Reference genes for RT-qPCR analysis in Musa acuminata genotypes contrasting in resistance to Fusarium oxysporum f. sp. cubense subtropical race 4.

Banana (Musa spp.) is the most widely consumed fruit globally. Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (Foc), is a highly threatening disease to banana production. Resistance genes to Foc exist in wild Musa genotypes such as Musa acuminata subsp. burmannicoides var. Calcutta 4. Whilst real-time PCR (RT-qPCR) is appropriate for accurate analysis of gene expression in pathways involved in host defence responses, reference genes with stable expression under specific biotic stress conditions and host tissue types are necessary for normalization of sample variation. In this context, the stability in potential host reference genes ACT1, APT, EF1α, GAPDH, αTUB, RAN, UBIQ1, UBIQ2, βTUB1, βTUB3, L2 and ACTA1 was evaluated in total RNA samples from root tissues in Calcutta 4 (resistant) and Musa sp. cultivar Prata-anã (susceptible) extracted during interaction with Foc subtropical race 4 (STR4). Expression stability was calculated using the algorithms geNorm, NormFinder and BestKeeper. βTUB3 and L2 were identified as the most stable in Calcutta 4, with ACTA1 and GAPDH the most stable in Prata-anã. These reference genes for analysis of gene expression modulation in the Musa-Foc STR4 pathosystem are fundamental for advancing understanding of host defence responses to this important pathogen.