Genetic Analysis Of Nuclear And Cytoplasmic Genomes Of Ten Citrus Somatic Hybrids

Citrus is one of the most important fruit crops in the world. Protoplast fusion circumvented reproductive barriers such as polyembryony and female and/or male sterility encountered in conventional breeding, and paves the way for citrus cultivar improvement. To date, numerous citrus somatic hybrids were regenerated in the world and in our group. Inheritance analysis of their nuclear and cytoplasmic genomes will help enrich plant somatic cell genetics knowledge and guide their utilization in citrus breeding. Herein, ten citrus somatic hybrids were evaluated by SSR, cpSSR and CAPS analysis. The main results were as follows:(1) Flow cytometry was employed to analyze their ploidy level: "Hongju tangerine + Citrange", "Hongju tangerine + Goutou sour orange", "Bonanza orange + Rough lemon", and "Kinnow tangerine + Bendizao tangerine" are tetraploid; There are tetraploid and diploid regenerated plants in "Page tangelo + Valencia orange" and "Hongju tangerine + Rough lemon". "Kinnow tangerine + Goutou sour orange", "Kinnow tangerine + Pineapple orange", "Kinnow tangerine + Jincheng orange", and "Murcott + Anliucheng orange" are diploids;(2) SSR analysis showed that "Hongju tangerine + Citrange", "Hongju tangerine + Goutou sour orange", "Bonanza orange + Rough lemon", "Kinnow tangerine + Bendizao tangerine" are somatic hybrids, "Kinnow tangerine + Goutou sour orange" is diploid hybrid, and remaining combinations are cybrids. The SSR banding of "Kinnow Tangerine + Goutou sour orange", "Page tangelo + Valencia orange" showed that some new bands were absent in the regenerated plants. The banding of "Hongju tangerine + Citrange" showed some plants lost their parents' markers. Both phenomenon appeared at "Hongju tangerine + Goutou sour orange". The results showed that the fusion process is accompanied with genetic recombination;(3) The cpSSR analysis revealed random segregation in cpDNA of the regenerated plants. At the same time, coexistence of cpDNA was observed in No. 6 plant of "Hongju tangerine + Citrange";(4) For mtDNA, CAPS analysis showed that mtDNA were all derived from the...