Wang Fang, Ning Duo, Chen Yang, Dang Cong, Han Nai-Shun, Liu Yu'e, Ye Gong-Yin
State Key Laboratory of Rice Biology, Ministry of Agriculture Key Laboratory of Agricultural Entomology, Insect Physiology and Biochemistry, Institute of Insect Sciences, Zhejiang University Hangzhou, China.
State Key Laboratory of Rice Biology, China National Rice Research Institute Hangzhou, China.
Front Plant Sci. 2015 Dec 24;6:1181. doi: 10.3389/fpls.2015.01181. eCollection 2015.
Bt proteins are the most widely used insecticidal proteins in transgenic crops for improving insect resistance. We previously observed longer nymphal developmental duration and lower fecundity in brown planthopper (BPH) fed on Bt rice line KMD2, although Bt insecticidal protein Cry1Ab could rarely concentrate in this non-target rice pest. In the present study, we performed microarray analysis in an effort to detect Bt-independent variation, which might render Bt rice more defensive and/or less nutritious to BPH. We detected 3834 and 3273 differentially expressed probe-sets in response to BPH infestation in non-Bt parent Xiushui 11 and Bt rice KMD2, respectively, only 439 of which showed significant differences in expression between rice lines. Our analysis revealed a shift from growth to defense responses in response to BPH infestation, which was also detected in many other studies of plants suffering biotic and abiotic stresses. Chlorophyll biosynthesis and basic metabolism pathways were inhibited in response to infestation. IAA and GA levels decreased as a result of the repression of biosynthesis-related genes or the induction of inactivation-related genes. In accordance with these observations, a number of IAA-, GA-, BR-signaling genes were downregulated in response to BPH. Thus, the growth of rice plants under BPH attack was reduced and defense related hormone signaling like JA, SA and ET were activated. In addition, growth-related hormone signaling pathways, such as GA, BR, and auxin signaling pathways, as well as ABA, were also found to be involved in BPH-induced defense. On the other side, 51 probe-sets (represented 50 genes) that most likely contribute to the impact of Bt rice on BPH were identified, including three early nodulin genes, four lipid metabolic genes, 14 stress response genes, three TF genes and genes with other functions. Two transcription factor genes, bHLH and MYB, together with lipid transfer protein genes LTPL65 and early nodulin gene ENOD93, are the most likely candidates for improving herbivore resistance in plants.
Bt蛋白是转基因作物中应用最广泛的杀虫蛋白,用于提高抗虫性。我们之前观察到,以Bt水稻品系KMD2为食的褐飞虱若虫发育历期更长,繁殖力更低,尽管Bt杀虫蛋白Cry1Ab很少在这种非靶标水稻害虫体内积累。在本研究中,我们进行了微阵列分析,以检测与Bt无关的变化,这种变化可能使Bt水稻对褐飞虱更具防御性和/或营养更低。我们分别在非Bt亲本秀水11和Bt水稻KMD2中检测到3834个和3273个因褐飞虱侵害而差异表达的探针集,其中只有439个在水稻品系间表现出显著的表达差异。我们的分析揭示了褐飞虱侵害后从生长反应到防御反应的转变,这在许多其他关于遭受生物和非生物胁迫的植物的研究中也有发现。侵染后叶绿素生物合成和基本代谢途径受到抑制。由于生物合成相关基因的抑制或失活相关基因的诱导,IAA和GA水平下降。根据这些观察结果,许多IAA、GA、BR信号基因在褐飞虱侵害后下调。因此,褐飞虱攻击下水稻植株的生长受到抑制,与防御相关的激素信号如JA、SA和ET被激活。此外,还发现与生长相关的激素信号通路,如GA、BR和生长素信号通路,以及ABA也参与了褐飞虱诱导的防御。另一方面,可以确定51个探针集(代表50个基因)最有可能对Bt水稻对褐飞虱的影响起作用,包括3个早期结瘤素基因、4个脂质代谢基因、14个应激反应基因、3个转录因子基因和具有其他功能的基因。两个转录因子基因bHLH和MYB,以及脂质转移蛋白基因LTPL65和早期结瘤素基因ENOD93,是提高植物抗食草动物能力最有可能的候选基因。