Characterization of a Non-Flowering Cabbage Mutant Discovered 42 Years Ago

Abstract

A non-flowering natural cabbage mutant among the open-pollinated line ‘T15’ was found 42 years ago. The mutant was named ‘nfc’ (non-flowering cabbage) and has been propagated vegetatively by cuttings. ‘nfc’ hardly flowers during the spring season even after plenty of low-temperature periods. This study characterized the non-flowering trait of ‘nfc’ and assumed the mechanism. In the first experiment, we investigated the flowering characteristics of ‘T15’ and ‘nfc’ over three years. Throughout the 3-year cultivation period, all ‘T15’ plants flowered, while the flowering ratios of ‘nfc’ propagated by cuttings at the 1st, 2nd, and 3rd year were 0%, 32%, and 4%, respectively. In the last two years, other traits were also investigated in detail. The flowering dates of ‘nfc’ flowering plants were later than those of ‘T15’, and the average numbers of flowering shoots per flowering plant of ‘nfc’ were lower than those of ‘T15’. Moreover, the terminal bud of ‘nfc’ flowering plants continued to grow vegetatively, even when their lateral shoots flowered. In the second experiment, to verify the hypothesis that ‘nfc’ is a chimeric plant, we investigated protoplast-regenerated plants’ flowering characteristics from mesophyll protoplasts of ‘nfc’. We obtained colonies derived from different protoplasts of ‘nfc’ and regenerated plants from each colony (nfcPP lines). Suppose the ‘nfc’ is a chimeric plant, in that case, protoplast-regenerated plants’ flowering characteristics should be the same for each colony they derived. However, both flowering and non-flowering plants appeared in the same nfcPP lines derived from a single colony. From this, we concluded that ‘nfc’ is not a chimeric plant on flowering characteristics. These results indicate that ‘nfc’ is a mutant that maintains its flowering ability, but its flowering is strongly suppressed by some factors other than its structural characteristics.