Global Transcriptomic Analysis of Targeted Silencing of Two Paralogous ACC Oxidase Genes in Banana.

Among 18 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase homologous genes existing in the banana genome there are two genes, and , that participate in banana fruit ripening. To better understand the physiological functions of and , two hairpin-type siRNA expression vectors targeting both the and were constructed and incorporated into the banana genome by -mediated transformation. The generation of and RNAi transgenic banana plants was confirmed by Southern blot analysis. To gain insights into the functional diversity and complexity between and , transcriptome sequencing of banana fruits using the Illumina next-generation sequencer was performed. A total of 32,093,976 reads, assembled into 88,031 unigenes for 123,617 transcripts were obtained. Significantly enriched Gene Oncology (GO) terms and the number of differentially expressed genes (DEGs) with GO annotation were 'catalytic activity' (1327, 56.4%), 'heme binding' (65, 2.76%), 'tetrapyrrole binding' (66, 2.81%), and 'oxidoreductase activity' (287, 12.21%). Real-time RT-PCR was further performed with mRNAs from both peel and pulp of banana fruits in and RNAi transgenic plants. The results showed that expression levels of genes related to ethylene signaling in ripening banana fruits were strongly influenced by the expression of genes associated with ethylene biosynthesis.