Project description: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 plants and a phloem-feeding insect pest, the vine mealybug Planococcus ficus. Plants were exposed to P. ficus for periods of 6 hours and 96 hours, after which they were analysed for gene expression levels using microarrays and quantitative real-time PCR (qPCR). Both methods showed that grapevine displayed only a minimal response to mealybug feeding at the transcript level at both time periods. Intermediate grapevine exposure times (24, 48 and 72 hours) to P. ficus feeding were investigated using qPCR analysis of ten additional genes associated with known plant defense responses. Results showed that only a single gene, pathogenesis-related protein 1, was differentially expressed after 48 hours of mealybug feeding. During the course of mealybug feeding, however, a number of other genes were significantly up- or down-regulated at certain time points. Thus, it appears as if grapevine responds minimally to feeding by P. ficus as well as within a very narrow time period. The relative lack of grapevine plant defense mechanisms may be a result of the feeding strategies of mealybugs.
Project description:MicroRNAs (miRNAs) are a class of endogenous small RNAs that play important roles in growth, development, and environmental stress response processes in plants. Ulmus pumila is a typical deciduous broadleaved tree species of north temperate, and is widely distributed in central and northern Asia, which has important economic and ecological value. With the spread and aggravate of soil salinisation, salt stress has become a major abiotic stress that highly affects the normal growth and development of U. pumila. However, to date, no investigation into the influence of salt stress on U. pumila miRNAs has been reported. To identify miRNAs and predict their target mRNA genes under salt stress, three small RNA libraries were generated and sequenced from CK (without salt stress), LSS (light salt stress for a short time) and MSL (medium-heavy salt stress for a long time) roots of U. pumila seedlings. Through integrative analysis, 245 conserved miRNAs representing 30 families and 64 novel miRNAs were identified, of which 89 exhibited altered expression level under salt stress, and 232 potential targets for the miRNAs were predicted and annotated in U. pumila. The expressions of six differentially expressed miRNAs were validated by qRT-PCR. These salt responsive miRNAs may play crucial roles in U. pumila defense against salt stress, and our miRNA data provides valuable information regarding further functional analysis of miRNAs involved in salt tolerance of U. pumila and other forest tree species.