Morphology, fertility and cross-compatibility of somatic hybrids between Brassica oleracea L. and B. campestris L.

Abstract

Thirty-one somatic hybrids between a heat tolerant cabbage cultivar ‘Yoshin’ ( Brassica oleracea var. capitata L.) and a Chinese cabbage cultivar ‘Kenshin’ ( Brassica campestris var. pekinensis L.) were obtained with the aim of breeding new Brassica vegetables adapted to tropical areas. After excluding two hexaploid somatic hybrids, 29 individuals were investigated for pollen fertility and seed set after self-pollination and back-crossing with the parental species. All 29 amphidiploid somatic hybrids showed pollen fertility higher than 70%, and 28 set seeds by self-pollination (2.2 seeds per silique). The hybrids were cross-compatible with Chinese cabbage (1.5 seeds per silique), while practically incompatible with cabbage. Progeny lines obtained by self-pollination had larger leaves than, and intermediate leaf shape of, the parental species. The lines obtained by back-crossing with Chinese cabbage showed larger leaves than the parents and similar leaf shape to Chinese cabbage. These progeny lines, on the whole, exhibited an appreciably wide variation in both leaf size and shape. Variation was found also within the lines for leaf shape. The somatic hybrid method, therefore, could provide new genetic variations to be used to develop new vegetable cultivars.