Expression of sugarcane genes induced by inoculation with Gluconacetobacter diazotrophicus and Herbaspirillum rubrisubalbicans

Several Brazilian sugarcane varieties have the ability to grow with little addition of inorganic nitrogen fertilizers, showing high contributions of Biological Nitrogen Fixation (BNF). A particular type of nitrogen-fixing association has been described in this crop, where endophytic diazotrophs such as Gluconacetobacter diazotrophicus and Herbaspirillum spp. colonize plant tissues without causing disease symptoms. In order to gain insight into the role played by the sugarcane in the interaction between this plant and endophytic diazotrophs, we investigated gene expression profiles of sugarcane plants colonized by G. diazotrophicus and H. rubrisubalbicans by searching the sugarcane expressed sequence tag SUCEST Database (http://sucest.lad.ic.unicamp.br/en/). We produced an inventory of sugarcane genes, candidates for exclusive or preferential expression during the nitrogen-fixing association. This data suggests that the host plant might be actively involved in the establishment of the interaction with G. diazotrophicus and H. rubrisubalbicans.Diversos genótipos brasileiros de cana-de-açúcar são capazes de crescer com baixa adição de adubos nitrogenados, obtendo elevadas contribuições da Fixação Biológica de Nitrogênio (FBN). Um tipo especial de associação com bactérias fixadoras de nitrogênio foi descrito em cana-de-açúcar, onde as bactérias endofíticas, como Gluconacetobacter diazotrophicus e Herbaspirillum spp., colonizam o interior dos tecidos vegetais, sem causar sintomas de doença. Com o objetivo de tentar entender o papel da cana-de-açúcar nesse tipo de associação, nós investigamos os perfis de expressão gênica de plantas colonizadas pelos diazotróficos endofíticos, usando o banco de dados do SUCEST. Um catálogo com os genes de cana-de-açúcar que são candidatos a se expressar exclusivamente ou preferencialmente durante a associação foi gerado. Esses dados preliminares sugerem que a cana-de-açúcar deve ter uma participação ativa na interação, respondendo a diversos processos metabólicos durante a associação.199206Fundação 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

Purification and circular dichroism of recombinant MntC.

<p>(A): 12% SDS-PAGE showing purified recombinant protein MntC (1) and after removal of N-terminal polyhistidine tag (2) by enterokinase (asterisk); molecular mass marker (M). (B) MntC circular dichroism spectrum: predominant α-helical secondary structure is shown. Far-UV CD spectrum is presented as an average of five scans recorded from 182 to 262 nm; , molar ellipticity.</p

Binding of MntC to ECM components as a function of protein concentration.

<p>(A) Collagen type IV (CIV), (B) laminin (LAM), (C) cellular fibronectin (CF), (D) plasma fibronectin (PF), (E) plasminogen (PLG), (F) fibrinogen (FIB). LigBC and LIC10301 were included as positive and negative controls, respectively. Recombinant protein concentrations ranged from 0 to 2 µM. Each point represents the mean absorbance value at 492 nm ± the standard error of two independent experiments, each performed in duplicate. MntC binding to each ECM component was compared to LIC10301 binding to these molecules by the two-tailed t test (* <i>p</i><0.05).</p

Expression of sugarcane genes induced by inoculation with Gluconacetobacter diazotrophicus and Herbaspirillum rubrisubalbicans

Several Brazilian sugarcane varieties have the ability to grow with little addition of inorganic nitrogen fertilizers, showing high contributions of Biological Nitrogen Fixation (BNF). A particular type of nitrogen-fixing association has been described in this crop, where endophytic diazotrophs such as Gluconacetobacter diazotrophicus and Herbaspirillum spp. colonize plant tissues without causing disease symptoms. In order to gain insight into the role played by the sugarcane in the interaction between this plant and endophytic diazotrophs, we investigated gene expression profiles of sugarcane plants colonized by G. diazotrophicus and H. rubrisubalbicans by searching the sugarcane expressed sequence tag SUCEST Database (<A HREF="http://sucest.lad.ic.unicamp.br/en/">http://sucest.lad.ic.unicamp.br/en/</A>). We produced an inventory of sugarcane genes, candidates for exclusive or preferential expression during the nitrogen-fixing association. This data suggests that the host plant might be actively involved in the establishment of the interaction with G. diazotrophicus and H. rubrisubalbicans

ABAP1 is a novel plant Armadillo BTB protein involved in DNA replication and transcription

In multicellular organisms, organogenesis requires a tight control of the balance between cell division and cell differentiation. Distinct signalling pathways that connect both cellular processes with developmental cues might have evolved to suit different developmental plans. Here, we identified and characterized a novel protein that interacts with pre-replication complex (pre-RC) subunits, designated Armadillo BTB Arabidopsis protein 1 (ABAP1). Overexpression of ABAP1 in plants limited mitotic DNA replication and decreased cell proliferation in leaves, whereas ABAP1 downregulation increased cell division rates. Activity of ABAP1 in transcription was supported by its association with the transcription factor AtTCP24. The ABAP1–AtTCP24 complex bound specifically to the promoters of AtCDT1a and AtCDT1b in vitro and in vivo. Moreover, expression levels of AtCDT1a and AtCDT1b were reduced in ABAP1-overexpressing plants and they were increased in plants with reduced levels of ABAP1. We propose that ABAP1 participates in a negative feedback loop regulating mitotic DNA replication during leaf development, either by repressing transcription of pre-RC genes and possibly by regulating pre-RC utilization through direct association with pre-RC components