Pollen Wall and Aperture Development in Helianthus annuus (Compositae: Heliantheae)

Citations Over TimeTop 10% of 1978 papers

Abstract

Wall development of tricolpate pollen of sunflower was studied by light and by scanning and transmission electron microscopy. The wall and colpi are initiated during the tetrad stage, producing a young, spinulate, two-layered exine (ektexine and endexine) separated by a “spacer layer.” After release from the tetrads, the individual microspores round up and enlarge. The exine layers increase in thickness and complexity from sporopollenin contributed by the tapetum and microspores. During the mid-vacuolate microspore stage, the tapetum becomes plasmodial and surrounds the developing microspores. At the vacuolate pollen stage, after the wall and colpi are completely formed, the plasmodial tapetum breaks down and releases its contents into the locule. Some of the contents are presumably utilized by the pollen to make storage reserves while other components, such as lipids and proteins, fill the spaces within the pollen wall exine. Pollen wall ontogeny provides a scheme of terms for mature composite walls in general. The various events associated with microsporogenesis in sunflower are compared with those reported in other pertinent studies.

Related Papers

• → The HKM gene, which is identical to the MS1 gene of Arabidopsis thaliana, is essential for primexine formation and exine pattern formation(2005)60 cited
• → Elasticity in engineering(1953)56 cited
• → ACOS5 is required for primexine formation and exine pattern formation during microsporogenesis in Arabidopsis(2017)15 cited
• → Exine and the Role of the Tapetum in Pollen Development(1968)30 cited
• → A comparison of pollen wall development in normal and gametocide treated plants ofTriticum aestivum(1990)1 cited