Triploid Citrus Plants Obtained From Crossing The Diploids With Allotetraploid Somatic Hybrids

Interploid hybridization between allotetraploid and diploid plants is a most effective approach to produce seedless triploid citrus cultivars. And the triploid progenies can be used directly for breeding. In this paper, allotetraploid somatic hybrids, which were produced by protoplast fusion and have flowered in recent two years, were selected as male parents, while several elite diploid citrus cultivars in China were chosen as female parents. Embryos were collected from fruitlets 70-100 days after pollination, and then germinated in MT solid medium for regenerating healthy and vigorous plantlets. Facilitated by the embryo rescue technique, we got a number of triploid offsprings and the main results were as follows:1. In 2008-2009, Earlygold sweet orange (C. sinensis’Earlygold’), Red tangerine (C. reticulata’Dancy’), Fallglo (Citrus reticulata’Fallglo’), Huanong Bendizao tangerine (C. succosa Hort’Huanong’) and HB pummelo (C. grandis (L.) Osbeck’Hirado Buntan’) were selected as female parents to be pollinated by NS (’Nova’Tangelo+’Succari’Sweet orange, [C. reticulata×C. paradisi]’Nova’+C. sinensis’Succari’) and SD (C. sinensis ’Succari’+C. reticulata’Dancy’). Embryo rescue was carried out at 70-100 days after pollination. The plantlets obtained from embryo rescue were detected by flow cytometry and 102 were triploid plantlets from four combinations, there were Earlygold sweet orange×NS combination, Red tangerine×SD combination, HB pummelo×NS combination and HB pummelo×SD combination, and 3 tetraploid plantlets from Earlygold sweet orange×NS combination.2. Triploid and tetraploid plantlets were transplanted. So far, there were 101 triploid plantlets in the green house:28 ones in 40 lines from HB pummelo×NS combination,49 ones in 34 lines from HB pummelo×SD combination,10 ones in 4 lines from Earlygold sweet orange×NS combination and 2 plantlets from Red tangerine×SD combinations respectively. And 3 tetraploid plantlets were obtained from Earlygold sweet orange×NS combination but 2 survived after transplanting.All of these triploids can be used as valuable materials for seedless citrus breeding.