Ishizawa Hidehiro, Kuroda Masashi, Morikawa Masaaki, Ike Michihiko
Division of Sustainable Energy and Environmental Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
Division of Biosphere Science, Graduate School of Environmental Science, Hokkaido University, N10-W5, Kita-ku, Sapporo 060-0810, Japan.
Plant Physiol Biochem. 2017 Sep;118:667-673. doi: 10.1016/j.plaphy.2017.08.006. Epub 2017 Aug 9.
Bacteria colonizing the plant rhizosphere are believed to positively or negatively affect the host plant productivity. This feature has inspired researchers to engineer such interactions to enhance crop production. However, it remains to be elucidated whether rhizobacteria influences plant oxidative stress vis-a-vis other environmental stressors, and whether such influence is associated with their growth promoting/inhibiting ability. In this study, two plant growth-promoting bacteria (PGPB) and two plant growth-inhibiting bacteria (PGIB) were separately inoculated into axenic duckweed (Lemna minor) culture under laboratory conditions for 4 and 8 days in order to investigate their effects on plant oxidative stress and antioxidant activities. As previously characterized, the inoculation of PGPB and PGIB strains accelerated and reduced the growth of L. minor, respectively. After 4 and 8 days of cultivation, compared to the PGPB strains, the PGIB strains induced larger amounts of O, HO, and malondialdehyde (MDA) in duckweed, although all bacterial strains consistently increased O content by two times more than that in the aseptic control plants. Activities of five antioxidant enzymes were also elevated by the inoculation of PGIB, confirming the severe oxidative stress condition in plants. These results suggest that the surface attached bacteria affect differently on host oxidative stress and its response, which degree correlates negatively to their effects on plant growth.
定殖于植物根际的细菌被认为会对宿主植物的生产力产生正面或负面影响。这一特性激发了研究人员对这类相互作用进行调控以提高作物产量。然而，根际细菌相对于其他环境胁迫因子对植物氧化应激的影响，以及这种影响是否与其促进/抑制植物生长的能力相关，仍有待阐明。在本研究中，在实验室条件下，将两种植物促生细菌（PGPB）和两种植物抑生细菌（PGIB）分别接种到无菌浮萍（小浮萍）培养物中4天和8天，以研究它们对植物氧化应激和抗氧化活性的影响。如先前所述，接种PGPB和PGIB菌株分别加速和降低了小浮萍的生长。培养4天和8天后，与PGPB菌株相比，PGIB菌株在浮萍中诱导产生了更多的超氧阴离子（O）、过氧化氢（HO）和丙二醛（MDA），尽管所有细菌菌株均使超氧阴离子含量比无菌对照植物中的超氧阴离子含量持续增加了两倍多。接种PGIB也提高了五种抗氧化酶的活性，证实了植物中存在严重的氧化应激状况。这些结果表明，附着在植物表面的细菌对宿主氧化应激及其反应的影响不同，其影响程度与它们对植物生长的影响呈负相关。
