The J-protein AtDjB1 is required for mitochondrial complex I activity and regulates growth and development through ROS-mediated auxin signalling

• Published in: Journal of experimental botany 2016-05, Vol.67 (11), p.3481-3496
• Main Authors: Jia, Ning, Lv, Ting-Ting, Li, Mi-Xin, Wei, Shan-Shan, Li, Yan-Yi, Zhao, Chun-Lan, Li, Bing
• Format: Article
• Language: English
• Subjects: Arabidopsis - enzymology; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Electron Transport Complex I - metabolism; HSP40 Heat-Shock Proteins - genetics; HSP40 Heat-Shock Proteins - metabolism; Indoleacetic Acids - metabolism; Mixed Function Oxygenases; NADH Dehydrogenase; Plant Growth Regulators - metabolism; Reactive Oxygen Species - metabolism; RESEARCH PAPER; Signal Transduction
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/erw171

AtDjB1 is a mitochondria-located J-protein in Arabidopsis thaliana. It is involved in the regulation of plant growth and development; however, the exact mechanisms remain to be determined. We performed comparison analyses of phenotypes, auxin signalling, redox status, mitochondrial structure and function using wild-type plants, AtDjB1 mutants, rescued AtDjB1 mutants by AtDjB1 or YUCCA2 (an auxin synthesis gene), and AtDjB1 overexpression plants. AtDjB1 mutants (atj1-1 or atj1-4) exhibited inhibition of growth and development and reductions in the level of IAA and the expression of YUCCA genes compared to wild-type plants. The introduction of AtDjB1 or YUCCA2 into atj1-1 largely rescued phenotypic defects and the IAA level, indicating that AtDjB1 probably regulates growth and development via auxin. Furthermore, atj1-1 plants displayed a significant reduction in amount/activity of mitochondrial complex I compared to wild-type plants; this resulted in the accumulation of reactive oxygen species (ROS). Moreover, exogenous H₂O₂ markedly inhibited the expression of YUCCA genes in wild-type plants. In contrast, the reducing agent ascorbate increased the expression of YUCCA genes and IAA level in atj1-1 plants, indicating that the low auxin level observed in atj1-1 was probably due to the high oxidation status. Overall, the data presented here suggest that AtDjB1 is required for mitochondrial complex I activity and regulates growth and development through ROS-mediated auxin signalling in Arabidopsis.