A Novel Group of Oleosins Is Present Inside the Pollen ofArabidopsis

Kim, Hyun-Uk; Hsieh, Kai; Ratnayake, Chandra; Huang, Anthony H. C.

doi:10.1074/jbc.m109298200

Cited by 163 publications

(175 citation statements)

References 39 publications

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“…Five of the 16 members of the Arabidopsis oleosin family are specifically expressed in seeds (Kim et al, 2002;Jolivet et al, 2004;D'Andréa et al, 2007;Liu et al, 2012). In this study, we focused on the most abundant oleosins, OLE1, OLE2, and OLE4.…”

Section: Discussionmentioning

confidence: 99%

Specialization of Oleosins in Oil Body Dynamics during Seed Development in Arabidopsis Seeds

et al. 2014

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Oil bodies (OBs) are seed-specific lipid storage organelles that allow the accumulation of neutral lipids that sustain plantlet development after the onset of germination. OBs are covered with specific proteins embedded in a single layer of phospholipids. Using fluorescent dyes and confocal microscopy, we monitored the dynamics of OBs in living Arabidopsis (Arabidopsis thaliana) embryos at different stages of development. Analyses were carried out with different genotypes: the wild type and three mutants affected in the accumulation of various oleosins (OLE1, OLE2, and OLE4), three major OB proteins. Image acquisition was followed by a detailed statistical analysis of OB size and distribution during seed development in the four dimensions (x, y, z, and t). Our results indicate that OB size increases sharply during seed maturation, in part by OB fusion, and then decreases until the end of the maturation process. In single, double, and triple mutant backgrounds, the size and spatial distribution of OBs are modified, affecting in turn the total lipid content, which suggests that the oleosins studied have specific functions in the dynamics of lipid accumulation.The seed is a complex, specific structure that allows a quiescent plant embryo to cope with unfavorable germinating conditions and also permits dissemination of the species. To achieve these functions, seeds accumulate reserve compounds that will ensure the survival of the embryo and fuel the growth of the plantlet upon germination. Accumulation of lipids occurs in many eukaryotic cells and is a rather common means of storing carbon and energy. Lipid droplets (LDs) can be found in all eukaryotes, such as yeast (Saccharomyces cerevisiae;

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Section: Discussionmentioning

confidence: 99%

Specialization of Oleosins in Oil Body Dynamics during Seed Development in Arabidopsis Seeds

et al. 2014

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“…Five of the eight A. thaliana GRPs have been detected in the pollen coat (GRP14 and GRP16-GRP19; ref. 3); two others (GRP20 and GRP22) have messages that are expressed during pollen development (19); an additional putative protein (GRP21) is identified in this study. Mutations that eliminate the most abundant protein, GRP17, result in delayed pollen hydration (12).…”

mentioning

confidence: 96%

“…Moreover, it was not clear whether these rapid changes were a consequence of a particularly dynamic genomic region or instead were specific to GRP genes. We address these questions, assessing changes in the GRPs relative to their genomic neighbors in near (5-8 MY diverged) and more distant relatives (15)(16)(17)(18)(19)(20). This work provides insight into the molecular genetic mechanisms that drive the evolution of genes required for compatible mating and shows that rapid evolution of the GRPs is driven by their repetitive nature.…”

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confidence: 99%

Comparisons of pollen coat genes across Brassicaceae species reveal rapid evolution by repeat expansion and diversification

Fiebig

Kimport

Preuss

2004

Proc. Natl. Acad. Sci. U.S.A.

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Reproductive genes and traits evolve rapidly in many organisms, including mollusks, algae, and primates. Previously we demonstrated that a family of glycine-rich pollen surface proteins (GRPs) from Arabidopsis thaliana and Brassica oleracea had diverged substantially, making identification of homologous genes impossible despite a separation of only 20 million years. Here we address the molecular genetic mechanisms behind these changes, sequencing the eight members of the GRP cluster, along with 11 neighboring genes in four related species, Arabidopsis arenosa, Olimarabidopsis pumila, Capsella rubella, and Sisymbrium irio. We found that GRP genes change more rapidly than their neighbors; they are more repetitive and have undergone substantially more insertion͞ deletion events while preserving repeat amino acid composition. Genes flanking the GRP cluster had an average K a͞Ks Ϸ 0.2, indicating strong purifying selection. This ratio rose to Ϸ0.5 in the first GRP exon, indicating relaxed selective constraints. The repetitive nature of the second GRP exon makes alignment difficult; even so, K a͞Ks within the Arabidopsis genus demonstrated an increase that correlated with exon length. We conclude that rapid GRP evolution is primarily due to duplication, deletion, and divergence of repetitive sequences. GRPs may mediate pollen recognition and hydration by female cells, and divergence of these genes could correlate with or even promote speciation. We tested crossspecies interactions, showing that the ability of A. arenosa stigmas to hydrate pollen correlated with GRP divergence and identifying A. arenosa as a model for future studies of pollen recognition.T raits mediating reproduction often undergo rapid evolution, effectively restricting successful mating to a subset of available partners. Rapidly changing genes regulate sperm storage, sperm-egg binding, cell fusion, and spermatogenesis (1). In some cases, a selective advantage promotes divergence (positive selection); in other cases, relaxed selective constraints allow rapid change (neutral selection). On occasion, evolutionary changes are so great, or the species studied are sufficiently divergent, that homologs cannot be identified, and the nature of the selective pressures cannot be assessed (2, 3). Both mathematical models and experimental data demonstrate that rapid changes in sexual traits have the capacity to drive speciation and that the coevolution of genes encoding male and female traits can lead to reproductive isolation (4-9).In some plant families, highly divergent genes limit inbreeding through self-incompatibility; many molecules required for selfpollen recognition have been identified (10, 11). In contrast, few components that allow plants to discriminate interspecific pollen are understood. Identifying molecules that regulate this selective process has agricultural applications; the ability to control gene flow between species would facilitate the creation of new hybrids and the containment of genetically modified varieties. Here, we examined a rapid...

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“…A group of oleosin genes encoding GRPs (GRP14, are expressed in tapetum and pollen coat (Alves-Ferreira et al, 1997;Mayfield et al, 2001;Kim et al, 2002). Genes encoding several family II EXLs (EXL4, -5, and -6) are expressed in pollen coat (Mayfield et al, 2001), and a putative b-glucosidase gene, ATA27, is highly expressed in tapetum (Rubinelli et al, 1998).…”

Section: Expression Of Rga-regulated Genes In Different Floral Organsmentioning

confidence: 99%

Global Identification of DELLA Target Genes during Arabidopsis Flower Development

Hou

Shen

et al. 2008

Plant Physiology

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Gibberellin (GA) plays important roles in regulating many aspects of plant development. GA derepresses its signaling pathway by promoting the degradation of DELLA proteins, a family of nuclear growth repressors. Although the floral organ identity is established in flowers of the GA-deficient mutant ga1-3, the growth of all floral organs is severely retarded. In particular, abortive anther development in ga1-3 results in male sterility. Genetic analysis has revealed that various combinations of null mutants of DELLA proteins could gradually rescue floral organ defects in ga1-3 and that RGA is the most important DELLA protein involved in floral organ development. To elucidate the early molecular events controlled by RGA during flower development, we performed whole-genome microarray analysis to identify genes in response to the steroid-inducible activation of RGA in ga1-3 rgl2 rga 35S:RGA-GR. Although DELLA proteins were suggested as transcriptional repressors, similar numbers of genes were down-regulated or up-regulated by RGA during floral organ development. More than one-third of RGA down-regulated genes were specifically or predominantly expressed in stamens. A significant number of RGA-regulated genes are involved in phytohormone signaling or stress response. Further expression analysis through activation of RGA by steroid induction combined with cycloheximide identified eight genes as immediate targets of RGA. In situ hybridization and transgenic studies further showed that the expression pattern and function of several selected genes were consistent with the predictions from microarray analysis. These results suggest that DELLA regulation of floral organ development is modulated by multiple phytohormones and stress signaling pathways.

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A Novel Group of Oleosins Is Present Inside the Pollen ofArabidopsis

Cited by 163 publications

References 39 publications

Specialization of Oleosins in Oil Body Dynamics during Seed Development in Arabidopsis Seeds

Specialization of Oleosins in Oil Body Dynamics during Seed Development in Arabidopsis Seeds

Comparisons of pollen coat genes across Brassicaceae species reveal rapid evolution by repeat expansion and diversification

Global Identification of DELLA Target Genes during Arabidopsis Flower Development

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