A ScWIP5 gene confers fall armyworm resistance by reducing digestive enzyme activities in sugarcane

The fall armyworm, Spodoptera frugiperda, is one of the most dangerous pests to various crops. As the most crucial sugar crop, sugarcane is also constantly threatened by these pests. Plant wound-induced proteinase inhibitors (WIP) are natural defense proteins that play important roles in the defense system against insect attack. Breeding for resistance would be the best way to improve the variety characteristics and productivity of sugarcane. Screening and verification for potential plant endogenous insect-resistant genes would greatly improve the insect-resistant breeding progress of sugarcane.

A sugarcane WIP5 gene (ScWIP5) was up-regulated 536 times after insect feeding treatment on previous published transcriptome databases. ScWIP5 was then cloned and its potential role in sugarcane resistance to fall armyworm evaluated by construction of transgenic Nicotiana benthamiana. The toxicity of ScWIP5 transgenic N. benthamiana to fall armyworm showed lower weight gain and higher mortality compared to wild-type N. benthamiana feeding group. Furthermore, the concentration of JA and NbAOC, NbAOS, and NbLOX from the Jasmin acid biosynthesis pathway was significantly induced in ScWIP5 transgenic N. benthamiana compared to the control. In addition, digestive enzyme actives from the insect gut were also evaluated, and trypsin and cathepsin were significantly lower in insects fed with ScWIP5 transgenic N. benthamiana.

These results indicate that ScWIP5 might enhance insect resistance by increasing JA signal transduction processes and reducing insect digestive enzyme activities, thus impacting insect growth and development. © 2023 Society of Chemical Industry.