苹果Ty1-copia类逆转座子家族鉴定及特性分析

Identification and Characteristics of Apple Ty1-copia-like Retrotransposons

根据逆转座子RT保守序列设计引物,利用PCR方法从苹果‘嘎拉’中克隆了20条RT片段,分析苹果基因组内Ty1-copia类逆转座子家族特性及进化关系。结果显示,20条逆转录酶保守序列表现出了高度的异质性。结合已报道的37条苹果Ty1-copia类逆转座子RT片段,构建了系统发育树,发现家族1、3和4中具有转座活性的逆转座子的可能性较大;序列分析表明,Ty1-copia类逆转座子是苹果基因组内序列重组的热点。用RT序列为探针进行Southern杂交,发现苹果基因组内Ty1-copia类逆转座子拷贝数高、分布广泛。研究结果为进一步分离具有转座活性的苹果Ty1-copia类逆转座子及其人工诱导芽变奠定了基础。

In the attempt to investigate and understand the genetic relationship,characteristics and evolution of apple Ty1-copia-like LTR retrotransposon families,we cloned 20 conserved domains of reverse transcriptase（RT） genes of Ty1-copia-like LTR retrotransposons using degenerate primers aimed at RT conserved motifs from the cultivar ＇Gala＇.Sequence analysis of clones demonstrated that these fragments were highly heterogeneous.These 20 clones and previously reported 37 are combined for constructing phylogenetic tree.Group 1,Group 3 and Group 4 with closely related members inserted throughout the genome may contain transposable retrotransposons.Sequences analysis indicated that Ty1-copia-like retrotransposons were prone to recombination in apple genome.Southern blot hybridization using RT as a probe showed that Ty1-copia-like retrotransposons were integrated throughout the apple genome with high copy number,which made the retrotransposon possible an effective molecular marker to detect apple genome evolution events and to reveal its relationship with bud mutation.This work lays the foundation for isolating the transposable Ty1-copia-like retrotransposons in apple genome and will be useful for inducing apple bud mutations.