坛紫菜遗传连锁图谱的构建

Construction of a genetic linkage map for Porphyra haitanensis

以野生型坛紫菜纯系(♀)和红色型坛紫菜纯系(♂)作为杂交亲本,结合四分子分析法及单个体细胞克隆的丝状体途径,创建了由157个株系组成的坛紫菜DH作图群体,并用经过筛选的24对SRAP引物和16对SSR引物对父母本及作图群体各株系进行双标记分析,获得了224个多态性标记,其中157个标记符合孟德尔分离规律。根据标记间的连锁规律,首次构建了坛紫菜的分子遗传连锁图谱,所构建的遗传图谱由包含124个标记(含SRAP标记104个,SSR标记20个)的5个连锁群组成,总长度为879.2cM,平均标记间隔为7.09cM,各个连锁群长度为134.2～213.6cM,包含标记18～31个。最后采用3种不同方法计算得到坛紫菜的估计基因组长度平均为955.3cM,由此得到坛紫菜遗传连锁图谱的基因组覆盖率为92.0%。

Porphyra haitanensis is an important economic marine crop in south China. The development of the P. haitanensis cultivation is highly desirable to select or breed new lines of P. haitanensis with strong economic traits and use them for cultivation. Molecular markers and molecular genetic maps are pre- requisites for molecular breeding in any plant species. A comprehensive genetic linkage map for cultivated P. haitanensis has not yet been constructed. In this study,157 double haploid（ DH） lines[derived from a YS Ⅲ（ wild-type） ×RTPM（ red-type artificial pigmentation mutant） cross]were used as a mapping population in P. haitanensis. A total of 100 pairs of sequence-related amplified polymorphism（ SRAP） primers and 39 pairs of simple sequence repeat（ SSR） primers were used to detect polymorphisms between the two parents and 5 DH lines. Twenty-four SRAP and 16 SSR polymorphic primer pairs were selected to analyze the DH population. A linkage genetic map comprising 104 SRAP markers and 20 SSR markers in five linkage groups,witha total length of 879. 2 cM and an average of 7. 09 cM between markers was constructed. The linkage groups comprised 18 -31 markers ranging in length from 134. 2 to 213. 6 cM. The estimated genome length of P. haitanensis was 955. 3 cM,with a coverage of 92. 0% coverage. This is the first report of a comprehensive genetic map in P. haitanensis. The map presented here will provide a basis for the development of high-density genetic linkage maps,which will facilitate QTL mapping of desirable traits,and provide markers for MAS,map-based cloning of genes,and the introgression of beneficial genes from wild species into modern cultivars in P. haitanensis.