三倍体葡萄柚实生后代多倍体的发掘与SSR遗传鉴定

Exploitation of polyploids from open-pollinated triploid grapefruit progenies and their genetic identification by SSR molecular markers

【目的】从三倍体葡萄柚自然授粉的实生后代中发掘多倍体,希望获得一批多倍体新种质,并为探索三倍体遗传规律奠定基础。【方法】秋季采摘三倍体葡萄柚成熟果实,剥取种子,MT+1 mg·L-1GA3培养基播种,待种子萌发后,用流式细胞仪快速检测其倍性,并采用SSR(simple sequence repeat)分子标记鉴定其不同倍性后代植株的来源。【结果】获得了二倍体、三倍体、四倍体、五倍体、六倍体和疑似非整倍体等不同倍性的再生植株各172、52、7、1、1、18株。用13对多态性SSR引物鉴定其来源,结果表明,由二倍体可能三倍体母本所产生的1X配子与周边其他二倍体品种的花粉授粉而来,也可能由三倍体母本产生的重组型2X配子的无融合生殖而来;三倍体大部分由珠心细胞发育而来;四倍体为杂交起源的四倍体;五倍体和六倍体与母本(三倍体葡萄柚)的带型完全相同。【结论】上述活体材料的发掘为柑橘多倍体育种奠定了种质基础。

【Objective】To exploit spontaneous polyploids as new germplasm from seedling progenies of open pollinated triploid grapefruit.【Method】Fruits of triploid grapefruit were harvested in autumn. Seeds were collected and cultured in vitro. Flow cytometry was applied to verify the seedlings' ploidy level,and simple sequence repeat(SSR) markers were used to characterize their genetic origin.【Results】172 Diploid,52 triploid,18 tetraploid,one pentaploid,one hexaploid and 18 putative aneuploid seedlings were identified from the recovered plants respectively. The genetic origin of these polyploids obtained by embryo rescue were determined by 13 SSR markers,and the results showed that diploid might be 1X gamete pollinated and fertilized by nearby 1X pollen grain from other citrus cultivars,or it might be a product of apomixes of recombinant 2X female gamete. Triploids were mostly derived from nucellar cells. Pentaploid and hexaploid have exactly the same banding pattern as the female parent.【Conclusion】These newly exploited polyploids hold great potential for citrus breeding.