The development of alternatives for the use of chemical pesticides for plant disease control is the present-day and ongoing challenge for achieving sustainable agriculture. Pseudomonas fluorescens SF4c, native strain from wheat, produces tailocins (phage-tail-like bacteriocins) with antimicrobial activity against several phytopathogenic strains. We thus investigated the efficacy of foliar application of these bacteriocins to control the bacterial-spot disease in tomato caused by Xanthomonas vesicatoria Xcv Bv5-4a. The disease severity and incidence index were reduced by 44 and 36%, respectively; while the number of viable cells of X. vesicatoria Xcv Bv5-4a decreased after bacteriocin treatment. Furthermore, bacteriocin was effective in reducing bacterial-spot-disease symptoms on tomato fruits even when applied 12 h after infection. Tailocin activity was not affected by abiotic influences such as adjuvant, light and temperature and, biotic factors such as apoplastic-fluids. In contrast, no antibacterial activity of these tailocins was observed when the bacteriocin was exposed to extremely dry conditions. Finally, that no cytotoxic effects on mammalian cells were observed with this representative tailocins is highly significant and demonstrates the safety of such compounds in humans. All these findings indicate that the SF4c tailocins represent an attractive alternative to copper-containing bactericides for use in the control of bacterial spot.

开发化学农药来控制植物病害的替代方法是实现可持续农业的当前和持续的挑战。荧光假单胞菌SF4c是小麦的天然菌株，可产生对多种植物病原菌具有抗微生物活性的tailocins（噬菌体尾状细菌素）。因此，我们研究了叶面施用这些细菌素来控制番茄中由黄单胞菌Xcv Bv5-4a引起的细菌斑病的功效。疾病的严重程度和发生率分别降低了44％和36％；而X. vesicatoria的活细胞数细菌素处理后，Xcv Bv5-4a降低。此外，细菌素即使在感染后12 h仍可有效减轻番茄果实上的细菌性斑点病症状。大环蛋白的活性不受非生物因素的影响，如佐剂，光照和温度以及生物因素（如质外性流体）。相反，当细菌素暴露于极端干燥的条件下时，未观察到这些尾巴素的抗菌活性。最后，用这种代表性的尾巴素未观察到对哺乳动物细胞的细胞毒性作用是高度显着的，并证明了此类化合物在人类中的安全性。所有这些发现表明，SF4c尾蛋白代表了用于控制细菌斑的含铜杀菌剂的诱人替代品。