Bel Yolanda, Galeano Magda, Baños-Salmeron Mireya, Andrés-Antón Miguel, Escriche Baltasar
Institute BIOTECMED/Department of Genetics, University of Valencia, Burjassot, Spain.
R&D Department of Koppert España, S.L., Almeria, Spain.
Appl Microbiol Biotechnol. 2024 Dec 3;108(1):525. doi: 10.1007/s00253-024-13365-2.
The global imperative to enhance crop protection while preserving the environment has increased interest in the application of biological pesticides. Bacillus thuringiensis (Bt) is a Gram-positive bacterium that can produce nematicidal proteins and accumulate them in parasporal crystals. Root-knot nematodes are obligate root plant parasitic which are distributed worldwide, causing severe damages to the infested plants and, consequently, large yield reductions. In this work, we have evaluated the toxicity of the Bt crystal proteins Cry5, Cry21, App6, and Xpp55 against two root-knot nematodes belonging to the Meloidogyne genus (M. incognita and M. javanica). The results show that all four proteins, when solubilized, were highly toxic for both nematode species. To check the potential of using Bt strains producing nematicidal crystal proteins as biopesticides to control root-knot nematodes in the field, in planta assays were conducted, using two wild Bt strains which produced Cry5 or a combination of App6 and Cry5 proteins. The tests were carried out with cucumber or with tomato plants infested with M. javanica J2, irrigated with spore + cristal mixtures of the respective strains. The results showed that the effectiveness of the nematicidal activity was plant-dependent, as Bt was able to reduce emerged J2 in tomato plants but not in cucumber plants. In addition, the toxicity observed in the in planta assays was much lower than expected, highlighting the difficulty of the proteins supplied as crystals to exert their toxicity. This emphasizes the delivery of the Bt proteins as crucial for its use to control root-knot nematodes. KEY POINTS: • Solubilized Cry5, Cry21, App6 and Xpp55 Bt proteins are toxic to M. javanica. • Cry21 toxicity to M. incognita is similar to that of Cry5, App6, and Xpp55 proteins. • The Cry5 and App6 toxicities on M. javanica after Bt irrigation is crop dependent.
在保护环境的同时加强作物保护这一全球要务，增加了人们对生物农药应用的兴趣。苏云金芽孢杆菌（Bt）是一种革兰氏阳性细菌，能够产生杀线虫蛋白并将其积累在伴孢晶体中。根结线虫是专性根寄生植物线虫，分布于世界各地，会对受侵染植物造成严重损害，进而导致大幅减产。在这项研究中，我们评估了Bt晶体蛋白Cry5、Cry21、App6和Xpp55对两种根结线虫（南方根结线虫和爪哇根结线虫）的毒性。结果表明，这四种蛋白溶解后对两种线虫都具有高毒性。为了检验使用产生杀线虫晶体蛋白的Bt菌株作为生物农药在田间防治根结线虫的潜力，我们使用了两种产生Cry5或App6与Cry5蛋白组合的野生Bt菌株进行了植物体内试验。试验分别在黄瓜或感染了爪哇根结线虫J2期幼虫的番茄植株上进行，用各自菌株的孢子+晶体混合物进行灌溉。结果表明，杀线虫活性的有效性取决于植物，因为Bt能够减少番茄植株上出土的J2期幼虫数量，但对黄瓜植株却没有效果。此外，在植物体内试验中观察到的毒性远低于预期，这突出了以晶体形式提供的蛋白发挥毒性的难度。这强调了Bt蛋白的递送对于其用于防治根结线虫的至关重要性。要点：• 溶解后的Cry5、Cry21、App6和Xpp55 Bt蛋白对爪哇根结线虫有毒。• Cry21对南方根结线虫的毒性与Cry5、App6和Xpp55蛋白相似。• Bt灌溉后Cry5和App6对爪哇根结线虫的毒性取决于作物。
