Abo-Elyousr Kamal A M, Abdel-Rahim Ismail R, Almasoudi Najeeb M, Alghamdi Sameera A
Department of Arid Land Agriculture, Faculty of Meteorology, Environment and Arid Land Agriculture, King Abdulaziz University, Jeddah 80208, Saudi Arabia.
Botany and Microbiology Department, Faculty of Science, Assiut University, Assiut 71516, Egypt.
J Fungi (Basel). 2021 Sep 10;7(9):745. doi: 10.3390/jof7090745.
This study aimed to evaluate the efficacy of endophytic bacterium to control common bean rust disease under greenhouse conditions. Endophytic bacterium ASU15 was isolated from fresh asymptomatic common bean, identified using biochemical and molecular characteristics. In vitro, the inhibitory effect of different concentrations of (1 × 10, 1 × 10 and 1 × 10), as well as fungicide ortiva (0.01%) on uredospores germination of were tested using water agar medium. The concentration showing the highest reduction of uredospores germination was at 1 × 10, while there was complete inhibition of uredospores germination associated with using ortiva. Scanning electron microscope exhibited the ability of cells to attack the cell wall of the fungal uredospores germ tubes of , causing obvious cell wall breakdown. The activities of chitinase, lipase, and protease produced by ASU15, in vitro, were evaluated spectrophotometrically. Chitinolytic, proteolytic, and lipolytic activities were exhibited, contributing 55.26, 3.87, and 26.12 U/mL, respectively. Under greenhouse conditions, treated plants with ASU15 (two days before pathogen inoculation or at the same time of pathogen inoculation) or fungicide reduced the disease severity, compared to the control. Applying ASU15 at the same time of pathogen inoculation showed reduction in disease severity (69.9%), higher than application before pathogen inoculation (54.9%). This study is considered the first report that demonstrates the mycoparasitic strategy of for controlling . In conclusion, our results revealed that ASU15 affords a significant disease reduction that may be attributed to direct suppression of pathogen spores germination.
本研究旨在评估内生细菌在温室条件下防治普通菜豆锈病的效果。内生细菌ASU15从新鲜无症状的普通菜豆中分离得到，通过生化和分子特征进行鉴定。在体外，使用水琼脂培养基测试了不同浓度（1×10、1×10和1×10）的内生细菌以及杀菌剂ortiva（0.01%）对菜豆夏孢子萌发的抑制作用。显示出对夏孢子萌发抑制率最高的浓度为1×10，而使用ortiva可完全抑制夏孢子萌发。扫描电子显微镜显示内生细菌细胞能够攻击菜豆锈菌夏孢子萌发管的细胞壁，导致明显的细胞壁破裂。对内生细菌ASU15在体外产生的几丁质酶、脂肪酶和蛋白酶的活性进行了分光光度法评估。内生细菌表现出几丁质分解、蛋白水解和脂肪分解活性，分别贡献55.26、3.87和26.12 U/mL。在温室条件下，与对照相比，用内生细菌ASU15（在病原菌接种前两天或与病原菌接种同时）或杀菌剂处理的植株病害严重程度降低。在病原菌接种同时施用内生细菌ASU15显示病害严重程度降低（69.9%），高于在病原菌接种前施用（54.9%）。本研究被认为是首次报道内生细菌控制菜豆锈病的重寄生策略。总之，我们的结果表明内生细菌ASU15能显著降低病害，这可能归因于对病原菌孢子萌发的直接抑制。
