Thanwisai Lalita, Kim Tran Hong Thi, Siripornadulsil Wilailak, Siripornadulsil Surasak
Department of Microbiology, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand.
Department of Microbiology, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand; Research Center for Environmental and Hazardous Substance Management, Khon Kaen University, Khon Kaen 40002, Thailand.
Plant Physiol Biochem. 2022 Dec 1;192:72-86. doi: 10.1016/j.plaphy.2022.09.021. Epub 2022 Sep 27.
The effect of the endophytic Cupriavidus taiwanensis KKU2500-3 on the Cd toxicity of KDML105 rice seedlings was investigated in a 10 μM CdCl hydroponic system. As demonstrated after bacterial inoculation of germinating rice seeds, KKU2500-3 colonized all rice plant parts. In RB (Rice + KKU2500-3) and RBC (Rice + KKU2500-3+Cd), KKU2500-3 effectively colonized and was detected at a markedly higher number in the root surface and interior than in shoots and leaves. The activities of antioxidant enzymes ascorbate peroxidase (APOX), glutathione reductase (GR), and superoxide dismutase (SOD) and the proline content in inoculated rice were higher in roots and aboveground tissues. RBC exhibited a higher reduced-to-oxidized glutathione ratio in roots and leaves (3-55%) but a lower malondialdehyde content (8-78%). Phytochelatins (PCs) were detected in all rice tissues, but their levels in RBC were 13-70% lower than those in RC (Rice + Cd), demonstrating that the induction of PCs in rice was unrelated to KKU2500-3. The Cd levels in roots and shoots were lower in RBC than RC, and the root-to-shoot Cd translocation factor was 0.6-62.2% lower. At 30 DAT, the Cd levels in RBC roots and shoots were 30.2% and 73.7% lower, respectively, than those in RC. Colonized KKU2500-3 activated GR and increased the proline content to overcome rice Cd toxicity. These effects may trap Cd in plant cells and reduce its translocation. Hence, KKU2500-3 synergistically interacts with rice to detoxify Cd at early growth stages, and KDML105 rice grains with low Cd accumulation could be produced if this interaction is maintained until late growth stages.
在10 μM CdCl水培系统中研究了内生台湾贪铜菌KKU2500-3对KDML105水稻幼苗镉毒性的影响。在对发芽的水稻种子接种细菌后发现，KKU2500-3定殖于水稻植株的所有部位。在RB（水稻+KKU2500-3）和RBC（水稻+KKU2500-3+镉）中，KKU2500-3有效地定殖，且在根表面和内部的检测数量明显高于地上部分（茎和叶）。接种水稻中抗氧化酶抗坏血酸过氧化物酶（APOX）、谷胱甘肽还原酶（GR）和超氧化物歧化酶（SOD）的活性以及脯氨酸含量在根和地上组织中较高。RBC在根和叶中的还原型谷胱甘肽与氧化型谷胱甘肽的比率较高（3-55%），但丙二醛含量较低（8-78%）。在所有水稻组织中均检测到植物螯合肽（PCs），但其在RBC中的水平比RC（水稻+镉）低13-70%，表明水稻中PCs的诱导与KKU2500-3无关。RBC中根和地上部分的镉含量低于RC，根到地上部分的镉转运系数低0.6-62.2%。在处理30天后，RBC根和地上部分的镉含量分别比RC低30.2%和73.7%。定殖的KKU2500-3激活GR并增加脯氨酸含量以克服水稻镉毒性。这些作用可能将镉捕获在植物细胞中并减少其转运。因此，KKU2500-3在水稻生长早期与水稻协同作用以解毒镉，如果这种相互作用维持到生长后期，则可以生产出镉积累量低的KDML105水稻籽粒。
