Percorrer por autor "Pereira, Ana Marta"
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- Arabinogalactan proteins: decoding the multifaceted roles in plant reproductionPublication . Silva, Jessy; Moreira, Diana; Ferreira, Maria João; Pereira, Ana Marta; Pereira, Luís Gustavo; Coimbra, SílviaArabinogalactan proteins (AGPs) are highly glycosylated cell wall proteins essential for plant growth and reproduction. AGPs are extensively decorated with arabinogalactan polysaccharides, composed primarily of arabinose and galactose, along with minor sugars such as glucuronic acid, fucose, and rhamnose. Their glycosylation patterns and glycosylphosphatidylinositol anchor enable interactions with receptors, modulating signal transduction pathways critical for reproduction. AGPs also associate with cell wall components like pectin and hemicellulose, impacting cellulose deposition and cell wall integrity. Recent research highlights AGPs’ role as calcium (Ca2+) capacitors, regulating Ca2+ storage and release during crucial reproductive stages. Despite significant progress, their precise molecular mechanisms remain elusive. In this review, we explore the multifaceted roles of AGPs in plant reproduction, shedding light on the recent progress in their involvement in signalling pathways, cell wall interactions, and Ca2+ homeostasis, while highlighting the ongoing research needed to fully understand their mechanisms in reproductive success.
- Eight hydroxyproline-O-galactosyltransferases play essential roles in female reproductive developmentPublication . Moreira, Diana; Kaur, Dasmeet; Fourbert-Mendes, Sara; Showalter, Allan M.; Coimbra, Sílvia; Pereira, Ana MartaIn angiosperms, ovules give rise to seeds upon fertilization. Thus, seed formation is dependent on both successful ovule development and tightly controlled communication between female and male gametophytes. During establishment of these interactions, cell walls play a pivotal role, especially arabinogalactan-proteins (AGPs). AGPs are highly glycosylated proteins decorated by arabinogalactan side chains, representing 90 % of the AGP molecule. AGP glycosylation is initiated by a reaction catalysed by hydroxyproline-O-galactosyltransferases (Hyp-GALTs), specifically eight of them (GALT2–9), which add the first galactose to Hyp residues. Five Hyp-GALTs (GALT2, 5, 7, 8 and 9) were previously described as essential for AGP functions in pollen and ovule development, pollen-pistil interactions, and seed morphology. In the present work, a higher order Hyp-GALT mutant (23456789) was studied, with a high degree of under-glycosylated AGPs, to gain deeper insight into the crucial roles of these eight enzymes in female reproductive tissues. Notably, the 23456789 mutant demonstrated a high quantity of unfertilized ovules, displaying abnormal callose accumulation both at the micropylar region and, sometimes, throughout the entire embryo sac. Additionally, this mutant displayed ovules with abnormal embryo sacs, had a disrupted spatiotemporal distribution of AGPs in female reproductive tissues, and showed abnormal seed and embryo development, concomitant with a reduction in AGP-GlcA levels. This study revealed that at least three more enzymes exhibit Hyp-O-GALT activity in Arabidopsis (GALT3, 4 and 6), and reinforces the crucial importance of AGP carbohydrates in carrying out the biological functions of AGPs during plant reproduction.