Submitted to: Plant Biology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 7/16/2005
Publication Date: 7/21/2005
Citation: Zhang, H., Farag, M., Ryu, C., Payton, P.R., Kloepper, J., Pare, P. 2005. Genome-wide analysis of plant-growth promotion in arabidopsis triggered by volatile chemicals from rhizobacteria[abstract]. Plant Biology Annual Meeting. Paper No. 399.
Technical Abstract: Plant growth-promoting rhizobacteria (PGPR) constitute a wide range of root-colonizing bacteria that can enhance plant growth by increasing seed germination, plant weight, and crop yields. Some PGPR strains regulate plant growth by mimicking synthesis of plant hormones including indole-3-acetic acid, cytokinins, or gibberilins, while others increase mineral and nitrogen availability in the soil. We have recently observed that certain bacterial volatiles can trigger growth promotion in Arabidopsis however, underlying molecular mechanisms responsible for growth promotion have yet to be characterized. By performing micro-array analysis, we have begun to probe for Arabidopsis genes that are differentially expressed with exposure to bacterial volatiles. Within 48-hours of PGPR exposure, over 500 filtered transcripts (ca. 2% of the total transcripts screened) were selectively up or down regulated. Differentially expressed transcripts included genes involved in cell wall modifications and auxin-regulated responses that may well play a central role in induced growth promotion. Induction of an iron transporter (IRT1), which is often linked with a plant’s photosynthetic output lead to the observation that GB03 volatiles effectively increase PSII efficiency.The microarray data suggest a possible role of photosynthesis and hormone balance in growth promotion triggered by PGPR volatiles. Genes that drive photosynthesis include: light harvesting and iron transport genes. To probe what impact transcriptional level changes may have on photosynthesis, several leaf-level parameters including, photosynthetic efficiency, pigment content, and iron homostatsis are being measured.