Differential expression patterns of arabinogalactan proteins in Arabidopsis thaliana reproductive tissues

Abstract

Arabinogalactan proteins (AGPs) are heavily glycosylated proteins existing in all members of the plant kingdom and are differentially distributed through distinctive developmental stages. Here, we showed the individual distributions of specific Arabidopsis AGPs: AGP1, AGP9, AGP12, AGP15, and AGP23, throughout reproductive tissues and indicated their possible roles in several reproductive processes. AGP genes specifically expressed in female tissues were identified using available microarray data. This selection was confirmed by promoter analysis using multiple green fluorescent protein fusions to a nuclear localization signal, β-glucuronidase fusions, and in situ hybridization as approaches to confirm the expression patterns of the AGPs. Promoter analysis allowed the detection of a specific and differential presence of these proteins along the pathway followed by the pollen tube during its journey to reach the egg and the central cell inside the embryo sac. AGP1 was expressed in the stigma, style, transmitting tract, and the chalazal and funiculus tissues of the ovules. AGP9 was present along the vasculature of the reproductive tissues and AGP12 was expressed in the stigmatic cells, chalazal and funiculus cells of the ovules, and in the septum. AGP15 was expressed in all pistil tissues, except in the transmitting tract, while AGP23 was specific to the pollen grain and pollen tube. The expression pattern of these AGPs provides new evidence for the detection of a subset of specific AGPs involved in plant reproductive processes, being of significance for this field of study. AGPs are prominent candidates for male-female communication during reproduction.

Characterization of a pollen-specific agp1-like protein in Arabidopsis thaliana

“…They serve as recognition signals, nutritional supply or guidance for the pollen tube [13,14]. AGPs have been identified as a group of hydroxyproline-rich glycoproteins, differentially expressed throughout plant development [12][13][14][15]. Previous studies have shown that AGPs were identified in pollen tubes of several plant species, and tube growth was affected by the Yariv phenyl .…”

“…These experimental evidence suggests that AGPs play an important role in pollen tube extension or guidance [17]. Analysis of the Arabidopsis thaliana genome revealed that 47 genes code for AGP polypeptide backbones [15]. ''Classical'' AGPs include an Nterminal secretion sequence, a central domain rich in Pro/Hyp and a C-terminal hydrophobic domain for signaling [12,14,15,17] Herein, we characterized an Arabidopsis AGP1-LIKE PROTEIN (ALP; At3g26110), which have been shown to have 47% homology at the amino acid level to At1g24520.1 (BCP1), POLLEN PROTEIN1 in Brassica campestris [18].…”

“…Analysis of the Arabidopsis thaliana genome revealed that 47 genes code for AGP polypeptide backbones [15]. ''Classical'' AGPs include an Nterminal secretion sequence, a central domain rich in Pro/Hyp and a C-terminal hydrophobic domain for signaling [12,14,15,17] Herein, we characterized an Arabidopsis AGP1-LIKE PROTEIN (ALP; At3g26110), which have been shown to have 47% homology at the amino acid level to At1g24520.1 (BCP1), POLLEN PROTEIN1 in Brassica campestris [18]. Previous reports have shown that BCP1 was highly expressed in tapetum and microspores and it is essential for pollen fertility [18,19].…”

Desenvolvimento floral e do óvulo e aspectos da reprodução em Aechmea sp. e Vriesea sp. (Bromeliaceae)

“…Podem ainda encontrar-se em corpos multivesiculares intracelulares e corpos multilamelares nos vacúolos (FERGUSON et al, 1999). (COIMBRA et al, 2005;2007;2009;PEREIRA et al, 2014) e Brassica napus (EL-TANTAWY et al, 2013), nesses estudos as AGPs foram diferentementes expressas durante o desenvolvimento gametofítico. Li et al (1992) e Jauh e Lord (1996) verificaram que AGPs se depositam nas paredes dos tubos polínicos e acredita-se que desempenhem importante papel no desenvolvimento da antera e do grão de pólen (PEREIRA et al, 2006;LEVITIN et al, 2008;COIMBRA et al, 2009;MA;SUNDARESAN, 2010;COSTA et al, 2013) .…”

“…Evidências implicando AGPs na reprodução sexual foram obtidas por diversos grupos, para várias espécies (COIMBRA; SALEMA, 1997;DUARTE, 2003;COIMBRA et al, 2005;EL-TANTAWY et al, 2013) e têm demonstrado ser diferencialmente expressas durante o desenvolvimento gametófito, tornando-se um importante marcador do desenvolvimento reprodutivo (COIMBRA et al, 2007(COIMBRA et al, , 2009PEREIRA et al, 2014). As cinco fases da microsporogênese de A. gamosepala mostram uma clara diferenciação na organização celular e na atividade de RNA.…”