Somaclonal variation with early juice-sac granulation obtained by inter-specific protoplast fusion in citrus

Abstract

SummarySix plants with an early juice–sac granulation trait derived from inter-specific protoplast fusions between embryogenic calli of ‘Bonanza’ navel orange (Citrus sinensis [L.] Osbeck) and mesophyll protoplasts of ‘Dahongpao Red’ tangerine (C. reticulata Blanco) were analysed by flow cytometry and by using molecular markers, including simple sequence repeats (SSR) and restriction fragment length polymorphism (RFLP). The results indicated that all six plants were diploids and had inherited their nuclear DNA from the embryogenic callus parent ‘Bonanza’ navel orange. However, an analysis of morphological and fruit characteristics, and measurements of components of the cell walls in the juice-sacs, showed that they were not true-to-type for ‘Bonanza’ navel orange, especially for fruit traits such as juice-sac granulation and navel structure. These results confirmed that these plants were not hybrids, and were more likely to be somaclonal variants that arose during the regeneration of the navel orange protoplasts. These plants will provide material for studying the mechanism of granulation in juice-sacs, a common phenomenon during the storage of pummelo and other citrus fruits.