类芽孢杆菌QHZ11对马铃薯黑痣病的生防效果

The biocontrol effect of Paenibacillus jamilae QHZ11 on potato black scurf

摘要:

[背景] 马铃薯黑痣病是由立枯丝核菌（Rhizoctonia solani）引起的一种典型土传病害，目前该病害生物防治的菌种资源比较有限，相应菌株生防机制的研究更是缺乏。[目的] 明确马铃薯黑痣病病原菌立枯丝核菌（R. solani） JT18的拮抗菌QHZ11对马铃薯黑痣病的生防效果，揭示QHZ11对黑痣病的部分防治机理。[方法] 在灭菌土壤中分别接种R. solani JT18（CK），R. solani JT18和普通有机肥（Organic Fertilized，OF），R.solaniJT18和氨基酸有机肥（AA+OF）及R. solani JT18和QHZ11生物有机肥（BOF11），结合实时荧光定量PCR （Real-Time Fluorescence Quantitative PCR，RT-qPCR）等方法，研究马铃薯全生育期不同处理R.solaniJT18在马铃薯根际和植株不同部位的数量变化及拮抗菌QHZ11与R.solaniJT18的数量消长规律，同时比较不同处理黑痣病的病情指数及相应的防效。[结果] RT-qPCR结果表明，随马铃薯生育进程的推进，马铃薯根际、根系和匍匐茎R.solaniJT18的数量在各处理中均呈现先升高至块茎膨大期到达峰值后下降的趋势，而且各部位R.solaniJT18的数量为CK>OF>AA+OF>BOF11且根际>根系>匍匐茎；拮抗菌QHZ11的数量变化趋势与R.solaniJT18相同，但峰值在块茎形成期，并且同时期同一部位QHZ11的定殖数量均显著高于R.solaniJT18，甚至高出2个数量级，说明QHZ11占用了一定的营养资源和生态位点，严重抑制了R.solaniJT18的生长和繁殖。病情结果表明：CK病情指数最高，OF、AA+OF和BOF11处理均显著低于CK，其中BOF11处理发病最轻；生防结果则相反，为BOF11>AA+OF>OF处理，说明普通有机肥、氨基酸有机肥及生物有机肥均可不同程度地防治马铃薯黑痣病，其中以生物有机肥效果最显著。[结论] QHZ11以有机肥为载体施入土壤后，可以通过在马铃薯根际及植株不同部位竞争营养和生态位点，从而有效抑制黑痣病病原菌R.solaniJT18的生存和繁殖，起到显著的生防效果，这对QHZ11生物有机肥的应用和推广具有重要意义，并为进一步研究QHZ11的生防机制奠定了基础。

Abstract:

[Background] Potato black scurf is a typical soil-borne disease caused by Rhizoctonia solani. At present, the bacterial resources for biological control of the disease are relatively limited, and the researches on the biological control mechanisms of corresponding strains are more lacking. [Objective] To clarify the biocontrol effect of QHZ11-an antagonistic bacteria of Rhizoctonia solani JT18, and reveal its partial biological control mechanisms on potato black scurf. [Methods] R. solani JT18 (CK), R. solani JT18 and ordinary organic fertilizer (OF), R. solani JT18 and amino acid organic fertilizer (AA+OF) and R. solani JT18 and QHZ11 biological organic fertilizer (BOF11) were inoculated respectively into the sterilized soil. Using real-time fluorescent quantitative PCR (RT-qPCR) method to study the quantity changes of R. solani JT18, and law of quantity's increase and declining between the antagonistic antibacterial QHZ11 and R. solani JT18 under the different treatments in the rhizosphere and different parts of the plant during the whole growth period of potato. At the same time, we compared the disease index of black scurf of different treatments and the corresponding control effects.[Results] The results of RT-qPCR showed that with the progress of potato growth, the quantity of R. solani JT18 in potato rhizosphere, roots and stolons under each treatment increased to the peak in the tuber expansion period, and then decreased. The quantity of R. solani JT18 in each part was:CK>OF>AA+OF>BOF11, rhizosphere>root>stolon. The quantity of antagonistic antimicrobial QHZ11 showed the same trend as R. solani JT18, but its peak appeared in the tuber formation period, and the colonization quantity of QHZ11 was significantly higher than R. solani JT18 in the same part of the same period, even two orders of magnitude higher. It showed that the existence of QHZ11 occupied certain nutrient resources and niches, which severely inhibited the growth and reproduction of R. solani JT18. The results of the disease showed that the disease index of CK was the highest, another three treatments were significantly lower than CK in which BOF11 had the least disease incidence. The results of biocontrol were just opposite, which were BOF11>AA+OF>OF. It showed that ordinary organic fertilizer, amino acid organic fertilizer and bio-organic fertilizer could control potato black scurf to varying degrees, among which bio-organic fertilizer had the most significant effect. [Conclusion] After QHZ11 is made into bio-organic fertilizer and applied to the soil, it can effectively inhibit the survival and reproduction of pathogen of black scurf by competing for nutrition and niches in the rhizosphere and different parts of potato plant, thereby achieving significant biocontrol effect. It is of great significance to the application and promotion of bio-organic fertilizer of QHZ11, and lays a foundation to further research the biological control mechanism of QHZ11.