Wu Xiaojing, Wu Tingquan, Long Juying, Yin Qian, Zhang Yong, Chen Lei, Liu Ruoxue, Gao Tongchun, Dong Hansong
Key Laboratory of Monitoring and Management of Plant Pathogens and Insect Pests, Ministry of Agriculture of China, Nanjing Agricultural University, Nanjing 210095, China.
J Biosci. 2007 Sep;32(6):1119-31. doi: 10.1007/s12038-007-0113-1.
Harpin proteins from plant pathogenic bacteria can stimulate hypersensitive cell death (HCD), drought tolerance, defence responses against pathogens and insects in plants, as well as enhance plant growth. Recently, we identified nine functional fragments of HpaG;Xooc, a harpin protein from Xanthomonas oryzae pv.oryzicola, the pathogen that causes bacterial leaf streak in rice. Fragments HpaG;1-94'HpaG;10-42, and HpaG;62-138, which contain the HpaG;Xooc regions of the amino acid sequence as indicated by the number spans, exceed the parent protein in promoting growth, pathogen defence and HCD in plants. Here we report improved productivity and biochemical properties of green tea (Camellia sinensis) in response to the fragments tested in comparison with HpaG;Xooc and an inactive protein control. Field tests suggested that the four proteins markedly increased the growth and yield of green tea, and increased the leaf content of tea catechols, a group of compounds that have relevance in the prevention and treatment of human diseases. In particular, HpaG;1-94 was more active than HpaG;Xooc in expediting the growth of juvenile buds and leaves used as green tea material and increased the catechol content of processed teas. When tea shrubs were treated with HpaH;Xooc and HpaG;1-94 compared with a control, green tea yields were over 55% and 39% greater, and leaf catechols were increased by more than 64% and 72%, respectively. The expression of three homologues of the expansin genes, which regulate plant cell growth, and the CsCHS gene encoding a tea chalcone synthase, which critically regulates the biosynthesis of catechols, were induced in germinal leaves of tea plants following treatment with HpaG;1-94 or HpaG;Xooc. Higher levels of gene expression were induced by the application of HpaG;1-94 than HpaG;Xooc. Our results suggest that the harpin protein, especially the functional fragment HpaG;1-94, can be used to effectively increase the yield and improve the biochemical properties of green tea, a drink with medicinal properties.
来自植物致病细菌的harpin蛋白可刺激植物发生过敏细胞死亡（HCD）、提高耐旱性、引发针对病原体和昆虫的防御反应，还能促进植物生长。最近，我们鉴定出了水稻白叶枯病菌（Xanthomonas oryzae pv.oryzicola）中harpin蛋白HpaG;Xooc的九个功能片段，该病菌会导致水稻细菌性条斑病。片段HpaG;1 - 94、HpaG;10 - 42和HpaG;62 - 138，其氨基酸序列的跨度涵盖了HpaG;Xooc的区域，在促进植物生长、抵御病原体和引发HCD方面比母体蛋白表现更为出色。在此，我们报告了与HpaG;Xooc和无活性蛋白对照相比，经测试的片段处理后绿茶（Camellia sinensis）的生产力和生化特性得到了改善。田间试验表明，这四种蛋白显著提高了绿茶的生长量和产量，并增加了茶叶儿茶素的含量，儿茶素是一组与人类疾病防治相关的化合物。特别是，HpaG;1 - 94在促进用作绿茶原料的幼芽和叶片生长方面比HpaG;Xooc更具活性，并提高了加工后茶叶的儿茶素含量。与对照相比，当茶树用HpaH;Xooc和HpaG;1 - 94处理时，绿茶产量分别提高了55%以上和39%以上，叶片儿茶素含量分别增加了64%以上和72%以上。在用HpaG;1 - 94或HpaG;Xooc处理后，茶树的新生叶片中诱导表达了三种调控植物细胞生长的伸展蛋白基因同源物，以及一个编码茶查尔酮合酶的CsCHS基因，该酶对儿茶素的生物合成起关键调控作用。与HpaG;Xooc相比，施用HpaG;1 - 94诱导的基因表达水平更高。我们的研究结果表明，harpin蛋白，尤其是功能片段HpaG;1 - 94，可有效用于提高绿茶产量并改善其生化特性，绿茶是一种具有药用价值的饮品。
