Fig. 7.

Evolutionary analysis of the structural properties and model of evolution of Lon paralogs in the plant kingdom. (A) Phylogenetic classification of Lon paralogs in the plant lineage showing the evolution of the N-terminal dual-targeting domains (squares) and the SSD domains (circles). The asterisk indicates papaya Lon that retained a single Lon1-type gene copy. (B) Model of gene duplication events driving the molecular evolution of Lon genes in land plants. Lon genes might have evolved from an ancestral gene with twin pre-sequences for dual-targeting and a Lon1-type SSD domain. Independent events of gene duplications, classified as early, intermediate, and recent, occurred together with mutational changes evolving the modern Lon genes in embryophytes.