Guérin Fabien, Gladieux Pierre, Le Cam Bruno
UMR077 PAVE, INRA, F-49071 Beaucouze, France.
Fungal Genet Biol. 2007 Apr;44(4):284-92. doi: 10.1016/j.fgb.2006.10.005. Epub 2006 Dec 12.
Plant resistance based on a gene-for-gene relationship tends not to be durable because virulent strains can emerge through mutation and colonize formerly resistant cultivars over large areas. Our objective was to determine the origin and colonization history of newly virulent strains of the fungus Venturia inaequalis. Four hundred and eighty-one strains from seven multi-cultivar orchards within a 300km wide area were collected from a cultivar carrying the overcome Vf-gene (Vfcv populations) and from non-Vf cultivars (nVfcv populations). Using 9 microsatellite loci, we showed that Vfcv populations were closely related though highly differentiated, indicating they have been recently founded following rare long distance dispersal events from a common origin. Assignment tests revealed that the Vfcv populations had not emerged from any of the nVfcv populations. Vfcv populations had a low diversity and were strongly differentiated from nVfcv populations several years after the first reported breakdown, suggesting reproductive isolation between the two populations.
基于基因对基因关系的植物抗性往往不持久，因为毒性菌株可通过突变出现，并在大面积上定殖于以前具有抗性的品种。我们的目标是确定苹果黑星病菌新毒性菌株的起源和定殖历史。从一个携带已被克服的Vf基因的品种（Vfcv群体）和非Vf品种（nVfcv群体）中，收集了来自300公里宽区域内7个多品种果园的481个菌株。使用9个微卫星位点，我们表明Vfcv群体虽然高度分化但密切相关，这表明它们最近是在罕见的长距离扩散事件后从一个共同起源建立起来的。分配测试表明，Vfcv群体并非从任何nVfcv群体中出现。首次报道抗性丧失几年后，Vfcv群体多样性较低，且与nVfcv群体有强烈分化，这表明两个群体之间存在生殖隔离。
