贝莱斯芽胞杆菌5YN8生物被膜在防治番茄灰霉病过程中的功能研究

番茄灰霉病是由灰葡萄孢菌Botrytis cinerea引起的番茄上重要的土传病害之一，危害番茄果实、叶、茎等部位，严重制约番茄的安全生产，微生物菌剂的施用被认为是防治该病害的有效措施。前期研究发现贝莱斯芽胞杆菌5YN8能够显著防治番茄灰霉病，本研究通过构建相关基因突变体，探究生物被膜在5YN8防病过程中的作用，结果显示生物被膜增强突变体具有更致密的褶皱，而减弱突变体生物被膜光滑。进一步研究发现，菌株5YN8及其突变体处理14 d后，生物被膜减弱突变显著减少细菌在叶面的定殖，而增强突变则提升其定殖。另外，生物被膜减弱突变体防病效果显著降低，∆spo0A对灰霉病防效仅为16.02%，而生物被膜增强突变体∆abrB、∆sinR防病效果显著增强，分别达80.77%、78.94%。相关性分析表明，5YN8的抑菌率、叶面定殖与其防效显著正相关。综合结果表明，5YN8生物被膜的形成依赖保守基因的调控，通过改变生防菌定殖及抑菌能力影响对番茄灰霉病防效。上述研究将为生防菌5YN8的功能修饰增强及在番茄灰霉病的应用提供理论基础。     

Effect of antifungal hydroxypropyl methylcellulose-beeswax edible coatings on gray mold development and quality attributes of cold-stored cherry tomato fruit

Edible composite coatings based on hydroxypropyl methylcellulose (HPMC), beeswax (BW), and food preservatives with antifungal properties, were evaluated on cherry tomatoes during cold storage. Food preservatives selected from previous research work included sodium propionate (SP), potassium carbonate (PC), ammonium phosphate (APh) and ammonium carbonate (AC). Cherry tomatoes artificially inoculated with Botrytis cinerea were coated and stored up to 15 d at 5 °C followed by 7 d of shelf-life at 20 °C. All antifungal HPMC-BW coatings significantly reduced gray mold development on inoculated and cold-stored cherry tomatoes, the SP-based coating being the most effective. Analytical and sensory fruit quality was also evaluated after cold storage and shelf-life. The AC-based coating was the most effective to control weight loss and maintain the firmness of coated cherry tomatoes. Respiration rate, firmness, color, sensory flavor, off-flavor, and fruit appearance were not adversely affected by the application of the antifungal coatings. Overall, the application of HPMC-BW edible composite coatings containing AC could be a promising treatment to extend the postharvest life of cherry tomatoes. Further studies should focus on the modification of some physical characteristics of the coatings in order to enhance the general performance and provide higher peel gloss.     

柑橘青霉病防治的研究进展

柑橘青霉病是柑橘采后在储藏和运输工程中的重要病害,可造成巨大的经济损失,主要由意大利青霉(Penicillium italicum)和指状青霉(P. digitatum)引起。为了更有效地预防和控制柑橘青霉病的发生和发展,为柑橘的运输和保存工作提供科学依据,本文归纳了柑橘青霉病的物理、化学和生物防治方法所采用的主要技术手段和制剂,分析并总结了不同防治措施的优缺点,提出了柑橘青霉病防治后续研究的方向及策略。指出深入探究柑橘青霉病菌的致病机制和生物源制剂对柑橘青霉病的防控机理,推进生物防治方法与化学或物理防治方法联用,能为新型药剂的开发和建立良好的综合防治管理策略奠定基础。     

Applications of salt solutions before and after harvest affect the quality and incidence of postharvest gray mold of ‘Italia’ table grapes

The efficacy of some potassium and calcium based salts, namely potassium sulphate (PS), potassium sorbate (PSo), potassium carbonate (PC), potassium bicarbonate (PB), calcium sulphate (CS), calcium chelate (CCh), calcium chloride (CC) and calcium silicate (CSi) against gray mold of ‘Italia’ table grapes, was evaluated. In in vitro experiments, PSo, PC, PB, and CCh completely inhibited mycelial growth of Botrytis cinerea at 0.25%. Under artificial inoculation, salts at 1% (immersed or sprayed) showed a variable effect against the pathogen. For natural infection, salt solutions (1%, w/v) were applied according to three strategies: (a) spray (one week) before harvest, (b) immersion after harvest, and (c) combined treatments spray and immersion. The decay incidence of gray mold was evaluated after 30 days at 2 ± 1 °C and 90–95% RH, followed by 7 days of shelf-life at 22 ± 2 °C. All tested salts significantly reduced the decay incidence of gray mold as compared to a water control for the three strategies. The percentages of reduction ranged between 77–100, 91–98, and 61–100% for the preharvest treatment, in combined application, and in the postharvest treatment, respectively. PB and PSo were the most effective salts, completely inhibiting development of gray mold when applied before harvest and as a postharvest treatment. The influence of salts on physical and chemical properties of berry quality including total soluble solids, titratable acidity, pH, color index, weight losses and microbiological profiles was also investigated. New strategies are needed with the critical goal of controlling gray mold of grapes with no fungicide residues. Salts applied just before harvest may be an effective way to minimize gray mold during storage.     

多年生黑麦草粘菌病研究初报

多年生黑麦草是长江三角洲地区的园林绿化植物,在每年7月上中旬至8月中旬会发生严重的粘菌病,造成黑麦草生长不良。该病由灰绒泡菌(Physarum cinereum)粘菌引起。经过2年多的野外调查,该粘菌主要危害多年生黑麦草,狗牙根、白三叶。     

尖孢镰刀菌F-1对草莓灰霉病防控效果及机制初探

草莓灰霉病是草莓种植期间和采后主要真菌性病害,严重影响草莓的产量和品质。本研究通过离体试验对比了水杨酸、哈茨木霉、尖孢镰刀菌菌株F-1和F-2防治草莓果实灰霉病发生的效果,发现非致病性尖孢镰刀菌菌株F-1具有良好的防治效果。田间防效测定结果显示,F-1对草莓灰霉病的防治效果达到了70.06%,与400 g/L嘧霉胺悬浮剂的1000倍稀释液的防效相当。进而探讨了该菌防控草莓灰霉病发生的机制,结果表明该菌株的发酵液能降低灰霉病菌丝的粘附性,对灰葡萄孢孢子萌发的抑制率为19.8%,且能诱导提高草莓过氧化氢酶和过氧化物酶的活性。F-1的孢子能有效提高草莓超氧化物歧化酶和过氧化氢酶的活性,同时接种F-1孢子和发酵液则能最高限度地提高草莓过氧化氢酶、过氧化物酶和超氧化物歧化酶的活性,最高值分别达到13.6、158.9和269 U/g。