XVI International Botanical Congess

Developmental phases can be distinguished in the definition of the archesporium and the early life of the embryo: 1. isolation of the megasporocyte and the functional spore derived from it, 2. maturation of the specialised walls of the embryo sac and reinforcement from nucellar cells, 3. differentiation of synergids and filiform apparatuses, 4. blocking of the pollen tube pathway during fertilization, and 5. development of a compound cutinized envelope of four or six fused layers after fertilization. For the nascent haploid generation, maximum vulnerability in respect to pathogen invasion and transition from diplophase control occurs during these phases. Many features form a prophylactic shield and are key components of the angiosperms in general, which may have contributed to their evolutionary success as a group. Search http://www.jic.bbsrc.ac.uk