Expression of Pinellia pedatisecta Agglutinin PPA Gene in Transgenic Sugarcane Led to Stomata Patterning Change and Resistance to Sugarcane Woolly Aphid, Ceratovacuna lanigera Zehntner

The sugarcane woolly aphid is one of the main pests of sugarcane worldwide. The Pinellia pedatisecta agglutinin (PPA) gene has been demonstrated to function towards aphid resistance in other crops. In our study, in order to investigate the PPA function towards aphid control in sugarcane and its underlying mechanism, the PPA gene was overexpressed in a sugarcane Zhongzhe 1 (ZZ1) cultivar in independent transgenic sugarcane lines. It was confirmed in this study that PPA transgenic sugarcane can resist aphids via detecting the aphids’ development and tracing the survival number on PPA−transgenic sugarcane lines as well as PPA negative control lines. The mechanism of PPA lectin−associated defense against aphids was preliminarily explored. Stomatal patterning differences of sugarcane leaves between PPA−transgenic sugarcane lines and negative control lines were found. PPA overexpression led to an increase in stomata number and a decrease in stomata size that might have changed the transpiration status, which is critical for aphids’ passive feeding. Moreover, the antioxidant enzyme, sugar, tannin and chlorophyll content in sugarcane leaves before and after aphid infestation was determined. The results indicated that PPA overexpression in sugarcane resulted in an increase in antioxidant enzyme activity and tannin content, as well as a reduction in the decline of certain sugars. These together may improve sugarcane resistance against the sugarcane woolly aphid.