A survey of proteinases active during meiotic development

Abstract

Microsporogenesis in Lilium longiflorum Thunb. is a naturally synchronous process and affords a system in which to study stage-specific events of meiosis and anther development. Zymogram gel analyses were conducted with extracts from a variety of stages of anther development to identify proteinases which likely play roles in anther metabolism. These experiments revealed that several proteinases are present at different stages of anther development, and class-specific inhibitors were used to classify these enzymes. Proteolytic activities increased as anther development proceeded and these activities were temporally correlated with the apoptotic events which precede dehiscence, as well as with events crucial for the maturation of viable pollen.

Programmed cell death progressively models the development of anther sporophytic tissues from the tapetum and is triggered in pollen grains during maturation

“…Previously, PCD in the anther was reported to occur primarily during tapetum disappearance (Clément et al, 1998;Papini et al, 1999;Wang et al, 1999;Wu and Cheung, 2000) and during anther dehiscence (Schreiber et al, 2004;Wu and Cheung, 2000), however, we have shown here that PCD affects all the anther tissues including both sporophytic diploid and gametophytic haploid tissues, which is also consistent with the presence of proteinase (a PCD marker) in this organ (DeGuzman and Riggs, 2000). Moreover, following each step of pollen development, we have further determined the spatial and temporal location of PCD in the whole anther.…”

“…In Lilium longiflorum, serine proteases that are known to be implicated in PCD are secreted in the loculus by the tapetum during microspore vacuolization (Taylor et al, 1997). Similar proteinases were found in the anther of Lilium (DeGuzman and Riggs, 2000) and Solanum melongena (Xu and Chye, 1999) at developmental stages correlated with apoptotic events. Proteinases may thus be good candidates for spreading of PCD in the anther in response to hormonal signalling.…”

“…In particular, using this model genus the understanding of the relationships between the anther diploid sporophytic tissues and the haploid gametophytic cells via the locular fluid have been significantly enhanced in the last decade (Aouali et al, 2001). The identification of active proteinases in the anther of Lilium temporally correlated with apoptotic events preceding anther and pollen maturation indicates that PCD may affect both the sporophytic and gametophytic tissue during development (DeGuzman and Riggs, 2000). Recently, we have optimized a protocol allowing the accurate separation of the sporophytic and the gametophytic parts of the anther (Aouali et al, 2001).…”

Molecular characterization of a miraculin-like gene differentially expressed during coffee development and coffee leaf miner infestation

“…These three tissues suVer programmed cell death (PCD), which is essential for microspore maturation and release (Wu and Cheun 2000). De Guzman and Riggs (2000) demonstrated that proteolysis increases during anther development and is temporally correlated with the PCD of anther tissues, preceding pollen liberation. Together with the RNA blot results, which showed that CoMir is down-regulated in senescent open Xowers (Fig.…”

A Puromycin-Sensitive Aminopeptidase Is Essential for Meiosis inArabidopsis thaliana [W]

“…A recent study of microsporogenesis in Lilium longiflorium has revealed that proteinase activity is closely correlated with meiotic development. There is a temporal increase in general proteolytic activity commencing around midzygotene that persists throughout the remainder of prophase I (DeGuzman and Riggs, 2000). One class of proteases, the aminopeptidases cleave amino acids from the N terminus of oligopeptides.…”