Pollen ontogeny in Cichorium intybus L.

Abstract

Abstract Cichorium intybus L. is a highly self-incompatible species: haploids obtained in vitro through androgenesis would be of benefit in producing homozygous doubled haploids. The microsporogenesis and microgametogenesis of C. intybus is investigated using LM, TEM and SEM to obtain information which could be exploited in anther and/or microspore culture experiments and to ascertain whether the plastid change during pollen development 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 after a limited parietal phase becomes amoeboid, losing the inner tangential and radial cell walls at the microspore stage. During pollen development the tapetum degenerates and tapetal cells have a discontinuous plasma membrane. Starch accumulation occurs only during pollen maturation, starting after the first mitotic division: at anthesis pollen grains 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 behaviour of the species.