小麦秆锈菌新小种Ug99及其对我国的影响分析

Ug99(TTKS)是1999年在乌干达首次发现的对最重要小麦抗秆锈病基因Sr31有强毒力的秆锈菌新小种。大量证据显示:该小种不仅具有极其特殊的毒力组合而且传播十分迅速,除在中非乌干达、东非肯尼亚、埃塞俄比亚、苏丹流行外,Ug99现已越过红海、传到了阿拉伯国家也门,以及巴基斯坦的沿海地区,越来越逼近我国。Ug99堪称我国的超毒小种,我国最典型的秆锈菌小种只能分别克服或Sr5或Sr9 e或Sr11单基因抗性,而Ug99不仅具有Sr5、Sr9 e、Sr11的联合毒力,而且还具有Sr21、Sr31、Sr38的联合毒力,而我国从未有小种能克服后者的抗性。1B/1L(含Sr31)易位系曾是我国使用的重要秆锈抗源,必对Ug99高度脆弱,我国118份小麦品种在KARI的测定结果表明,高感品种频率98.3%。一旦Ug99入侵我国,其他流行条件也完全具备。因此,充分作好防范Ug99流行的准备十分必要。

Ug99,a new virulent race of Puccinia graminis f.sp. tritici,and its effect on China

Ug99(designated as TTKS),found in Uganda in 1999,is a new virulent race of Puccinia graminis f.sp.tritici on Sr31,the backbone of stem rust resistance worldwide.It is evident that this race not only contains a unique combination of virulence but was disseminating very fast from Uganda in Central Africa to Kenya,Ethiopia and Sudan in Eastern Africa,and now is crossing Red Sea to Yemen in Arab or even to the coastal area in Pakistan in Southern Asia,which is close to China.Ug99 could be called a superior virulent race to widely-used and Sr31-carrying Chinese wheat cultivars or stem rust resistant sources.The number of virulent genes contained in Ug99 was more than the total carried in all Chinese stem rust races.For instance,the virulence of Sr5,Sr9e or Sr11 was the typical races.However,besides the virulence of Sr5,Sr9e and Sr11,Ug99 contains additional virulence of Sr21,Sr31and Sr38,which have never been found in Chinese stem rust races.As mentioned above,there is an urgent risk from Ug99,if there are no preventive practices.Once Ug99 invaded in China,a catastrophic result could be seen.