Identification of suitable internal control genes for gene expression analysis of banana in response to BBTV infection

Banana is one of the most abundant crops produced annually in the Philippines. The presence of banana bunchy top virus (BBTV) leading to banana bunchy top disease is one of the factors hindering the continuous production of the fruit crop. The use of an appropriate and stable internal control gene as reference in validation of differentially-expressed genes in an organism is important. This study aims to identify appropriate internal control genes for differential gene expression analysis in Musa balbisiana and Musa acuminata specific for BBTV infection. RNA extraction, complementary DNA (cDNA) synthesis and RT-qPCR (quantitative real time polymerase chain reaction) of BBTV-resistant and BBTV-susceptible Musa genotypes were performed. The RT-qPCR quantification data were then subjected to analysis on RefFinder software and geomean ranking values were calculated along with the four statistical algorithms (delta C_q, Genorm, BestKeeper and NormFinder). Based on the comprehensive ranking values in the software, L2 gene was the most suitable internal control gene for the differential expression analysis of both BBTV-resistant and BBTV-susceptible banana accessions. The internal control gene is recommended for the validation of selected candidate resistance and host factor genes in response to BBTV infection.