The Role Of Atmyb44Transcription Factors In Bacteria Signal Molecules AHLs-Mediated Root Growth In Arabidopsis

Many bacteria use small signal molecules to communicate with each other and to coordinate their collective behavior-a process commonly referred to as quorum sensing (QS). the most common QS signals are N-acyl-homoserine lactones (AHLS). Bacterial QS plays roles in many physiological processes, such as symbiosis, virulence, bioluminescence, sporulation, biofilm formation, antibiotic production, swarming and plasmid conjugal transfer.In recent years, accumulating evidence demonstrates that AHLs also have an impact on root formation of plant.However, Only little is known about the molecular mechanism of plants reacting to these bacterial signals. It is of great importance to investigate how plant senses the bacterial QS signal.Transcription factors are critical regulators of the changes in gene expression that drive developmental processes and environmental stress responses. AtMYB44belongs to the R2R3-MYB subgroup22transcription factor family in Arabidopsis (Arabidopsis thaliana). In this study we performed a transcriptomic analysis for Arabidopsis thaliana seedlings responses to bacterial QS molecules, N-3-oxo-hexanoyl-homoserine lactone (3OC6-HSL) and the N-3-oxo-octanoyl-homoserine lactone (3OC8-HSL) using a29k Arabidopsis Genome Array. To assess the accuracy of microarray data, we found that AtMYB44gene is up-regulated expressions with plants treated with3OC6-HSL and3OC8-HSL, and subjected to quantitative real-time PCR (qRT-PCR) analysis. We found the microarray and qRT-PCR data showed a good correlation.Several studies indicated that AtMYB44regulated root elongation of plant induced by AHLs. The promoting effects of AHLs on root elongation were abolished and exaggerated in the atmyb44T-DNA insertion mutants and transgenic lines over-expressing AtMYB44, respectively.In the present study, we found that the expression of AtMYB44is induced by treatment with two types of AHL, N-3-oxo-hexanoyl-homoserine lactone (3OC6-HSL) and3OC8-HSL. The transcriptions of several genes involved in auxin and cytokinin signaling pathways were regulated by AtMYB44upon AHL treatments. Our results suggested that AtMYB44play a role in AHL-mediated root elongation via regulating the expression of auxin-and cytokinin-related genes.It is proved that AtMYB44play important roles in plant defense, we analyzed the role of the AtMYB44transcription factors from Arabidopsis in AHL-mediated defense against the Ecc.Our results implied that AtMYB44is a negative regulator in arabidopsis defense response against Ecc.