Microspore culture

Abstract

The ability of immature gametophytic cells of some Angiosperms to develop into sporophytes has its foundation in the similar developmental switch found in Pteridophytes (Fernandez et al.,1993). This parallel has been drawn in a number of reviews (Dunwell, 1978, 1992) and although the detail will not be repeated here, it is worth drawing attention again to one of these earlier studies in which Hirsch (1975) showed a definite nutritional role of sucrose in determining the balance of gametophytic to sporophytic development in Microgramma vaccinifolia. Her conclusion was that increased carbohydrate supply (4% sucrose) stimulated the production of sporophytes and that starvation conditions favoured gametophyte development. This concept of starvation will be considered below in relation to theories of microspore embryo development. In the same context, a recent study of Equisetum arvense has, for the first time, shown an interesting difference in sensitivity of gametophytic and sporophytic tissue to the microtubule inhibitor oryzalin (Kuriyama et al.,1994). This finding is pertinent to the observations on the importance of cytoskeletal structure in embryo formation (Iqbal et al., 1994), and it is to be hoped that this type of comparative study may eventually provide clues about the factors controlling this developmental switch in higher plants.