The analysis of an Arabidopsis triple knock-down mutant reveals functions for MBF1 genes under oxidative stress conditions.
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 over-expression (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 possible negative regulator of HSP genes was discussed.
Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531, S2002LRK Rosario, Argentina.
Débora Pamela
DP
Arce
Andrea Verónica
AV
Godoy
Kenichi
K
Tsuda
Ken-Ichi
K
Yamazaki
Estela Marta
EM
Valle
María José
MJ
Iglesias
María Florencia
MF
Di Mauro
Claudia Anahí
CA
Casalongué
D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D055785:Gene Knockdown Techniques; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D016254:Mutagenesis, Insertional; D009995:Osmosis; D018384:Oxidative Stress; D018749:RNA, Plant / Q000235:genetics; D036226:Seedlings / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D014867:Water / Q000378:metabolism
D029681:Arabidopsis Proteins; D006360:Heat-Shock Proteins; C491466:MBF1 protein, Arabidopsis; D018749:RNA, Plant; D015534:Trans-Activators; D014867:Water