×Butyagrus nabonnandii (Prosch.) Vorster (ARECACEAE): evidências da origem híbrida por meio de análises anatômicas e moleculares

Abstract

×Butyagrus nabonnandii is a hybrid palm from the cross Butia odorata and Syagrus romanzoffiana, restricted to Brazil and Uruguay. It belongs to the subfamily Arecoideae, tribe Cocoseae, and subtribe Attaleinae as its parental species. Increasingly, leaf anatomy has become a central taxonomic tool in Arecaceae. However, other tools, such as molecular biology, are considered of interest for taxonomy. Thus far, the identification of this hybrid relied only on its morphology, which revealed intermediate characters of both parents. This study evaluates the hybrid origin of ×B. nabonnandii using anatomical and molecular tools, inferring whether plant anatomy and molecular biology are taxonomically useful tools. Leaves of the three taxa were collected in five municipalities of Rio Grande do Sul State, Brazil, during 2021 and 2022. For the anatomical approach, the central portion of the pinna was sectioned, including the margin, intermediate region, and midrib. For the molecular approach, first, different methods of preservation and maceration of genomic DNA extracted from leaves and stipes of ×B. nabonnandii were tested. Next, we evaluated the sequenced regions of the WRKY gene family to determine their effectiveness in identifying hybrids between B. odorata and S. romanzoffiana. Pinnae anatomy proved useful in identifying the hybrid and differentiating it from the parental species. The DNA isolated from leaves and stipes of ×B. nabonnandii, regardless of the method, presented good quality as the genomic regions of interest were amplified. In addition, it was possible to infer the hybridization between B. odorata and S. romanzoffiana and, thus, identify the hybrid resulting from this cross. These results demontrated that plant anatomy and molecular biology are tools as valuable as plant mophology for identifying ×B. nabonnandii and proving its hybrid origin.