Cellular organisation in meiotic and early post-meiotic rice anthers

Abstract

We have used fluorescent, confocal laser and transmission electron microscopy (TEM) to examine cellular organisations, including callose (1,3-beta-glucan) behaviour, in meiotic and early post-meiotic rice anthers. These features are critical for pollen formation and provide information to better understand pollen sterility caused by abiotic stress in rice and other monocotyledonous species. Among organelles during meiosis, abundant plastids, mitochondria and nuclei of the anther cells show distinctive features. Chloroplasts in the endothecium store starch and indicate a potential for photosynthetic activity. During meiosis, the middle layer cells are markedly compressed and at the tetrad stage are either vacuolated or filled with degenerating electron-opaque organelles. Viable mitochondria, stained with Rhodamine 123, are seen in the endothecium and tapetum, but the mitochondria in the middle layer are not stained during meiosis. The radial walls of the tapetum are disorganised and degenerating, indicating the formation of a syncytium; pro-orbicules are located at the locular walls at the tetrad stage. Immunohistochemical studies show that the sporogenous cells are entirely enveloped by a thick callosic layer at early meiosis. Cell plate callose was assembled in a plane between the dyad cells. In the tetrads, however, callose formed only at the centre, showing that the tetrad microspores are not enveloped but separated by callose walls. Thick, undulating electron-opaque walls around the tetrads indicate the beginning of exinous microspore wall differentiation.

Two ATP Binding Cassette G (ABCG) Transporters, OsABCG26 and OsABCG15, Collaboratively Regulate Rice Male Reproduction

“…In plant vegetative organs, such as stems and leaves, it is believed that cuticular lipid biosynthesis occurs exclusively within epidermal cells (Sieber et al, 2000;Nawrath, 2002;Panikashvili et al, 2007). Previous reports showed that plastids could not been found in anther epidermal cells (Mamun et al, 2005a(Mamun et al, , 2005b, which implies that lipid de novo synthesis cannot occur within anther epidermal cells. Therefore, it is not surprising that several tapetum-expressed lipid metabolism genes are involved in anther cuticle formation (Li et al, 2010;Shi et al, 2011;Yang et al, 2014).…”

Recent Discoveries on the Roles of Polyphosphates in Plants

“…Acidocalcisome-like organelles have been reported in other plant organs with active cell division, such as in anthers during the onset of meiosis (Mamun et al 2005) and in meristematic areas of roots from pea and barley seedlings (Olbrich et al 2007). Interestingly, the vacuoles of these seedlings later merge together to form a central vacuole, similar to the merging of the acidocalcisomes and contractile vacuole of protists (Olbrich et al 2007).…”

Mechanism of low‐temperature‐induced pollen failure in rice

“…At the premeiotic development stage, the epidermal cells have a well‐structured cuticle and contain a complete set of normal organelles. These cells during early meiotic development possess plastids containing amylaceous starch reserves (Mamun et al, 2005a). Sucrose exported from the adjacent endothecium (or due to sugars loading via anther wall cells from the filament) is stored as starch in these organelles (Mamun et al, 2005b).…”