Regulation of the inductive phase of microspore embryogenesis in Brassica napus

In cultured microspores from Brassica napus, embryogenesis can be synchronously and irreversibly induced by elevating the culture temperature to 32°C for a minimum of 8 h. Culture at 18°C allows gametophytic development to continue, and results in the formation of pollen in vitro. This allows us to study the temperature controlled switch in developmental fate from gametophytic development to embryogenic development by molecular means. Analysis of protein synthetic patterns by [35S]-methionine incorporation and 2-dimensional gel electrophoresis, revealed that 25 proteins were differentially synthesized during the induction of microspore embryogenesis. Most of these proteins (17) appeared to belong to the class of heat shock proteins (HSPs). Four of these HSPs have been identified by Western blotting using antibodies raised against HSP17, HSP68 and HSP70. One protein that was only synthesized under embryogenic culture conditions, and did not belong to the heat inducible HSPs, is a candidate marker for early embryogenic development

Embryogenesis from isolated microspores of tulip : towards developing F1 hybrid varieties

This report describes advances in the technique of embryogenesis from tulip microspores in culture. High temperature pretreatment (32°C) of bulbs, which contain fully developed inflorescences, had a positive effect on the production of microspore embryos. The pretreatment shortened the time for embryo formation and stimulated the progression from the multicellular microspore stage into the embryo proper. Early unicellular microspores were found to be better starting material for culture than mid unicellular microspores. The technique of microspore embryogenesis was applicable to various tulip cultivars. The improved protocol now allows the production of large numbers of microspore-derived plants, and the further evaluation of doubled haploid plant technology for tulip