Formation of Pollen in the Anther of Lilium Ii. The Function of the Surrounding Tissues in the Formation of Pollen and Pollen Wall

Abstract

IntheLilium anther a peritapetal andtapetal membrane aremade bythe tapetal cells. During the young microspore stage thepro-orbicules receive a matrix ofmainly carbohydrates similar to thatof the sexine. The plasma-membrane of the tapetal cells forms membrane-like lamellae. During the vacuolization of the microspore the orbicule diameter increases. In the channels made by the endoplasmic reticulum theglobules ofsporopollenin areproduced. Thelipid inclusions accumulate and globules containing carotenoid increase in the plastids. Both elements fuse and form the "Pollenkitt" during degeneration of thetapetal cell. Some sporopollenin globules fuse and form a second generation of orbicules. Thecell of the middle layer next to the tapetal cell contains lipid granules. Theotherfourcells ofthemiddle layer lose their starch at thestage oftheyoung microspore and after mitosis thelipid granules areproduced. Asa source fornutrients intheloculus thestarch of the middle layer cells hasan important function. Aninteraction model isschematically presented.

Pollen and Tapetum Development in Male FertileRosmarinus OfficinalisL. (Lamiaceae)

“…( I ) An electron opaque, in part globular layer covering the surface of the remaining outer tangential and radial tapetal walls isolating the locule from the exterior; and (11) small electron opaque granules in the fibrous walls of the anther tapetum. The electron opaque layer (I) is comparable with thin, partly fibrillar peritapetal membranes developing along the oirter tangential walls (adjacent to the middle layer), as already described for several taxa (Reznickova & Willemse 1980, Polowick & Sawhney 1993; further on cf. Bhandari 1984, andShivanna &Johri 1985, for reviews).…”

Starch Turnover and Metabolism during Flower and Early Embryo Development

“…These starch waves were suggested to sustain growth and differentiation of the anther wall layers, to translocate nutrients to the highly active tapetum and to the loculus, to provide carbon skeletons for the formation of lipid droplets within the pollen grain, and to store excess food during the anther maturation phase (Reznickova and Willemse, 1980;Miki-Hiroshige and Nakamura, 1983;Pacini and Franchi, 1983;Clément et al, 1994;Clément and Pacini, 2001). In this work, apart from confirming the occurrence of these waves in Arabidopsis, we unraveled the existence of a third wave of starch amylogenesis/ amylolysis in the staminal envelope just before anthesis.…”

Immunological Characterization of a Tapetal Protein in Developing Anthers of Lilium longiflorum

“…For instance, lignification occurs on the wall of the endothecium (10). Both the endothecial and middle cells are enlarged and the breakdown products of starch in the cells serve as a nutritive source for the microspores and pollen grains (26). In the anther wall, the tapetum is the innermost layer that surrounds the sporogenous tissue.…”

“…The tapetum has drawn much attention because of its apparently nutritive physiological role during microspore and pollen development. The tapetum is also involved in the production of proteins and enzymes (such as callase), the formation of the pollen wall, the production and release of locular fluid, and of pollenkitt, tryphine, and recognition substances all deposited in the pollen wall (5,14,26).…”

“…A number of studies on the stamen of lily have documented the histological changes during anther growth (12,14,26,34). Only a few reports have dealt with anther proteins and mRNAs from which the proteins were translated.…”