Production and identification of ×Brassicoraphanus distant hybrids between radish (Raphanus sativus L.) and kohlrabi (Brassica oleracea L. var. Caulorapa DC.)

Abstract

ABSTRACT A fertility obstacle exists in hybrid production between distant related species, particularly from different genera. In the present study, by using tissue culture and chromosome doubling technology, radish (Raphanus sativus L.) and kohlrabi (Brassica oleracea L. var. caulorapa DC.) were subjected to intergeneric distant hybridisation. Through a combination of bud pollination and ovary rescue technology, five putative hybrids were obtained, and three of which were identified as true hybrids with the hybrid acquisition frequency of 0.85%. After tissue culture propagation and colchicine doubling treatment, ×Brassicoraphanus allotetraploids were obtained. Chromosome counting confirmed one plant as allotetraploid with a chromosome doubling rate of 2.70% and 14 seedlings with partial chromosome doubling at a chimaeral rate of 37.8%. The allotetraploid hybrid exhibited normal morphological characteristics, fertile pollen, fuller flower buds and developed pods, compared with the primary hybrid plants. In the present study, the distant hybrid plant that combines the R and C genomes was created to provide basic materials for producing new radish germplasm and to act as a useful bridge for gene transfer between the vegetable species of Brassica and Raphanus.