51
|
Tan XY, Liu XL, Wang W, Jia DJ, Chen LQ, Zhang XQ, Ye D. Mutations in the Arabidopsis nuclear-encoded mitochondrial phage-type RNA polymerase gene RPOTm led to defects in pollen tube growth, female gametogenesis and embryogenesis. PLANT & CELL PHYSIOLOGY 2010; 51:635-49. [PMID: 20231244 DOI: 10.1093/pcp/pcq029] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The mitochondrial genes in Arabidopsis thaliana are transcribed by a small family of nuclear-encoded T3/T7 phage-type RNA polymerases (RPOTs). At least two nuclear-encoded RPOTs (RPOTm and RPOTmp) are located in mitochondria in A. thaliana. Their genetic roles are largely unknown. Here we report the characterization of novel mutations in the A. thaliana RPOTm gene. The mutations did not affect pollen formation, but significantly retarded the growth of the rpoTm mutant pollen tubes and had an impact on the fusion of the polar nuclei in the rpoTm mutant embryo sacs. Moreover, development of the rpoTm/- mutant embryo was arrested at the globular stage. The rpoTm rpoTmp double mutation could enhance the rpoTm mutant phenotype. Expression of RPOTmp under control of the RPOTm promoter could not complement the phenotype of the rpoTm mutations. All these data indicate that RPOTm is important for normal pollen tube growth, female gametogenesis and embryo development, and has distinct genetic and molecular roles in plant development, which cannot be replaced by RPOTmp.
Collapse
Affiliation(s)
- Xiao-Yun Tan
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, PR China
| | | | | | | | | | | | | |
Collapse
|
52
|
Chantha SC, Gray-Mitsumune M, Houde J, Matton DP. The MIDASIN and NOTCHLESS genes are essential for female gametophyte development in Arabidopsis thaliana. PHYSIOLOGY AND MOLECULAR BIOLOGY OF PLANTS : AN INTERNATIONAL JOURNAL OF FUNCTIONAL PLANT BIOLOGY 2010; 16:3-18. [PMID: 23572950 PMCID: PMC3550630 DOI: 10.1007/s12298-010-0005-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Female gametophyte development in Arabidopsis thaliana follows a well-defined program that involves many fundamental cellular processes. In this study, we report the involvement of the Arabidopsis thaliana MIDASIN1 (AtMDN1) gene during female gametogenesis through the phenotypic characterization of plants heterozygous for an insertional mdn1 mutant allele. The MDN1 yeast ortholog has previously been shown to encode a non-ribosomal protein involved in the maturation and assembly of the 60S ribosomal subunit. Heterozygous MDN1/mdn1 plants were semisterile and mdn1 allele transmission through the female gametophyte was severely affected. Development of mdn1 female gametophyte was considerably delayed compared to their wild-type siblings. However, delayed mdn1 female gametophytes were able to reach maturity and a delayed pollination experiment showed that a small proportion of the female gametophytes were functional. We also report that the Arabidopsis NOTCHLESS (AtNLE) gene is also required for female gametogenesis. The NLE protein has been previously shown to interact with MDN1 and to be also involved in 60S subunit biogenesis. The introduction of an AtNLE-RNA interference construct in Arabidopsis led to semisterility defects. Defective female gametophytes were mostly arrested at the one-nucleate (FG1) developmental stage. These data suggest that the activity of both AtMDN1 and AtNLE is essential for female gametogenesis progression.
Collapse
Affiliation(s)
- Sier-Ching Chantha
- />Institut de Recherche en Biologie Végétale (IRBV), Département de sciences biologiques, Université de Montréal, 4101 rue Sherbrooke est, Montréal, QC Canada H1X 2B2
| | - Madoka Gray-Mitsumune
- />Institut de Recherche en Biologie Végétale (IRBV), Département de sciences biologiques, Université de Montréal, 4101 rue Sherbrooke est, Montréal, QC Canada H1X 2B2
| | - Josée Houde
- />Institut de Recherche en Biologie Végétale (IRBV), Département de sciences biologiques, Université de Montréal, 4101 rue Sherbrooke est, Montréal, QC Canada H1X 2B2
| | - Daniel P. Matton
- />Institut de Recherche en Biologie Végétale (IRBV), Département de sciences biologiques, Université de Montréal, 4101 rue Sherbrooke est, Montréal, QC Canada H1X 2B2
| |
Collapse
|
53
|
Jahnke S, Sarholz B, Thiemann A, Kühr V, Gutiérrez-Marcos JF, Geiger HH, Piepho HP, Scholten S. Heterosis in early seed development: a comparative study of F1 embryo and endosperm tissues 6 days after fertilization. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2010; 120:389-400. [PMID: 19915820 DOI: 10.1007/s00122-009-1207-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2009] [Accepted: 10/22/2009] [Indexed: 05/12/2023]
Abstract
Heterosis specifies the superior performance of heterozygous individuals and although used in plant breeding the underlying molecular mechanisms still remain largely elusive. In this study, we demonstrate the manifestation of heterosis in hybrid maize embryo and endosperm tissue 6 days after fertilization in crosses of several inbred lines. We provide a comparative analysis of heterosis-associated gene expression in these tissues by a combined approach of suppression subtractive hybridization and microarray hybridizations. Non-additive expression pattern indicated a trans-regulatory mechanism to act early after fertilization in hybrid embryo and endosperm although the majority of genes showed mid-parental expression levels in embryo and dosage dependent expression levels in endosperm. The consistent expression pattern within both tissues and both inbred line genotype combinations of genes coding for chromatin related proteins pointed to heterosis-related epigenetic processes. These and genes involved in other biological processes, identified in this study, might provide entry points for the investigation of regulatory networks associated with the specification of heterosis.
Collapse
Affiliation(s)
- Stephanie Jahnke
- Biocenter Klein Flottbek, University of Hamburg, Ohnhorststrasse 18, 22609 Hamburg, Germany
| | | | | | | | | | | | | | | |
Collapse
|
54
|
Li N, Yuan L, Liu N, Shi D, Li X, Tang Z, Liu J, Sundaresan V, Yang WC. SLOW WALKER2, a NOC1/MAK21 homologue, is essential for coordinated cell cycle progression during female gametophyte development in Arabidopsis. PLANT PHYSIOLOGY 2009; 151:1486-97. [PMID: 19734265 PMCID: PMC2773048 DOI: 10.1104/pp.109.142414] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2009] [Accepted: 08/30/2009] [Indexed: 05/19/2023]
Abstract
Morphogenesis requires the coordination of cell growth, division, and cell differentiation. Female gametogenesis in flowering plants, where a single haploid spore undergoes continuous growth and nuclear division without cytokinesis to form an eight-nucleate coenocytic embryo sac before cellularization, provides a good system to study the genetic control of such processes in multicellular organisms. Here, we report the characterization of an Arabidopsis (Arabidopsis thaliana) female gametophyte mutant, slow walker2 (swa2), in which the progression of the mitotic cycles and the synchrony of female gametophyte development were impaired, causing an arrest of female gametophytes at the two-, four-, or eight-nucleate stage. Delayed pollination test showed that a portion of the mutant ovules were able to develop into functional embryo sacs and could be fertilized. SWA2 encodes a nucleolar protein homologous to yeast NUCLEOLAR COMPLEX ASSOCIATED PROTEIN1 (NOC1)/MAINTENANCE OF KILLER21 that, together with NOC2, is involved in preribosome export from the nucleus to the cytoplasm. Similarly, SWA2 can physically interact with a putative Arabidopsis NOC2 homologue. SWA2 is expressed ubiquitously throughout the plant, at high levels in actively dividing tissues and gametophytes. Therefore, we conclude that SWA2 most likely plays a role in ribosome biogenesis that is essential for the coordinated mitotic progression of the female gametophyte.
Collapse
|
55
|
Dickinson HG, Grant-Downton R. Bridging the generation gap: flowering plant gametophytes and animal germlines reveal unexpected similarities. Biol Rev Camb Philos Soc 2009; 84:589-615. [DOI: 10.1111/j.1469-185x.2009.00088.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
|
56
|
Chen J, Walsh B. Method for the mapping of a female partial-sterile locus on a molecular marker linkage map. TAG. THEORETICAL AND APPLIED GENETICS. THEORETISCHE UND ANGEWANDTE GENETIK 2009; 119:1085-1091. [PMID: 19621212 DOI: 10.1007/s00122-009-1110-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Accepted: 06/25/2009] [Indexed: 05/28/2023]
Abstract
The female gametophyte is an absolutely essential structure for angiosperm reproduction, and female sterility has been reported in a number of crops. In this paper, a maximum-likelihood method is presented for estimating the position and effect of a female partial-sterile locus in a backcross population using the observed data of dominant or codominant markers. The ML solutions are obtained via Bailey's method. The process for the estimating of the recombination fractions and the viabilities of female gametes are described, and the variances of the estimates of the parameters are also presented. Application of the method is demonstrated using a set of simulated data. This method circumvents the problems of the traditional mapping methods for female sterile genes which were based on data from seed set or embryo-sac morphology and anatomy.
Collapse
Affiliation(s)
- Jianguo Chen
- Faculty of Life Science, Hubei University, 430062 Wuhan, China.
| | | |
Collapse
|
57
|
Liu M, Yuan L, Liu NY, Shi DQ, Liu J, Yang WC. GAMETOPHYTIC FACTOR 1, involved in pre-mRNA splicing, is essential for megagametogenesis and embryogenesis in Arabidopsis. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2009; 51:261-71. [PMID: 19261069 DOI: 10.1111/j.1744-7909.2008.00783.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
RNA biogenesis is essential and vital for accurate expression of genes. It is obvious that cells cannot continue normal metabolism when RNA splicing is interfered with. sgt13018 is such a mutant, with partial loss of function of GAMETOPHYTIC FACTOR 1 (GFA1); a gene likely involved in RNA biogenesis in Arabidopsis. The mutant is featured in the phenotype of diminished female gametophyte development at stage FG5 and is associated with the arrest of early embryo development in Arabidopsis. Bioinformatics data showed that homologs of gene GFA1 in yeast and human encode putative U5 snRNP-specific proteins required for pre-mRNA splicing. Furthermore, the result of yeast two-hybrid assay indicated that GFA1 physically interacted with AtBrr2 and AtPrp8, the putative U5 snRNP components, of Arabidopsis. This investigation suggests that GFA1 is involved in mRNA biogenesis through interaction with AtBrr2 and AtPrp8 and functions in megagametogenesis and embryogenesis in plant.
Collapse
Affiliation(s)
- Man Liu
- Key Laboratory of Molecular and Developmental Biology, National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | | | | | | | | | | |
Collapse
|
58
|
Huang L, Chen XY, Rim Y, Han X, Cho WK, Kim SW, Kim JY. Arabidopsis glucan synthase-like 10 functions in male gametogenesis. JOURNAL OF PLANT PHYSIOLOGY 2009; 166:344-52. [PMID: 18760496 DOI: 10.1016/j.jplph.2008.06.010] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Revised: 06/06/2008] [Accepted: 06/06/2008] [Indexed: 05/09/2023]
Abstract
Callose or beta-1,3-glucan performs multiple functions during male and female gametophyte development. Callose is synthesized by 12 members of the glucan synthase-like (GSL) gene family in Arabidopsis thaliana. To elucidate the biological roles of Arabidopsis GSL family members during sexual development, we initiated a reverse genetic approach with T-DNA insertional mutagenesis lines. We screened T-DNA insertion lines for all members of the GSL gene family and detected homozygous mutant seedlings for all members except GSL10. Three independent alleles in GSL10, gsl10-1, gsl10-3 and gsl10-4 showed distorted segregation (1:1:0) of T-DNA inserts rather than Mendelian segregation (1:2:1). By genetic analysis through reciprocal cross, we determined that gsl10 pollen could not be transmitted to descendent. The mutant pollen of GSL10/gsl10 plants at tetrad and microspore stages were not different from that of wild type, suggesting that GSL10 is not essential for normal microspore growth. Analysis of GSL10/gsl10 hemizygous pollen during development revealed abnormal function in asymmetric microspore division. gsl10 mutant microspores failed to enter into mitosis. Unlike the previously described functions of GSL1, GSL2 and GSL5, GSL10 involves an independent process of pollen development at the mitotic division stage.
Collapse
Affiliation(s)
- Lijun Huang
- Division of Applied Life Science (BK21 Program), Graduate School of Gyeongsang National University, Jinju, Republic of Korea
| | | | | | | | | | | | | |
Collapse
|
59
|
Curtis MJ, Belcram K, Bollmann SR, Tominey CM, Hoffman PD, Mercier R, Hays JB. Reciprocal chromosome translocation associated with TDNA-insertion mutation in Arabidopsis: genetic and cytological analyses of consequences for gametophyte development and for construction of doubly mutant lines. PLANTA 2009; 229:731-45. [PMID: 19082841 PMCID: PMC4186712 DOI: 10.1007/s00425-008-0868-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2008] [Accepted: 11/19/2008] [Indexed: 05/19/2023]
Abstract
Chromosomal rearrangements may complicate construction of Arabidopsis with multiple TDNA-insertion mutations. Here, crossing two lines homozygous for insertions in AtREV3 and AtPOLH (chromosomes I and V, respectively) and selfing F1 plants yielded non-Mendelian F2 genotype distributions: frequencies of +/++/+ and 1/1 2/2 progeny were only 0.42 and 0.25%. However, the normal development and fertility of double mutants showed AtPOLH-1 and AtREV3-2 gametes and 1/1 2/2 embryos to be fully viable. F2 distributions could be quantitatively predicted by assuming that F1 selfing produced inviable (1,2) and (+,+) gametophytes 86% of the time. Some defect intrinsic to the F1 selfing process itself thus appeared responsible. In selfing AtREV3 (+/2 ) single mutants, imaging of ovules and pollen showed arrest or abortion, respectively, of half of gametophytes; however, gametogenesis was normal in AtREV3 ( 2/2 ) homozygotes. These findings, taken together, suggested that T-DNA insertion at AtREV3 on chromosome I had caused a reciprocal I-V translocation. Spreads of meiosis I chromosomes in selfing AtREV3 (+/2 ) heterozygotes revealed the predicted cruciform four-chromosome structures, which fluorescence in situ hybridization showed to invariably include both translocated and normal chromosomes I and V. Sequencing of the two junctions of T-DNA with AtREV3 DNA and the two with gene At5g59920 suggested translocation via homologous recombination between independent inverted-repeat T-DNA insertions. Thus, when crosses between TDNA-insertion mutants yield anomalous progeny distributions, TDNA-linked translocations should be considered.
Collapse
Affiliation(s)
- Marc J Curtis
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR, USA
| | | | | | | | | | | | | |
Collapse
|
60
|
Han S, Green L, Schnell DJ. The signal peptide peptidase is required for pollen function in Arabidopsis. PLANT PHYSIOLOGY 2009; 149:1289-1301. [PMID: 19168645 PMCID: PMC2649412 DOI: 10.1104/pp.108.130252] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2008] [Accepted: 01/20/2009] [Indexed: 05/27/2023]
Abstract
The Signal Peptide Peptidases (SPP) are members of the Intramembrane Cleaving Proteases, which are involved in an array of protein-processing and intracellular signaling events in animals. Arabidopsis (Arabidopsis thaliana) has six genes encoding SPP-like proteins, the physiological functions of which are unknown. As a first step in defining the roles of the SPPs in plants, we examined the distribution and activities of Arabidopsis SPP (AtSPP; accession no. At2g03120), the SPP-like gene with the highest degree of similarity to human SPP. The protease is expressed at low levels throughout the plant, with the highest levels in emerging leaves, roots, and floral tissues. Homozygous plants carrying a T-DNA insertion mutation in AtSPP, spp-2, could not be recovered, and transmission of the mutant allele through pollen was reduced to less than 2% in reciprocal cross experiments. Although viable, pollen from spp-2 heterozygous plants exhibited a 50% reduction in germination rate and a disruption in male germ unit organization. These data demonstrate that AtSPP is required for male gametophyte development and pollen maturation in Arabidopsis.
Collapse
Affiliation(s)
- Sungwon Han
- Department of Biochemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | | | | |
Collapse
|
61
|
Alandete-Saez M, Ron M, McCormick S. GEX3, expressed in the male gametophyte and in the egg cell of Arabidopsis thaliana, is essential for micropylar pollen tube guidance and plays a role during early embryogenesis. MOLECULAR PLANT 2008; 1:586-98. [PMID: 19825564 DOI: 10.1093/mp/ssn015] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Double fertilization in flowering plants occurs when the two sperm cells, carried by the pollen tube, are released in a synergid cell of the embryo sac and then fertilize the egg and the central cell. Proteins on the surfaces of the sperm, egg, central, and synergid cells might be important for guidance and recognition/fusion of the gametes. Here, we present functional analyses of Arabidopsis GEX3, which encodes a plasma membrane-localized protein that has homologs in other plants. GEX3 is expressed in both the vegetative and sperm cells of the male gametophyte and in the egg cell of the female gametophyte. Transgenic lines in which GEX3 was down-regulated or overexpressed, using the Arabidopsis GEX2 promoter, had reduced seed set. Reciprocal crosses and imaging after pollination with a reporter line showed that, in both cases, the defect causing reduced seed set occurred in the female. In the antisense lines, micropylar pollen tube guidance failed. In the overexpression lines, fertilization of mutant ovules was mostly blocked because pollen tube guidance failed, although, occasionally, non-viable embryos were formed. We conclude that properly regulated expression of GEX3 in the egg cell of Arabidopsis is essential for pollen tube guidance.
Collapse
Affiliation(s)
- Monica Alandete-Saez
- Department of Plant and Microbial Biology, USDA/ARS-UC-Berkeley, Albany, CA 94710, USA
| | | | | |
Collapse
|
62
|
Liu J, Zhang Y, Qin G, Tsuge T, Sakaguchi N, Luo G, Sun K, Shi D, Aki S, Zheng N, Aoyama T, Oka A, Yang W, Umeda M, Xie Q, Gu H, Qu LJ. Targeted degradation of the cyclin-dependent kinase inhibitor ICK4/KRP6 by RING-type E3 ligases is essential for mitotic cell cycle progression during Arabidopsis gametogenesis. THE PLANT CELL 2008; 20:1538-54. [PMID: 18552199 PMCID: PMC2483368 DOI: 10.1105/tpc.108.059741] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Revised: 05/01/2008] [Accepted: 05/31/2008] [Indexed: 05/19/2023]
Abstract
Following meiosis, plant gametophytes develop through two or three rounds of mitosis. Although the ontogeny of gametophyte development has been defined in Arabidopsis thaliana, the molecular mechanisms regulating mitotic cell cycle progression are not well understood. Here, we report that RING-H2 group F 1a (RHF1a) and RHF2a, two RING-finger E3 ligases, play an important role in Arabidopsis gametogenesis. The rhf1a rhf2a double mutants are defective in the formation of male and female gametophytes due to interphase arrest of the mitotic cell cycle at the microspore stage of pollen development and at female gametophyte stage 1 of embryo sac development. We demonstrate that RHF1a directly interacts with and targets a cyclin-dependent kinase inhibitor ICK4/KRP6 (for Interactors of Cdc2 Kinase 4/Kip-related protein 6) for proteasome-mediated degradation. Inactivation of the two redundant RHF genes leads to the accumulation of ICK4/KRP6, and reduction of ICK4/KRP6 expression largely rescues the gametophytic defects in rhf1a rhf2a double mutants, indicating that ICK4/KRP6 is a substrate of the RHF E3 ligases. Interestingly, in situ hybridization showed that ICK4/KRP6 was predominantly expressed in sporophytes during meiosis. Our findings indicate that RHF1a/2a-mediated degradation of the meiosis-accumulated ICK4/KRP6 is essential to ensure the progression of subsequent mitoses to form gametophytes in Arabidopsis.
Collapse
Affiliation(s)
- Jingjing Liu
- National Laboratory for Protein Engineering and Plant Genetic Engineering, Peking-Yale Joint Research Center for Plant Molecular Genetics and AgroBiotechnology, College of Life Sciences, Peking University, Beijing 100871, People's Republic of China
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
63
|
Colombo M, Masiero S, Vanzulli S, Lardelli P, Kater MM, Colombo L. AGL23, a type I MADS-box gene that controls female gametophyte and embryo development in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 54:1037-48. [PMID: 18346189 DOI: 10.1111/j.1365-313x.2008.03485.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
MADS-box transcription factors are key regulators of plant developmental processes. While the function of MIKC (type II) MADS-box genes has been intensively studied, only limited data are available for the other more recently identified classes of MADS-box genes, despite these latter comprising more than 60% of the Arabidopsis MADS-box gene family. Here we describe the function of AGL23, an Arabidopsis type I MADS-box gene belonging to the Malpha subfamily. We show that AGL23 plays an important role during development of the female gametophyte and embryo. The agl23-1 mutant forms a functional megaspore. However, at this stage female gametophyte development is arrested and the megaspore persists during subsequent phases of ovule development. Despite the incomplete penetrance of the female gametophyte defect, plants homozygous for the agl23-1 mutation were never identified. Analysis of developing seeds showed that embryos homozygous for the agl23-1 allele are albino and unable to give rise to viable plants. Electron microscopy analysis revealed that this phenotype is due to the absence of chloroplasts, strongly suggesting that AGL23 is involved in controlling the biogenesis of organelles during embryo development.
Collapse
Affiliation(s)
- Monica Colombo
- Dipartimento di Biologia, Università degli Studi di Milano, via Celoria 26, 20133 Milano, Italy
| | | | | | | | | | | |
Collapse
|
64
|
Márton ML, Dresselhaus T. A comparison of early molecular fertilization mechanisms in animals and flowering plants. ACTA ACUST UNITED AC 2008. [DOI: 10.1007/s00497-007-0062-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
|
65
|
|
66
|
Uchiumi T, Shinkawa T, Isobe T, Okamoto T. Identification of the major protein components of rice egg cells. JOURNAL OF PLANT RESEARCH 2007; 120:575-9. [PMID: 17558543 DOI: 10.1007/s10265-007-0095-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2007] [Accepted: 04/11/2007] [Indexed: 05/15/2023]
Abstract
The female gamete, the egg cell, is a specially differentiated haploid cell that develops into an embryo following fertilization. In the present study, we analyzed egg cell lysates by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and subsequent mass spectrometry-based proteomics technology and identified the major proteins expressed in rice egg cells. The proteins identified included glyceraldehyde-3-phosphate dehydrogenase, ascorbate peroxidase and heat shock protein 90. The abundant existence of chaperons and antioxidant enzymes in plant egg cells indicates that the major protein components of plant egg cells are partly analogous to those of mammalian eggs and oocytes.
Collapse
Affiliation(s)
- Takao Uchiumi
- Department of Biological Sciences, Tokyo Metropolitan University, Minami-osawa 1-1, Hachioji, Tokyo, 192-0397, Japan
| | | | | | | |
Collapse
|
67
|
Segregation distortion in Arabidopsis gametophytic factor 1 (gfa1) mutants is caused by a deficiency of an essential RNA splicing factor. ACTA ACUST UNITED AC 2007. [DOI: 10.1007/s00497-007-0046-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
68
|
Portereiko MF, Lloyd A, Steffen JG, Punwani JA, Otsuga D, Drews GN. AGL80 is required for central cell and endosperm development in Arabidopsis. THE PLANT CELL 2006; 18:1862-72. [PMID: 16798889 PMCID: PMC1533969 DOI: 10.1105/tpc.106.040824] [Citation(s) in RCA: 155] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
During plant reproduction, the central cell of the female gametophyte becomes fertilized to produce the endosperm, a storage tissue that nourishes the developing embryo within the seed. The molecular mechanisms controlling the specification and differentiation of the central cell are poorly understood. We identified a female gametophyte mutant in Arabidopsis thaliana, fem111, that is affected in central cell development. In fem111 female gametophytes, the central cell's nucleolus and vacuole fail to mature properly. In addition, endosperm development is not initiated after fertilization of fem111 female gametophytes. fem111 contains a T-DNA insertion in AGAMOUS-LIKE80 (AGL80). FEM111/AGL80 is a member of the MADS box family of genes that likely encode transcription factors. An AGL80-green fluorescent protein fusion protein is localized to the nucleus. Within the ovule and seed, FEM111/AGL80 is expressed exclusively in the central cell and uncellularized endosperm. FEM111/AGL80 expression is also detected in roots, leaves, floral stems, anthers, and young flowers by real-time RT-PCR. FEM111/AGL80 is required for the expression of two central cell-expressed genes, DEMETER and DD46, but not for a third central cell-expressed gene, FERTILIZATION-INDEPENDENT SEED2. Together, these data suggest that FEM111/AGL80 functions as a transcription factor within the central cell gene regulatory network and controls the expression of downstream genes required for central cell development and function.
Collapse
|
69
|
Perrella G, Cremona G, Consiglio F, Errico A, Bressan RA, Conicella C. Screening for mutations affecting sexual reproduction after activation tagging inArabidopsis thaliana. J Appl Genet 2006; 47:109-11. [PMID: 16682750 DOI: 10.1007/bf03194608] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
In this work, a seed-set-based screening was performed on 70 lines of Arabidopsis thaliana after activation tagging mutagenesis to identify mutations in reproductive mechanisms. Five mutants showed significantly lower seed set than the wild type and confirmed the phenotype in the progeny. This phenotype was linked with the marker gene bar carried by T-DNA conferring glufosinate resistance. Genetic analysis revealed that the mutation inheritance was sporophytic in 3 mutants and gametophytic in 2 mutants. In addition, 2 mutants had an extra T-DNA copy. Thus activation tagging can be an effective strategy to identify new mutations affecting sporogenesis or gametogenesis.
Collapse
Affiliation(s)
- Giorgio Perrella
- DISSPA, Dept. of Soil, Plant and Environmental Sciences, University of Naples Federico II, Portici, Italy
| | | | | | | | | | | |
Collapse
|
70
|
Dresselhaus T. Cell-cell communication during double fertilization. CURRENT OPINION IN PLANT BIOLOGY 2006; 9:41-7. [PMID: 16324880 DOI: 10.1016/j.pbi.2005.11.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2005] [Accepted: 11/21/2005] [Indexed: 05/05/2023]
Abstract
Double fertilization in flowering seed plants requires intercellular signaling events between many interacting partners. The four cell types of the seven-celled female gametophyte communicate with each other to establish and maintain their identity. They secrete signaling molecules to guide the male gametophyte and to mediate sperm cell discharge and transport towards the two female gametes (the egg and central cell). After fusion of the gametes, guidance signals have to be removed to prevent polyspermy, embryo and endosperm development is induced generating daughter cells or nuclear regions of a different fate, and cell death is induced in the surrounding ovular cells. Until recently, little was known about the molecular nature of the signaling molecules that are involved in these processes. Now, small secreted proteins and peptides have been identified as prime candidates mediating several of these communication events.
Collapse
Affiliation(s)
- Thomas Dresselhaus
- Developmental Biology & Biotechnology, Biocenter Klein Flottbek, University of Hamburg, Ohnhorststrasse 18, 22609 Hamburg, Germany.
| |
Collapse
|
71
|
Kasahara RD, Portereiko MF, Sandaklie-Nikolova L, Rabiger DS, Drews GN. MYB98 is required for pollen tube guidance and synergid cell differentiation in Arabidopsis. THE PLANT CELL 2005; 17:2981-92. [PMID: 16214903 PMCID: PMC1276024 DOI: 10.1105/tpc.105.034603] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The synergid cells of the female gametophyte play a role in many steps of the angiosperm fertilization process, including guidance of pollen tube growth to the female gametophyte. However, the mechanisms by which the synergid cells become specified and develop their unique features during female gametophyte development are not understood. We identified MYB98 in a screen for Arabidopsis thaliana genes expressed in the female gametophyte. MYB98 is a member of the R2R3-MYB gene family, the members of which likely encode transcription factors. In the context of the ovule, MYB98 is expressed exclusively in the synergid cells, and mutations in this gene affect the female gametophyte specifically. myb98 female gametophytes are affected in two unique features of the synergid cell, pollen tube guidance and the filiform apparatus, but are otherwise normal. MYB98 also is expressed in trichomes and endosperm. Homozygous myb98 mutants exhibit no sporophytic defects, including trichome and endosperm defects. Together, these data suggest that MYB98 controls the development of specific features within the synergid cell during female gametophyte development.
Collapse
Affiliation(s)
- Ryushiro D Kasahara
- Department of Biology, University of Utah, Salt Lake City, Utah 84112-0840, USA
| | | | | | | | | |
Collapse
|
72
|
Köhler C, Grossniklaus U. Seed development and genomic imprinting in plants. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2005; 38:237-62. [PMID: 15881898 DOI: 10.1007/3-540-27310-7_10] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Genomic imprinting refers to an epigenetic phenomenon where the activity of an allele depends on its parental origin. Imprinting at individual genes has only been described in mammals and seed plants. We will discuss the role imprinted genes play in seed development and compare the situation in plants with that in mammals. Interestingly, many imprinted genes appear to control cell proliferation and growth in both groups of organisms although imprinting in plants may also be involved in the cellular differentiation of the two pairs of gametes involved in double fertilization. DNA methylation plays some role in the control of parent-of-origin-specific expression in both mammals and plants. Thus, although imprinting evolved independently in mammals and plants, there are striking similarities at the phenotypic and possibly also mechanistic level.
Collapse
Affiliation(s)
- Claudia Köhler
- Institute of Plant Biology and Zürich-Basel Plant Science Center, University of Zürich, Zollikerstrasse 107, 8008 Zürich, Switzerland
| | | |
Collapse
|
73
|
Tanaka H, Ishikawa M, Kitamura S, Takahashi Y, Soyano T, Machida C, Machida Y. The AtNACK1/HINKEL and STUD/TETRASPORE/AtNACK2 genes, which encode functionally redundant kinesins, are essential for cytokinesis in Arabidopsis. Genes Cells 2005; 9:1199-211. [PMID: 15569152 DOI: 10.1111/j.1365-2443.2004.00798.x] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cytokinesis is the critical step during which daughter cells are separated. We showed previously that a protein complex that consists of NACK1 (and NACK2) kinesin-like protein and NPK1 MAPKKK and its substrate NQK1 MAPKK are required for progression of cytokinesis in Nicotiana tabacum. The genome of Arabidopsis thaliana encodes homologues of NACK1 and NACK2, namely, AtNACK1/HINKEL and STUD/TETRASPORE/AtNACK2, respectively. Loss-of-function mutations in AtNACK1/HINKEL and STUD/TETRASPORE/AtNACK2 result in the occasional failure of somatic and male-meiotic cytokinesis, respectively. However, it is likely that these genes function redundantly to some extent in somatic tissues and female gametogenesis. We describe the phenotypes of Arabidopsis plants that have mutations in both the AtNACK1/HINKEL and STUD/TETRASPORE/AtNACK2 genes. These phenotypes suggest that the two genes are essential during both male and female gametogenesis. Female gametes with atnack1 atnack2 double mutations failed to cellularize and to generate a central cell, synergids and the egg cells. Male gametes with atnack1 atnack2 mutations were also not transmitted to the next generation. The AtNACK1/HINKEL and STUD/TETRASPORE/AtNACK2 genes for kinesin-like proteins have overlapping functions that are essential for gametogenetic cytokinesis. They appear to be essential components of a MAP kinase cascade that promotes cytokinesis of plant cells in both gametophytic (haploid) and sporophytic (diploid) proliferation.
Collapse
Affiliation(s)
- Hirokazu Tanaka
- College of Bioscience and Biotechnology, Chubu University and CREST, Japan Science and Technology Corporation, 1200 Matsumoto-cho, Kasugai, Aichi 487-8501, Japan
| | | | | | | | | | | | | |
Collapse
|
74
|
Shi DQ, Liu J, Xiang YH, Ye D, Sundaresan V, Yang WC. SLOW WALKER1, essential for gametogenesis in Arabidopsis, encodes a WD40 protein involved in 18S ribosomal RNA biogenesis. THE PLANT CELL 2005; 17:2340-54. [PMID: 15980260 PMCID: PMC1182493 DOI: 10.1105/tpc.105.033563] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The progression of mitotic division cycles and synchronous development between and within the male and female reproductive organs are essential for plant sexual reproduction. Little is known about the genetic control of the progression of mitotic cycles of the haploid genome during gametogenesis in higher plants. Here, we report the phenotypic and molecular characterization of an Arabidopsis thaliana mutant, slow walker1 (swa1), in which the progression of the mitotic division cycles of the female gametophyte was disrupted. Confocal microscopy revealed that megagametophyte development was asynchronous in swa1, causing embryo sacs to arrest at two-, four-, or eight-nucleate stages within the same pistil. A delayed pollination experiment showed that a small fraction of the swa1 embryo sacs were able to develop into functional female gametophytes. The swa1 mutation also showed a slight reduction in penetrance through the male gametophyte, although the pollen grains were morphologically normal. Molecular analysis indicates that SWA1 encodes a protein with six WD40 repeats that is localized in the nucleolus in interphase cells. The SWA1 gene is expressed in cells undergoing active cell divisions, including functional megaspores and the female gametophytic cells. RNA interference results indicated that knockout of SWA1 inhibited root growth significantly and led to the accumulation of unprocessed 18S pre-rRNA. These data suggest that SWA1 most likely plays a role in rRNA biogenesis that is essential for the progression of the mitotic division cycles during gametogenesis in plants.
Collapse
Affiliation(s)
- Dong-Qiao Shi
- Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
- Temasek Life Sciences Laboratory, National University of Singapore, Singapore 117604
| | - Jie Liu
- Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - Yan-Hui Xiang
- Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
| | - De Ye
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100094, China
| | - Venkatesan Sundaresan
- Plant Biology and Agronomy, Life Sciences Addition 1002, University of California, Davis, California 95616
| | - Wei-Cai Yang
- Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
- To whom correspondence should be addressed. E-mail ; fax 86-10-62551272
| |
Collapse
|
75
|
Barrell PJ, Grossniklaus U. Confocal microscopy of whole ovules for analysis of reproductive development: the elongate1 mutant affects meiosis II. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2005; 43:309-20. [PMID: 15998316 DOI: 10.1111/j.1365-313x.2005.02456.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Analysis of female meiosis (megasporogenesis) and embryo sac development (megagametogenesis) in angiosperms is technically challenging because the cells are enclosed within the nucellus and ovule tissues of the female flower. This is in contrast to male sporogenesis and gametogenesis where development can readily be observed through the easily dissectable developing anthers. Observation of embryo sac development is a particular problem in crassinucellate ovules such as those of maize. To overcome the problems in observing reproductive development, we developed a simple Feulgen staining procedure optimized for use with confocal microscopy to observe reproductive progression in the crassinucellate ovules of maize. The procedure greatly facilitates the observation of nuclei and cell structures of all stages of megasporogenesis and embryo sac development. The high resolution obtained using the technique enabled us to readily visualize chromosomes from individual cells within ovule tissue samples of maize. A propidium iodide staining technique was also used and compared with the Feulgen-based technique. Static cytometry of relative DNA content of individual nuclei was possible using Imaris software on both Feulgen and propidium iodide-stained samples. The techniques also proved successful for the observation of Arabidopsis and Hieracium aurantiacum female gametophyte and seed development, demonstrating the general applicability of the techniques. Using both staining methods, we analysed the maize meiotic mutant elongate1, which produces functional diploid instead of haploid embryo sacs. The precise defect in meiosis from which diploid embryo sacs arise in elongate1 has not previously been reported. We used confocal microscopy followed by static cytometry using Imaris software to show that the defect by which diploid embryo sacs arise in the maize mutant elongate1 is the absence of meiosis II with one of the dyad cells directly initiating megagametogenesis.
Collapse
Affiliation(s)
- Philippa J Barrell
- Institute of Plant Biology & Zürich-Basel Plant Science Center, University of Zürich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland
| | | |
Collapse
|
76
|
Lorbiecke R, Steffens M, Tomm JM, Scholten S, von Wiegen P, Kranz E, Wienand U, Sauter M. Phytosulphokine gene regulation during maize (Zea mays L.) reproduction. JOURNAL OF EXPERIMENTAL BOTANY 2005; 56:1805-19. [PMID: 15897229 DOI: 10.1093/jxb/eri169] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The sulphated pentapeptide phytosulphokine (PSK) was identified as a substance that promotes cell division in low-density suspension cultures and has been implicated in various aspects of tissue differentiation in plants. The peptide is derived from PSK precursor proteins that are encoded by small gene families. The physiological roles of PSK are still not clearly defined and little is known about expression of members of the PSK precursor gene family in any plant species. In this study, highly regulated tissue and cell type-specific expression are described for four PSK genes from maize (Zea mays L.) in female and male gametophytes, and during seed development. ZmPSK1 and ZmPSK3 were specifically and differentially expressed in cells of female and male gametophytes and in female and male gametes. In anthers ZmPSK1 or ZmPSK3 transcripts were found, for example, at high levels in secretory tapetal cells which support developing microspores. ZmPSK1 mRNA was abundant in mature pollen including sperm cells. ZmPSK1 and ZmPSK3 transcripts were also detected in egg and central cells of the female gametophyte and ZmPSK1 mRNA was present in synergids, indicating that the PSK peptide probably plays a role during gametogenesis, pollen germination, and fertilization. In developing maize kernels all four ZmPSK genes were expressed, albeit with striking differences in their expression patterns. It is proposed here that PSK is required for numerous but defined processes during gametophyte and early sporophyte development. In general, PSK availability appears to be controlled through transcriptional regulation in a tissue and cell type-specific and development-dependent manner.
Collapse
Affiliation(s)
- René Lorbiecke
- Biozentrum Klein-Flottbek und Botanischer Garten, Universität Hamburg, Ohnhorststrasse 18, D-22609 Hamburg, Germany
| | | | | | | | | | | | | | | |
Collapse
|
77
|
Niewiadomski P, Knappe S, Geimer S, Fischer K, Schulz B, Unte US, Rosso MG, Ache P, Flügge UI, Schneider A. The Arabidopsis plastidic glucose 6-phosphate/phosphate translocator GPT1 is essential for pollen maturation and embryo sac development. THE PLANT CELL 2005; 17:760-75. [PMID: 15722468 PMCID: PMC1069697 DOI: 10.1105/tpc.104.029124] [Citation(s) in RCA: 152] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2004] [Accepted: 01/13/2005] [Indexed: 05/18/2023]
Abstract
Plastids of nongreen tissues can import carbon in the form of glucose 6-phosphate via the glucose 6-phosphate/phosphate translocator (GPT). The Arabidopsis thaliana genome contains two homologous GPT genes, AtGPT1 and AtGPT2. Both proteins show glucose 6-phosphate translocator activity after reconstitution in liposomes, and each of them can rescue the low-starch leaf phenotype of the pgi1 mutant (which lacks plastid phosphoglucoisomerase), indicating that the two proteins are also functional in planta. AtGPT1 transcripts are ubiquitously expressed during plant development, with highest expression in stamens, whereas AtGPT2 expression is restricted to a few tissues, including senescing leaves. Disruption of GPT2 has no obvious effect on growth and development under greenhouse conditions, whereas the mutations gpt1-1 and gpt1-2 are lethal. In both gpt1 lines, distorted segregation ratios, reduced efficiency of transmission in males and females, and inability to complete pollen and ovule development were observed, indicating profound defects in gametogenesis. Embryo sac development is arrested in the gpt1 mutants at a stage before the fusion of the polar nuclei. Mutant pollen development is associated with reduced formation of lipid bodies and small vesicles and the disappearance of dispersed vacuoles, which results in disintegration of the pollen structure. Taken together, our results indicate that GPT1-mediated import of glucose 6-phosphate into nongreen plastids is crucial for gametophyte development. We suggest that loss of GPT1 function results in disruption of the oxidative pentose phosphate cycle, which in turn affects fatty acid biosynthesis.
Collapse
|
78
|
de F Maraschin S, Vennik M, Lamers GEM, Spaink HP, Wang M. Time-lapse tracking of barley androgenesis reveals position-determined cell death within pro-embryos. PLANTA 2005; 220:531-40. [PMID: 15449059 DOI: 10.1007/s00425-004-1371-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2004] [Accepted: 07/20/2004] [Indexed: 05/19/2023]
Abstract
Following abiotic stress to induce barley (Hordeum vulgare L.) androgenesis, the development of 794 enlarged microspores in culture was monitored by time-lapse tracking. In total, 11% of the microspores tracked developed into embryo-like structures (type-I pathway), 36% formed multicellular structures (type-II pathway) and 53% of the microspores followed gametophytic divisions, accumulated starch and died in the first days of tracking (type-III pathway). Despite the microspore fate, enlarged microspores showed similar morphologies directly after stress treatment. Ultrastructural analysis, however, revealed two morphologically distinct cell types. Cells with a thin intine layer and an undifferentiated cytoplasm after stress treatment were associated with type-I and type-II pathways, whereas the presence of differentiated amyloplasts and a thick intine layer were associated with the type-III pathway. Tracking revealed that the first morphological change associated with embryogenic potential was a star-like morphology, which was a transitory stage between uninucleate vacuolated microspores after stress and the initiation of cell division. The difference between type-I and type-II pathways was observed during the time they displayed the star-like morphology. During the transition phase, embryo-like structures in the type-I pathway were always released out of the exine wall at the opposite side of the pollen germ pore, whereas in the type-II pathway multicellular structures were unable to break the exine and to release embryo-like structures. Moreover, by combining viability studies with cell tracking, we show that release of embryo-like structures was preceded by a decrease in viability of the cells positioned at the site of exine wall rupture. These cells were also positively stained by Sytox orange, a cell death indicator. Thereby, we demonstrate, for the first time, that a position-determined cell death process marks the transition from a multicellular structure into an embryo-like structure during barley androgenesis.
Collapse
Affiliation(s)
- Simone de F Maraschin
- Center for Phytotechnology LU/TNO, Leiden University, Wassenaarseweg 64, 2333 AL, Leiden, The Netherlands.
| | | | | | | | | |
Collapse
|
79
|
Abstract
Although the process of gamete formation in plants has many unique features, much has been learnt from the comparative analysis between plants and other eukaryotic systems. Plants have a number of factors that have made them desirable for the analysis of gamete development; these include late germline specification, the non-lethality of mutations affecting gamete development and the large size of their chromosomes. The availability of the fully annotatedArabidopsisgenome and comparative analysis using yeast, animal andE. colihas led to the identification and functional characterisation of many genes with roles in gamete development, principally those associated with meiosis, recombination and DNA repair. The advantages that plants give with the use of mutant screens to identify genes associated with gamete formation have also provided access to genes that are difficult to characterise by alternative routes. This has yielded novel information regarding the processes of gamete formation in higher plants. The times may now be changing with the advantages that plants provide serving to advance knowledge of gamete formation in other eukaryotic systems.
Collapse
Affiliation(s)
- Zoe A Wilson
- Plant Sciences Division, School of Biosciences, Sutton Bonington Campus, University of Nottingham, Nottingham LE12 5RD, UK.
| | | |
Collapse
|
80
|
Sorensen AM, Kroeber S, Saedler H. The ABNORMAL GAMETOPHYTES (AGM) Gene Product of Arabidopsis Demonstrates a Role in Mitosis During Gamete Development. ACTA ACUST UNITED AC 2004; 45:905-13. [PMID: 15295074 DOI: 10.1093/pcp/pch106] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Screening a T-DNA mutagenized population of Arabidopsis thaliana for reduced seed set and segregation distortion led to the isolation of the ABNORMAL GAMETOPHYTES (AGM) mutant. Homozygous plants were never recovered, but heterozygous plants showed mitotic defects during gametogenesis resulting in approximately 50% abortion of both the male and female gametes. Isolation of the genomic sequence flanking the co-segregating T-DNA element led to the identification of a gene located on chromosome 5, predicted to encode a transmembrane protein. BLAST homology searches identified two homologous proteins that are not redundant, as is clear from the existence of the agm mutant. Unexpectedly, expression studies using the beta-glucuronidase reporter gene suggest that AGM and its closest Arabidopsis homolog are mostly expressed in cells undergoing mitosis. Thus, AGM is not a gametophytic gene as originally speculated on the basis of segregation distortion, but rather classified as an essential gene crucial to the process of mitosis in plants.
Collapse
Affiliation(s)
- Anna-Marie Sorensen
- Max Planck Institute for Plant Breeding Research, Department of Molecular Plant Genetics, Carl-von-Linné Weg 10, D-50829-Cologne, Germany.
| | | | | |
Collapse
|
81
|
Hennig L, Gruissem W, Grossniklaus U, Köhler C. Transcriptional programs of early reproductive stages in Arabidopsis. PLANT PHYSIOLOGY 2004; 135:1765-75. [PMID: 15247381 PMCID: PMC519088 DOI: 10.1104/pp.104.043182] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2004] [Revised: 04/19/2004] [Accepted: 04/23/2004] [Indexed: 05/18/2023]
Abstract
The life cycle of flowering plants alternates between a diploid sporophytic and a haploid gametophytic generation. After fertilization of each the egg and central cells by one male gamete, the development of both fertilization products occurs coordinated with the maternally derived seed coat and carpel tissues forming the fruit. The reproduction program is likely to involve the concerted activity of many genes. To identify genes with specific functions during reproduction, we have analyzed the expression profile of more than 22,000 genes present on the Arabidopsis ATH1 microarray during three stages of flower and fruit development. We found 1,886 genes regulated during reproductive development and 1,043 genes that were specifically expressed during reproduction. When compared to cells from an Arabidopsis suspension culture, S-phase genes were underrepresented and G2 and M-phase genes were strongly enriched in the set of specific genes, indicating that important functions during reproduction are exerted in the G2 and M phases of the cell cycle. Many potential signaling components, such as receptor-like protein kinases, phosphatases, and transcription factors, were present in both groups of genes. Members of the YABBY, MADS box, and Myb transcription factor families were significantly overrepresented in the group of specific genes, revealing an important role of these families during reproduction. Furthermore, we found a significant enrichment of predicted secreted proteins smaller than 15 kD that could function directly as signaling molecules or as precursors for peptide hormones. Our study provides a basis for targeted reverse-genetic approaches aimed to identify key genes of reproductive development in plants.
Collapse
Affiliation(s)
- Lars Hennig
- Institute of Plant Sciences and Zurich-Basel Plant Science Center, Swiss Federal Institute of Technology, ETH Center, CH-8092 Zurich, Switzerland
| | | | | | | |
Collapse
|
82
|
|
83
|
Hicks GR, Rojo E, Hong S, Carter DG, Raikhel NV. Geminating pollen has tubular vacuoles, displays highly dynamic vacuole biogenesis, and requires VACUOLESS1 for proper function. PLANT PHYSIOLOGY 2004; 134:1227-39. [PMID: 14988481 PMCID: PMC389947 DOI: 10.1104/pp.103.037382] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2003] [Revised: 01/02/2004] [Accepted: 01/28/2004] [Indexed: 05/18/2023]
Abstract
Vacuoles perform multiple functions in plants, and VCL1 (VACUOLESS1) is essential for biogenesis with loss of expression in the vcl1 mutant leading to lethality. Vacuole biogenesis plays a prominent role in gametophytes, yet is poorly understood. Given the importance of VCL1, we asked if it contributes to vacuole biogenesis during pollen germination. To address this question, it was essential to first understand the dynamics of vacuoles. A tonoplast marker, delta-TIP::GFP, under a pollen-specific promoter permitted the examination of vacuole morphology in germinating pollen of Arabidopsis. Our results demonstrate that germination involves a complex, yet definable, progression of vacuole biogenesis. Pollen vacuoles are extremely dynamic with remarkable features such as elongated (tubular) vacuoles and highly mobile cytoplasmic invaginations. Surprisingly, vcl1 did not adversely impact vacuole morphology in pollen germinated in vitro. To focus further on VCL1 in pollen, reciprocal backcrosses demonstrated reduced transmission of vcl1 through male gametophytes, indicating that vcl1 was expressive after germination. Interestingly, vcl1 affected the fertility of female gametophytes that undergo similarly complex vacuole biogenesis. Our results indicate that vcl1 is lethal in the sporophyte but is not fully expressive in the gametophytes. They also point to the complexity of pollen vacuoles and suggest that the mechanism of vacuole biogenesis in pollen may differ from that in other plant tissues.
Collapse
Affiliation(s)
- Glenn R Hicks
- Center for Plant Cell Biology and Department of Botany and Plant Sciences, University of California, Riverside, Riverside, California 92521, USA
| | | | | | | | | |
Collapse
|
84
|
Affiliation(s)
- Ramin Yadegari
- Department of Plant Sciences, University of Arizona, Tucson, Arizona 85721-0036, USA.
| | | |
Collapse
|
85
|
Olsen OA. Nuclear endosperm development in cereals and Arabidopsis thaliana. THE PLANT CELL 2004; 16 Suppl:S214-27. [PMID: 15010513 PMCID: PMC2643391 DOI: 10.1105/tpc.017111] [Citation(s) in RCA: 306] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Affiliation(s)
- Odd-Arne Olsen
- Pioneer Hi-Bred International, A DuPont Company, Johnston, Iowa 50131, USA.
| |
Collapse
|
86
|
Magnard JL, Lehouque G, Massonneau A, Frangne N, Heckel T, Gutierrez-Marcos JF, Perez P, Dumas C, Rogowsky PM. ZmEBE genes show a novel, continuous expression pattern in the central cell before fertilization and in specific domains of the resulting endosperm after fertilization. PLANT MOLECULAR BIOLOGY 2003; 53:821-836. [PMID: 15082928 DOI: 10.1023/b:plan.0000023672.37089.00] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Two novel maize genes expressed specifically in the central cell of the female gametophyte and in two compartments of the endosperm (the basal endosperm transfer layer and the embryo surrounding region) were characterized. The ZmEBE (embryo sac/basal endosperm transfer layer/embryo surrounding region) genes were isolated by a differential display between the upper and the lower half of the kernel at 7 days after pollination (DAP). Sequence analysis revealed ORFs coding for two closely related proteins of 304 amino acids (ZmEBE-1) and 286 amino acids (ZmEBE-2). This size difference was due to differences in the splicing of the two genes. Both protein sequences showed significant similarity to the DUF239 family of Arabidopsis, a group of 22 proteins of unknown function, a small number of which are putative peptidases. ZmEBE genes had a novel cell type-specific expression pattern in the central cell before and the resulting endosperm after fertilization. RT-PCR analysis showed that the expression of both genes started before pollination in the central cell and continued in the kernel up to 20 DAP with a peak at 7 DAP. In situ hybridization revealed that the expression in the kernel was restricted to the basal transfer cell layer and the embryo surrounding region of the endosperm. The expression of ZmEBE-1 was at least 10 times lower than that of ZmEBE-2. Similarly to other genes expressed in the endosperm, ZmEBE-1 expression was subject to a parent-of-origin effect, while no such effect was detected in ZmEBE-2. Sequence analysis of upstream regions revealed a potential cis element of 33 bp repeated 7 times in ZmEBE-1 and ZmEBE-2 between positions -900 and -100. The 1.6 kb ZmEBE-2 upstream sequence containing the seven R7 elements was able to confer expression in the basal endosperm to a Gus reporter gene. These data indicate that ZmEBE is potentially involved in the early development of specialized domains of the endosperm and that this process is possibly already initiated in the central cell, which is at the origin of the endosperm.
Collapse
MESH Headings
- Alternative Splicing
- Amino Acid Sequence
- Base Sequence
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- DNA, Plant/chemistry
- DNA, Plant/genetics
- DNA, Plant/isolation & purification
- Fertilization
- Gene Expression Profiling
- Gene Expression Regulation, Plant
- In Situ Hybridization
- Molecular Sequence Data
- Plant Proteins/genetics
- Polymorphism, Restriction Fragment Length
- Promoter Regions, Genetic/genetics
- RNA, Plant/genetics
- RNA, Plant/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Seeds/cytology
- Seeds/genetics
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Time Factors
- Zea mays/genetics
Collapse
Affiliation(s)
- Jean-Louis Magnard
- RDP, UMR 5667 INRA-CNRS-ENSL-UCBL, ENS-Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France
| | | | | | | | | | | | | | | | | |
Collapse
|
87
|
Nonomura KI, Miyoshi K, Eiguchi M, Suzuki T, Miyao A, Hirochika H, Kurata N. The MSP1 gene is necessary to restrict the number of cells entering into male and female sporogenesis and to initiate anther wall formation in rice. THE PLANT CELL 2003; 15:1728-39. [PMID: 12897248 PMCID: PMC167165 DOI: 10.1105/tpc.012401] [Citation(s) in RCA: 217] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2003] [Accepted: 06/10/2003] [Indexed: 05/17/2023]
Abstract
The function of the novel gene MSP1 (MULTIPLE SPOROCYTE), which controls early sporogenic development, was elucidated by characterizing a retrotransposon-tagged mutation of rice. The MSP1 gene encoded a Leu-rich repeat receptor-like protein kinase. The msp1 mutation gave rise to an excessive number of both male and female sporocytes. In addition, the formation of anther wall layers was disordered and the tapetum layer was lost completely. Although the mutation never affected homologous chromosome pairing and chiasma maintenance, the development of pollen mother cells was arrested at various stages of meiotic prophase I, which resulted in complete male sterility. Meanwhile, plural megaspore mother cells in a mutant ovule generated several megaspores, underwent gametogenesis, and produced germinable seeds when fertilized with wild-type pollen despite disorganized female gametophytes. In situ expression of MSP1 was detected in surrounding cells of male and female sporocytes and some flower tissues, but never in the sporocytes themselves. These results suggest that the MSP1 product plays crucial roles in restricting the number of cells entering into male and female sporogenesis and in initiating anther wall formation in rice.
Collapse
Affiliation(s)
- Ken-Ichi Nonomura
- Experimental Farm/Plant Genetics Laboratory, National Institute of Genetics, Yata1111, Mishima, Shizuoka 411-8540, Japan.
| | | | | | | | | | | | | |
Collapse
|
88
|
Abstract
The plant life cycle alternates between a diploid sporophyte generation and a haploid gametophyte generation. The angiosperm female gametophyte is critical to the reproductive process. It is the structure within which egg cell production and fertilization take place. In addition, the female gametophyte plays a role in pollen tube guidance, the induction of seed development, and the maternal control of seed development. Genetic analysis in Arabidopsis has uncovered mutations that affect female gametophyte development and function. Mutants defective in almost all stages of development have been identified, and analysis of these mutants is beginning to reveal features of the female gametophyte developmental program. Other mutations that affect female gametophyte function have uncovered regulatory genes required for the induction of endosperm development. From these studies, we are beginning to understand the regulatory networks involved in female gametophyte development and function. Further investigation of the female gametophyte will require complementary approaches including expression-based approaches to obtain a complete profile of the genes functioning within this critical structure.
Collapse
Affiliation(s)
- Gary N Drews
- Department of Biology, University of Utah, Salt Lake City, Utah 84112, USA.
| | | |
Collapse
|
89
|
Hejátko J, Pernisová M, Eneva T, Palme K, Brzobohatý B. The putative sensor histidine kinase CKI1 is involved in female gametophyte development in Arabidopsis. Mol Genet Genomics 2003; 269:443-53. [PMID: 12774227 DOI: 10.1007/s00438-003-0858-7] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2003] [Accepted: 04/28/2003] [Indexed: 10/26/2022]
Abstract
Embryo sac formation is a fundamental step in sexual reproduction in plants. However, the key players involved in the development of the female gametophyte remain elusive. We present data indicating that a two-component sensor histidine kinase, CKI1, originally implicated in cytokinin perception, is required for completion of megagametogenesis in Arabidopsis. We isolated a loss-of-function mutation in CKI1 resulting from an insertion of the En-1 transposon into the CKI1 coding sequence. Genetic analysis revealed that the mutant allele, cki1-i, could not be transmitted through the female germ line. Confocal laser scanning microscopy identified a block in megagametogenesis, characterized by the abortion of the central vacuole in mutant embryo sacs, and degradation of the developing female gametophyte after completion of all mitotic divisions. The recovery of two independent stable alleles and one revertant wild-type allele resulting from En-1 excision confirmed unambiguously the causal link between the cki1-i mutation and the abnormal phenotype. In situ localization of CKI1 mRNA and histochemical analysis of stable transformants harboring the uidA gene under the control of CKI1 promoter revealed that expression of CKI1 starts at the very beginning of female gametophyte development, and continues until fertilization. This suggests that the developing embryo sac may remain sensitive to signals recognized by CKI1 throughout megagametogenesis. Furthermore, expression of the paternally transmitted CKI1 was detected early after fertilization. The results indicate a role for a two-component signaling system during female gametophyte development, and provide the first evidence that gametophytic expression of a sensor-like molecule is essential for specific processes during megagametogenesis.
Collapse
Affiliation(s)
- J Hejátko
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, 61265 Brno, Czech Republic
| | | | | | | | | |
Collapse
|
90
|
Herrero M. Male and female synchrony and the regulation of mating in flowering plants. Philos Trans R Soc Lond B Biol Sci 2003; 358:1019-24. [PMID: 12831467 PMCID: PMC1693204 DOI: 10.1098/rstb.2003.1285] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Successful mating clearly requires synchronous development of the male and female sexual organs. Evidence is accumulating that this synchrony of development also persists after pollination, with both pollen and pistil following complex, but highly integrated developmental pathways. The timing of the male-female interaction is crucial for the pistil, which, far from being a mature passive structure, is engaged in a continuing programme of development: only being receptive to the advances of the pollen for a relatively short window of time. This developmental programme is most conspicuous in the ovary, and this review focuses on the interaction between the male and female tissues in this structure. The review first considers pollen tube development in the ovary, concentrating of the mechanisms by which its growth is modulated at various control points associated with structures within the ovary. Second, alterations to this 'normal' developmental programme are reviewed and considered in the context of a breakdown of developmental synchrony. Finally, the consequences of male-female developmental synchrony and asynchrony are explored. Clearly, a synchronous male-female relationship leads to a successful fertilization. However, lack of synchrony also occurs, and could emerge as a powerful tool to investigate the regulation of mating.
Collapse
Affiliation(s)
- M Herrero
- Department of Pomology, Estación Experimental de Aula Dei, CSIC, Apartado 202, 50080 Zaragoza, Spain.
| |
Collapse
|
91
|
Ilarslan H, Horner HT, Palmer RG. Megagametophyte abnormalities of near-isogenic female partial-sterile soybean mutants ( Glycine max; Leguminosae). JOURNAL OF PLANT RESEARCH 2003; 116:141-9. [PMID: 12736785 DOI: 10.1007/s10265-003-0084-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2002] [Accepted: 12/20/2002] [Indexed: 05/24/2023]
Abstract
Megagametogenesis of soybean, Glycine max (L.) Merr., cultivars Clark and Clark k2, and F1 hybrid of Clark (female parent) crossed with Clark k2 (male parent) were studied using stereo light microscopy and confocal scanning laser microscopy. Reproductive development in Clark and Clark k2 plants was compared to F1 hybrid plants. In mature pods, 6.4% of the ovules of Clark, 8.1% of the ovules of Clark k2, and 41.4% of the ovules of F1 hybrid plants were aborted. This female partial sterility was due to incomplete megagametophyte development: undeveloped polar nuclei-or developed but not in a position for fertilization; increased megagametophyte wall thickness; abnormal shape and/or premature degeneration of synergids and intact synergids throughout the life of the ovule; egg cell not well-developed or absent; and megagametophyte remaining uninucleate. Each of these abnormalities contributed to either lack of double fertilization or early megagametophyte abortion.
Collapse
Affiliation(s)
- Hilal Ilarslan
- Department of Biology, Ankara University, 06100, Tandogan, Ankara, Turkey
| | | | | |
Collapse
|
92
|
Abstract
We report here the genetic identification of a female partial-sterile mutant derived from soybean mutant L67-3483. L67-3483, which originated from the cultivar Clark after X-ray irradiation, is male and female fertile. All F1 plants in reciprocal pollinations of L67-3483 with 'Clark', 'Minsoy', or 'BSR 101' were female partial sterile. Partial sterility is expressed in the heterozygous condition at a single locus and upon self-pollination this locus exhibits a 1:1 segregation pattern. This locus is located on the terminus of the soybean molecular linkage group D1b+W, between simple sequence repeat (SSR) markers Satt157 and Satt266, and is linked to each by 5.3 and 1.2 cM, respectively. This gene is transmitted through both female and male gametes and there was no segregation distortion of SSR markers linked to this gene. We concluded that this female partial-sterile gene is a new mutation class, and differs from the previously reported mutation classes in soybean, i.e., sporophytic mutation, gametophytic female-specific mutation, and general gametophytic mutation. Restriction of recombination around the mutant gene suggested that this gene is located near or within (a) small inversion(s) or adjacent to (a) chromosomal deletion(s).
Collapse
Affiliation(s)
- K K Kato
- Department of Crop Science, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro, Hokkaido, 080-8555 Japan
| | | |
Collapse
|
93
|
Higashiyama T, Kuroiwa H, Kuroiwa T. Pollen-tube guidance: beacons from the female gametophyte. CURRENT OPINION IN PLANT BIOLOGY 2003; 6:36-41. [PMID: 12495749 DOI: 10.1016/s1369-5266(02)00010-9] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The sperm cell of a flowering plant cannot migrate unaided and it must be transported by the pollen-tube cell before successful fertilization can occur. The pollen tube is precisely guided to the target female gametophyte, the embryo sac, which contains the egg cell. The mechanism that precisely directs the pollen tube through the pistil to the female gametophyte has been studied for more than a century. There has been controversy over whether a diffusible signal attracts the pollen tube or whether female tissues define its path. Emerging genetic and physiological data show that the female gametophyte produces at least two directional signals, and that at least one of these signals is diffusible and derived from the two synergid cells.
Collapse
Affiliation(s)
- Tetsuya Higashiyama
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo, Japan.
| | | | | |
Collapse
|
94
|
Abstract
The term apomixis encompasses a suite of processes whereby seeds form asexually in plants. In contrast to sexual reproduction, seedlings arising from apomixis retain the genotype of the maternal parent. The transfer of apomixis and its effective utilization in crop plants (where it is largely absent) has major advantages in agriculture. The hallmark components of apomixis include female gamete formation without meiosis (apomeiosis), fertilization-independent embryo development (parthenogenesis), and developmental adaptations to ensure functional endosperm formation. Understanding the molecular mechanisms underlying apomixis, a developmentally fascinating phenomenon in plants, is critical for the successful induction and utilization of apomixis in crop plants. This review draws together knowledge gained from analyzing ovule, embryo, and endosperm development in sexual and apomictic plants. It consolidates the view that apomixis and sexuality are closely interrelated developmental pathways where apomixis can be viewed as a deregulation of the sexual process in both time and space.
Collapse
Affiliation(s)
- Anna M Koltunow
- Commonwealth Scientific and Industrial Research Organization, Plant Industry, P.O. Box 350, Glen Osmond, South Australia 5064, Australia.
| | | |
Collapse
|
95
|
Grini PE, Jürgens G, Hülskamp M. Embryo and endosperm development is disrupted in the female gametophytic capulet mutants of Arabidopsis. Genetics 2002; 162:1911-25. [PMID: 12524359 PMCID: PMC1462375 DOI: 10.1093/genetics/162.4.1911] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The female gametophyte of higher plants gives rise, by double fertilization, to the diploid embryo and triploid endosperm, which develop in concert to produce the mature seed. What roles gametophytic maternal factors play in this process is not clear. The female-gametophytic effects on embryo and endosperm development in the Arabidopsis mea, fis, and fie mutants appear to be due to gametic imprinting that can be suppressed by METHYL TRANSFERASE1 antisense (MET1 a/s) transgene expression or by mutation of the DECREASE IN DNA METHYLATION1 (DDM1) gene. Here we describe two novel gametophytic maternal-effect mutants, capulet1 (cap1) and capulet2 (cap2). In the cap1 mutant, both embryo and endosperm development are arrested at early stages. In the cap2 mutant, endosperm development is blocked at very early stages, whereas embryos can develop to the early heart stage. The cap mutant phenotypes were not rescued by wild-type pollen nor by pollen from tetraploid plants. Furthermore, removal of silencing barriers from the paternal genome by MET1 a/s transgene expression or by the ddm1 mutation also failed to restore seed development in the cap mutants. Neither cap1 nor cap2 displayed autonomous seed development, in contrast to mea, fis, and fie mutants. In addition, cap2 was epistatic to fis1 in both autonomous endosperm and sexual development. Finally, both cap1 and cap2 mutant endosperms, like wild-type endosperms, expressed the paternally inactive endosperm-specific FIS2 promoter GUS fusion transgene only when the transgene was introduced via the embryo sac, indicating that imprinting was not affected. Our results suggest that the CAP genes represent novel maternal functions supplied by the female gametophyte that are required for embryo and endosperm development.
Collapse
Affiliation(s)
- Paul E Grini
- ZMBP, Developmental Genetics Department, University of Tübingen, D-72076 Tübingen, Germany
| | | | | |
Collapse
|
96
|
Christensen CA, Gorsich SW, Brown RH, Jones LG, Brown J, Shaw JM, Drews GN. Mitochondrial GFA2 is required for synergid cell death in Arabidopsis. THE PLANT CELL 2002; 14:2215-32. [PMID: 12215516 PMCID: PMC150766 DOI: 10.1105/tpc.002170] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2002] [Accepted: 05/19/2002] [Indexed: 05/19/2023]
Abstract
Little is known about the molecular processes that govern female gametophyte (FG) development and function, and few FG-expressed genes have been identified. We report the identification and phenotypic analysis of 31 new FG mutants in Arabidopsis. These mutants have defects throughout development, indicating that FG-expressed genes govern essentially every step of FG development. To identify genes involved in cell death during FG development, we analyzed this mutant collection for lines with cell death defects. From this analysis, we identified one mutant, gfa2, with a defect in synergid cell death. Additionally, the gfa2 mutant has a defect in fusion of the polar nuclei. We isolated the GFA2 gene and show that it encodes a J-domain-containing protein. Of the J-domain-containing proteins in Saccharomyces cerevisiae (budding yeast), GFA2 is most similar to Mdj1p, which functions as a chaperone in the mitochondrial matrix. GFA2 is targeted to mitochondria in Arabidopsis and partially complements a yeast mdj1 mutant, suggesting that GFA2 is the Arabidopsis ortholog of yeast Mdj1p. These data suggest a role for mitochondria in cell death in plants.
Collapse
Affiliation(s)
- Cory A Christensen
- Department of Biology, University of Utah, Salt Lake City, Utah 84112-0840, USA
| | | | | | | | | | | | | |
Collapse
|
97
|
Choi Y, Gehring M, Johnson L, Hannon M, Harada JJ, Goldberg RB, Jacobsen SE, Fischer RL. DEMETER, a DNA glycosylase domain protein, is required for endosperm gene imprinting and seed viability in arabidopsis. Cell 2002; 110:33-42. [PMID: 12150995 DOI: 10.1016/s0092-8674(02)00807-3] [Citation(s) in RCA: 518] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We isolated mutations in Arabidopsis to understand how the female gametophyte controls embryo and endosperm development. For the DEMETER (DME) gene, seed viability depends only on the maternal allele. DME encodes a large protein with DNA glycosylase and nuclear localization domains. DME is expressed primarily in the central cell of the female gametophyte, the progenitor of the endosperm. DME is required for maternal allele expression of the imprinted MEDEA (MEA) Polycomb gene in the central cell and endosperm. Ectopic DME expression in endosperm activates expression of the normally silenced paternal MEA allele. In leaf, ectopic DME expression induces MEA and nicks the MEA promoter. Thus, a DNA glycosylase activates maternal expression of an imprinted gene in the central cell.
Collapse
Affiliation(s)
- Yeonhee Choi
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | | | | | | | | | | | | | | |
Collapse
|
98
|
Endo M, Matsubara H, Kokubun T, Masuko H, Takahata Y, Tsuchiya T, Fukuda H, Demura T, Watanabe M. The advantages of cDNA microarray as an effective tool for identification of reproductive organ-specific genes in a model legume, Lotus japonicus. FEBS Lett 2002; 514:229-37. [PMID: 11943157 DOI: 10.1016/s0014-5793(02)02371-2] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
To understand the molecular mechanisms intrinsic to reproductive organ development a cDNA microarray, fabricated from flower bud cDNA clones, was used to isolate genes, which are specifically expressed during the development of the anther and pistil in Lotus japonicus. Cluster analysis of the microarray data revealed 21 and 111 independent cDNA groups, which were specifically expressed in immature and mature anthers, respectively. RT-PCR was performed to provide a direct assessment of the accuracy and reproducibility of our approach. Confirmation of our results suggests that cDNA microarray technology is an effective tool for identification of novel reproductive organ-specific genes.
Collapse
Affiliation(s)
- Makoto Endo
- Laboratory of Plant Breeding, Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka 020-8550, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
99
|
Chaudhury AM, Koltunow A, Payne T, Luo M, Tucker MR, Dennis ES, Peacock WJ. Control of early seed development. Annu Rev Cell Dev Biol 2002; 17:677-99. [PMID: 11687501 DOI: 10.1146/annurev.cellbio.17.1.677] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Seed development requires coordinated expression of embryo and endosperm and has contributions from both sporophytic and male and female gametophytic genes. Genetic and molecular analyses in recent years have started to illuminate how products of these multiple genes interact to initiate seed development. Imprinting or differential expression of paternal and maternal genes seems to be involved in controlling seed development, presumably by controlling gene expression in developing endosperm. Epigenetic processes such as chromatin remodeling and DNA methylation affect imprinting of key seed-specific genes; however, the identity of many of these genes remains unknown. The discovery of FIS genes has illuminated control of autonomous endosperm development, a component of apomixis, which is an important developmental and agronomic trait. FIS genes are targets of imprinting, and the genes they control in developing endosperm are also regulated by DNA methylation and chromatin remodeling genes. These results define some exciting future areas of research in seed development.
Collapse
Affiliation(s)
- A M Chaudhury
- CSIRO Plant Industry, GPO BOX 1600, ACT 2601, Australia.
| | | | | | | | | | | | | |
Collapse
|
100
|
Abstract
Maternal control of higher plant seed development is likely to involve female sporophytic as well as female gametophytic genes. While numerous female sporophytic mutants control the production of the ovule and the embryo sac true maternal effect mutations affecting embryo and endosperm development are rare in plants. A new class of female gametophytic mutants has been isolated that controls autonomous development of endosperm. Molecular analyses of these genes, known as FIS class genes, suggest that they repress downstream seed development genes by chromatin remodelling. Expression of the FIS genes in turn is modulated by parent specific expression or genomic imprinting which in turn is controlled by DNA methylation. Thus maternal control of seed development is a complex developmental event influenced by both genetic and epigenetic processes.
Collapse
Affiliation(s)
- A M Chaudhury
- CSIRO Plant Industry, GPO BOX 1600 ACT 2601, Australia.
| | | |
Collapse
|