Genome Sequence and Mutational Analysis of Plant-Growth-Promoting Bacterium Agrobacterium tumefaciens CCNWGS0286 Isolated from a Zinc-Lead Mine Tailing
Genome Sequence and Mutational Analysis of Plant-Growth-Promoting Bacterium Agrobacterium tumefaciens CCNWGS0286 Isolated from a Zinc-Lead Mine Tailing
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从锌铅尾矿中分离出的促进植物生长的根癌农杆菌 CCNWGS0286 的基因组序列和突变分析
DOI：
10.1128/aem.01200-12
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发表时间：
2012-08-01
影响因子：
4.4
通讯作者：
Wei, Gehong
中科院分区：
文献类型：
--
作者：
Hao, Xiuli;Xie, Pin;Wei, Gehong
摘要从生长在锌铅尾矿中的刺槐根瘤中分离到一株植物生长促生菌根癌农杆菌CCNWGS0286，该菌具有较高的金属抗性，并能在金属污染环境中促进刺槐的生长。我们的目标是确定细菌的金属抗性或产生植物激素的能力在锌胁迫下对寄主植物的生长有更大的影响。通过转座子诱变，获得了8个锌敏感突变株和1个锌敏感突变株，其吲哚-3-乙酸(IAA)产量降低。通过逆转录聚合酶链式反应(RT-PCR)结合转座子基因干扰对其基因组序列和转录进行分析，结果表明，在根癌农杆菌CCNWGS0286的锌稳态过程中，ZntA-4200和转录调控因子ZntR1起着重要的作用。此外，一个可能的寡酮环化酶/脂转运蛋白的中断减少了IAA的合成，也显示出对锌和镉的抗性降低，但对铜的抗性没有影响。在温室研究中，即使在锌污染的环境中，接种根癌农杆菌CCNWGS0286的假相思菌株的生物量也比没有接种的显著增加。有趣的是，根癌农杆菌CCNWGS0286、根癌农杆菌C58和锌敏感突变体12-2(zntA：：Tn5)和15-6(低IAA产量)在提高植物生物量方面的差异表明，植物激素而不是编码抗锌决定基因的基因是促进污染土壤中植物生长的主导因素。
ABSTRACT The plant-growth-promoting bacterium Agrobacterium tumefaciens CCNWGS0286, isolated from the nodules of Robinia pseudoacacia growing in zinc-lead mine tailings, both displayed high metal resistance and enhanced the growth of Robinia plants in a metal-contaminated environment. Our goal was to determine whether bacterial metal resistance or the capacity to produce phytohormones had a larger impact on the growth of host plants under zinc stress. Eight zinc-sensitive mutants and one zinc-sensitive mutant with reduced indole-3-acetic acid (IAA) production were obtained by transposon mutagenesis. Analysis of the genome sequence and of transcription via reverse transcriptase PCR (RT-PCR) combined with transposon gene disruptions revealed that ZntA-4200 and the transcriptional regulator ZntR1 played important roles in the zinc homeostasis of A. tumefaciens CCNWGS0286. In addition, interruption of a putative oligoketide cyclase/lipid transport protein reduced IAA synthesis and also showed reduced zinc and cadmium resistance but had no influence on copper resistance. In greenhouse studies, R. pseudoacacia inoculated with A. tumefaciens CCNWGS0286 displayed a significant increase in biomass production over that without inoculation, even in a zinc-contaminated environment. Interestingly, the differences in plant biomass improvement among A. tumefaciens CCNWGS0286, A. tumefaciens C58, and zinc-sensitive mutants 12-2 (zntA::Tn5) and 15-6 (low IAA production) revealed that phytohormones, rather than genes encoding zinc resistance determinants, were the dominant factor in enhancing plant growth in contaminated soil.