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

Abstract

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.

Potential of Bacterial Endophytes as Plant Growth Promoting Factors

“…[12] demonstrated that plant entry by the endophytic bacterium Enterobacter asburiae JM22 was assisted by ability of the bacterium to hydrolyze plant cell wall-bound cellulose. On the other hand, the bacterial species Herbaspirillum seropedicae, which lacks genes for degrading plant cell walls, is also a successful endophyte, confirming the existence of other strategies to penetrate plant tissues [42,43]. It not currently known whether there is any specific form of communication (other than chemotaxis) between endophytic bacteria and plants that is involved in the colonization of the internal tissues of plants, comparable to the mechanisms used by various Rhizobia spp.…”

Root exudate profiling of maize seedlings inoculated with Herbaspirillum seropedicaeand humic acids

“…The members of this genus have been tested in the formulation of biofertilizers, with variable success in field crop trials ( [16][17][18][19] and references therein [20][21][22][23]). The whole genome sequence of H. seropedicae has been published [24]. The species' capacity for N fixation, production of auxin and other phytohormones, and the colonization of diverse plant species has been previously demonstrated [25][26][27].…”

Análise Fisiológica do Co-cultivo das BPCV Herbaspirillum seropedicae SmR1 e Azospirillum brasilense AbV5 com Plântulas de Trigo in vitro sob Condições de Estresse Hídrico.

“…A bactéria H. seropedicae SmR1 apresenta um diferencial em relação a A. brasilense AbV5 -a existência no seu genoma de um gene que codifica a ACC desaminase, enzima que atua decompondo um dos percursores do etileno, o 1-aminociclopropano-1-carboxilato (ACC), em ácido alfa-ceto-butírico (ACB) e amônio 2 . O AIA produzido por ambas as bactérias pode estimular a síntese do ACC pelo aumento da atividade da ACC sintase 3 e inibir a transformação do ACC em etileno pela diminuição da atividade da ACC oxidase 2 .…”

“…A bactéria H. seropedicae SmR1 apresenta um diferencial em relação a A. brasilense AbV5 -a existência no seu genoma de um gene que codifica a ACC desaminase, enzima que atua decompondo um dos percursores do etileno, o 1-aminociclopropano-1-carboxilato (ACC), em ácido alfa-ceto-butírico (ACB) e amônio 2 . O AIA produzido por ambas as bactérias pode estimular a síntese do ACC pelo aumento da atividade da ACC sintase 3 e inibir a transformação do ACC em etileno pela diminuição da atividade da ACC oxidase 2 . O objetivo deste trabalho foi estudar duas variedades de trigo da COODETEC, CD120 e uma cultivar ancestral, "Frontana", para verificar o efeito fisiológico das bactérias H. seropedicae SmR1 e A. brasilense AbV5 em plântulas de trigo in vitro com um agente promotor de estresse hídrico no meio de cultivo, o polietilenoglicol (PEG).…”