Genome of Herbaspirillum seropedicae Strain SmR1, a Specialized Diazotrophic Endophyte of Tropical Grasses

The molecular mechanisms of plant recognition, colonization, and nutrient exchange between diazotrophic endophytes and plants are scarcely known. Herbaspirillum seropedicae is an endophytic bacterium capable of colonizing intercellular spaces of grasses such as rice and sugar cane. The genome of H. seropedicae strain SmR1 was sequenced and annotated by The Paraná State Genome Programme—GENOPAR. The genome is composed of a circular chromosome of 5,513,887 bp and contains a total of 4,804 genes. The genome sequence revealed that H. seropedicae is a highly versatile microorganism with capacity to metabolize a wide range of carbon and nitrogen sources and with possession of four distinct terminal oxidases. The genome contains a multitude of protein secretion systems, including type I, type II, type III, type V, and type VI secretion systems, and type IV pili, suggesting a high potential to interact with host plants. H. seropedicae is able to synthesize indole acetic acid as reflected by the four IAA biosynthetic pathways present. A gene coding for ACC deaminase, which may be involved in modulating the associated plant ethylene-signaling pathway, is also present. Genes for hemagglutinins/hemolysins/adhesins were found and may play a role in plant cell surface adhesion. These features may endow H. seropedicae with the ability to establish an endophytic life-style in a large number of plant species

Laboratory surveillance of dengue in Rio Grande do Sul, Brazil, from 2007 to 2013.

BACKGROUND: According to official records, dengue was introduced in Brazil in the 80's; since then several epidemics have occurred. Meanwhile, in Rio Grande do Sul (RS, Southern Brazil) the first autochthonous case occurred only in 2007. METHODOLOGY AND PRINCIPAL FINDINGS: In this study we report laboratory surveillance of dengue cases and seasonality of positive cases, describe serotypes and characterize the epidemiological pattern of dengue in RS from 2007 to 2013. A total of 9,779 serum samples from patients with suspected dengue fever were collected and submitted to molecular and/or serological analyses for dengue virus identification and serotyping, based on viral isolation, NS1 antigen detection and qRT-PCR, or Dengue IgM capture ELISA and MAC-ELISA. The first autochthonous dengue case in RS was confirmed in 2007 (DENV-3). While in 2008 and 2009 only imported cases were registered, autochthonous infection waves have been occurring since 2010. The highest number of dengue infections occurred in 2010, with DENV-1 and DENV-2 outbreaks in Northwestern RS. In 2011, another DENV-1 and DENV-2 outbreak occurred in the Northwestern region; moreover, DENV-4 was detected in travelers. In 2012, DENV-1 and DENV-4 co-circulated. DENV-2 circulation was only detected again in 2013, in high frequency (56.7%), co-circulating with DENV-4 (35%). Most infections occur in adults during summer. Differences in prevalence between genders were observed in 2007 (60% females), 2008 (60.8% males) and 2009 (77.5% males). CONCLUSIONS: According to results of dengue surveillance, there was an increase in the number of dengue cases in RS and of cities infested with Aedes aegypti, possibly as a consequence of introduction of new serotypes and the difficulty of health programs to control the vector

Dengue cases in the State of Rio Grande do Sul according to age (2007–2013)^a.

a<p>Number of positive cases and percentages are ratio among positive cases by total samples tested by year.</p>b<p>Standardized adjusted residuals ≥2 according to data of test χ² = 294.49, <i>p</i><0.001.</p>c<p>N.I.: not informed (data was not informed in the <i>Dengue Notification Form</i>).</p

Frequency distribution of positive dengue cases in the State of Rio Grande do Sul, according to gender (2007–2013).

<p>Frequency distribution of positive dengue cases in the State of Rio Grande do Sul, according to gender (2007–2013).</p

Seasonality of positive dengue cases in the State of Rio Grande do Sul, Southern Brazil, according to months (2007–2013).

<p>Seasonality of positive dengue cases in the State of Rio Grande do Sul, Southern Brazil, according to months (2007–2013).</p

Dengue cases in the State of Rio Grande do Sul according to serotypes (2007–2013).

a<p>Percentages are ratio among dengue serotypes by positive samples.</p

Molecular mechanisms probably involved in plant colonization and plant growth promotion identified in the <i>H. seropedicae</i> SmR1 genome.

<p>Plant signals can modulate the expression of bacterial genes coding for adhesins, type IV <i>pili</i> and enzymes of lipopolysaccharide (LPS) synthesis, triggering bacterial attachment to root surfaces. The molecular communication involves bacterial protein secretion and phytohormones to stimulate plant growth and modulate plant defense response. In addition, modulation of plant ethylene levels by ACC deaminase may contribute to plant growth promotion. The success of the endophytic association depends on a compatible genetic background that leads to benefits for both organisms.</p

The type III secretion system gene cluster of <i>H. seropedicae</i> SmR1 and other organisms.

<p>Genes of the same color in different organisms are homologous. Genes colored in black have no counterpart in the genomic regions shown.</p

The genome of <i>Herbaspirillum seropedicae</i> SmR1.

<p>From inside to outside 1) G+C content; 2) GC skew; 3) genes color-coded according the COG functional categories; genes in the + strand and − strand are represented in the inside and outside circles respectively; 4) rRNAS operons; 5) putative horizontally transferred regions identified using IVOM: light red indicates low score and dark red indicates high score; 6) regions of <i>H. seropedicae</i> genome identical to castor bean (<i>Ricinus communis</i>) sequences (minimum of 200 bp in length and higher than 90% in identity).</p