植物LTR反转录转座子的研究进展

反转录转座子是真核生物基因组中普遍存在的一类可移动的遗传因子,它们以RNA为媒介,在基因组中不断自我复制。在高等植物中,反转录转座子是基因组的重要成分之一。反转录转座子可以分为5大类型,其中以长末端重复（LTR）类型报道较多。LTR类型由于其首尾具有长末端重复序列,内部含有PBS、PPT、GAG和POL开放阅读框、TSD等结构,可以采用生物信息学软件进行预测。LTR反转录转座子的活性受到自身甲基化和环境因素的影响,DNA甲基化抑制反转录转座子转座,而外界环境的刺激能够激活转座子,从而影响插入位点周边基因的表达。同时由于LTR反转录转座子在植物中普遍存在,丰富的拷贝数以及多态性为新型分子标记（RBIP、SSAP、IRAP、REMAP）的开发提供了良好的素材。该文对近年来国内外有关植物反转录转座子的类型、结构特征、 LTR反转录转座子的活性及其影响因素、 LTR反转录转座子的预测以及标记开发等方面的研究进展进行综述。

Review of LTR Retrotransposons in Plants

Retrotransposons in eucaryon are mobile genetic elements with ubiquitousdistribution,these elements can amplify themselves via RNA intermediates and increase their copy numbers in genome.In high plants,retrotransposon is an important component of genome.Retrotransposons can be divided into five types,the LTR retrotransposons,an important subclass of transposable elements,are well suited for computational identification,as they contain two long terminal repeats (LTRs) and features such as PBS,PPT,GAG and POL open reading frames,TSD.Recent research indicated that methylation of LTR retrotransposon and environments seemed to be affecting the jump of retrotransposons.Retrotransposons could be inhibited by high degree of DNA methylation and activated by environments,which influence the function of surrounding genes.The characteristics of LTR retrotransposons,such as ubiquitous distribution,abundant copy number and insertional polymorphism in plant species,provide an excellent basis for the development of molecular markers,e.g.,RBIP,SSAP,IRAP,REMAP.In this review,we summarize the recent progress about the types and structures of retrotransposons,inhabitation and activation of LTR retrotransposons and their computational identification,molecular marker development.