Differential gene expression of rice roots inoculated with the diazotroph Herbaspirillum seropedicae
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Background and aims
Rice (Oryza sativa L.) is the primary source of carbohydrate for the majority of the World's population. Herbaspirillum seropedicae is a diazotroph that lives within and on the surface of rice roots. It can promote the growth of rice, partly by supplying it with fixed nitrogen.
To better understand the rice–H. seropedicae interaction, cDNA libraries from rice roots either inoculated (RRCH) or uninoculated (RRSH) with the diazotroph were obtained and analysed.
Potential differentially expressed genes identified from the libraries encoded a metallothionein-like protein type 1, a NOD26-like membrane integral protein ZmNIP2-1, a thionin family protein, an oryzain gamma chain precursor, stress-associated protein 1 (OsISAP1), probenazole-inducible protein PBZ1 and auxin- and ethylene-responsive genes. Differential expression was analysed by qRT-PCR for some of these genes and confirmed in most cases. The expression of stress- and defence-related genes coding for thionins, PBZ1 and OsISAP1 was repressed, while expression of a metallothionein gene was induced by inoculation with H. seropedicae. In contrast, expression of auxin-responsive genes was repressed, while expression of ethylene genes was either repressed or induced. The possible involvement of these and other genes in plant-bacterial interactions is discussed.
The decrease in expression of the defence-related proteins PBZ1 and thionins in the rice–H. seropedicae association, suggests that the bacteria modulate plant defence responses during colonisation. The expression of genes responsive to auxin and ethylene also appears to be regulated by the bacteria.
KeywordsExpressed sequence tag Herbaspirillum seropedicae Rice Oryza sativa Plant–bacterial interaction qRT-PCR
Expressed sequence tag
Plant-growth promoting rhizobacteria
Pattern recognition receptor
Pathogen-associated molecular pattern
Rice annotation project-database
Ethylene response factor
Auxin response factor
Ozyza sativa subspecies indica stress-associated protein
Receptor-like protein kinase
Type three secretion system
Indole acetic acid
We are grateful to Roseli Prado and Julieta Pie for technical support, Embrapa Arroz Feijão and Instituto Riograndense do Arroz for providing seeds. We also thank Euan K. James for revising the final version of this manuscript. This work was supported by CNPq-Instituto do Milênio, INCT-FBN, CNPq and CAPES.
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