Changes in gene expression in canola roots induced by ACC-deaminase-containing plant-growth-promoting bacteria.
The technique of RNA arbitrarily primed-polymerase chain reaction (RAP-PCR) was used to study changes in gene expression over time in canola roots treated with the 1-aminocyclopropane-1-carboxylate (ACC) deaminase-containing plant-growth-promoting bacterium Enterobacter cloacae UW4 and to compare the changes with those in a mutant of E. cloacae UW4 in which the ACC deaminase structural gene acdS was replaced by homologous recombination with acdS with an intentional knockout containing a tetracycline resistance gene. Genes that were either up- or down-regulated over a three-day period in canola plants treated with wild-type or mutant bacteria were isolated, cloned, and sequenced; all appeared to have high homology with Arabidopsis thaliana genes. The upregulated genes included a cell division cycle protein 48 homolog and a eukaryotic translation initiation factor 3 subunit 7 gene homolog. The downregulated genes included one encoding a glycine-rich RNA binding protein with a function in RNA processing or binding during ethylene-induced stress, which is expressed only in roots, and another gene thought to be involved in a defense signaling pathway. All RAP-PCR results were verified using Northern blotting. These data, indicate that roots isolated from canola seeds treated with the ACC deaminase-producing E. cloacae UW4 upregulate genes involved in cell division and proliferation but down-regulate stress genes. This data is in agreement with a model in which ACC deaminase-containing plant-growth-promoting bacteria reduce plant stress and induce root elongation and proliferation in plants, largely by lowering ethylene levels.
Hontzeas
Nikos
N
Department of Biology, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
Saleh
Saleema S
SS
Glick
Bernard R
BR
D000595:Amino Acid Sequence; D029688:Brassica napus / Q000235:genetics* / Q000378:metabolism; D019755:Carbon-Carbon Lyases / Q000494:pharmacology*; D016972:Enterobacter cloacae / Q000235:genetics*; D015870:Gene Expression / Q000187:drug effects*; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism*; D016133:Polymerase Chain Reaction / Q000379:methods*
C033634:1-aminocyclopropane-1-carboxylate deaminase; D019755:Carbon-Carbon Lyases