Studies on in vitro culture of excised buds in mulberry tree

I. Effects of growth substances on the development of shoots and organ formation from winter buds

Abstract

Tissue culture is one of the useful method for the study of physiological problems in woody plants such as flowering, bud dormancy and bud growth, because correlations among tissues or organs might be eliminated under defined conditions in tissue culture system. From this point of view, in vitro culture of isolated winter buds of mulberry tree was carried out. Results obtained are as follows.
1. When an excised winter bud (var. Kenmochi) was cultured on MURASHIGE and SKOOG'S medium containing benzyl adenine at 0.1 to 1.0mg/l, it sprouted within 2 weeks and a leaflet with stem grew in a month after planting. Continuous cultivation over more than a month caused differentiation of roots from basal part of the shoot.
2. Auxins, when they were added alone to the medium, exerted no effect on bud sprouting but induced callus at the base of the bud. When auxins were added together with benzyl adenine the time of rooting was fastened.
3. Adventitious buds were rarely formed on main nerves of leaflets on medium with benzyl adenine at 1mg/l.
4. There seemed to exist three types of varieties among 16 ones cultured on medium with benzyl adenine at 1mg/l. They are as follows.
Type A: Leaves with stem grow and shoot is formed.
B: A few leaves without stem grow and shoot is not formed.
C: Either leaf or stem hardly grows.