【作者】 刘坤；

【导师】 刘凤权；

【作者基本信息】 南京农业大学 ， 植物病理学， 2012， 硕士

【摘要】 我国梨产量约占世界总产量2/3,出口量约占世界出口量的1/6,中国梨在世界梨产业发展中有着举足轻重的地位。然而,梨腐烂病在我国各大梨产区每年都有大量发生。由腐烂病引起的减产、树木枯死,甚至毁园现象也经常出现的,这就对我国的梨产业发展构成极大威胁。本研究针对梨腐烂病开展了化学药剂筛选、生防菌株筛选等相关探索,并取得了一定的研究进展：1.通过比较不同接种方法得到,以PDA菌丝圆饼作为接种体时,利用烫伤接种法接种的梨树枝条的发病率最高,初步建立了梨腐烂病菌的室内离体接种方法体系；2.跟踪监测发酵滤液中半乳糖醛酸酶(polygalacturonase, PG)的活力,证明：梨腐烂病菌能够产生PG这一致病因子。并且,在发酵培养基中,PG的活力与菌体各个生长时期同步变化。此外,半乳糖醛酸酶活力在接种后5-6d活力最高。3.本研究从河北昌黎梨园根际土壤样品中分离纯化得到一株对梨腐烂病菌有明显抑制作用菌株CL-9,拮抗圈达到12mm,经鉴定为多黏类芽孢杆菌(Paenibacillus polymyxa).抗菌活性物质检测结果显示,该菌产生蛋白酶和纤维素酶,但不产生几丁质酶和β-1,3-葡聚糖酶。此外,该菌代谢产物可以抑制梨腐烂病菌丝的正常生长。代谢产物处理后的腐烂病菌菌丝越来越致密、短粗,分支也明显减少。同时加热处理代谢产物也具有相似的作用。室内测定该菌对梨轮纹病菌、梨腐烂病菌、梨炭疽病菌和稻瘟病菌等15种重要园艺和粮食作物病原真菌均具有较好的拮抗作用,拮抗圈的范围从5mm到17mm不等。本研究所获得的生防细菌CL-9拮抗活性高,拮抗谱广,为后续利用该菌研制生防菌剂防治梨腐烂病及其他作物病害提供了技术支撑,可以作为化学防治的一种有益补充,减少农药污染。4.CL-9菌株室内模拟治疗、预防和治愈梨腐烂病试验表明,无论是发病率,还是病斑长度,都表明CL-9菌株对腐烂病菌明显具有生防作用；5.通过室内药剂筛选,我们从20种常见的杀菌剂中筛到5种高效、低毒化学防控药剂。更多还原

【Abstract】 Pear production in China accounts for about2/3of the world and the exports accounts for about1/6.As the largest pear-producing country, China plays a pivotal role in the development of pear. However, pear canker comes on so much every year in the major pear-producing areas in China that it leads to lower production, trees’ death, and even more the gardens’ destruction. So the disease has brought a great threat to pear industry in our country.This article has made some progress on chemical and bio-control bacteria lab screening for pear canker:1. Comparing the different methods of vaccination, the author has found a basic inoculation method to pear canker.2. Detected PG activity in fermentation broth, and results showed that V.ambiens could also secrete PG,as an infectious agent of pathogenic fungi.In addition, the PG activity changed with the fungus growing in mediem.Otherwise, after inoculated about5days, the enzyme is in its highest activity.3. Strain CL-9was isolated and purified from soil samples in pear tree’s rhizosphere in Changli in Hebei Provence. The stain has obvious inhibition effect on Valsa ambiens(Pers.)(inhibition zone AR=12mm). It’s identified as Paenibacillus polymyxa. It can produce two kinds of hydrolases, proteinase and glucanase, but no chitinase or glucanase. And it’s indicated by antagonistic tests that the fermentation filtrate could produce some kind of active compounds which can significantly inhibit the growth of V. ambiens. After handled by filtrate and heated filtrate, the hypha changed into tighter, tubbier, and less branches. Meanwhile, stain CL-9has a wide range of antagonistic spectrum which shows obvious inhibition to15pathogens of common fungal diseases on crops and horticulture plants. The radius of inhibition zones changes from5mm to17mm. The strain has higher antipathogenic activities and a wide antagonist spectrum that could supply a technological foundation for developing bioagent. As an addition to chemicals, it will turn down the chemical pollution. 4. Strain CL-9has been proved that it has much bio-control effect on pear canker in indoor simulation tests, whether by lowing incidence or reducing length of scab.5. This article screened5kinds of higher efficiency, lower toxicity fungicides (EC50<50) from20common kinds, in chemical screening experiments.更多还原