First, second, third, and fifth authors: Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico Chascomús, Universidad Nacional de General San Martín-Consejo Nacional de Investigaciones Científicas y Técnicas (IIB-INTECH/UNSAM-CONICET), Chascomús, Argentina; fourth author: Departament de Bioquímica i Biologia Molecular, Facultat de Ciències Biològiques, Universitat de València, València, Spain; and fifth author: Instituto de Fisiología y Recursos Genéticos Vegetales, Instituto Nacional de Tecnología Agropecuaria (IFRGV-INTA), Córdoba, Argentina.
Phytopathology. 2019 Mar;109(3):375-383. doi: 10.1094/PHYTO-07-18-0262-R. Epub 2019 Jan 7.
Endophytic bacteria colonize inner plant tissues and thrive at the apoplast, which is considered its main reservoir. Because this niche is the place where the main molecular events take place between beneficial and pathogenic microorganisms, the aim of this work was to characterize culturable endophytic bacteria from apoplastic fluids obtained from field-grown canola leaves and analyze their potential for biological control of diseases caused by Xanthomonas campestris, Sclerotinia sclerotiorum, and Leptosphaeria maculans. Dual-culture analysis indicated that three isolates (Apo8, Apo11, and Apo12) were able to inhibit the growth of all three phytopathogens. Sequencing of the 16S ribosomal RNA and rpoD genes of these isolates revealed that they are closely related to Pseudomonas viridiflava. One of the isolates, Apo11, was able to diminish the propagation of X. campestris in whole-plant assays. At the same time, Apo11 inoculation reduced the necrotic lesions provoked by S. sclerotiorum on canola leaves. This protective effect might be due to the induction of resistance in the host mediated by salicylic and jasmonic acid signaling pathways or the production of compounds with antimicrobial activity. At the same time, Apo11 inoculation promoted canola plant growth. Thus, the isolate characterized in this work has several desirable characteristics, which make it a potential candidate for the formulation of biotechnological products to control plant diseases or promote plant growth.
内生细菌定殖于植物内部组织，并在质外体中生长，质外体被认为是其主要的栖息地。由于这个小生境是有益和致病微生物之间主要分子事件发生的地方，本工作的目的是从田间生长的油菜叶片中获得的质外体液中分离可培养的内生细菌，并分析它们在生物防治黄单胞菌、核盘菌和黑胫病菌引起的病害方面的潜力。双培养分析表明，有 3 个分离株（Apo8、Apo11 和 Apo12）能够抑制所有 3 种植物病原菌的生长。对这些分离株的 16S 核糖体 RNA 和 rpoD 基因进行测序表明，它们与绿脓假单胞菌密切相关。其中一个分离株 Apo11 能够在全株试验中减少黄单胞菌的繁殖。同时，Apo11 接种减少了油菜叶片上核盘菌引起的坏死斑。这种保护作用可能是由于水杨酸和茉莉酸信号通路介导的宿主抗性的诱导，或产生具有抗菌活性的化合物。同时，Apo11 接种促进了油菜植物的生长。因此，本工作中所鉴定的分离株具有几个理想的特性，使其成为生物防治植物病害或促进植物生长的生物技术产品的潜在候选物。
