Isolation and Characterization of a Novel SOMATIC EMBRYOGENESIS RECEPTOR KINASE Gene Expressed in the Fern Adiantum capillus-veneris During Shoot Regeneration In Vitro

Abstract

SOMATIC EMBRYOGENESIS RECEPTOR KINASE (SERK) genes are expressed primarily in seed plants and are involved in the development of embryos from already-differentiated plant cells. This study provides the first evidence for the existence of a SERK gene, designated AcvSERK1, in a fern, Adiantum capillus-veneris. AcvSERK1 belongs to a small family of receptor-like kinases (RLKs), and its sequence and conserved structure closely resemble SERK homologs in other land plants. Phylogenetic analysis of the SERK gene family showed that AcvSERK1 forms a clade with SERK-like genes from non-seed plants and is a member of the SERK1/2 genes group, involved in somatic embryogenesis. Moreover, our analyses reveal that AcvSERK1 is expressed throughout the entire process of embryo development, but its levels decrease with the formation of shoots and seedlings. Additionally, in situ hybridization showed that AcvSERK1 is expressed during green globular body (GGB)-derived somatic embryogenesis and in meristematic calluses. Our results indicate that the AcvSERK1 gene is a good marker for differentiated cells that are capable of forming embryos in A. capillus-veneris, suggesting that SERK genes have played an important role in embryogenesis during the evolution of land plants.