西藏大麦与条锈菌互作系统演化特点初探

ON THE EVOLUTION OF THE BARLEY-YELLOW RUST PATHOSYSTEM IN TIBET

本文从条锈菌寄生专化性和毒性组成、条锈病流行循环、大麦品种抗性及混合品种中病害流行等几个方面初步探讨了西藏大麦与条锈菌互作系统演化的特点。认为它是一个经历了长期共同选择和共同进化的稳定系统。系统中,条锈菌毒性类型丰富,以毒性中等偏弱的为主体;品种的防御机制有成株期部分抗性,品种混合的稳定作用等。在西藏地区,条锈病可以独立完成流行循环,保证了系统组分长期共同存在的场所。

The evolution of the barley-yellow rust(Puccinia striiformis f.sp.hordei)interacting system was discussed in the preliminary studies of the pathogen'sparasitic specificity and virulence,disease cycles,epidemics in the mix-ture of varieties,and analysis of the mechanisms of barley resistance inTibet.It was considered that the pathosystem was a stabilized system,havingundergone a long period of co-selection and coevolution for the two componen-ts,in which the rust fungi had varied in various virulences,mainly consis-ting of medium and weak virulent isolates,while the barley host had variedin mechanisms for partial resistance in the adult stage,as well as in thestabilization of varietal mixture among plots and regions.The disease cyclesof the overwintering and oversummering was accomplishcd independentlyin Tibet,which supplied the place of variation for the two components.The finding of the stability and very low virulence of the disease in thesystem provided the evidence that the Tibet plateau might be an originalcenter of the cultivated barley(Hordeum vulgare)