The analysis of an Arabidopsis triple knock-down mutant reveals functions for MBF1 genes under oxidative stress conditions

ARCE DP, GODOY AV, TSUDA K, YAMAZAKI K, VALLE EM, DI MAURO MF, IGLESIAS MJ, CASALONGUÉ CA

JOURNAL OF PLANT PHYSIOLOGY

Elsevier

Año: 2010 vol. 164 p. 194 - 200

0176-1617

<!-- /* Font Definitions */ @font-face {font-family:"MS Mincho"; panose-1:2 2 6 9 4 2 5 8 3 4; mso-font-alt:"ＭＳ 明朝"; mso-font-charset:128; mso-generic-font-family:roman; mso-font-format:other; mso-font-pitch:fixed; mso-font-signature:1 134676480 16 0 131072 0;} @font-face {font-family:"@MS Mincho"; panose-1:0 0 0 0 0 0 0 0 0 0; mso-font-charset:128; mso-generic-font-family:roman; mso-font-format:other; mso-font-pitch:fixed; mso-font-signature:1 134676480 16 0 131072 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"MS Mincho"; mso-ansi-language:EN-US; mso-fareast-language:EN-US;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Transcriptional co-activators of the Multiprotein Bridging Factor 1 (MBF1) type belong to a small multigenic family that controls gene expression by connecting transcription factors and the basal transcription machinery. In this report, a triple knock-down mutant (abc-) for the Arabidopsis thaliana MBF1 genes AtMBF1a, AtMBF1b and AtMBF1c was generated. The phenotypic characterization using oxidative agents such as hydrogen  peroxide and methyl viologen revealed that the abc- mutant was more sensitive to oxidative stress. The triple knock-down mutant, abc- was also sensitive to osmotic stress mediated by high concentrations of sorbitol. Furthermore, the abc- phenotype was partially or completely rescued by AtMBF1c cDNA overexpression (abc- +c) depending on physiological and developmental conditions. AtMBF1s regulate the expression of ABR1, which is a member of the ethylene response factor family and acts as ABA repressor. Thus, we conclude that AtMBF1 gene family may function as a regulatory component of the cross-talk node between ethylene, ABA and stress signal pathways.  Furthermore, higher levels of a HSP70 mRNA and an immunoreactive HSP70 protein were detected in the abc- mutant. The participation of MBF1c as a posible negative regulator of HSP genes was discussed.