Abstract The association between plants and their pollinators is essential for increasing the diversity in angiosperms. Morphological and physiological traits, mainly floral scent, can influence the pollination dynamics and select pollinators for each plant species. In this work, we studied two proteins involved in producing volatile organic compounds in plants, conyferyl alcohol acyltransferase (CFAT) and benzoyl-CoA:benzyl alcohol/phenyl ethanol benzoyl transferase (BPBT) genes. We aimed to understand these proteins with respect to evolutionary and structural aspects and functions in Solanaceae using phylogenetic methods and comparative molecular modeling. We used Bayesian inference to describe the proteins’ evolutionary history using Petunia x hybrida as a query to search for homologs in the Solanaceae family. Theoretical 3D models were obtained for both proteins using Panicum virgatum as a template. The phylogenetic tree included several different enzymes with diverse biological roles in Solanaceae, displaying the transferase domain. We identified only one sequence of CFAT in the databases, which belongs to Petunia x hybrida, and found several BPBT sequences from the genera Nicotiana, Solanum, and Capsicum. The 3D structures of CFAT and BPBT have two different domains, and we have identified the amino acid residues essential for the enzymatic activity and interaction with substrates.

Abstract Alcohol dehydrogenases belong to the large superfamily of medium-chain dehydrogenases/reductases, which occur throughout the biological world and are involved with many important metabolic routes. We considered the phylogeny of 190 ADH sequences of animals, fungi, and plants. Non-class III Caenorhabditis elegans ADHs were seen closely related to tetrameric fungal ADHs. ADH3 forms a sister group to amphibian, reptilian, avian and mammalian non-class III ADHs. In fishes, two main forms are identified: ADH1 and ADH3, whereas in amphibians there is a new ADH form (ADH8). ADH2 is found in Mammalia and Aves, and they formed a monophyletic group. Additionally, mammalian ADH4 seems to result from an ADH1 duplication, while in Fungi, ADH formed clusters based on types and genera. The plant ADH isoforms constitute a basal clade in relation to ADHs from animals. We identified amino acid residues responsible for functional divergence between ADH types in fungi, mammals, and fishes. In mammals, these differences occur mainly between ADH1/ADH4 and ADH3/ADH5, whereas functional divergence occurred in fungi between ADH1/ADH5, ADH5/ADH4, and ADH5/ADH3. In fishes, the forms also seem to be functionally divergent. The ADH family expansion exemplifies a neofunctionalization process where reiterative duplication events are related to new activities.

The genes encoding 13 classes of pathogenesis-related (PR) proteins were examined for positive selection using maximum-likelihood (ML) models of codon substitution. The study involved 194 sequences from 54 species belonging to 37 genera. Although the sizes of the sequences examined varied from 237 bp for PR12 to 1,110 bp for PR7, most classes (9 out of 13) contained sequences made up of more than 400 nucleotides. Signs of positive selection were obtained for sites in PR proteins 4, 6, 8, 9 and 15 using an ML-based Bayesian method and likelihood ratio tests. These results confirm the importance of positive selection in proteins related to defense mechanisms already observed in a wide array of organisms.