Continuous-time modeling of cell fate determination in Arabidopsis flowers

<p>Abstract</p> <p>Background</p> <p>The genetic control of floral organ specification is currently being investigated by various approaches, both experimentally and through modeling. Models and simulations have mostly involved boolean or related methods, and so far a quantitative, continuous-time approach has not been explored.</p> <p>Results</p> <p>We propose an ordinary differential equation (ODE) model that describes the gene expression dynamics of a gene regulatory network that controls floral organ formation in the model plant <it>Arabidopsis thaliana</it>. In this model, the dimerization of MADS-box transcription factors is incorporated explicitly. The unknown parameters are estimated from (known) experimental expression data. The model is validated by simulation studies of known mutant plants.</p> <p>Conclusions</p> <p>The proposed model gives realistic predictions with respect to independent mutation data. A simulation study is carried out to predict the effects of a new type of mutation that has so far not been made in <it>Arabidopsis</it>, but that could be used as a severe test of the validity of the model. According to our predictions, the role of dimers is surprisingly important. Moreover, the functional loss of any dimer leads to one or more phenotypic alterations.</p

Identification and Characterization of a Mef2 Transcriptional Activator in Schistosome Parasites

Myocyte enhancer factor 2 protein (Mef2) is an evolutionarily conserved activator of transcription that is critical to induce and control complex processes in myogenesis and neurogenesis in vertebrates and insects, and osteogenesis in vertebrates. In Drosophila, Mef2 null mutants are unable to produce differentiated muscle cells, and in vertebrates, Mef2 mutants are embryonic lethal. Schistosome worms are responsible for over 200 million cases of schistosomiasis globally, but little is known about early development of schistosome parasites after infecting a vertebrate host. Understanding basic schistosome development could be crucial to delineating potential drug targets. Here, we identify and characterize Mef2 from the schistosome worm Schistosoma mansoni (SmMef2). We initially identified SmMef2 as a homolog to the yeast Mef2 homolog, Resistance to Lethality of MKK1P386 overexpression (Rlm1), and we show that SmMef2 is homologous to conserved Mef2 family proteins. Using a genetics approach, we demonstrate that SmMef2 is a transactivator that can induce transcription of four separate heterologous reporter genes by yeast one-hybrid analysis. We also show that Mef2 is expressed during several stages of schistosome development by quantitative PCR and that it can bind to conserved Mef2 DNA consensus binding sequences

Rice early flowering1, a CKI, phosphorylates DELLA protein SLR1 to negatively regulate gibberellin signalling

The plant hormone gibberellin (GA) is crucial for multiple aspects of plant growth and development. To study the relevant regulatory mechanisms, we isolated a rice mutant earlier flowering1, el1, which is deficient in a casein kinase I that has critical roles in both plants and animals. el1 had an enhanced GA response, consistent with the suppression of EL1 expression by exogenous GA3. Biochemical characterization showed that EL1 specifically phosphorylates the rice DELLA protein SLR1, proving a direct evidence for SLR1 phosphorylation. Overexpression of SLR1 in wild-type plants caused a severe dwarf phenotype, which was significantly suppressed by EL1 deficiency, indicating the negative effect of SLR1 on GA signalling requires the EL1 function. Further studies showed that the phosphorylation of SLR1 is important for maintaining its activity and stability, and mutation of the candidate phosphorylation site of SLR1 results in the altered GA signalling. This study shows EL1 a novel and key regulator of the GA response and provided important clues on casein kinase I activities in GA signalling and plant development

A Regulatory Network for Coordinated Flower Maturation

For self-pollinating plants to reproduce, male and female organ development must be coordinated as flowers mature. The Arabidopsis transcription factors AUXIN RESPONSE FACTOR 6 (ARF6) and ARF8 regulate this complex process by promoting petal expansion, stamen filament elongation, anther dehiscence, and gynoecium maturation, thereby ensuring that pollen released from the anthers is deposited on the stigma of a receptive gynoecium. ARF6 and ARF8 induce jasmonate production, which in turn triggers expression of MYB21 and MYB24, encoding R2R3 MYB transcription factors that promote petal and stamen growth. To understand the dynamics of this flower maturation regulatory network, we have characterized morphological, chemical, and global gene expression phenotypes of arf, myb, and jasmonate pathway mutant flowers. We found that MYB21 and MYB24 promoted not only petal and stamen development but also gynoecium growth. As well as regulating reproductive competence, both the ARF and MYB factors promoted nectary development or function and volatile sesquiterpene production, which may attract insect pollinators and/or repel pathogens. Mutants lacking jasmonate synthesis or response had decreased MYB21 expression and stamen and petal growth at the stage when flowers normally open, but had increased MYB21 expression in petals of older flowers, resulting in renewed and persistent petal expansion at later stages. Both auxin response and jasmonate synthesis promoted positive feedbacks that may ensure rapid petal and stamen growth as flowers open. MYB21 also fed back negatively on expression of jasmonate biosynthesis pathway genes to decrease flower jasmonate level, which correlated with termination of growth after flowers have opened. These dynamic feedbacks may promote timely, coordinated, and transient growth of flower organs

Two euAGAMOUS genes control C-function in Medicago truncatula

[EN] C-function MADS-box transcription factors belong to the AGAMOUS (AG) lineage and specify both stamen and carpel identity and floral meristem determinacy. In core eudicots, the AG lineage is further divided into two branches, the euAG and PLE lineages. Functional analyses across flowering plants strongly support the idea that duplicated AG lineage genes have different degrees of subfunctionalization of the C-function. The legume Medicago truncatula contains three C-lineage genes in its genome: two euAG genes (MtAGa and MtAGb) and one PLENA-like gene (MtSHP). This species is therefore a good experimental system to study the effects of gene duplication within the AG subfamily. We have studied the respective functions of each euAG genes in M. truncatula employing expression analyses and reverse genetic approaches. Our results show that the M. truncatula euAG- and PLENA-like genes are an example of subfunctionalization as a result of a change in expression pattern. MtAGa and MtAGb are the only genes showing a full C-function activity, concomitant with their ancestral expression profile, early in the floral meristem, and in the third and fourth floral whorls during floral development. In contrast, MtSHP expression appears late during floral development suggesting it does not contribute significantly to the C-function. Furthermore, the redundant MtAGa and MtAGb paralogs have been retained which provides the overall dosage required to specify the C-function in M. truncatula.This work was funded by grants BIO2009-08134 and BIO2012-39849-C02-01 from the Spanish Ministry of Economy and Competitiveness and the Ramon y Cajal Program (RYC-2007-00627 to CGM). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Serwatowska, J.; Roque Mesa, EM.; Gómez Mena, MC.; Constantin, GD.; Wen, J.; Mysore, KS.; Lund, OS.... (2014). Two euAGAMOUS genes control C-function in Medicago truncatula. PLoS ONE. 9(8):103770-1-103770-12. https://doi.org/10.1371/journal.pone.0103770S103770-1103770-1298Prunet, N., & Jack, T. P. (2013). Flower Development in Arabidopsis: There Is More to It Than Learning Your ABCs. Flower Development, 3-33. doi:10.1007/978-1-4614-9408-9_1Causier, B., Schwarz-Sommer, Z., & Davies, B. (2010). Floral organ identity: 20 years of ABCs. Seminars in Cell & Developmental Biology, 21(1), 73-79. doi:10.1016/j.semcdb.2009.10.005Irish, V. F. (2010). The flowering of Arabidopsis flower development. The Plant Journal, 61(6), 1014-1028. doi:10.1111/j.1365-313x.2009.04065.xHeijmans, K., Morel, P., & Vandenbussche, M. (2012). MADS-box Genes and Floral Development: the Dark Side. Journal of Experimental Botany, 63(15), 5397-5404. doi:10.1093/jxb/ers233Bowman, J. L., Smyth, D. R., & Meyerowitz, E. M. (1989). Genes directing flower development in Arabidopsis. The Plant Cell, 1(1), 37-52. doi:10.1105/tpc.1.1.37Yanofsky, M. F., Ma, H., Bowman, J. L., Drews, G. N., Feldmann, K. A., & Meyerowitz, E. M. (1990). The protein encoded by the Arabidopsis homeotic gene agamous resembles transcription factors. Nature, 346(6279), 35-39. doi:10.1038/346035a0Bradley, D., Carpenter, R., Sommer, H., Hartley, N., & Coen, E. (1993). Complementary floral homeotic phenotypes result from opposite orientations of a transposon at the plena locus of antirrhinum. Cell, 72(1), 85-95. doi:10.1016/0092-8674(93)90052-rPinyopich, A., Ditta, G. S., Savidge, B., Liljegren, S. J., Baumann, E., Wisman, E., & Yanofsky, M. F. (2003). Assessing the redundancy of MADS-box genes during carpel and ovule development. Nature, 424(6944), 85-88. doi:10.1038/nature01741Liljegren, S. J., Ditta, G. S., Eshed, Y., Savidge, B., Bowman, J. L., & Yanofsky, M. F. (2000). SHATTERPROOF MADS-box genes control seed dispersal in Arabidopsis. Nature, 404(6779), 766-770. doi:10.1038/35008089Davies, B., Motte, P., Keck, E., Saedler, H., Sommer, H., & Schwarz-Sommer, Z. (1999). PLENA and FARINELLI: redundancy and regulatory interactions between two Antirrhinum MADS-box factors controlling flower development. The EMBO Journal, 18(14), 4023-4034. doi:10.1093/emboj/18.14.4023Kramer, E. M., Jaramillo, M. A., & Di Stilio, V. S. (2004). Patterns of Gene Duplication and Functional Evolution During the Diversification of the AGAMOUS Subfamily of MADS Box Genes in Angiosperms. Genetics, 166(2), 1011-1023. doi:10.1534/genetics.166.2.1011Becker, A. (2003). The major clades of MADS-box genes and their role in the development and evolution of flowering plants. Molecular Phylogenetics and Evolution, 29(3), 464-489. doi:10.1016/s1055-7903(03)00207-0Irish, V. F. (2003). The evolution of floral homeotic gene function. BioEssays, 25(7), 637-646. doi:10.1002/bies.10292Zahn, L. M., Leebens-Mack, J. H., Arrington, J. M., Hu, Y., Landherr, L. L., dePamphilis, C. W., … Ma, H. (2006). Conservation and divergence in the AGAMOUS subfamily of MADS-box genes: evidence of independent sub- and neofunctionalization events. Evolution Development, 8(1), 30-45. doi:10.1111/j.1525-142x.2006.05073.xFerrandiz, C. (2000). Negative Regulation of the SHATTERPROOF Genes by FRUITFULL During Arabidopsis Fruit Development. Science, 289(5478), 436-438. doi:10.1126/science.289.5478.436Ma, H., Yanofsky, M. F., & Meyerowitz, E. M. (1991). AGL1-AGL6, an Arabidopsis gene family with similarity to floral homeotic and transcription factor genes. Genes & Development, 5(3), 484-495. doi:10.1101/gad.5.3.484Savidge, B., Rounsley, S. D., & Yanofsky, M. F. (1995). Temporal relationship between the transcription of two Arabidopsis MADS box genes and the floral organ identity genes. The Plant Cell, 7(6), 721-733. doi:10.1105/tpc.7.6.721Colombo, M., Brambilla, V., Marcheselli, R., Caporali, E., Kater, M. M., & Colombo, L. (2010). A new role for the SHATTERPROOF genes during Arabidopsis gynoecium development. Developmental Biology, 337(2), 294-302. doi:10.1016/j.ydbio.2009.10.043Fourquin, C., & Ferrándiz, C. (2012). Functional analyses of AGAMOUS family members in Nicotiana benthamiana clarify the evolution of early and late roles of C-function genes in eudicots. The Plant Journal, 71(6), 990-1001. doi:10.1111/j.1365-313x.2012.05046.xKapoor, M., Tsuda, S., Tanaka, Y., Mayama, T., Okuyama, Y., Tsuchimoto, S., & Takatsuji, H. (2002). Role of petuniapMADS3in determination of floral organ and meristem identity, as revealed by its loss of function. The Plant Journal, 32(1), 115-127. doi:10.1046/j.1365-313x.2002.01402.xPan, I. L., McQuinn, R., Giovannoni, J. J., & Irish, V. F. (2010). Functional diversification of AGAMOUS lineage genes in regulating tomato flower and fruit development. Journal of Experimental Botany, 61(6), 1795-1806. doi:10.1093/jxb/erq046Pnueli, L., Hareven, D., Rounsley, S. D., Yanofsky, M. F., & Lifschitz, E. (1994). Isolation of the tomato AGAMOUS gene TAG1 and analysis of its homeotic role in transgenic plants. The Plant Cell, 6(2), 163-173. doi:10.1105/tpc.6.2.163Dreni, L., & Kater, M. M. (2013). MADSreloaded: evolution of theAGAMOUSsubfamily genes. New Phytologist, 201(3), 717-732. doi:10.1111/nph.12555Brunner, A. M. (2000). Plant Molecular Biology, 44(5), 619-634. doi:10.1023/a:1026550205851Perl-Treves, R., Kahana, A., Rosenman, N., Xiang, Y., & Silberstein, L. (1998). Expression of Multiple AGAMOUS-Like Genes in Male and Female Flowers of Cucumber (Cucumis sativus L.). Plant and Cell Physiology, 39(7), 701-710. doi:10.1093/oxfordjournals.pcp.a029424Yu, D., Kotilainen, M., Pöllänen, E., Mehto, M., Elomaa, P., Helariutta, Y., … Teeri, T. H. (1999). Organ identity genes and modified patterns of flower development in Gerbera hybrida (Asteraceae). The Plant Journal, 17(1), 51-62. doi:10.1046/j.1365-313x.1999.00351.xDong, Z., Zhao, Z., Liu, C., Luo, J., Yang, J., Huang, W., … Luo, D. (2005). Floral Patterning in Lotus japonicus. Plant Physiology, 137(4), 1272-1282. doi:10.1104/pp.104.054288Hofer, J. M., & Noel Ellis, T. (2014). Developmental specialisations in the legume family. Current Opinion in Plant Biology, 17, 153-158. doi:10.1016/j.pbi.2013.11.014Fourquin, C., del Cerro, C., Victoria, F. C., Vialette-Guiraud, A., de Oliveira, A. C., & Ferrándiz, C. (2013). A Change in SHATTERPROOF Protein Lies at the Origin of a Fruit Morphological Novelty and a New Strategy for Seed Dispersal in Medicago Genus. Plant Physiology, 162(2), 907-917. doi:10.1104/pp.113.217570Hewitt EJ (1966) Sand and Water Culture Methods Used in the Study of Plant Nutrition. Farnham Royal, UK: Commonwealth Agricultural Bureau.Cheng, X., Wang, M., Lee, H.-K., Tadege, M., Ratet, P., Udvardi, M., … Wen, J. (2013). An efficient reverse genetics platform in the model legumeMedicago truncatula. New Phytologist, 201(3), 1065-1076. doi:10.1111/nph.12575D’ Erfurth, I., Cosson, V., Eschstruth, A., Lucas, H., Kondorosi, A., & Ratet, P. (2003). Efficient transposition of theTnt1tobacco retrotransposon in the model legumeMedicago truncatula. The Plant Journal, 34(1), 95-106. doi:10.1046/j.1365-313x.2003.01701.xTadege, M., Ratet, P., & Mysore, K. S. (2005). Insertional mutagenesis: a Swiss Army knife for functional genomics of Medicago truncatula. Trends in Plant Science, 10(5), 229-235. doi:10.1016/j.tplants.2005.03.009Tadege, M., Wen, J., He, J., Tu, H., Kwak, Y., Eschstruth, A., … Mysore, K. S. (2008). Large-scale insertional mutagenesis using the Tnt1 retrotransposon in the model legume Medicago truncatula. The Plant Journal, 54(2), 335-347. doi:10.1111/j.1365-313x.2008.03418.xCheng, X., Wen, J., Tadege, M., Ratet, P., & Mysore, K. S. (2010). Reverse Genetics in Medicago truncatula Using Tnt1 Insertion Mutants. Plant Reverse Genetics, 179-190. doi:10.1007/978-1-60761-682-5_13Benlloch, R., d’ Erfurth, I., Ferrandiz, C., Cosson, V., Beltrán, J. P., Cañas, L. A., … Ratet, P. (2006). Isolation of mtpim Proves Tnt1 a Useful Reverse Genetics Tool in Medicago truncatula and Uncovers New Aspects of AP1-Like Functions in Legumes. Plant Physiology, 142(3), 972-983. doi:10.1104/pp.106.083543Larkin, M. A., Blackshields, G., Brown, N. P., Chenna, R., McGettigan, P. A., McWilliam, H., … Higgins, D. G. (2007). Clustal W and Clustal X version 2.0. Bioinformatics, 23(21), 2947-2948. doi:10.1093/bioinformatics/btm404Altschul, S. (1997). Gapped BLAST and PSI-BLAST: a new generation of protein database search programs. Nucleic Acids Research, 25(17), 3389-3402. doi:10.1093/nar/25.17.3389Tamura, K., Dudley, J., Nei, M., & Kumar, S. (2007). MEGA4: Molecular Evolutionary Genetics Analysis (MEGA) Software Version 4.0. Molecular Biology and Evolution, 24(8), 1596-1599. doi:10.1093/molbev/msm092Dellaporta, S. L., Wood, J., & Hicks, J. B. (1983). A plant DNA minipreparation: Version II. Plant Molecular Biology Reporter, 1(4), 19-21. doi:10.1007/bf02712670Schmittgen, T. D., & Livak, K. J. (2008). Analyzing real-time PCR data by the comparative CT method. Nature Protocols, 3(6), 1101-1108. doi:10.1038/nprot.2008.73Constantin, G. D., Krath, B. N., MacFarlane, S. A., Nicolaisen, M., Elisabeth Johansen, I., & Lund, O. S. (2004). Virus-induced gene silencing as a tool for functional genomics in a legume species. The Plant Journal, 40(4), 622-631. doi:10.1111/j.1365-313x.2004.02233.xWesley, S. V., Helliwell, C. A., Smith, N. A., Wang, M., Rouse, D. T., Liu, Q., … Waterhouse, P. M. (2001). Construct design for efficient, effective and high-throughput gene silencing in plants. The Plant Journal, 27(6), 581-590. doi:10.1046/j.1365-313x.2001.01105.xGuerineau F, Mullineaux P (1993) Plant transformation and expression vectors. In: Croy R, editor. Plant Molecular Biology. Oxford, UK: Bios Scientific Publishers, Academic Press. pp. 121–147.Clough, S. J., & Bent, A. F. (1998). Floral dip: a simplified method forAgrobacterium-mediated transformation ofArabidopsis thaliana. The Plant Journal, 16(6), 735-743. doi:10.1046/j.1365-313x.1998.00343.xBenlloch, R., Roque, E., Ferrándiz, C., Cosson, V., Caballero, T., Penmetsa, R. V., … Madueño, F. (2009). Analysis of B function in legumes: PISTILLATA proteins do not require the PI motif for floral organ development inMedicago truncatula. The Plant Journal, 60(1), 102-111. doi:10.1111/j.1365-313x.2009.03939.xRoque, E., Serwatowska, J., Cruz Rochina, M., Wen, J., Mysore, K. S., Yenush, L., … Cañas, L. A. (2012). Functional specialization of duplicated AP3-like genes inMedicago truncatula. The Plant Journal, 73(4), 663-675. doi:10.1111/tpj.12068Flanagan, C. A., Hu, Y., & Ma, H. (1996). Specific expression of the AGL1 MADS-box gene suggests regulatory functions in Arabidopsis gynoecium and ovule development. The Plant Journal, 10(2), 343-353. doi:10.1046/j.1365-313x.1996.10020343.xSieburth, L. E., & Meyerowitz, E. M. (1997). Molecular dissection of the AGAMOUS control region shows that cis elements for spatial regulation are located intragenically. The Plant Cell, 9(3), 355-365. doi:10.1105/tpc.9.3.355Busch, M. A. (1999). Activation of a Floral Homeotic Gene in Arabidopsis. Science, 285(5427), 585-587. doi:10.1126/science.285.5427.585Moyroud, E., Minguet, E. G., Ott, F., Yant, L., Posé, D., Monniaux, M., … Parcy, F. (2011). Prediction of Regulatory Interactions from Genome Sequences Using a Biophysical Model for the Arabidopsis LEAFY Transcription Factor. The Plant Cell, 23(4), 1293-1306. doi:10.1105/tpc.111.083329Grønlund, M., Constantin, G., Piednoir, E., Kovacev, J., Johansen, I. E., & Lund, O. S. (2008). Virus-induced gene silencing in Medicago truncatula and Lathyrus odorata. Virus Research, 135(2), 345-349. doi:10.1016/j.virusres.2008.04.005Mandel, M. A., Bowman, J. L., Kempin, S. A., Ma, H., Meyerowitz, E. M., & Yanofsky, M. F. (1992). Manipulation of flower structure in transgenic tobacco. Cell, 71(1), 133-143. doi:10.1016/0092-8674(92)90272-eMizukami, Y., & Ma, H. (1992). Ectopic expression of the floral homeotic gene AGAMOUS in transgenic Arabidopsis plants alters floral organ identity. Cell, 71(1), 119-131. doi:10.1016/0092-8674(92)90271-dCannon, S. B., Sterck, L., Rombauts, S., Sato, S., Cheung, F., Gouzy, J., … Young, N. D. (2006). Legume genome evolution viewed through the Medicago truncatula and Lotus japonicus genomes. Proceedings of the National Academy of Sciences, 103(40), 14959-14964. doi:10.1073/pnas.0603228103Young, N. D., & Bharti, A. K. (2012). Genome-Enabled Insights into Legume Biology. Annual Review of Plant Biology, 63(1), 283-305. doi:10.1146/annurev-arplant-042110-103754Jager, M. (2003). MADS-Box Genes in Ginkgo biloba and the Evolution of the AGAMOUS Family. Molecular Biology and Evolution, 20(5), 842-854. doi:10.1093/molbev/msg089Johansen, B., Pedersen, L. B., Skipper, M., & Frederiksen, S. (2002). MADS-box gene evolution—structure and transcription patterns. Molecular Phylogenetics and Evolution, 23(3), 458-480. doi:10.1016/s1055-7903(02)00032-5Rutledge, R., Regan, S., Nicolas, O., Fobert, P., Côté, C., Bosnich, W., … Stewart, D. (1998). Characterization of an AGAMOUS homologue from the conifer black spruce ( Picea mariana ) that produces floral homeotic conversions when expressed in Arabidopsis. The Plant Journal, 15(5), 625-634. doi:10.1046/j.1365-313x.1998.00250.xParcy, F., Nilsson, O., Busch, M. A., Lee, I., & Weigel, D. (1998). A genetic framework for floral patterning. Nature, 395(6702), 561-566. doi:10.1038/26903Causier, B., Bradley, D., Cook, H., & Davies, B. (2009). Conserved intragenic elements were critical for the evolution of the floral C-function. The Plant Journal, 58(1), 41-52. doi:10.1111/j.1365-313x.2008.03759.xAiroldi, C. A., & Davies, B. (2012). Gene Duplication and the Evolution of Plant MADS-box Transcription Factors. Journal of Genetics and Genomics, 39(4), 157-165. doi:10.1016/j.jgg.2012.02.008Giménez, E., Pineda, B., Capel, J., Antón, M. T., Atarés, A., Pérez-Martín, F., … Lozano, R. (2010). Functional Analysis of the Arlequin Mutant Corroborates the Essential Role of the ARLEQUIN/TAGL1 Gene during Reproductive Development of Tomato. PLoS ONE, 5(12), e14427. doi:10.1371/journal.pone.0014427Kater, M. M., Colombo, L., Franken, J., Busscher, M., Masiero, S., Van Lookeren Campagne, M. M., & Angenent, G. C. (1998). Multiple AGAMOUS Homologs from Cucumber and Petunia Differ in Their Ability to Induce Reproductive Organ Fate. The Plant Cell, 10(2), 171-182. doi:10.1105/tpc.10.2.171Tsuchimoto, S., van der Krol, A. R., & Chua, N. H. (1993). Ectopic expression of pMADS3 in transgenic petunia phenocopies the petunia blind mutant. The Plant Cell, 5(8), 843-853. doi:10.1105/tpc.5.8.843Airoldi, C. A., Bergonzi, S., & Davies, B. (2010). Single amino acid change alters the ability to specify male or female organ identity. Proceedings of the National Academy of Sciences, 107(44), 18898-18902. doi:10.1073/pnas.1009050107Causier, B., Castillo, R., Zhou, J., Ingram, R., Xue, Y., Schwarz-Sommer, Z., & Davies, B. (2005). Evolution in Action: Following Function in Duplicated Floral Homeotic Genes. Current Biology, 15(16), 1508-1512. doi:10.1016/j.cub.2005.07.063Birchler, J. A., & Veitia, R. A. (2007). The Gene Balance Hypothesis: From Classical Genetics to Modern Genomics. The Plant Cell, 19(2), 395-402. doi:10.1105/tpc.106.049338Birchler, J. A., & Veitia, R. A. (2009). The gene balance hypothesis: implications for gene regulation, quantitative traits and evolution. New Phytologist, 186(1), 54-62. doi:10.1111/j.1469-8137.2009.03087.xEdger, P. P., & Pires, J. C. (2009). Gene and genome duplications: the impact of dosage-sensitivity on the fate of nuclear genes. Chromosome Research, 17(5), 699-717. doi:10.1007/s10577-009-9055-9Freeling, M. (2006). Gene-balanced duplications, like tetraploidy, provide predictable drive to increase morphological complexity. Genome Research, 16(7), 805-814. doi:10.1101/gr.368140

EARLY FLOWERING AND REDUCED APICAL DOMINANCE RESULT FROM ECTOPIC EXPRESSION OF A RICE MADS BOX GENE

Recent studies with dicot plants reveal that floral organ development is controlled by a group of regulatory factors containing the MADS domain. In this study, we have isolated and characterized a cDNA clone from rice, OsMADS1, which encodes a MADS-domain-containing protein. The OsMADS1 amino acid sequence shows 56.2% identity to AGL2 and 44.4% identity to AP1. The MADS box region was the most homologous to other MAD S-domain-containing proteins. Northern blot analysis indicated that the rice MADS gene was preferentially expressed in floral organs. In situ localization studies showed that the transcript was uniformly present in young flower primordia and later became localized in palea, lemma, and ovary. Ectopic expression of OsMADS1 with the CaMV 35S promoter in transgenic tobacco plants dramatically alters development, resulting in short, bushy, early-flowering plants with reduced apical dominance. These results suggest that the OsMADS1 gene is involved in flower induction and that it may be used for genetic manipulation of certain plant species.X11117sciescopu

MADS-box protein complexes control carpel and ovule development in Arabidopsis

The AGAMOUS (AG) gene is necessary for stamen and carpel development and is part of a monophyletic clade of MADS-box genes that also includes SHATTERPROOF1 (SHP1), SHP2, and SEEDSTICK (STK). Here, we show that ectopic expression of either the STK or SHP gene is sufficient to induce the transformation of sepals into carpeloid organs bearing ovules. Moreover, the fact that these organ transformations occur when the STK gene is expressed ectopically in ag mutants shows that STK can promote carpel development in the absence of AG activity. We also show that STK, AG, SHP1, and SHP2 can form multimeric complexes and that these interactions require the SEPALLATA (SEP) MADS-box proteins. We provide genetic evidence for this role of the SEP proteins by showing that a reduction in SEP activity leads to the loss of normal ovule development, similar to what occurs in stk shp1 shp2 triple mutants. Together, these results indicate that the SEP proteins, which are known to form multimeric complexes in the control of flower organ identity, also form complexes to control normal ovule development