, MYB108 and WRKY75, were functionally analyzed using Arabidopsis mutants grown under long-term MD conditions. The results showed that the density of root hairs on the wild type (WT) was than that on the myb108 and wrky75 mutants under MD, implying that the mutants were more sensitive to MD than the WT. This research broadens our understanding the underlying molecular mechanism of banana seedlings adapted to the long-term MD condition.