Arabidopsis AGO4 loses its Cajal body localization when heterologously expressed in Nicotiana benthamiana

ABSTRACT

In plants, the RNA-directed DNA methylation (RdDM) pathway plays a major role in establishing DNA methylation. At least some components of the RdDM machinery, including the central component AGO4, are known to concentrate in a subnuclear compartment called the Cajal body in the model plant Arabidopsis thaliana. The molecular underpinnings of Cajal body localization, however, have remained elusive so far. Here, we found that Arabidopsis AGO4 (AtAGO4) fused to GFP does not present its typical Cajal body localization, when transiently expressed in Nicotiana benthamiana. Nevertheless, the endogenous AGO4 protein from N. benthamiana shows a clear accumulation in the Cajal body. Thus, our results suggest that the Cajal body localization of AtAGO4 requires specific molecular machinery that cannot be replaced by orthologues in N. benthamiana. This study presents an experimental system that could lead to mechanistic insights into the targeting of proteins to and localization in the Cajal body in plants.

KEYWORDS:

• AGO4
• Cajal body
• Nicotiana benthamiana
• Arabidopsis thaliana

Acknowledgments

We thank Xinyu Jian for technical and administrative assistance, Aurora Luque for technical assistance during this work, and all members of the Lozano-Duran laboratory for helpful discussions and suggestions. This work is supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (grants XDB27040206), and the Shanghai Center for Plant Stress Biology (Chinese Academy of Sciences).

Disclosure statement

No potential conflict of interest was reported by the author(s).