2018 ASHS Annual Conference

ABSTRACT

Citrus is the most important fruit crop in the world and in southern China. Cell engineering holds great potential for citrus genetic improvement. In our program, somatic hybrids from over 50 interspecific and intergeneric fusion combinations were produced which efficiently circumvented the reproductive barriers such as nucellar polyembryony, male/ female sterility encountered in citrus conventional breeding. Numerous autotetraploids, haploids and dihaploids were also produced and identified by SSR markers. Metabolic adaptation following genome doubling in citrus doubled diploids was revealed by non-targeted metabolomics. Some somatic hybrids / autotetraploids already flowered and set fruits, and served as pollen parents for seedless triploid production resulting in thousands of triploid plants from over 50 ploidy crosses being recovered and identified by embryo rescue, flow cytometry and SSR analysis. Facilitated by molecular marker analysis of numerous citrus somatic hybrids and cybrids, a strategy of male sterile cybrid production by symmetric fusion between embryogenic callus protoplasts of Satsuma mandarin (CMS type with sterile cytoplasm) and mesophyll protoplasts of elite seedy cultivars were put forward, and diploid cybrid plants containing sterile cytoplasm from Satsuma were regenerated, some cybrids already showed male sterility and seedless traits. The mechanism of male sterility in a citrus somatic cybrid is being conducted. Cell engineering combined with application of molecular marker and omics technology greatly enhanced the efficiency and targeted breeding of citrus cell engineering research.