单胚性二倍体为母本与异源四倍体杂交大规模创制柑橘三倍体

【目的】以单胚性的二倍体柑橘品种为母本与异源四倍体体细胞杂种杂交培育三倍体植株。【方法】选择亲本配置杂交组合进行人工授粉，授粉后70—100 d采幼果进行胚挽救，以流式细胞仪结合根尖染色体压片对再生植株进行倍性检测，最后进行SSR分子标记鉴定。【结果】2009—2012连续4年，以8个二倍体为母本、以4个异源四倍体体细胞杂种为父本，共配置14个倍性杂交组合，授粉花数3 347朵，坐果数678个，平均坐果率20.26%。实施胚挽救的果实数505个，培养种子12 357粒，经生芽、生根诱导培养共获得1 022个株系。通过对再生植株的倍性检测，共获得三倍体植株755个株系，四倍体19个株系。对华农红柚 × NH组合的三倍体、四倍体后代进行分子鉴定，表明三倍体和四倍体全部为双亲的有性杂种后代。【结论】本研究通过杂交获得的三倍体为我国无籽柑橘品种选育奠定了材料基础；同时获得的四倍体后代也为未来的柑橘三倍体育种提供了优良的亲本材料。

Extensive Citrus Triploid Breeding by Crossing Monoembryonic Diploid Females with Allotetraploid Male Parents

【Objective】 The objective of this experiment is to produce citrus triploid hybrids by interploid crossing between elite monoembryonic diploid varieties as female parents and allotetraploid somatic hybrids. 【Method】 Pollinations were carried out between the selected male and female parents. Fruits were collected at 70-100 d after pollination and immature seeds were cultured in vitro. Ploidy level of the plantlets was determined by flow cytometry and chromosome counting. The genetic origin of triploids and tetraploids was analyzed by SSR markers.【Result】 In successive four years from 2009 to 2012, 14 ploidy crosses using eight diploid cultivars as seed parents and four allotetraploid somatic hybrids as pollen parents, were carried out with a total of 3 347 flowers pollinated. With 678 fruits harvested, an average fruit set ratio of 20.26% was obtained. As a result, 1 022 plants were recovered from 12 357 seeds cultured in vitro, which derived from 505 fruits. By flow cytometry analysis and chromosome counting, a total of 755 triploids and 19 tetraploids were verified. The results of SSR markers showed that all the triploids and tetraploids from the cross of Huanong red pummelo × NH were of hybrid origin. 【Conclusion】 The triploids obtained from these crosses are valuable materials for the selection of new seedless citrus varieties. The tetraploid hybrids are also of great value as potential parents for citrus triploid breeding.