Zhang Ya, Wang Chong, Su Pin, Liao Xiaolan
Department of Plant Protection, College of Plant Protection, Hunan Agricultural University, Changsha, P. R. China; Hunan Provincial Key Laboratory for the Biology and Control of Plant Diseases and Plant Pests, Changsha, P. R. China.
Department of Chemistry, Science College, Hunan Agricultural University, Changsha, P. R. China.
PLoS One. 2015 Oct 13;10(10):e0140380. doi: 10.1371/journal.pone.0140380. eCollection 2015.
To develop new agents against strawberry grey mould and to aid in the development of biological pesticides, we investigated the inhibitory effect of a natural compound, phenazine-1-carboxamide (PCN), against Botrytis cinerea using a growth rate assay. Additionally, indoor toxicity and the in vitro control effect of PCN were further studied to determine its potential mechanisms of action on B. cinerea. PCN was inhibitory against B. cinerea with a 50% effective concentration (EC50) of 108.12 μg/mL; the toxicity of PCN was equivalent to that of carbendazim (CBM). The best in vitro control effect of PCN against grey mould in strawberry (fruit) reached 75.32%, which was slightly higher than that of CBM. The field control effect of PCN against grey mould reached a maximum of 72.31% at a PCN concentration of 700 μg/mL, which was 1.02 times higher than that of CBM. Fungistatic activity was observed at low concentrations of PCN, while high concentrations of PCN resulted in fungicidal activity against B. cinerea. This natural compound strongly inhibited both spore and sclerotium germination of B. cinerea, with the best relative inhibition rates of 77.03% and 82.11%, respectively. The inhibitory effect of PCN on mycelial growth of B. cinerea was significant and reached levels of 87.32%. Scanning electron microscopy observations revealed that after 48 h of PCN treatment, the mycelia appeared loose, locally twisted, and folded, with exudation of contents; the mycelia was withered and twisted, with edge burrs, deformations, ruptures and a sheet-like structure. Transmission electron microscopy observations revealed that after 48 h of PCN treatment, the structure of the cell nucleus was unclear and the vacuoles had ruptured; additionally, various organelles exhibited disordered structures, there were substantial non-membrane transparent inclusions, the cells were plasmolysed, the cell walls were collapsed in some cases, and the hyphal tissue was essentially necrotic. A PCN dosage of 35-140 μg/mL had no effect on the cell membrane permeability of the mycelia, while a PCN dosage of 700 μg/mL resulted in significant permeability. PCN inhibited B. cinerea toxin; the mycotoxin level was approximately 0.41 of the value recorded for the control at a PCN dosage of 700 μg/mL. PCN affected the activity of pectin methylgalacturonase (PMG), polygalacturonase (PG), cellulase (Cx) and β-glucosidase (BG); the lowest activities of PMG, PG, BG and Cx reached 0.3 U/mg, 0.62 U/mg, 0.64 U/mg, and 0.79 U/mg, respectively, after treatment with 700 μg/mL PCN.
为开发抗草莓灰霉病的新型药剂并助力生物农药的研发，我们采用生长速率测定法研究了天然化合物吩嗪 -1- 甲酰胺（PCN）对灰葡萄孢菌的抑制作用。此外，进一步研究了 PCN 的室内毒性及体外防治效果，以确定其对灰葡萄孢菌的潜在作用机制。PCN 对灰葡萄孢菌具有抑制作用，其 50% 有效浓度（EC50）为 108.12 μg/mL；PCN 的毒性与多菌灵（CBM）相当。PCN 对草莓（果实）灰霉病的最佳体外防治效果达 75.32%，略高于多菌灵。在 PCN 浓度为 700 μg/mL 时，其对灰霉病的田间防治效果最高达 72.31%，是多菌灵的 1.02 倍。低浓度的 PCN 表现出抑菌活性，而高浓度的 PCN 对灰葡萄孢菌具有杀菌活性。这种天然化合物强烈抑制灰葡萄孢菌的孢子和菌核萌发，相对抑制率分别高达 77.03% 和 82.11%。PCN 对灰葡萄孢菌菌丝生长的抑制作用显著，抑制率达 87.32%。扫描电子显微镜观察显示，PCN 处理 48 小时后，菌丝体变得松散、局部扭曲和折叠，有内含物渗出；菌丝体枯萎扭曲，边缘有毛刺、变形、破裂并呈片状结构。透射电子显微镜观察显示，PCN 处理 48 小时后，细胞核结构不清晰，液泡破裂；此外，各种细胞器结构紊乱，有大量无膜透明内含物，细胞发生质壁分离，部分细胞壁塌陷，菌丝组织基本坏死。35 - 140 μg/mL 的 PCN 剂量对菌丝体的细胞膜通透性无影响，而 700 μg/mL 的 PCN 剂量则导致细胞膜通透性显著增加。PCN 抑制灰葡萄孢菌毒素；在 PCN 剂量为 700 μg/mL 时，霉菌毒素水平约为对照值的 0.41。PCN 影响果胶甲基半乳糖醛酸酶（PMG）、多聚半乳糖醛酸酶（PG）、纤维素酶（Cx）和β-葡萄糖苷酶（BG）的活性；用 700 μg/mL PCN 处理后，PMG、PG、BG 和 Cx 的最低活性分别达到 0.3 U/mg、0.62 U/mg、0.64 U/mg 和 0.79 U/mg。
