Proteomic and histological analysis of in vitro callogenesis in three species of Miconia (Melastomataceae) reveals higher accumulation of proteins related to somatic embryogenesis and embryogenic competence in apomictic species

Abstract

In recent years, proteomics has become a powerful tool in vitro plant tissue culture research. In Miconia, the most diverse flowering plant genus in the Neotropics, these tools together were unexplored. The group is replete with cases of apomixis (asexual seed formation). Some studies indicate that apomixis may have similarities with somatic embryogenesis (SE). However, there is no investigation into whether explants from apomictic species can affect the accumulation of SE-related proteins in vitro morphogenesis processes, such as callogenesis. This study identifies differentially accumulated proteins related to SE in the callogenesis of three Miconia species with different reproductive systems and whether this can affect their embryogenic capacity. For this, we employed the shotgun comparative proteomics approach in a specific phase of callus proliferation of Miconia australis (obligate apomictic), Miconia hyemalis (facultative apomictic), and Miconia sellowiana (sexual). Comparative proteomic analysis revealed that 190 SE-related proteins were differentially accumulated and distributed among the three experimental comparisons. The calluses of apomictic species showed the highest number of up-accumulated proteins associated with SE. Histological examination of the calluses after 45 days of induction revealed the permanence of cells with meristematic characteristics in the apomictic species, however, in M. sellowiana there was greater cellular vacuolization. These results indicate that calluses of Miconia spp. originated from apomictic species may be better able to acquire embryogenic competence in vitro culture. This study is the first to explore and demonstrate the potential advantages of using proteomics to understand the molecular basis of in vitro morphogenesis in apomictic and sexual species of Miconia, highlighting new perspectives for future research in plant tissue culture.