Ralstonia solanacearum Dps Contributes to Oxidative Stress Tolerance and to Colonization of and Virulence on Tomato Plants
Ralstonia solanacearum Dps Contributes to Oxidative Stress Tolerance and to Colonization of and Virulence on Tomato Plants
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DOI：
10.1128/aem.01742-10
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发表时间：
2010-11-01
影响因子：
4.4
通讯作者：
Allen, Caitilyn
中科院分区：
文献类型：
--
作者：
Colburn-Clifford, Jennifer M.;Scherf, Jacob M.;Allen, Caitilyn
青枯雷尔氏菌是一种重要的土传植物病原菌，通过侵染寄主根系引起青枯病。然而，对该病原菌在根际和发病早期的行为知之甚少。番茄根分泌物对R.青枯菌菌株UW551上调类似Dps的基因，Dps是一种来自饥饿细胞的非特异性DNA结合蛋白，对其他细菌的胁迫存活至关重要。火箭筒在饥饿条件下，青枯菌DPS突变体对过氧化氢的敏感性增加，突变率增加。此外，氧化应激反应调节剂OxyR对dps表达有正调节作用。这些功能结果与Dps注释一致。dps突变体在自然土壤浸泡接种后，引起番茄青枯病的轻微延迟。然而，当细菌直接接种到宿主茎中时，dps突变体的毒力降低更明显，表明Dps有助于R。青枯菌适应植物内部环境。通过番茄植株的传代，野生型和dps突变株的过氧化氢耐受性都得到了短暂的提高，这表明R。青枯菌在适应宿主环境的过程中获得不依赖于Dps的氧化应激耐受性。dps突变株对番茄根的粘附力和番茄茎的定殖能力也降低。这些结果表明，Dps是重要的，当细胞处于饥饿或静止期，Dps有助于定量寄主植物定殖和青枯病毒力。他们进一步建议R.青枯菌在细菌性枯萎病周期中必须克服氧化应激。
Ralstonia solanacearum, an economically important soilborne plant pathogen, infects host roots to cause bacterial wilt disease. However, little is known about this pathogen's behavior in the rhizosphere and early in pathogenesis. In response to root exudates from tomato, R. solanacearum strain UW551 upregulated a gene resembling Dps, a nonspecific DNA binding protein from starved cells that is critical for stress survival in other bacteria. An R. solanacearum dps mutant had increased hydrogen peroxide sensitivity and mutation rate under starvation. Furthermore, dps expression was positively regulated by the oxidative stress response regulator OxyR. These functional results are consistent with a Dps annotation. The dps mutant caused slightly delayed bacterial wilt disease in tomato after a naturalistic soil soak inoculation. However, the dps mutant had a more pronounced reduction in virulence when bacteria were inoculated directly into host stems, suggesting that Dps helps R. solanacearum adapt to conditions inside plants. Passage through a tomato plant conferred transient increased hydrogen peroxide tolerance on both wild-type and dps mutant strains, demonstrating that R. solanacearum acquires Dps-independent oxidative stress tolerance during adaptation to the host environment. The dps mutant strain was also reduced in adhesion to tomato roots and tomato stem colonization. These results indicate that Dps is important when cells are starved or in stationary phase and that Dps contributes quantitatively to host plant colonization and bacterial wilt virulence. They further suggest that R. solanacearum must overcome oxidative stress during the bacterial wilt disease cycle.