Isolation and Characterization of a Gene Expressed during Early Embryo Sac Development in Apomictic Guinea Grass (Panicum maximum)

Ultrastructural Mechanisms of Aposporous Embryo Sac Initial Cell Appearance and Its Developmental Process in Gametophytic Apomicts of Guinea Grass (Panicum maximum)

“…Based on the observation of this study that the period of AIC appearance is the key to catch the apomixis genes, and ovary length can be used as an index to do sampling of the key period of AIC appearance, apomixis-specific gene-1 (ASG-1) and its family genes have been cloned from the key period of AIC appearance in facultative apomictic guinea grass using differential screening method (Chen et al 1999).…”

“…Although the same project had been conducted (Nakajima and Mochizuki 1983), a new conclusion will be expected using the method described here. Chen et al (1999) has reported that the ASG-1 gene was cloned using differential screening method based on ovary length as an index to sample the different developmental stages of facultative apomictic guinea grass. And then, the ASG-1 was used as a probe to do in situ hybridization in apomictic guinea grass, indicating that the signals of the gene expression were detected not only in the expected AIC and AIC-derived embryo sac but also in unexpected anther .…”

“…The thickness of cell wall increases, and plasmodesmata connections diminish leading to the end of symplastic transport and separating the cell from the other. Chen et al (1999) indicated that the ASG-1 gene isolated from stage of AIC appearance in facultative apomictic guinea grass, containing 1177 bp and 305 amino acids, shows the 45-48% positive similarity to polygalacturonase 1 beta chain precursor (Polyg 1) of Lycopersicon esculentum (Zhang et al 1992) that has a bifunctional plant proteins that interact with both structural components of the cell wall and catalytic proteins to localize and/or regulate metabolic activities within the cell wall. ASG-1 existing in AIC and AIC-derived embryo sac is also reported by in situ hybridization .…”

The classical Ubisch bodies carry a sporophytically produced structural protein (RAFTIN) that is essential for pollen development

“…12 A) and Ͼ90% identical to ESTs from inflorescences of various cereal species. All other significant ''hits'' (E value of Ͻ10 Ϫ4 ) were also only from plant accessions, but generally they had only Ϸ35% identity and included the following BURP domain proteins (29): a seed protein of faba bean (30); the ␤ subunit of polygalacturonase isoenzyme 1 from the developing fruit of tomato (31); an desiccation-induced protein of Arabidopsis (32); an auxin down-regulated protein (33) and an aluminum up-regulated protein (34) from soybean hypocotyl and roots, respectively; microspore embryo development-related protein from Brassica napus (29); an apomixisspecific gene product from the flower buds of guinea grass (35) that showed Ϸ45% aa sequence identity over the entire carboxydomain; and a seed coat protein found in developing soybean seed coats (36).…”

Use of the SSLP-based method for detection of rare apomictic events in a sexual AtSERK1 transgenic Arabidopsis population

“…Another proposed strategy entitles cloning of the apomictic genes and their transfer into sexual plants by transformation (reviewed by Koltunow et al 1995;Grossniklaus et al 1998a). So far, candidate genes for apomixis have been identified mainly by comparative gene expression studies during early stages of apomictic and sexual embryo development (Vielle-Calzada et al 1996;Chen et al 1999;Pessino et al 2001;Rodrigues et al 2003;Albertini et al 2004Albertini et al , 2005. On the other hand genes that are responsible for gamete reduction, parthenogenesis or autonomous endosperm formation in sexual species are regarded as more successful candidates for 'apomixis' genes.…”