Lambais M R, Ríos-Ruiz W F, Andrade R M
Departamento de Solos e Nutrição de Plantas, ESALQ, Universidade de São Paulo, Caixa Postal 9, 13418-900 Piracicaba, SP, Brazil.
Present address: Universidad Nacional de San Martín, Jr. Maynas 177, Tarapoto, San Martín, Peru.
New Phytol. 2003 Nov;160(2):421-428. doi: 10.1046/j.1469-8137.2003.00881.x.
• Degradation of reactive oxygen species in arbuscular mycorrhizas (AM) may be an efficient mechanism to attenuate the activation of plant defenses. Here, we evaluated the activities of superoxide dismutase (SOD), guaiacol-peroxidase (GPX) and catalase (CAT) in bean (Phaseolus vulgaris) mycorrhizal roots at different conditions and stages of symbiosis development. • Bean plants were inoculated with Glomus clarum (Gc) or G. intraradices (Gi), under low (LP) and high P (HP) concentrations, and grown under glasshouse conditions. In a second experiment, bean seeds were treated with formononetin and inoculated with Gc under LP and HP conditions. The activities of SOD, GPX and CAT were evaluated. • SOD was induced only in roots colonized by Gc, at a late stage of the symbiosis development under LP, and at an early stage under HP. GPX was induced in roots colonized by Gc at an early time point and suppressed later under LP. In general, CAT was induced in roots colonized by Gc under LP. CAT activities in roots were dependent on P and formononetin treatment. • The possible roles of SOD, GPX and CAT in AM are discussed.
• 丛枝菌根（AM）中活性氧的降解可能是减弱植物防御激活的一种有效机制。在此，我们评估了菜豆（Phaseolus vulgaris）菌根根中在共生发育的不同条件和阶段下超氧化物歧化酶（SOD）、愈创木酚过氧化物酶（GPX）和过氧化氢酶（CAT）的活性。
• 菜豆植株在低磷（LP）和高磷（HP）浓度下接种了明球囊霉（Gc）或根内球囊霉（Gi），并在温室条件下生长。在第二个实验中，菜豆种子用芒柄花素处理，并在LP和HP条件下接种Gc。评估了SOD、GPX和CAT的活性。
• SOD仅在LP条件下共生发育后期被Gc定殖的根中以及HP条件下早期被诱导。GPX在早期被Gc定殖的根中被诱导，随后在LP条件下被抑制。总体而言，LP条件下被Gc定殖的根中CAT被诱导。根中CAT活性取决于磷和芒柄花素处理。
• 讨论了SOD、GPX和CAT在AM中的可能作用。
