Ripening and dehiscence of the anther in some Crocus(Iridaceae) species

Abstract The anther development was examined in some Crocus species, by light and scanning electron microscopy. Epidermal cells develop a longitudinal stomium which is connected to the interlocular septum by cells with wide intercellular spaces.Endothecial cells are mono or bilayered, and they develop annular wall thickenings.Middle layer cells degenerate shortly after the microspore release. Tapetal cells are secretory with orbicules, and they form the tapetal membrane. The stomium disjoins from the interlocular septum after the lysis of the middle lamellae in the abscission region. The stomial cells break long before the flower opening, and in C. boryithey show signs of programmed cell death. Following the flower opening, the locular walls shrink tangentially, with flattening of epidermal cells and shortening of endothecial cells, and they bend up to turn inside out, exposing the pollen grains. The results are discussed in relation to the dehiscence mechanism

The complex structures of arabinogalactan-proteins and the journey towards understanding function

The original publication can be found at www.springerlink.comArabinogalactan-proteins (AGPs) are a family of complex proteoglycans found in all higher plants. Although the precise function(s) of any single AGP is unknown, they are implicated in diverse developmental roles such as differentiation, cell-cell recognition, embryogenesis and programmed cell death. DNA sequencing projects have made possible the identification of the genes encoding a large number of putative AGP protein backbones. In contrast, our understanding of how AGPs undergo extensive post-translational modification is poor and it is important to understand these processes since they are likely to be critical for AGP function. Genes believed to be responsible for post-translational modification of an AGP protein backbone, include prolyl hydroxylases, glycosyl transferases, proteases and glycosylphosphatidylinositol-anchor synthesising enzymes. Here we examine models for proteoglycan function in animals and yeast to highlight possible strategies for determining the function(s) of individual AGPs in plants.Yolanda Gaspar, Kim L. Johnson, James A. McKenna, Antony Bacic and Carolyn J. Schult