Inhibition of primary roots and stimulation of lateral root development in Arabidopsis thaliana by the rhizobacterium Serratia marcescens 90-166 is through both auxin-dependent and -independent signaling pathways.
The rhizobacterium Serratia marcescens strain 90-166 was previously reported to promote plant growth and induce resistance in Arabidopsis thaliana. In this study, the influence of strain 90-166 on root development was studied in vitro. We observed inhibition of primary root elongation, enhanced lateral root emergence, and early emergence of second order lateral roots after inoculation with strain 90-166 at a certain distance from the root. Using the DR5::GUS transgenic A. thaliana plant and an auxin transport inhibitor, N-1-naphthylphthalamic acid, the altered root development was still elicited by strain 90-166, indicating that this was not a result of changes in plant auxin levels. Intriguingly, indole-3-acetic acid, a major auxin chemical, was only identified just above the detection limit in liquid culture of strain 90-166 using liquid chromatography-mass spectrometry. Focusing on bacterial determinants of the root alterations, we found that primary root elongation was inhibited in seedlings treated with cell supernatant (secreted compounds), while lateral root formation was induced in seedlings treated with lysate supernatant (intracellular compounds). Further study revealed that the alteration of root development elicited by strain 90-166 involved the jasmonate, ethylene, and salicylic acid signaling pathways. Collectively, our results suggest that strain 90-166 can contribute to plant root development via multiple signaling pathways.
Shi
Chun-Lin
CL
Laboratory of Microbial Genomics, Industrial Biochemistry and Bioenergy Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, 305-803, Korea.
Park
Hyo-Bee
HB
Lee
Jong Suk
JS
Ryu
Sangryeol
S
Ryu
Choong-Min
CM
D017360:Arabidopsis / Q000254:growth & development* / Q000378:metabolism / Q000382:microbiology; D017077:Culture Media, Conditioned / Q000737:chemistry / Q000494:pharmacology; D003517:Cyclopentanes / Q000378:metabolism; D005030:Ethylenes / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism*; D054883:Oxylipins / Q000378:metabolism; D010797:Phthalimides / Q000494:pharmacology; D010937:Plant Growth Regulators / Q000494:pharmacology; D018517:Plant Roots / Q000254:growth & development* / Q000378:metabolism / Q000382:microbiology; D030821:Plants, Genetically Modified; D020156:Salicylic Acid / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development; D012706:Serratia marcescens / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*
D017077:Culture Media, Conditioned; D003517:Cyclopentanes; D005030:Ethylenes; D007210:Indoleacetic Acids; D054883:Oxylipins; D010797:Phthalimides; D010937:Plant Growth Regulators; C002687:alpha-naphthylphthalamic acid; C011006:jasmonic acid; C030737:indoleacetic acid; C036216:ethylene; D020156:Salicylic Acid