The objective of this study was to identify rice genes that are in response to the striped stem borer （SSB） （Chilo suppressalis Walker） feeding at the first to second larval stage. Using combined suppression subtractive hybridization （SSH） and dot blot approaches, we analyzed the induced defense genes that took place during the first 72 h of infesting intact rice （Oryza sativa L.） plants in sheath tissues with SSB larvae. By sequencing the whole SSH library, 39 expressed sequence tags involved in disease stress, insect stress or other stress responses were identified to be up-regulated by SSB larvae feeding. Among these genes, rice allene oxide cyclase （AOC）, terpene synthase （TPS） and four proteinase inhibitor （PI） genes were up-regulated by SSB larvae feeding. Real-time quantitative reverse transcription polymerase chain reaction analysis showed that four rice PI genes were already up-regulated at 6 h, and reached peaks between 6 h to 12 h. In addition, the transcription ofgene involving in jasmonate signaling pathway such as allene oxide cyclase （AOC） concerning rice early defense response to SSB feeding was activated after rice feeding by SSB for 2 h. Although the expression office terpene synthase （TPS） gene, involved in the biosynthesis ofmonoterpenes or diterpenes, was already up-regulated at 7 h, a significant increase in the expression was delayed until 12 h and reached its peak at 24 h. The present study identified six SSB-response genes and their expression patterns, which provides evidence and information to understand insect stress-response in plants.
Yang SunYong-Jun ZhangGuang-Chun CaoShao-Hua GuKong-Ming WuXi-Wu GaoYu-Yuan Guo
A gene encoding a novel G protein β subunit of β1 subclass, GβMmed was isolated from Microplitis mediator （Hymenoptera： Braconidae）. The full-length sequence of GβMmed is 1 119 bp, the cDNA contains a 1 023 bp open reading frame that encodes a protein with 340 amino acids, and the predicted molecular weight of GβMmed is 37.23 kDa and isoelectric point is 5.86. By the quantitative real-time RT-PCR method, the tissue-specific expression and quantitative changes in the developmental expression profile of GβMmed were detected. It was found that GβMmed was abundantly expressed in M. mediator antennae, head （without antennae）, thorax, abdomen, legs and the wings, and especially at high levels in abdomen. In antennae, expression varied through 1st day before emergence to 5-d-old adults, and had equal expression levels detected in females and males in total. In head, GβMmed expresses while initially high in females, and have another peaked in stage 4 and 1st day, in males showed a peak of GβMmed expression prior to emergence and relatively low levels after emergence. In female abdomen GβMmed expression levels have two peaks in stage 1 and the 5th d, but just have one peak in male abdomen in stage 1. In all other tissues expression was low and stable.
