SCI1 Is a Direct Target of AGAMOUS and WUSCHEL and Is Specifically Expressed in the Floral Meristematic Cells

The specified floral meristem will develop a pre-established number of floral organs and, thus, terminate the floral meristematic cells. The floral meristematic pool of cells is controlled, among some others, by WUSCHEL (WUS) and AGAMOUS (AG) transcription factors (TFs). Here, we demonstrate that the SCI1 (Stigma/style cell-cycle inhibitor 1) gene, a cell proliferation regulator, starts to be expressed since the floral meristem specification of Nicotiana tabacum and is expressed in all floral meristematic cells. Its expression is higher in the floral meristem and the organs being specified, and then it decreases from outside to inside whorls when the organs are differentiating. SCI1 is co-expressed with N. tabacum WUSCHEL (NtWUS) in the floral meristem and the whorl primordia at very early developmental stages. Later in development, SCI1 is co-expressed with NAG1 (N. tabacum AG) in the floral meristem and specialized tissues of the pistil. In silico analyses identified cis-regulatory elements for these TFs in the SCI1 genomic sequence. Yeast one-hybrid and electrophoresis mobility shift assay demonstrated that both TFs interact with the SCI1 promoter sequence. Additionally, the luciferase activity assay showed that NAG1 clearly activates SCI1 expression, while NtWUS could not do so. Taken together, our results suggest that during floral development, the spatiotemporal regulation of SCI1 by NtWUS and NAG1 may result in the maintenance or termination of proliferative cells in the floral meristem, respectively.Fil: Cruz, Joelma O.. Universidade de Sao Paulo; BrasilFil: Abramo Barrera San Martin, Juca. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentina. Universidade de Sao Paulo; BrasilFil: Lubini, Greice. Universidade de Sao Paulo; BrasilFil: Strini, Edward J.. Universidade de Sao Paulo; BrasilFil: Sobral, Rómulo. Universidade do Minho; PortugalFil: Pinoti, Vitor F.. Universidade de Sao Paulo; BrasilFil: Ferreira, Pedro B.. Universidade de Sao Paulo; BrasilFil: Thomé, Vanessa. Universidade de Sao Paulo; BrasilFil: Quiapim, Andréa C.. Universidade de Sao Paulo; BrasilFil: Dornelas, Marcelo C.. Universidade Estadual de Campinas; BrasilFil: Pranchevicius, Maria Cristina S.. Universidade Federal do São Carlos; BrasilFil: Madueño, Francisco. Consejo Superior de Investigaciones Científicas; EspañaFil: Costa, M. Manuela R.. Universidade do Minho; PortugalFil: Goldman, Maria Helena S.. Universidade de Sao Paulo; Brasi

Ontogenia floral do gênero Eleocharis R.Br.(Cyperaceae)

Eleocharis, pertencente a família Cyperaceae, é inserido na tribo Eleocharideae, da subfamília Cyperoideae. O gênero apresenta ampla distribuição geográfica e é caracterizado por apresentar inflorescência reduzida a uma única espigueta no ápice do colmo, sem brácteas involucrais e folhas reduzidas à bainha. A reprodução assexuada por propagação vegetativa, como por exemplo a pseudoviviparidade, é amplamente encontrada no gênero. A expressiva redução dos caracteres morfológicos dificulta o estabelecimento de uma classificação infragenérica que reflita a história evolutiva do gênero. Atualmente, o gênero está subdividido e quatro subgêneros: Eleocharis, Limnochloa, Scirpidium e Zinserlingia. O presente trabalho tem como finalidade ampliar o conhecimento da ontogenia floral dentro da família Cyperaceae; compreender as relações de homologias da inflorescência e da flor no gênero Eleocharis; comparar os padrões de desenvolvimento floral entre representantes de três subgêneros; e descrever a ontogenia da estrutura envolvida na pseudoviviparidade, denominada espigueta prolífera. Exemplares de 15 espécies do gênero foram analisadas em microscopia de luz e microscopia eletrônica de varredura. As inflorescências de Eleocharis são reduzidas a única espigueta e se desenvolvem na axila de uma bráctea, com dimensões reduzidas, proximal ao colmo. Ao longo do eixo da ráquila as flores se desenvolvem, em um arranjo helicoidal, na axila de brácteas florais. O padrão de desenvolvimento das flores é semelhante ao descrito para outras espécie da subfamília Cyperoideae. Porém, são encontradas variações no que diz respeito a disposição dos primórdios florais ao logo da espigueta; no número, padrão de desenvolvimento e micromorfologia dos estames; número de ramos do estigma; organização das peças periântica; e, "timing" de desenvolvimento dos verticilos. Entre as espécies pertencentes aos subgêneros Limnochloa e Scirpidium, poucas variações no padrão de desenvolvimento da flor foram encontradas, o que contribui para o estabelecimento desses subgêneros como grupos monofiléticos dentro do gênero Eleocharis. Por outro lado, diferenças significativas são encontradas entre espécies do subgênero Eleocharis, indicando um processo de especiação ativa entre alguns grupos de espécies do gênero Eleocharis. Em relação a pseudoviviparidade, nossos resultados demonstraram que a espigueta prolífera se desenvolve a partir de um meristema localizado na axila da bráctea proximal. Cada espigueta prolífera é formada por unidades simpodiais constituídas por um profilo adossado, uma bainha externa, uma interna e um colmo, que na região terminal desenvolve o primórdio de uma espigueta florífera, que pode ser abortado, e na axila da bráctea proximal ocorre desenvolvimento de uma nova espigueta prolífera. A partir do segundo entrenó de cada unidade simpodial se desenvolve um primórdio de raiz e no entrenó seguinte, um meristema intercalar, que promove o crescimento do colmo e a repetição do padrão de crescimento da planta por pseudoviviparidade. Nossos resultados indicam que a pseudoviviparidade pode coexistir com a reprodução sexuada, como uma estratégia de reprodução alternativa que permite a rápida propagação das populações

Correction: Increasing atmospheric CO2 and canopy temperature induces anatomical and physiological changes in leaves of the C4 forage species Panicum maximum.

[This corrects the article DOI: 10.1371/journal.pone.0212506.]

Increasing atmospheric CO2 and canopy temperature induces anatomical and physiological changes in leaves of the C4 forage species Panicum maximum.

Changes in leaf anatomy and ultrastructure are associated with physiological performance in the context of plant adaptations to climate change. In this study, we investigated the isolated and combined effects of elevated atmospheric CO2 concentration ([CO2]) up to 600 μmol mol-1 (eC) and elevated temperature (eT) to 2°C more than the ambient canopy temperature on the ultrastructure, leaf anatomy, and physiology of Panicum maximum Jacq. grown under field conditions using combined free-air carbon dioxide enrichment (FACE) and temperature free-air controlled enhancement (T-FACE) systems. Plants grown under eC showed reduced stomatal density, stomatal index, stomatal conductance (gs), and leaf transpiration rate (E), increased soil-water content (SWC) conservation and adaxial epidermis thickness were also observed. The net photosynthesis rate (A) and intrinsic water-use efficiency (iWUE) were enhanced by 25% and 71%, respectively, with a concomitant increase in the size of starch grains in bundle sheath cells. Under air warming, we observed an increase in the thickness of the adaxial cuticle and a decrease in the leaf thickness, size of vascular bundles and bulliform cells, and starch content. Under eCeT, air warming offset the eC effects on SWC and E, and no interactions between [CO2] and temperature for leaf anatomy were observed. Elevated [CO2] exerted more effects on external characteristics, such as the epidermis anatomy and leaf gas exchange, while air warming affected mainly the leaf structure. We conclude that differential anatomical and physiological adjustments contributed to the acclimation of P. maximum growing under elevated [CO2] and air warming, improving the leaf biomass production under these conditions

Elevated CO2 and warming affect pollen development in a tropical legume forage species

Global climate change is expected to have impacts on the physiological, phenological, and morphological traits of plants. However, the vulnerability of tropical plant reproductive processes in response to climate change events has been poorly studied. Here, we assess if warming and elevated CO2 compromise the pollen characteristics of Stylosanthes capitata Vogel, a tropical legume forage species. This work was conducted in a Trop-T-FACE (combined Free-Air Temperature Controlled Enhancement and Free-Air Carbon Dioxide Enrichment) facility, where we exposed the plants to four treatments: C (Control-ambient atmospheric carbon dioxide concentration [CO2] and ambient temperature); eCO2 (increase in [CO2] to 600 ppm and ambient temperature); eT (canopy temperature increase by 2°C and ambient [CO2]); and eCO2+eT, a combination of both treatments. We analyzed pollen morphology of samples taken from the different treatments through light microscopy (LM) and scanning electron microscopy (SEM). In addition, pollen viability was analyzed through colorimetry. Based on the histological LM analysis, the tapetum cells of pollen sacs showed early degeneration under eT (72%) added to hypertrophy under eCO2 (67%) and eCO2+eT (90%) treatments. SEM images showed compaction of pollen exine and less distinguishable pollen apertures in the treated plots (eCO2, eT, and eCO2+eT), possibly, by the early death of the tapetum cells. These morphological abnormalities may hinder the viability of pollen grains, as observed especially in the eCO2+eT treatment (%V=64%) that was the lowest in comparison with the Control (71%) and the other treatments (eCO2 = 69%, eT = 67%). These results indicate that during the reproductive cycle of S. capitata pollen sacs and pollen grains are vulnerable to warming, elevated CO2, and their combined effects.Fil: Alzate Marin, Ana Lilia. Universidade de Sao Paulo; BrasilFil: Pádua Teixeira, Simone. Universidade de Sao Paulo; BrasilFil: Correia da Rocha Filho, Léo. Universidade de Sao Paulo; BrasilFil: Bonifácio Anacleto, Fernando. Universidade de Sao Paulo; BrasilFil: Marlys Sá Rivas, Priscila. Universidade de Sao Paulo; BrasilFil: Abramo Barrera San Martin, Juca. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; ArgentinaFil: Martinez, Carlos Alberto. Universidade de Sao Paulo; Brasi

Cytogenetic characterization reveals differences in nuclear organization of cystic cells among Brazilian species of Triatoma (Heteroptera, Reduviidae)

Cytogenetic studies in triatomines have described the occurrence of holokinetic chromosomes, heterochromatin distribution and the location of rDNA (ribosomal DNA) sites, but few aspects of nuclear organization in this group have been discussed. We have focused on ultrastructural and cytogenetic features and differences in cystic cells of seminiferous tubules between five species of Triatoma. Cystic cells showed evidence of polyploidy events and heterochromatic blocks appeared predominantly in the central region of the nuclei. Cytogenetic analyses showed that there was variation in chromocenter number between species, and that the central regions were AT-rich [DAPI(+) (4',6-diamidino-2-phenylindole(+))], whereas the periphery was CG-rich (CMA(+)). Another characteristic was the distribution of 45S rDNA, which differed according to the chromosomal location of this sequence. In all we have compared aspects of nuclear organization, polyploidy, heterochromatin, rDNA site distribution and methylation levels, as well as the relationships between five species of Triatoma from a cystic cell perspective.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Bioactive organocopper compound from Pseudomonas aeruginosa inhibits the growth of Xanthomonas citri subsp. citri

Citrus canker is a lot destructive disease of citrus species. The challenge is to find new compounds that show strong antibiotic activity, low toxicity to plants and the environment. The objectives of the present study are (1) produce, purify and evaluate the antibiotic activity of secondary metabolites produced by induction by P. aeruginosa LV strain in vitro against Xanthomonas citri subsp. citri (strain 306), (2) study the potential for semi-purified secondary metabolites on foliar application to control citrus canker under greenhouse conditions, (3) identify the antibiotic activity in orange leaf mesophyll infected with strain 306 by electron microscopy. Two pure bioactive compounds were isolated, organocopper antibiotic compound and phenazine-1-carboxamide. The phenazine-1-carboxamide did not show any antibiotic activity under the experimental conditions used in this study. The organocopper antibiotic compound showed a high level of antibiotic activity with a minimum inhibitory concentration of 0.12 µg mL-1. In greenhouse tests for control of citrus canker in orange trees, the semi-purified fraction F3d, reduced lesion formation about 97%. The concentration used was five hundred times lower than recommended commercial product of metallic copper-based. Electron microscopy showed that F3d altered the exopolysaccharide matrix and causing cell lysis of the pathogen inside the citrus canker lesions. These results suggest that secondary metabolites produced by induction by P. aeruginosa LV strain has a high potential to be used as a bioproduct to control citrus canker