Cytology Observation Of "Yichang Papeda+Valencia Orange" Somatic Hybrid And Offspring Culture Of Two Sexual Combinations In Citrus

Citrus somatic hybrids are mainly used for cultivating new heteroresistance rootstock, improving scion and for male parent in triploidy breeding. Currently, few studies on pollen fertility, genetic stability and chromosome behavior during meiosis on these hybrids had been reported. In present investigations, the morphologic and cytology characteristics of leaves and flowers (including stamen and gynoecium) were analyzed among the somatic hybrids of 'Yichangpapeda (C.ichangenis Swingle) + Valencia orznge(C.sinensis Osbeck)', both fusion parents were adopted as controls. The results showed that the somatic hybrids' leave and flower were larger in size than both parents'. The pollen fertility of the somatic hybrids and its parents were observed and statistically analyzed, it was found that pollen fertility of the somatic hybrid was between the value of two parents, but biased to the more viable parent,,which indicated that the somatic hybrid pollen could be used as parent for diploid breeding. Chromosome behaviors during meiosis of the somatic hybrid and its parents were studied, it was found that the formation of chromosome during the prophase of meiosis was mainly composed of bivalence, besides at metaphase and anaphase many chromosome bridge and lagged chromosomes were observed,,these may provided some indirect evidence for the seedless allotetraploid somatic.Nucellar embryos are ubiquity in citrus, which hampered sexual progenies creation. To overcome this obstacle, monoembryo cultivar of HB pummelo was used as female parent to cross with Morcutte tangor. About 100 days after bagging, we divested the seeds from the unmature fruit, then we vaccinated the seeds to three kinds of culture mediums(MT, MT+ME, MT+GA3) for embryo rescuing, ultimately, more than 50 seedlings were recovered through embryo rescuing. Additionally, another sexual cross combination was conducted between Guoqing No.1 Satsuma(C. unshiu Marc. 'Guoqing No.1')×Shatangju tangerine (C.reticulata). 100 days after bagging, the seeds were divested from the unmature fruit, then after sterilized they were vaccinated to the same three kinds of culture mediums as mentioned above, after a series of subculture, more than 200 plantlets were obtained. SSR was performed to identify the sexual hybrids. No polymorphic markers among the population of Guoqing No.1 Satsuma×Shatanju tangerine, due to the closed genetic relationship between both parents, while high frequency (about 54%) of hybrid was obtained among the progenies of HB pummelo×Morcutte tangor. Present sexual population provided important candidate resources for citrus breeding.