Recessive Inheritance of Morphological Characteristics of Utsukushimatsu, Pinus densiflora f. umbraculifera

Abstract

Pinus densiflora f. umbraculifera, commonly known as utsukushimatsu, is a distinctively shaped form of Japanese red pine whose growth is restricted to a forest stand in Shiga Prefecture, Japan. The inheritance mode of morphological characteristics of utsukushimatsu was studied to preserve the genetic resource of this pine. As previously reported, F1 trees grown from open-pollinated seeds harvested from trees inhabiting the native stand showed two phenotypes: one resembling utsukushimatsu, which produces multiple trunks, and the other resembling normal P. densiflora, which produces one or a few trunks. In the present study, controlled pollination was carried out using F1 and normal P. densiflora trees. Segregation ratios of the two phenotypes observed in the F2 population showed that the morphological characteristics of utsukushimatsu are inherited recessively. This suggests that the mutation of one gene or a few closely linked genes controls the morphological characteristics of utsukushimatsu. Since multiple trunk formation of utsukushimatsu might be related to a loss of lateral bud inhibition, it follows that a simple gene mutation breaks apical dominance in P. densiflora.