Anther plastids in angiosperms

dIn the anther of angiosperms, all types of plastids are found in the cours e of pollen development. They are located in the different cell layers of t he microsporangium and have various functions that contribute to the format ion of the functional male gametophyte. This includes photosynthesis, stoma ta opening, sugar storage and/or mobilization, lipid synthesis and secretio n for pollenkitt formation, as well as serving as a physiological buffer un der stress conditions. They are also involved in plastid inheritance, but t o different extents, according to the species. The plastid is a semi-autonomous organelle. Plastid division in the anther is synchronous with cell division, except in the vegetative cell during pol len maturation. Furthermore, recent data seem to show that plastids are aff ected by programmed cell death and DNA degradation, which occur in the whol e anther throughout pollen development. However, the timing of plastid disa ppearance fluctuates in the different cell layers and also depending on spe cies. In vitro, following androgenesis, plastids that originate in the microspore are responsible for the occurrence of albino plantlets in Poaceae. This tr ait reflects the relative independence of the plastid genome when compared with that of the nucleus. In this family, microspore plastids may become so involved in programmed cell death that they are unable to follow the alter native sporopohytic program. The different pathways of plastid differentiation in neighboring anther cel l layers require an accurate regulation of cell development that remains wi dely unknown in the anther.