GROWTH AND MORPHOGENESIS OF GLOBULAR AND OLDER EMBRYOS OF CAPSELLA IN CULTURE

Abstract

Raghavan, V., and J. G. Torrey. (Harvard U., Cambridge, Mass.) Growth and morphogenesis of globular and older embryos of Capsella in culture. Amer. Jour. Bot. 50(6) : 540–551. Illus.1963.—Early heart‐shaped and older embryos of Capsella bursa‐pastoris (>80μ long), when cultured aseptically in a semi‐solid medium containing mineral salts, vitamins, and 2% sucrose, developed into small plantlets. When grown in a 12‐hr light/12‐hr dark cycle (light‐grown cultures), formation of the primary root system was suppressed in embryos<1000μ long, while embryos cultured in continuous dark routinely initiated a primary root system and several lateral roots. In embryos > 1000μ long, the inhibition of formation of the root system in light did not occur. Growth of the shoot apex of intermediate and torpedo‐shaped embryos was slightly accelerated in light. There was a correlation between the rate of growth of the embryos and their initial length. Better growth in length was observed in light‐grown than in dark‐grown cultures. Supplementing the basal medium with indoleacetic acid, kinetin, and adenine sulfate permitted successful development of globular embryos (<80μ long) in vitro. Although a high sucrose concentration or a high salt concentration in the medium partially replaced the effect of the growth factors in inducing development of the globular embryos, no absolute requirement for a high osmotic concentration in the medium was found. The results favor caution in interpreting the inability of small embryos to grow in terms of the osmotic conditions of the culture milieu.