Viçosa Federal University, Department of Plant Pathology of Host-Parasite Interaction, Viçosa Minas Gerais State, Brazil.
Phytopathology. 2012 Sep;102(9):892-8. doi: 10.1094/PHYTO-01-12-0014-R.
Considering the economic importance of anthracnose, caused by Colletotrichum sublineolum, and silicon (Si) to enhance sorghum resistance against this disease, this study aimed to investigate the effect of this element on leaf gas exchange and also the antioxidative system when infected by C. sublineolum. Plants from sorghum line CMSXS142 (BR 009 [Tx623] - Texas), growing in hydroponic culture with (+Si, 2 mM) or without (-Si) Si, were inoculated with C. sublineolum. Disease severity was assessed at 2, 4, 6, 8, and 10 days after inoculation (dai) and data were used to calculate the area under anthracnose progress curve (AUAPC). Further, the net carbon assimilation rate (A), stomatal conductance to water vapor (g(s)), internal-to-ambient CO₂ concentration ratio (C(i)/C(a)), and transpiration rate (E); the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR); the electrolyte leakage (EL), and the concentrations of hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) were determined. The AUAPC was reduced by 86% for the +Si plants compared with the -Si plants. The values of A, g(s), and E were lower upon inoculation of -Si plants in contrast to inoculated +Si plants with decreases of 31 and 60% for A, 34 and 61% for g(s), and 27 and 57% for E, respectively, at 4 and 8 dai. For the noninoculated plants, there was no significant difference between the -Si and +Si treatments for the values of A, g(s), and E. The C(i)/C(a) ratio was similar between the -Si and +Si treatments, regardless of the pathogen inoculation. The activities of SOD, CAT, APX, and GR tended to be higher in the +Si plants compared with the -Si plants upon inoculation with C. sublineolum. The EL significantly increased for -Si plants compared with +Si plants. The MDA concentration significantly increased by 31 and 38% at 4 and 8 dai, respectively, for the -Si plants compared with the +Si plants. Based on these results, Si may have a positive effect on sorghum physiology when infected by C. sublineolum through the maintenance of carbon fixation and also by enhancing the antioxidant system, which resulted in an increase in reactive oxygen species scavenging and, ultimately, reduced damage to the cell membranes.
考虑到炭疽病（由尖孢炭疽菌引起）和硅（Si）对提高高粱抗性的经济重要性，本研究旨在研究该元素对叶片气体交换的影响，以及感染尖孢炭疽菌时的抗氧化系统。在水培条件下，将来自 CMSXS142 高粱品系（BR 009 [Tx623] - Texas）的植物种植在有（+Si，2 mM）或没有（-Si）Si 的环境中，然后用尖孢炭疽菌接种。在接种后 2、4、6、8 和 10 天（dai）评估疾病严重程度，并使用该数据计算炭疽病进展曲线下面积（AUAPC）。此外，还测定了净碳同化率（A）、水蒸气气孔导度（g(s)）、内部到环境 CO₂浓度比（C(i)/C(a)）和蒸腾率（E）；超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、抗坏血酸过氧化物酶（APX）和谷胱甘肽还原酶（GR）的活性；电解质泄漏（EL）以及过氧化氢（H₂O₂）和丙二醛（MDA）的浓度。与-Si 植物相比，+Si 植物的 AUAPC 降低了 86%。与接种+Si 植物相比，接种-Si 植物的 A、g(s)和 E 值在接种后降低了 31%和 60%，A、g(s)和 E 值分别降低了 34%和 61%，E 值降低了 27%和 57%，分别为 4 和 8 dai。对于未接种的植物，-Si 和+Si 处理之间的 A、g(s)和 E 值没有显著差异。无论病原体接种与否，-Si 和+Si 处理之间的 C(i)/C(a)比值相似。与-Si 植物相比，接种尖孢炭疽菌后，+Si 植物的 SOD、CAT、APX 和 GR 活性往往更高。与+Si 植物相比，-Si 植物的 EL 显著增加。与+Si 植物相比，-Si 植物在 4 和 8 dai 时 MDA 浓度分别显著增加 31%和 38%。基于这些结果，Si 可能通过维持碳固定以及通过增强抗氧化系统对感染尖孢炭疽菌的高粱生理学产生积极影响，从而增加活性氧物质的清除，最终减少对细胞膜的损伤。
