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RbohB , a Phaseolus vulgaris NADPH oxidase gene, enhances symbiosome number, bacteroid size, and nitrogen fixation in nodules and impairs mycorrhizal colonization
Author(s) -
Arthikala ManojKumar,
SánchezLópez Rosana,
Nava Noreide,
Santana Olivia,
Cárdenas Luis,
Quinto Carmen
Publication year - 2014
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.12714
Subject(s) - symbiosis , biology , nitrogen fixation , phaseolus , rhizobia , rhizobium , reactive oxygen species , botany , root nodule , nodule (geology) , nadph oxidase , microbiology and biotechnology , inoculation , bacteria , horticulture , genetics , paleontology
Summary The reactive oxygen species ( ROS ) generated by respiratory burst oxidative homologs ( Rboh s) are involved in numerous plant cell signaling processes, and have critical roles in the symbiosis between legumes and nitrogen‐fixing bacteria. Previously, down‐regulation of RbohB in Phaseolus vulgaris was shown to suppress ROS production and abolish Rhizobium infection thread ( IT ) progression, but also to enhance arbuscular mycorrhizal fungal ( AMF ) colonization. Thus, Rboh s function both as positive and negative regulators. Here, we assessed the effect of enhancing ROS concentrations, by overexpressing PvRbohB , on the P. vulgaris– rhizobia and P. vulgaris – AMF symbioses. We estimated superoxide concentrations in hairy roots overexpressing PvRbohB , determined the status of early and late events of both Rhizobium and AMF interactions in symbiont‐inoculated roots, and analyzed the nodule ultrastructure of transgenic plants overexpressing PvRbohB . Overexpression of PvRbohB significantly enhanced ROS production, the formation of IT s, nodule biomass, and nitrogen‐fixing activity, and increased the density of symbiosomes in nodules, and the density and size of bacteroides in symbiosomes. Furthermore, Pv CAT , early nodulin, Pv SS 1 , and Pv GOGAT transcript abundances were elevated in these nodules. By contrast, mycorrhizal colonization was reduced in roots that overexpressed RbohB . Overexpression of PvRbohB augmented nodule efficiency by enhancing nitrogen fixation and delaying nodule senescence, but impaired AMF colonization.