RESUMO
Late embryogenesis abundant (LEA) proteins include eight multigene families that are expressed in response to water loss during seed maturation and in vegetative tissues of desiccation tolerant species. To elucidate LEA proteins evolution and diversification, we performed a comprehensive synteny and phylogenetic analyses of the eight gene families across 60 complete plant genomes. Our integrated comparative genomic approach revealed that synteny conservation and diversification contributed to LEA family expansion and functional diversification in plants. We provide examples that: 1) the genomic diversification of the Dehydrin family contributed to differential evolution of amino acid sequences, protein biochemical properties, and gene expression patterns, and led to the appearance of a novel functional motif in angiosperms; 2) ancient genomic diversification contributed to the evolution of distinct intrinsically disordered regions of LEA_1 proteins; 3) recurrent tandem-duplications contributed to the large expansion of LEA_2; and 4) dynamic synteny diversification played a role on the evolution of LEA_4 and its function on plant desiccation tolerance. Taken together, these results show that multiple evolutionary mechanisms have not only led to genomic diversification but also to structural and functional plasticity among LEA proteins which have jointly contributed to the adaptation of plants to water-limiting environments.
Assuntos
Evolução Molecular , Filogenia , Proteínas de Plantas/genética , Plantas/genética , Aclimatação/genética , Duplicação Gênica , Genoma de Planta , Família Multigênica , SinteniaRESUMO
Miconia ligustroides (DC.) Naudim, popularly known as "vassoura-preta" or "jacatirão-do-brejo" is widely distributed in Brazil. It is a recommended species for restoration of riparian areas and its fruits are attractive to wildlife. However, little is known about the morphology of its fruits and diaspores. Such morphological characterization studies are important for species identification, corroborating future studies of phenology and germination. Therefore, the fruits, diaspores and germination of M. ligustroides were morphologically characterized by observations through naked eye, stereoscopic microscopy and scanning electron microscopy. Analyses of chemical composition of seeds were also performed. The fruits are spherical and uniform within the analyzed sample, having a large number of tiny obtriangular yellowish-brown diaspores. The diaspores are considered ananfitropos, and have crystals in their external envelope. Concerning chemical composition, they are proteins. Germination is of phanerocotylar type and starts at 12 Days After Sowing (DAS); at 17 DAS each diaspore may produce up to three seedlings. The morphological characterization performed in this work was efficient to describe the fruits, seeds and germination of this species, thus providing the basis for future studies.
Miconia ligustroides (DC.) Naudim, popularmente conhecida como vassoura-preta ou jacatirão-do-brejo, é amplamente distribuída no Brasil. É uma espécie recomendada para restauração de matas ciliares, e seus frutos são atrativos à fauna. No entanto, pouco se conhece acerca da morfologia de seus frutos e diásporos, e é sabido que estudos de caracterização morfológica são importantes para a identificação de espécies, além de corroborarem estudos futuros de fenologia e germinação. Portanto, os frutos, diásporos e geminação de M. ligustroides foram caracterizados morfologicamente por meio de observações visuais a olho nu, em microscópio estereoscópico e por meio de Microscopia Eletrônica de Varredura. Análises da composição química das sementes também foram realizadas. Os frutos são esféricos e uniformes dentro da amostra analisada. Possuem grande número de diminutos diásporos castanho-amarelados e obtriangulares. Os diásporos são considerados ananfítropos e possuem cristais em seu envoltório externo. Quanto à composição química, são proteicos. A germinação é do tipo fanerocotiledonar e inicia-se aos 12 Dias Após Semeadura (DAS), sendo que aos 17 DAS cada diásporo pode originar até três plântulas. A caracterização morfológica realizada neste trabalho foi eficiente em descrever os frutos, sementes e germinação desta espécie, de modo a subsidiar estudos futuros.
