First insights into grapevine transcriptional responses as a result of vine mealybug Planococcus ficus feeding

Abstract

Plant response to insect feeding appears to be highly specific with regard to the organisms in the system. Here, we report on the interaction between grapevine Vitis vinifera L. plants and a phloem-feeding insect pest, the vine mealybug Planococcus ficus (Homoptera: Pseudococcidae). Plants were exposed to P. ficus for periods of 6 and 96 h, respectively, after which they were analysed for differences in gene expression levels using microarrays. Grapevine displayed a fairly low response to mealybug feeding, with only 107 and 149 transcripts being differentially expressed compared to uninfested control plants after 6 and 96 h of mealybug feeding, respectively. Most of these genes are known to be expressed by grapevine or other plants as a response to microbial pathogen attack. In addition, intermediate exposure times (24, 48 and 72 h) of grapevine plants to P. ficus feeding were investigated using qPCR analysis of ten genes associated with known plant defence responses. Results showed that only a single gene, pathogenesis-related protein 1, was differentially expressed after 48 h of mealybug feeding compared to control plants. Therefore, our study has shown that on a transcriptional level grapevine plants respond weakly to attack by vine mealybugs, which is analogous to a range of other studies on plant responses to piercing-sucking insects.