<p>This work is focused on the molecular genetic basis for morphological change in evolution. Genes belonging to the MADS-box gene family, which includes members, that determine angiosperm floral organ identity, were isolated and characterised from two non-angiosperm plants; Norway spruce (<i>Picea abies</i>) and the club moss (<i>Lycopodium annotinum</i>).</p><p>The exon/intron organisation of the isolated genes was determined, and its significance as an independent test of the position of a gene within the gene family tree evaluatad. identity genes were identified. One Norway spruce gene, <i>DAL2</i>, is an ortholog to</p><p>Norway spruce genes that are closely related to the angiosperm floral organ angiosperm C-class MADS-box genes that specify stamen and carpel identity. The expression of <i>DAL2</i> in male and female cones suggests that orthologous genes in conifers and argiosperms determine the identities of pollen- and seed-bearing structures. Constitutive expression of <i>DAL2</i> in the angiosperm Arabidopsis resulted in homeotic conversions very similar to those resulting from constiutive expression of the Arabidopsis C-class gene.</p><p>Angiosperm B-class MADS-box genes determine petal and stamen identity. The isolated Norway spruce B-class orthologs: <i>DAL11, DAL12</i>, and <i>DAL13</i> are expressed in the developing male cones exclusively, suggesting a conserved function of B-class related genes in the determination of pollen forming organs among seed plants.</p><p>No orthologs to the floral organ identity genes couId be isolated from the club moss, suggesting that the origin of these gene classes may be coupled to the origin of the pollen and the seed.</p><p>The club moss MADS-box genes, <i>LAMB2, LAMB4</i> and <i>LAMB6</i>, conform structurally to plant type MADS-box genes, whereas <i>LAMB1</i> is divergent in details. The genes <i>LAMB3</i> and <i>LAMB5 </i>encode shorter proteins.</p><p><i>LAMB1</i> expression is restricted to reproductive structures, whereas <i>LAMB2</i>, <i>LAMB4, LAMB5</i> and <i>LAMB6</i> are broadly expressed. The implications from these expression patterns on the ancestral function of plant type MADS-box genes are discussed. </p>
| Identifer | oai:union.ndltd.org:UPSALLA/oai:DiVA.org:uu-1194 |
| Date | January 2000 |
| Creators | Svensson, Mats |
| Publisher | Uppsala University, Department of Evolutionary Biology, Uppsala : Acta Universitatis Upsaliensis |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Doctoral thesis, comprehensive summary, text |
| Relation | Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1104-232X ; 573 |
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