烟草野生种eIF4E1-S同源基因的多样性与马铃薯Y病毒抗性分析

The diversity of eIF4E1-S gene in tobacco wild species and the resistance to Potato virus Y

【背景和目的】在栽培烟草中,真核生物翻译起始因子(Eukaryotic translation initiation factor 4E1,eIF4E1-S)的缺失或突变能够抗马铃薯Y病毒(Potato virus Y,PVY)侵染。为了解烟草野生种eIF4E1-S同源基因的多样性和PVY抗性状况,预测野生种含有抗PVY新基因(即不同于eIF4E1-S基因缺失或突变的基因)的可能性。【方法】本文设计了普通烟草eIF4E1-S和其同源基因eIF4E1H-T(非感病基因)的特异引物,扩增测定了34个烟草野生种的同源基因cDNA序列,分析了野生种PVY抗性与感马铃薯Y病毒属病毒eIF4E蛋白关键结构域序列(loop1和loop2)的相关性。【结果】在eIF4E1-S同源基因的系统进化树上,绒毛烟草组(Tomentosae)的4个抗PVY野生种Nicotiana otophora、N.setchelli、N.tomentosa、N.tomentosiformis聚成一组,loop1和loop2的氨基酸序列与eIF4E1H-T一致,这4个野生种对PVY的抗性可能与eIF4E1进化为eIF4E1H-T有关、包含抗PVY新基因的可能性较低。圆锥烟草组(Paniculatae)的4个抗PVY野生种N.benavidesii、N.raimondii、N.cordifolia、N.knightiana聚成一组,同源基因氨基酸序列与eIF4E1-S一致率高于eIF4E1H-T,但loop1和loop2氨基酸序列相互之间差异较大,这4个野生种包含抗PVY新基因的可能性中等。与eIF4E1-S聚成一个小分支的N.glauca、N.noctiflore、N.africana高抗5个PVY分离物(包含可克服va抗性的PVY分离物),其中N.glauca、N.noctiflore的同源基因loop1氨基酸序列与eIF4E1-S相同,loop2与eIF4E1-S之间只有1-2个氨基酸差异,N.africana同源基因loop1与eIF4E1-S和eIF4E1H-T差异较大、loop2与eIF4E1-S之间只有1个氨基酸差异(V97M)。推测这3个野生种的PVY抗性与eIF4E1的突变无关且含有新的抗PVY基因可能性高,可作为重点抗源研究利用。【结论】根据PVY侵染栽培烟草所利用的寄主因子eIF4E1-S基因的同源基因的多样性,抗PVY烟草野生种存在抗PVY新基因的可能性划分为高、中和低三档。N.glauca、N.noctiflore、N.africana含有新的抗PVY基因可能性高于其他供试野生种。

[Background and Objective]Eukaryotic translation initiation factor 4E1(eIF4E1-S)is tobacco recessive resistance gene to Potato virus Y(PVY).Elucidating the eIF4E1-S diversity and PVY resistance of tobacco wild species is helpful for finding new resistant resources for tobacco breeding.[Methods]In this paper,the eIF4E1 gene cDNA and deduced amino acid sequence of 34 tobacco wild species were determined by eIF4E1 gene amplifying and sequencing,and the phylogenetic tree was constructed by MEGA6 software UPGMA.[Results]In phylogenetic trees,for the four PVY resistant wild species in the Tomentosae group,such as N.otophora,N.setchelli,N.tomentosa,N.tomentosiformis,their resistance to PVY may be related to the evolution from eIF4E1-S to eIF4E1H-T;for the 4 PVY resistant wild species N.benavidesii,N.raimondii,N.cordifolia,N.knightiana in Paniculatae group,their homologous gene amino acid sequence was more consistent with eIF4E1-S than with eIF4E1H-T.The N.glauca,N.africana,and N.noctiflore,which have resistance to 5 PVY isolates(including PVY isolates that can break va resistance)were clustered into a small branch with eIF4E1-S.It was speculated that the PVY resistance of these 3 wild species was independent of eIF4E1 variation and may contain new PVY resistance gene(s).The wild species with PVY resistance,which is different from eIF4E1-S deficiency or variant homologous,is of great breeding value.[Conclusion]According to the diversity of the host factor eIF4E1-S gene used by PVY infection,the probability of the presence of new PVY resistant gene(i.e.not belonging to eIF4E1-S gene loss or mutation)in the tobacco wild species can be divided into high,medium and low third grades.N.glauca,N.noctiflore,and N.africana are more likely to contain new PVY resistant genes than other wild species.