Evaluation of the role of Medicago truncatula Zn finger CCHC type protein after heterologous expression in Arabidopsis thaliana

Abstract

Zinc finger proteins bind nucleic acids or act in transcriptional or translational regulation. The present study aimed to explore the effect of heterologous expression of the Medicago truncatula gene (Mt-Zn-CCHC), which encodes a Zinc finger CCHC type protein, in Arabidopsis thaliana. The Mt-Zn-CCHC gene, which affects seed size in M. truncatula, was used for construction of transgenic A. thaliana transcriptional reporter plants expressing pMt-Zn-CCHC::GUS::GFP, as well as lines with modified expression – overexpressed (OE) and knockdown (RNAi). In silico analysis of the promoter cis-elements of pAt-Zn-CCHC and pMt-Zn-CCHC suggested regulation during meristem activity, seed development, as well as cold stress. The expression of pMt-Zn-CCHC was localized in shoot apical meristem and in the base of the siliques. In the RNAi lines, successfully repressed endogenous At-Zn-CCHC expression resulted in shortened stem and reduction in silique number, silique size, seed number per silique, and decreased expression of the meristem marker AtSWP. In the gain-of-function lines, overexpression of Mt-Zn-CCHC acted as a positive regulator in silique and seed parameters, as well as increased AtSWP expression. Cold treatment of WT plants demonstrated upregulation of the endogenous At-Zn-CCHC and the RD29A cold marker gene. In the OE line, RD29A transcription was induced by cold faster but in the RNAi line, slower. The overall data support the roles of the studied Zn-CCHC gene in the development of shoot meristem, seeds and cold response, which highlights this protein as a conserved regulator in plant reproduction and stress signal transduction. Supplemental data for this article is available online at https://doi.org/10.1080/13102818.2021.2006786 .