Arthikala Manoj-Kumar, Montiel Jesús, Nava Noreide, Santana Olivia, Sánchez-López Rosana, Cárdenas Luis, Quinto Carmen
Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México, UNAM, Apartado Postal 510-3, Cuernavaca, Morelos 62271, México.
Plant Cell Physiol. 2013 Aug;54(8):1391-402. doi: 10.1093/pcp/pct089. Epub 2013 Jun 20.
Plant NADPH oxidases (RBOHs) regulate the early stages of rhizobial infection in Phaseolus vulgaris and affect nodule function in Medicago truncatula. In contrast, the role of RBOHs in the plant-arbuscular mycorrhizal (AM) symbiosis and in the regulation of reactive oxygen species (ROS) production during the establishment of the AM interaction is largely unknown. In this study, we assessed the role of P. vulgaris Rboh (PvRbohB) during the symbiosis with the AM fungus, Rhizophagus irregularis. Our results indicate that the PvRbohB transcript is significantly up-regulated in the mycorrhized roots of P. vulgaris. Further, the PvRbohB promoter was found to be active during the invasion of R. irregularis. Down-regulation of PvRbohB transcription by RNAi (RNA interference) silencing resulted in diminished ROS levels in the transgenic mycorrhized roots and induced early hyphal root colonization. Interestingly, the size of appressoria increased in PvRbohB-RNAi roots (760 ± 70.1 µm) relative to controls (251 ± 73.2 µm). Finally, the overall level of mycorrhizal colonization significantly increased in PvRbohB-RNAi roots [48.1 ± 3.3% root length colonization (RLC)] compared with controls (29.4 ± 1.9% RLC). We propose that PvRbohB negatively regulates AM colonization in P. vulgaris.
植物NADPH氧化酶（呼吸爆发氧化酶同源蛋白，RBOHs）调控菜豆根瘤菌感染的早期阶段，并影响蒺藜苜蓿的根瘤功能。相比之下，RBOHs在植物与丛枝菌根（AM）共生关系中以及在AM相互作用建立过程中对活性氧（ROS）产生的调控作用在很大程度上尚不清楚。在本研究中，我们评估了菜豆Rboh（PvRbohB）在与AM真菌不规则球囊霉共生过程中的作用。我们的结果表明，PvRbohB转录本在菜豆菌根化的根中显著上调。此外，发现PvRbohB启动子在不规则球囊霉侵入期间具有活性。通过RNA干扰（RNAi）沉默使PvRbohB转录下调，导致转基因菌根化根中的ROS水平降低，并诱导了菌丝早期定殖于根。有趣的是，与对照（251±73.2 µm）相比，PvRbohB-RNAi根中附着胞的大小增加（760±70.1 µm）。最后，与对照（29.4±1.9%根长定殖率，RLC）相比，PvRbohB-RNAi根中菌根定殖的总体水平显著增加[48.1±3.3%根长定殖率（RLC）]。我们提出，PvRbohB对菜豆中AM定殖起负调控作用。
