Nascimento Kelly Juliane Telles, Debona Daniel, França Sueny Kelly Santos, Gonçalves Mariana Gabriele Marcolino, DaMatta Fábio Murilo, Rodrigues Fabrício Ávila
Phytopathology. 2014 Nov;104(11):1183-91. doi: 10.1094/PHYTO-02-14-0047-R.
Frogeye leaf spot, caused by Cercospora sojina, is one of the most important leaf diseases of soybean worldwide. Silicon (Si) is known to increase the resistance of several plant species to pathogens. The cultivars Bossier and Conquista, which are susceptible and resistant, respectively, to frogeye leaf spot, supplied and nonsupplied with Si were examined for the activities of defense enzymes and the concentrations of total soluble phenolics (TSP) and lignin-thioglycolic acid (LTGA) derivatives at 8, 14, and 16 days after inoculation (dai) with C. sojina. The importance of cell wall degrading enzymes (CWDE) to the infection process of C. sojina and the effect of Si on their activities were also determined. Soybean plants were grown in hydroponic culture containing either 0 or 2 mM Si (-Si and +Si, respectively) and noninoculated or C. sojina inoculated. Severity of frogeye leaf spot was higher in cultivar Bossier plants than cultivar Conquista and also in the +Si plants compared with their -Si counterparts. Except for the concentrations of TSP and LTGA derivatives, activities of defense enzymes and the CWDE did not change for +Si noninoculated plants regardless of the cultivar. The activities of lipoxygenases, phenylalanine ammonia-lyases, chitinases, and polyphenoloxidases as well as the activities of CWDE decreased for the +Si inoculated plants. The results from this study demonstrated that defense enzyme activities decreased in soybean plants supplied with Si, which compromised resistance to C. sojina infection.
由大豆尾孢菌引起的蛙眼叶斑病是全球大豆最重要的叶部病害之一。已知硅（Si）可增强多种植物对病原体的抗性。分别对接种和未接种硅的、对蛙眼叶斑病敏感的品种博西尔（Bossier）和抗病品种征服者（Conquista）进行了研究，测定了接种大豆尾孢菌后8、14和16天（接种后天数，dai）的防御酶活性、总可溶性酚（TSP）浓度以及木质素 - 巯基乙酸（LTGA）衍生物浓度。还确定了细胞壁降解酶（CWDE）对大豆尾孢菌感染过程的重要性以及硅对其活性的影响。大豆植株种植在分别含有0或2 mM硅（分别为 - Si和 + Si）的水培培养液中，分为未接种或接种大豆尾孢菌处理。博西尔品种植株上的蛙眼叶斑病严重程度高于征服者品种，并且 + Si植株相较于 - Si植株病情更严重。除了TSP和LTGA衍生物浓度外，无论品种如何， + Si未接种植株的防御酶和CWDE活性均未发生变化。对于 + Si接种植株，脂氧合酶、苯丙氨酸解氨酶、几丁质酶和多酚氧化酶的活性以及CWDE活性均下降。本研究结果表明，供应硅的大豆植株中防御酶活性降低，这削弱了对大豆尾孢菌感染的抗性。
