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

Background

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

Results

A sugarcane WIP5 gene (ScWIP5) was 536 times up regulated after insect feeding treatment on previous published transcriptome databases. Then, ScWIP5 was cloned and evaluated its potential role in sugarcane resistance to fall armyworm 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 jasmonic acid (JA) and NbAOC, NbAOS, NbLOX from Jasmin acid biosynthesis pathway was significantly induced in ScWIP5 transgenic N. benthamiana compared to 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.

Conclusion

These results indicated that ScWIP5 might enhance insect‐resistance by increasing JA signal transduction processes and reducing insect digestive enzyme activities, thus impacting insect growth and development.

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