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ABSTRACT HpaG(Xooc), produced by Xanthomonas oryzae pv. oryzicola, is a member of harpin group of proteins that stimulate plant growth, hypersensitive cell death (HCD), and pathogen defense. The protein contains two copies of the glycine-rich motif (GRM), a characteristic of harpins, and a cysteine, which is absent in other harpins. Genetic modification generated the pro-tein mutants HpaG(Xooc)MG (MG) by deleting GRMs and HpaG(Xooc)C47T (C47T) by replacing cysteine with threonine. When applied to tobacco plants, C47T and MG were 1.2- and 1.7-fold stronger, respectively, than HpaG(Xooc) in inducing HCD, which occurred consistently with expression of the marker genes hin1 and hsr203. The proteins markedly alleviated infection of tobacco by Tobacco mosaic virus and Arabidopsis and tomato by Pseudomonas syringae. Treating tobacco plants with HpaG(Xooc), C47T, and MG decreased the viral infection by 58, 81, and 92%, respectively. In Arabidopsis and tomato plants treated with HpaG(Xooc), C47T, or MG, P. syringae multiplication was inhibited; bacterial population multiplied in 5 days in these plants were ca. 160-, 1,260-, or 15,860-fold smaller than that in control plants. So pathogen defense was induced in both plants. Defense-related genes Chia5, NPR1, and PR-1a were expressed consistently with resistance. In response to HpaG(Xooc), C47T, and MG, aerial parts and roots of tomato plants increased growth by 15 and 53%, 25 and 77%, and 46 and 106%, relative to controls. The expansin gene, EXP2, involved in the cell expansion and plant growth was expressed coordinately with plant growth promotion. These results suggest that the presence of GRM and cysteine in HpaG(Xooc) represses the effects of the protein in plants. 相似文献
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Plant glutathione S‐transferase (GST) forms a major part of the herbicide detoxification enzyme network in plants. A GST cDNA was isolated from Echinochloa crus‐galli and characterised. The gene, designated EcGST1 (E. crus‐galli GeneBank no: JX518596 ), has a 684 bp open reading frame predicted to encode a 25 kD protein. Sequence alignment showed that EcGST1 is a GST homologue. Its expression in response to quinclorac treatment was monitored in seedlings (leaves and roots) and adult plants (leaves, roots, stems and seeds) of quinclorac‐resistant (R) and susceptible (S) biotypes of E. crus‐galli. EcGST1 expression was 1.5–3 times greater in the R plants than in the S plants. However, after exposure to quinclorac, the difference in the expression levels of EcGST1 in R plants, compared with S plants, increased to a ratio of 6–10. Enhanced EcGST1 levels should enable greater quinclorac detoxification following quinclorac stimulation in R plants. GST‐based metabolism may be partially responsible for resistance to quinclorac in E. crus‐galli. The results suggest a new resistance mechanism for this R biotype in Chinese rice fields. 相似文献
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乌副盔蚧的生物学及其防治研究 总被引:6,自引:0,他引:6
乌副盔蚧Parasaissetia nigra(Nietner)是柑桔及许多园林植物的一种重要害虫,在广州一年发生8~9代,各代历期变化为28~66天。雌成虫产卵量为64~208粒,卵的孵化率高达95~100%。第1龄爬行若虫的出壳高峰在上午10时左右。该虫的种群数量秋季明显上升。调查得到寄生性和捕食性天敌共9种,5种寄生蜂中,以胶蚧红眼啮小蜂Tetrastichus purpureus和日本软蚧蚜小蜂Coccophagus japonicus两种为最主要。杀虫剂试验表明,用2.5%溴氰菊酯1:2000倍液喷雾或以40%氧化乐果1:6倍液涂干可防治此虫。 相似文献
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于2014—2018年冬季,在广西桂南地区、桂中、桂西和桂东南地区选择不同类型甘蔗地,调查黏虫发生及为害情况。结果表明,新植蔗和收割后焚烧蔗叶的宿根蔗地极少发现黏虫,而收割后蔗叶(直接或粉碎)还田的宿根蔗地发现有不同龄期的幼虫为害,老蔗地亦发现老熟幼虫或蛹,但虫口密度低。数据显示,广西桂南地区冬季甘蔗地黏虫虫口密度最大。其中,2017年南宁市武鸣区虫口密度最高,达8.9头/m^2,其次是桂东南地区,桂中地区和桂西地区极少或未发现黏虫。 相似文献