| 論文英文摘要 |
Cabbage black rot disease (CBRD) caused by Xanthomonas campestris pv. campestris (Xcc) is a seedborne disease that causes severe yield losses. Therefore, reducing the pathogen on seed could be a possible strategy to control CBRD. Our previous study revealed that CBRD could be controlled by bacterial suspensions of Bacillus amyloliquefaciens PMB05 in Xcc-infested seeds. However, such treatments still require a process of seed soaking and subsequent drying. Under this limitation, this study intends to further explore whether using powder prepared by fermentation broths to treat infested seeds can still effectively reduce the occurrence of CBRD. In order to use maltodextrin as a carrier, it was first proved that seed germination was not inhibited by treatment with maltodextrin directly. Then, the mixture of B. amyloliquefaciens PMB05 fermentation broth and maltodextrin was spray-dried; the number of endospores reached more than 10^9 CFU/mL under the treatment with three distinct inlet temperatures. The 0.1% powder was further mixed with cabbage seeds, results showed that seed germination ratio was increased by the powders from the inlet temperature at 140 ℃ and 160 ℃. In addition, we also found that the inhibition of seed germination by the powder from the inlet temperature of 120 ℃ might be due to the compounds produced from maltodextrin during the spray drying process. Furthermore, the PMB05 powder produced at 160 ℃ of inlet temperature showed more than 90% of the survival rate for over 16 weeks at room temperature and 4 ℃ in this state. Most importantly, the disease incidence and disease severity of CBRD on seedlings were reduced significantly when the Xcc-infested seeds were coated with 0.1% of the PMB05 powder. In addition, we also found that the leaves obtained from the seed treatment can trigger stronger plant immune response signals upon the induction of a bacterial elicitor, suggesting that the seed treatment might give cabbage a more comprehensive protective effect. Combining the above results, we concluded that coating seeds with PMB05 powder is a convenient and effective way to control CBRD. |