Overexpression of BAK1 causes salicylic acid accumulation and deregulation of cell death control genes.
Since the BRI1-Associated Receptor Kinase 1 (BAK1) was firstly identified as a co-receptor of BRI1 that mediates brassinosteroids (BR) signaling, the functional roles of BAK1, as a versatile co-receptor for various ligand-binding leucine-rich repeat (LRR)-containing receptor-like kinase (RLKs), are being extended to involvement with plant immunity, cell death, stomatal development and ABA signaling in plants. During more than a decade of research on the BAK1, it has been known that transgenic Arabidopsis plants overexpressing BAK1 tagged with various reporters do not fully represent its natural functions. Therefore, in this study, we characterized the transgenic plants in which native BAK1 is overexpressed driven by its own promoter. We found that those transgenic plants were more sensitive to BR signaling but showed reduced growth patterns accompanied with spontaneous cell death features that are different from those seen in BR-related mutants. We demonstrated that more salicylic acid (SA) and hydrogen peroxide were accumulated and that expressions of the genes that are known to regulate cell death, such as BONs, BIRs, and SOBIR, were increased in the BAK1-overexpressing transgenic plants. These results suggest that pleiotropic phenotypic alterations shown in the BAK1- overexpressing transgenic plants result from the constitutive activation of SA-mediated defense responses.
Department of Biological Science, Sookmyung Women's University, Seoul, South Korea.
Sun Young
SY
Kim
Department of Biological Science, Sookmyung Women's University, Seoul, South Korea.
Yun
Y
Shang
Department of Life Science, Chung-Ang University, Seoul, South Korea.
Se-Hwan
SH
Joo
Department of Life Science, Chung-Ang University, Seoul, South Korea.
Seong-Ki
SK
Kim
Department of Biological Science, Sookmyung Women's University, Seoul, South Korea. Electronic address: khnam514@sookmyung.ac.kr.
Kyoung Hee
KH
Nam
D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D017360:Arabidopsis / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000378:metabolism*; D025461:Feedback, Physiological / Q000502:physiology; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D020156:Salicylic Acid / Q000378:metabolism*; D015854:Up-Regulation / Q000502:physiology
D051017:Apoptosis Regulatory Proteins; D029681:Arabidopsis Proteins; C463660:BAK1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases; D020156:Salicylic Acid
BAK1-Overexpression; Cell death; Defense response; Growth; Salicylic acid