磷素积累导致马铃薯疮痂病加重及高效拮抗菌筛选

Phosphorus accumulation aggravates potato common scab and to be controlled by phosphorus-solubilizing bacteria

近年来,由致病性链霉菌(Streptomyces)引起的疮痂病在全世界各马铃薯产区普遍发生,危害程度逐年加重;病原菌土传和种传,难以防控,已成为威胁马铃薯产业可持续发展的重要瓶颈.本研究发现,磷肥施用量与疮痂病危害程度高度相关.磷素在土壤中大量沉积不仅诱发致病性链霉菌的快速繁殖,也显著降低了拮抗菌的丰度和拮抗功能.平板和盆栽实验结果表明,疮痂链霉菌(S.scabies)对Ca_(3)(PO_(4))2吸收具有喜好性,基质中Ca_(3)(PO_(4))_(2)含量越高,病原菌繁殖速度越快,马铃薯块茎发病率和病情指数亦越高.代谢组学和X射线光电子能谱分析发现,疮痂链霉菌可通过分泌有机酸,将难溶性的Ca_(3)(PO_(4))_(2)转化成可溶性的HPO_(4)^(2-)供其生长繁殖所需,过量的H_(2)PO_(4)^(-)不利于其生存.实验证明,具有解磷功能的拮抗菌防控效果更好.我们筛选到一株具有溶磷功能的拮抗菌DX-9,可将Ca_(3)(PO_(4))_(2)转化成H2PO4-,有效降低土壤中Ca_(3)(PO_(4))_(2)的含量,对马铃薯疮痂病的田间防效可达70%.DX-9的规模化应用,将有望实现马铃薯疮痂病的有效防控.

As the fourth largest food crop,potato plays an important role in ensuring the stability of the human food supply[1,2].However,potato common scab(CS)induced by pathogenic Streptomyces occurs globally,and the harm is increasing year by year[3].Potato CS has become a key problem that urgently needs to be solved in the potato industry.The research on preventing potato CS has been carried out for more than 100 years[4],yet limited breakthroughs have been achieved so far.Therefore,the investigation of the main mechanism leading to CS and the effective strategy to control CS for industrialized applications is needed.