POLLEN ONTOGENY IN CICHORIUM-INTYBUS L

Cichorium intybus L. is a highly self-incompatible species: haploids o btained in vitro through androgenesis would be of benefit in producing homozygous doubled haploids. The microsporogenesis and microgametogen esis of C intybus is investigated using LM, TEM and SEM to obtain info rmation which could be exploited in anther and/or microspore culture e xperiments and to ascertain whether the plastid change during pollen d evelopment is related to the androgenic recalcitrant behaviour of this species: anthers of this species are not induced by in vitro culture to produce haploid calli or embryos. C. intybus has a tapetum which af ter a Limited parietal phase becomes amoeboid losing the inner tangent ial and radial cell walls at the microspore stage. During pollen devel opment the tapetum degenerates and tapetal cells have a discontinuous plasma membrane. Starch accumulation occurs only during pollen maturat ion, starting after the first mitotic division: at anthesis pollen gra ins are engorged, mainly with starch. These results are compared with observations made on other Compositae and the accumulation pattern of reserves is evaluated in relation to the androgenic recalcitrant behav iour of the species.