水稻内生菠萝泛菌YJ76吲哚产量上调突变株的鉴定及生理性状

菠萝泛菌(Pantoea ananatis)YJ76是从水稻"越富"品种中分离的优势内生菌,与宿主水稻互作时具有多种促生作用,其分泌的吲哚作为细菌种内及种间的信号分子参与调控多种生理生化行为。目的]筛选获得与吲哚调控相关的突变株,鉴定突变位点并研究突变基因对菌株的生存适应性以及对宿主水稻定殖和促生的影响,为研究吲哚调控通路奠定基础。方法]用双亲本接合法构建YJ76的mTn5转座子插人突变文库,以染色体步移TAIL-PCR技术鉴定突变基因,最后探究基因突变对菌体产生的影响。结果]筛选到1株吲哚产量大幅上升的YJ76突变株M04,鉴定突变位点为一个长度195 bp未报道过的新基因,将其命名为ipc(indole production control),基因突变后增强了YJ76对重金属、四环素和酸的抗性,也增强了菌体对宿主水稻定殖和促生的能力。结论]吲哚产量上调的ipc突变株能够提高菌体生存适应性并增强其对宿主水稻定殖和促生的能力。

Identification and characterization of an indole production-upregulated mutant of rice endophytic Pantoea ananatis YJ76

Objective] To obtain and identify mutants related to indole regulation will provide functional genes responding for bacterial survival adaptability and in-planta colonization/association, which will be significant to the study of indole regulation pathway. Methods] A mutant library of YJ76 was constructed by mTn5 transposon mutagenesis method, from which the mutant genes could be identified by using the high-efficiency TAIL PCR (hiTAIL-PCR) technique. Results] A mutant strain named M04 with significantly increased indole production was selected from the mutant library of YJ76, and the mutation site was identified as a new gene (195 bp), which we named as ipc (indole production control) gene. This mutation enhanced the bacterial resistance to heavy metals, tetracycline and acids, and also enhanced the colonizing/plant growth-promoting ability of the endophyte on rice.Conclusion] By carrying ipc mutation, the mutant strain increased indole production, resulting in the improved survival adaptability and higher association ability on the host rice.