木霉菌生物防治作用机制与应用研究进展
通讯作者: 刘峰(1984—),男,黑龙江哈尔滨人,讲师,博士,研究方向为植物遗传育种,E-mail:coy24@163.com。
责任编辑: 侯春晓
收稿日期: 2020-09-11 网络出版日期: 2020-11-11
基金资助: |
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Received: 2020-09-11 Online: 2020-11-11
作者简介 About authors
阮盈盈(1992—),女,浙江宁波人,农艺师,硕士,研究方向为生物防治和遗传育种,E-mail:2670732696@qq.com。
木霉菌是一种资源丰富且在植物病害生物防治中应用较为广泛的生防真菌。本文概述了木霉菌的生物学特性和木霉菌在植物病虫害防治的生防机制,包括竞争、重寄生和抗生等作用,以及木霉菌与植物互作中对植物促生和诱导植物抗性的机制,并阐述了木霉菌在多种植物病害防治中的应用与防治效果。随着生防技术的日益提高,木霉菌商品化制剂越来越趋于多样化并在各个国家取得良好的生物防治效果,但在木霉菌剂的开发与应用中仍有很多问题有待解决。针对木霉菌生防机制与木霉菌商品化制剂开发应用的研究,有利于减少化学农药的使用,推动植物病害生物防治进程。
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阮盈盈, 刘峰.
在传统的农作物栽培过程中,化肥农药的不合理施用,以及长期单一农作物大面积种植导致农田生态环境破坏、植物病虫害问题日益频繁,同时还造成农作物农药残留,以及土壤、水体环境污染等问题[1]。随着农业绿色发展新思想的提出,人们更加迫切地寻求安全有效、环境友好型植物病害防治措施[2]。生物防治主要是通过有益生物及其产物对植物中有害生物进行牵制,从而达到防治植物病虫害的目的,能够有效减少化肥农药的施用[3]。木霉菌作为一类广泛用于植物病虫害防治的生物真菌,主要存在于土壤、空气和植物表面等生态环境,可以有效防治多种植物病虫害。本文围绕木霉菌生物学特性、生防机制和木霉菌在生物防治中的应用等多个方面,系统全面地阐述了木霉菌在植物病虫害防治的研究进展,并且对木霉菌在生物防治中存在的问题与前景进行了初步探讨,为今后木霉菌在生物防治中的研究与应用提供参考。
1 木霉菌概述
木霉菌(Trichoderma)属于真菌门、知菌亚门、丝孢纲、丝孢目、丛梗孢科,其有性阶段为子囊菌亚门、肉座目、肉座科的肉座菌属[4] ,木霉属是Persoon于1794年建立的。根据 Gams等[5]的分类系统,该属分为肉座(Hypocreanum)、长枝组(Longibrachiatum)、木霉组(Trichoderma)和粗梗组(Pachybasium)4个组,包括哈茨木霉(Trichoderma harzianum)、绿色木霉(Trichoderma viride)、深绿木霉(Trichoderma atroviride)、黄绿木霉(Trichoderma aureoviride)等104个种。据报道,目前已发现了250多种木霉菌种[6]。随着分子生物学研究技术的日益发展,木霉菌鉴定从原来的主要依赖显微镜观察形态转变为通过分子水平上的系统演化分析,并建立了基于rpb2、ITS和tef1序列的DNA条形码快速鉴定系统,可以准确、快速地鉴定木霉菌[7]。除此之外,还建立了可以比对木霉属序列相似性的TrichoBLAST数据库(
大量研究表明,多数木霉菌可产生生物活性物质,并对植物病原真菌、植物病原线虫等具有拮抗作用。生物活性物质包括次级代谢产物和细胞壁降解酶类等物质,可以有效提高农作物的抗逆性,减少植物病害并促进植物生长。经研究该种群中的绿色木霉、哈茨木霉等对葡萄孢属(Botrytis)、镰刀菌属(Fusarium)和丝核菌属(Rhizoctonia)等18个属[8]的29种植物病原真菌均有不同程度的抑制作用。
木霉菌在培养基中菌落最初为致密丛束状或棉絮状,白色或白灰色。待分生孢子成熟后,菌落从中央至边缘,逐渐变为绿色或黄绿色的菌落,极少数为白色,分生孢子梗通过菌丝的侧枝生长。木霉菌具有极强的环境适应性,适宜在温暖湿润的环境下生长繁殖。最适合木霉菌生长的温度一般在20~28 ℃,不过在6~32 ℃木霉菌依然可以生长;木霉菌生长适宜高湿度环境,90%以上的空气相对湿度有利于木霉菌生长与产孢;尽管光照对木霉菌丝生长影响不大,但光照条件下还是利于木霉菌产生分生孢子;木霉菌能够在pH 1.5~9.0生长,其中生长最适pH 为5.0~5.5;马铃薯葡萄糖琼脂培养基(PDA)是木霉菌生长最常用的培养基。木霉菌可以通过利用碳源、氮源,以及铜、镁、铁等无机盐离子促进生长和产孢[12]。
2 木霉菌生防机制
根据已有的研究结果,木霉菌对植物病原菌具有多种生防机制。目前被广泛认同的有以下几种,包括竞争作用、重寄生作用、抗生作用、诱导抗性作用、促生作用和协同拮抗作用[13]。
2.1 木霉菌的竞争作用
2.2 木霉菌的重寄生作用
2.3 木霉菌的抗生作用
抗生作用主要是指木霉菌通过分泌拮抗性物质来抑制植物病原菌的生长。木霉菌可产生上百种抗菌次生代谢产物,包括木霉素、胶霉素、绿木霉素、抗菌肽等[20]。这些次生代谢产物能够起到抗菌、促进植物生长的作用,可为农用抗生素的开发提供丰富的材料。陈凯等[21]研究发现,绿色木霉LTR-2的代谢产物对尖孢镰刀菌萎蔫专化型具有明显的抑制作用,抑制率可达54.81%;陈志敏等[22]研究发现,绿色木霉菌TG050 609分泌的具有挥发性的次生代谢物质可以使烟草疫霉的菌丝不规则生长、破碎甚至溶解,证明了木霉菌对烟草疫霉具有抗生作用。此外,多数木霉菌株能产生具有抑菌活性物质——抗菌肽(peptaibols),它能抑制多种植物病原菌,还可与细胞壁降解酶协同作用于病原真菌,有效抑制其生长。有研究表明,部分木霉菌能够产生挥发性代谢物质,不同程度抑制了病菌菌落生长,有的抑菌率可以达到80%以上[23]。
2.4 木霉菌的诱导抗性作用
2.5 木霉菌的协同拮抗作用
2.6 木霉菌的促生作用
3 木霉菌在植物病害生物防治中的应用
早在1932年,Weindling[33]首次观察到木素木霉(Trichoderma lignorum)的菌丝缠绕着立枯丝核菌(Rhizoctonia solani)的菌丝,使立枯丝核菌菌丝原生质凝结,细胞液泡消失,最终导致立枯丝核菌解体,证明木霉产生了胞外干扰物质,有效抑制了立枯丝核菌的生长。接着便出现了大量利用木霉菌防治植物病害的研究成果。根据现有资料显示,木霉菌至少对18个属 29 种植物病原真菌具有拮抗作用[34]。木霉菌对多种植物病原真菌均有防治效果,如立枯丝核菌(Rhizoctonia solani)[32]、尖孢镰刀菌(Fusarium oxysporum)[35]、核盘菌(Sclerotinia sclerotiorum)[36]、葡萄孢属真菌(Botrytis spp.)[37]等。此外,木霉菌对植物病原线虫与植物病原细菌都具有防治作用。目前,木霉菌已普遍用于棉花黄萎病、作物灰霉病、番茄灰霉病、瓜类枯萎病、马铃薯干腐病、烟草根腐病等植物病害的生物防治[38]。在园林植物中,木霉菌对樱花白粉病、杨树烂皮病、杨树叶枯病等多种病菌有明显的抑制作用[39]。此外,在药用植物方面,木霉菌对川穹、人参等的病害也具有良好的防治效果[40]。
目前,木霉菌在植物病害生物防治领域发挥了巨大的应用价值与潜力,世界各地都有利用木霉菌防治植物病害的研究报道。景芳等[41]研究发现,长枝木霉T6生防菌剂对辣椒立枯病有良好的防治作用,能够有效控制辣椒病害的蔓延,防效高达54.8%,比化学农药多菌灵的防效提高了12.5%;姚彦坡[42]研究表明,哈茨木霉菌对辣椒和马铃薯疫病具有良好的防治效果,不仅可以抑制土壤中疫病的生长,减少病原菌的种群数量,还能有效降低植物死苗率和病情指数;杨榕等[43]研究发现,接种木霉菌MF-2的黄瓜幼苗植株地上部生物量提高了39.07%,促生作用显著,并提高了土壤有益微生物的数量;孟庆果等[44]使用50倍棘孢木霉菌制剂液来防治苹果腐烂病,防治效果达到88.24%,明显高于噻霉酮对苹果的防治效果;叶乃玮等[45]研究发现,不同木霉菌株对香蕉枯萎病菌具有不同程度拮抗作用,组合木霉菌可湿性粉剂处理显著提高了香蕉产量;李琳[46]研究表明,棘孢木霉菌对不同病原菌具有不同的作用效果,其中对玉米大斑病病菌的抑制效果较佳,高达77.91%,其次是腐霉菌和镰刀菌,抑制效果最差的是玉米纹枯病病菌。将木霉菌用于植物病虫害的防治,既能抑制病原菌的生长,有利于植物生长,又能减少化学农药的使用,有利于保护生态环境。
4 木霉菌商业化制剂及开发应用
随着生防技术日益成熟,木霉菌商品化制剂种类也趋于多样。主要可分为四类:(1)可湿性粉剂,由分生孢子粉、粉状载体与湿润剂混合而成。(2)颗粒剂,由分生孢子与载体混合搅拌而成。(3)混配剂,由孢子粉与化学杀菌剂在适宜载体上按比例混合而成。(4)悬乳剂,由分生孢子悬浮在植物油、矿物油、乳化剂等组成的乳液中配制而成。目前市场上的木霉菌生物制剂中,哈茨木霉(T.harzianum)最多,其次是绿色木霉(T.viride)和康宁木霉(T.koningii)。在植物病害防治上应用较广泛的木霉菌剂主要包括哈茨木霉T-39的商品化制剂Trichodex(Makhteshim Chemical Works Ltd,以色列)、哈茨木霉T-22的商品制剂RootShield(Bioworks,美国)、哈茨木霉和多孢木霉(T.polysporum)混合菌剂Binab TF(Binab Bio Innovation AB,瑞典)、深绿木霉T.atroviride菌剂Sentinel(Novozymes,丹麦),以及哈茨木霉菌剂Supresivit(Borregaard Bioplant,丹麦)等。这些木霉菌剂在植物病害防治中取得了良好的防治效果和增产作用。
5 生物防治的前景与展望
我国作为传统的农业大国,农业在国民经济中占有重要作用。随着农耕模式的变革及全球温室化的影响,植物病害日益严重。目前植物病害防治以化学防治为主,通过喷洒杀虫剂、杀菌剂等方式进行防治。尽管化学防治效果良好,有助于农业增产,但是人们不科学使用化学农药造成人类生存的环境严重污染,并且引起病原物抗药性增强。大量的实验证明,木霉菌具有良好的生物防治作用,能够减少化学农药的使用。市面上的木霉菌生物防治剂依旧不多,需寻求更多、更有效适合生产的菌株加入生物防治的队伍中。尽管木霉菌在农业应用中有着巨大的发展前景,但在木霉菌的开发利用过程中依旧存在一些问题。由于木霉菌的孢子制剂一般为活菌制剂,在田间应用时经常受到湿度、温度、土壤酸碱、土壤中微生物群落等各种自然因素影响,因此,田间试验性状表现不稳定,生物防治效果会减弱。此外,生物防治制剂的货架期较短,有些菌剂需在低温保存条件下才能保证其施用时的活菌浓度。
木霉在植物病害生物防治的应用中依旧有很多问题有待解决。首先是发掘生产高效菌株,可以通过基因工程技术筛选出耐化学农药、耐低温的生防工程菌株;同时要研制开发适合于多种施用方法的高效木霉菌剂,增强防治效果,并且要提高木霉菌剂加工技术,延长生物防治菌剂的货架期。其次,还需探究木霉菌与其他微生物的联合作用。另外,我国许多农民对过量使用化肥农药的危害了解甚少,对生物防治菌剂的认可度普遍不高,因此,提高农民环保意识,有利于促进生物防治应用的示范推广。
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