The MtWOX and MtCLE genes in the regulation of Medicago truncatula somatic embryogenesis

Plant somatic cells can be reprogrammed into totipotent embryonic cells that are able to form differentiated embryos in a process called somatic embryogenesis (SE). SE can occur naturally in various plant species and it is widely used for clonal propagation, transformation and regeneration of different crops. This process is regulated by hormone treatment and many proteins, among which WUSCHEL-related homeobox (WOX) transcription factors are believed to play crucial roles. The WOX family is involved in the regulation of a wide range of key developmental programs in different plant organs and tissues. CLE peptides are well-known hormonal regulators of plant development. WOX and CLE genes can be related to each other through feedback regulatory loops. 
Our previous studies have shown that MtWOX9-1 stimulates SE in Medicago truncatula [1] and overexpression of the MtWOX9-1 gene increases the expression level of the MtCLE08, MtCLE16, MtCLE18 genes in SE. In this study, we examine the overexpression effect of MtCLE08, 16, and 18 on the expression level of MtWOX9-1 gene and a number of other MtWOX genes, which were shown to change expression in SE according to the transcriptomic data. No significant impact of MtCLE overexpression on any MtWOX gene under study was found. 
Our findings could be a helpful point for searching and studying new morphogenetic regulators controlling SE and could have a positive impact on plant biotechnology in improving the transformation and regeneration capacity for other legumes. 
The research was supported by grant from the Russian Foundation for Basic Research No. 20-016-00124.