“ITOSAI No. 1”, a new late bolting cultivar of Chinese cabbage (Brassica rapa L.)

Abstract

‘ITOSAI No. 1’ is a new Chinese cabbage F₁ cultivar that shows extremely late bolting. Late-bolting BrFLC genes derived from ‘Leafy Parental Green No. 2’ were introduced to the parents of the Chinese cabbage F₁ cultivar ‘Tiny-chouchou’ with backcrossing and DNA marker selection. In spring sowing under a low temperature, ‘ITOSAI No. 1’ showed extremely late bolting compared to commercial late-bolting F₁ cultivars. Other characteristics of ‘ITOSAI No. 1’, except the late bolting, are almost the same as ‘Tiny-chouchou’, including no trichomes. It is suitable for use in salads. Whereas the existing commercial F₁ cultivars bolted after 10 to 20 days of chilling treatment, ‘ITOSAI No. 1’ needs more than 40 days to induce bolting. ‘ITOSAI No. 1’ is an epoch-making cultivar which enables us to cultivate Chinese cabbage in spring without heating and covering materials.