Plant growth promoting rhizobacteria provide an innovative solution to address challenges in sustainable agro-ecosystems, improving plant growth as well as acting as agents of biocontrol. In this study autochthonous bacteria were isolated from the rhizosphere of processing tomato plants (Solanum lycopersicum L.) cultivated with conservation agriculture practices (i.e., reduced tillage and cover crops), and evaluated for both growth-promoting activities (PGPAs), and antagonistic potential against the phytopathogenic pest Sclerotinia sclerotiorum. Considering the several activities of PGPR, we decided to structure the screening with a hierarchic approach, starting from testing the capability of fixing nitrogen. The obtained bacteria were processed through the molecular typing technique rep-PCR (Repetitive Extragenic Palindromic) in order to discriminate microbial strains with the same profiles, and identified via 16S rDNA sequencing. Thirty-eight selected isolates were screened in vitro for different activities related to plant nutrition and plant growth regulation as well as for antifungal traits. Isolated bacteria were found to exhibit different efficiencies in indoleacetic acid production and siderophore production, phosphate solubilization and biocontrol activity against the widespread soil-borne plant pathogen S. sclerotiorum. All the 38 bacterial isolates showed at least one property tested. With a view to detect the suitable candidates to be developed as biofertilizers, the selected isolates were ranked by their potential ability to function as PGPR. Thus, consortium of native PGPR bacteria inoculants may represent a suitable solution to address the challenges in sustainable agriculture, to ensure crop yield and quality, lowering the application of chemicals input.

中文翻译：

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长期减少耕种和遮盖作物后，从番茄植物根际中分离和筛选胞外PGPR。

促进根瘤菌生长的植物提供了创新的解决方案，以应对可持续农业生态系统中的挑战，改善植物生长并充当生物防治剂。在这项研究中原地细菌从番茄植物处理的根际分离（番茄大号。）与保护性农业实践（即，减少耕作和覆盖作物）种植，并评价二者的生长促进活性（PGPAs），和拮抗潜在对抗植物致病性菌核盘菌。考虑到PGPR的几种活性，我们决定从测试固定氮的能力开始，采用分层方法构建筛选。通过分子分型技术rep-PCR（重复性外源回文）对获得的细菌进行处理，以区分具有相同谱图的微生物菌株，并通过16S rDNA测序进行鉴定。在体外筛选了38种分离株，筛选出与植物营养和植物生长调节有关的不同活性以及抗真菌性状。发现分离的细菌在吲哚乙酸生产和铁载体生产，磷酸盐溶解和对广泛的土壤传播的植物病原菌S. sclerotiorum的生防活性方面表现出不同的效率。。所有38种细菌分离株均显示出至少一种经测试的特性。为了检测适合作为生物肥料开发的候选物，按其作为PGPR的潜在能力对选定的分离株进行排名。因此，天然PGPR细菌孕育剂联盟可能是解决可持续农业挑战，确保作物产量和质量，降低化学品投入量的合适解决方案。