Genetic relationships and polyploid origins in the Lippia alba complex

• Published in: American journal of botany Vol. 107; no. 3; pp. 466 - 476
• Main Authors: Lopes, Juliana M. L., Carvalho, Humberto Henrique, Zorzatto, Cristiane, Azevedo, Ana Luisa S., Machado, Marco Antonio, Salimena, Fátima Regina G., Grazul, Richard M., Gitzendanner, Matthew A., Soltis, Douglas E., Soltis, Pamela S., Viccini, Lyderson F.
• Format: Journal Article
• Language: English
• Published: United States Botanical Society of America, Inc 01.03.2020
• Subjects: Bayes Theorem; Bayesian analysis; Brazil; Chemical compounds; Complexity; Deoxyribonucleic acid; Diploids; DNA; essential oil; Gene sequencing; Genetic analysis; genetic and chemical variation; Genetic distance; Genetic relationship; Genomes; Humans; Levels; linalool‐ and citral‐producing plants; Lippia; Lippia alba; medicinal plant; microsatellites; Morphology; nuclear and plastid genes; Nucleotide sequence; Origins; Phylogeny; polyploid lineages; Polyploidy; Tropical environments; Tropical plants; tropics; Verbenaceae; whole‐genome duplication; Brazil; microsatellites; nuclear and plastid genes; Verbenaceae; linalool- and citral-producing plants; tropics; whole-genome duplication; medicinal plant; essential oil; genetic and chemical variation; polyploid lineages
• ISSN: 0002-9122; 1537-2197
• DOI: 10.1002/ajb2.1443

Premise Plant genomes vary in size and complexity due in part to polyploidization. Latitudinal analyses of polyploidy are biased toward floras of temperate regions, with much less research done in the tropics. Lippia alba has been described as a tropical polyploid complex with diploid, triploid, tetraploid, and hexaploid accessions. However, no data regarding relationships among the ploidal levels and their origins have been reported. Our goals are to clarify the relationships among accessions of Lippia alba and the origins of each ploidal level. Methods We investigated 98 samples representing all five geographical regions of Brazil and all ploidal levels using microsatellite (SSR) allelic variation and DNA sequences of ITS and trnL‐F. Nine morphological structures were analyzed from 33 herbarium samples, and the chemical compounds of 78 accessions were analyzed by GC–MS. Results Genetic distance analysis, the alignment block pattern, as well as RAxML and Bayesian trees showed that accessions grouped by ploidal level. The triploids form a well‐defined group that originated from a single group of diploids. The tetraploids and hexaploid grouped together in SSR and trnL‐F analyses. The recovered groups agree with chemical data and morphology. Conclusions The accessions grouped by ploidal level. Only one origin of triploids from a single group of diploids was observed. The tetraploid origin is uncertain; however, it appears to have contributed to the origin of the hexaploid. This framework reveals linkages among the ploidal levels, providing new insights into the evolution of a polyploid complex of tropical plants.