Development of the silique of Arabidopsis Thaliana

Abstract

Using the silique of Arabidopsis as a model system, we are studying fruit development by a combination of cytological, cytochemical and molecular techniques. Within the floral bud the early gynoecium develops with differentiation of two major vascular bundles and two meristematic regions. The latter give rise to the ovules and combine to form the septum which separates the two loculi of the maturing fruit. Development of the carpel walls results in the differentiation of three specific layers, the endocarp, the mesocarp and the exocarp. After fertilisation absicission zones form between the carpel walls and the major vascular supplies to the developing ovules. The patterns of differentiation result in the dehiscence mechanism which disperses seeds from the shattering fruit. Such fruit shatter and seed dispersal mechanisms represent significant problems in a number of agricultural crops causing loss of seed yield and the distribution of volunteers. We have described the cytological events associated with the differentiation of the major tissue types associated with carpel and septal development, and identified a number of probes which act, by immunocytochemistry, in situ hybridisation or enzymecytochemistry, as appropriate markers for specific phases of differentiation. We have compared the development of the meristic clvl mutant, which shows anomalies in gynoecial development, with that of wild type, and are screening EMS-mutated stock for other variants of fruit development.