Selection and validation of stable reference genes for gene expression analysis in response to sweetpotato weevil infestation (Cylas formicarius (Fabricius)) in [Ipomoea batatas (L.) Lam] and [Ipomoea mauritiana (Jacq.)]

Sweetpotato is an important tropical tuber crop and serve as a rich source of essential nutrients vitamins C and E, B, iron, zinc, potassium and fiber. In spite of its nutritional value and agricultural importance as a food crop sweetpotato weevil infestation remains as a threat which leads to 80–90% loss for sweetpotato cultivation. Ipomoea. mauritiana was identified as one of the resistant wild genotype for sweetpotato weevil resistance. In the present study 10 candidate reference genes were used for RT-qPCR study for Ipomoea batatas and I. mauritiana. The stability of their expression was analyzed using two software, RefFinder and EndoGeneAnalyzer. The samples consisted of leaves and roots from I. batatas and I. mauritiana plants from different environmental conditions (uninfested and sweetpotato weevil infested). The results of Ct values analysis showed that the expression of ADP-ribosylation factor (ARF) was stable in root whereas histone H2B was found to be stable in leaves of I. batatas and I. mauritiana. The leaf samples of H2B, GAP, PLD and CYC were validated as the most suitable reference gene. Similarly the root samples of ARF, ACT, H2B and GAP were validated as the most suitable reference gene. This is the first study to report the selection of stable reference genes in I. batatas and wild tuberous I. mauritiana in response to sweetpotato weevil infestation.