利用微生物防除根寄生杂草列当

根寄生杂草列当(Orobanche spp.)已经严重制约全球许多地区的农业发展,寻找有效防除措施迫在眉睫。由于列当具有特殊生活史且与寄主关系密切,常规防除杂草措施难以达到理想防效。目前,尚无既能有效防除列当又不对寄主造成危害且便于大规模推广应用的列当防除措施。在众多列当防除措施中,微生物防除越来越引起关注和重视。本文对微生物防除列当的国内外研究进展及防除机理进行了综述。目前,列当生防微生物的研究主要集中在镰刀菌(Fusarium spp.)等列当病原菌和根瘤菌(Rhizobium spp.)等列当寄主植物共生菌上。微生物防除列当的机制主要包括两方面:一是通过产生代谢产物直接影响列当的萌发和生长,或通过降解列当种子萌发诱导物质间接影响列当的萌发;二是通过提高寄主植物自身对列当的抗性间接影响列当的寄生和生长。此外,本文还重点介绍了植物土传病害的土壤拮抗微生物防除列当杂草的可行性及研究进展。植物土传病害病原菌和列当均首先通过在地下侵染作物的根系进而危害作物正常生长,而作物抗土传病害的机理也与抗列当的机理类似。因此,存在于土壤中具有防治植物土传病害能力的微生物可能也具有防除根寄生杂草列当的功能。本团队前期试验从植物土传病害的土壤拮抗微生物中筛选到在盆栽试验中能够有效防除向日葵列当(O.cumana Wallr.)和瓜列当(O.aegyptiaca Pers.)的放线菌各1株,分别为淡紫褐链霉菌(Streptomyces enissocaesilis Sveshnikova)和密旋链霉菌(Streptomyces pactum Bhuyan B.K)。其中,密旋链霉菌的菌剂在田间试验中既降低了瓜列当的出土数量又增加了番茄的产量。总之,微生物是防除根寄生杂草列当的一条有效途径。

Use of microorganisms in controlling parasitic root weed Orobanche spp.

Parasitic root weed Orobanche spp. has already severely constrained the development of agriculture in many areas around the world and it is therefore urgent to develop effective control measures of Orobanche spp. As this parasitic root weed has a specific life cycle and is highly intimate to its host plants, it is difficult to develop an ideal control measure based on traditional practices. Up till now, there has been no measure to effectively control Orobanche spp. to make it completely harmless to host plants and easily applicable at large field scale. Among the control measures available, the use of micro-organisms has increased concerns. In this paper, national and global efforts to control Orobanche spp. by the use of micro-organisms and the mechanisms of the control measures are summarized. Until now, research on biocontrol of Orobanche spp. by the use of micro-organisms has focused on pathogens of Orobanche spp., such as Fusarium spp. and symbiotic bacteria (such as Rhizobium spp.) of host plants. The mechanisms of the use of micro-organisms to control Orobanche spp. have involved in two ways:one is to secrete metabolites that directly inhibited the germination and growth of Orobanche spp. or to indirectly affect the germination of Orobanche spp. by the degradation of the chemical compounds which stimulated the germination of Orobanche spp.; another way is to indirectly affect the parasitic behavior and growth of Orobanche spp. by enhancing host plant resistance against Orobanche spp. Furthermore, the possibility and research advances by the use of soil-borne antagonistic micro-organisms against soil-borne plant pathogens in controlling weedy Orobanche spp. have been discussed. Both soil-borne plant pathogens and Orobanche spp. first infected plant roots underground and then damaged normal growth of the plants. Resistances of plants to soil-borne plant diseases were similar to those of Orobanche spp. Thus, micro-organisms that isolated from soils and controlled soil-borne plant diseases may also have the potential to control parasitic root weed Orobanche spp. We screened out one actinomycete strain (Streptomyces enissocaesilis Sveshnikova) and one actinomycete strain (Streptomyces pactum Bhuyan B.K.) from soil-borne mic-organisms that against soil-borne plant diseases. These two strains effectively controlled O. cumana Wallr. and O. aegyptiaca Pers., respectively, in pot experiments. The application of S. pactum inoculum in field experiment reduced the epigaeous number of O. aegyptiaca and increased the yield of tomato, simultaneously. In conclusion, the use of micro-organisms to control parasitic root weed Orobanche spp. is an effective measure.