荔枝两个F1杂交群体的EST-SSR鉴定及多样性分析

Identification and Genetic Diversity Analysis of Two F_1 Hybrid Populations of Litchi(Litchi chinensis Sonn.) Using EST-SSR Markers

为了更好地在荔枝杂交育种中判别真杂种,以荔枝两个人工杂交群体‘雪怀子’ב桂味’和‘雪怀子’ב焦核三月红’的F1代为材料,利用EST-SSR标记进行真假杂种鉴定,创建作图群体,并对两个群体进行遗传多样性分析。结果表明,分别采用4对引物组合即可实现对两个杂交群体F1代单株100%的鉴定,两个群体的159个单株均为真杂种;且两个群体后代叶片形态存在变异,基因型上产生了不同于亲本的扩增谱带。经聚类分析发现,群体‘雪怀子’ב桂味’113个F1单株被聚为6大类(相似性系数0.68),63.72%(72株)后代与父本聚为一类,28.3%(32株)单株与双亲距离较远,推测这些单株中出现了较大的遗传重组或变异。在相似系数0.642处,‘雪怀子’ב焦核三月红’组合的46株杂种后代分为两大类,该组合大部分单株(60.87%)与母本亲缘关系较近,具有偏母本遗传倾向。可见,EST-SSR标记适合荔枝真假杂种鉴定,两个F1作图群体的创建为荔枝遗传连锁图谱构建奠定基础,同时为荔枝的品种改良积累材料。

In order to better distinguish true hybrids in breeding of litchi, EST-SSR markers were used to identify and study the genetic diversity of two F1 hybrid progenies of litchi. The hybrid natures of 159 offsprings from the two cross combinations of litchi, ＇ Xuehuaizi＇ x＇ Guiwei＇ and ＇ Xuehuaizi＇ x＇ Jiaohesanyuehong＇, and the genetic relationship between parents and offsprings were analyzed. The four EST-SSR primers selected from 35 pair primers revealed a hybrids identification rate of 100% in two hybrid F1 populations, respective. A total of 159 F1 progenies from two cross combinations were proved to be true hybrids, and we successfully produced two genetic mapping populations. In addition, there are much richly phenotypic variations among the progenies and new alleles presented and （or） specific bands of parents absented in partial individuals. The cluster analysis showed that 113 F1 plants from the cross combination of ＇Xuehuaizi＇ x ＇Guiwei＇ were clustered into 6 categories （similarity coefficient of 0.68）. Of them, 63.72% （72 plants） clustered into one group with father. The genetic distance of 32 plants （28.3%） with their parents was far which indicated that recombinant or larger variation appeared in these plants. At the similarity coefficient of 0.642, the combination of ＇Xuehuaizi＇ x＇Jiaohesanyuehong＇ were divided into two categories, and most plants （60.87%） showed closer genetic relationship with mother considering partial maternal genetic tendency. It is concluded that the EST-SSR markers are suitable for assessing the genetic diversity and identifying the true hybrids in litchi. The two F1 populations built successfully by us has established the basis for the further genetic linkage mapping, and at the same time the newly accessions will be useful for litchi genetic improvement in future breeding.