@article {Steane:2004p8020, title = {Phylogenetic relationships between Clerodendrum (Lamiaceae) and other Ajugoid genera inferred from nuclear and chloroplast DNA sequence data}, journal = {Molecular Phylogenetics and Evolution}, volume = {32}, number = {1}, year = {2004}, month = {Jul}, pages = {39{\textendash}45}, abstract = {Over the last two centuries the circumscription of the large, pan-tropical genus Clerodendrum (Lamiaceae) has changed frequently, as different authorities have added or removed taxa on the basis of various morphological characters. With the development of molecular methods for systematic research the process of circumscribing taxa has become increasingly analytical. When morphology signals the possibility that taxa are closely related, molecular methods can be used to test the hypothesis objectively. Aegiphila, Amasonia, Huxleya, and Kalaharia are similar morphologically to Clerodendrum. In this paper we use nuclear ribosomal ITS and chloroplast ndhF sequence data to clarify the positions of these four genera relative to Clerodendrum. We show that the Australian monotypic genus Huxleya evolved from within Clerodendrum. Accordingly, we sink Huxleya into Clerodendrum and make a new combination, Clerodendrum linifolium.}, keywords = {Cell Nucleus, Chloroplasts, Clerodendrum, Dna, Genes: Plant, Likelihood Functions, Phylogeny, RNA: Ribosomal, Species Specificity}, doi = {10.1016/j.ympev.2003.11.011}, author = {Dorothy A Steane and Rogier P J de Kok and Richard G Olmstead} } @article {Lindqvist:2007p7988, title = {Polyglutamine variation in a flowering time protein correlates with island age in a Hawaiian plant radiation}, journal = {BMC Evol Biol}, volume = {7}, year = {2007}, month = {Jan}, pages = {105}, abstract = {BACKGROUND: A controversial topic in evolutionary developmental biology is whether morphological diversification in natural populations can be driven by expansions and contractions of amino acid repeats in proteins. To promote adaptation, selection on protein length variation must overcome deleterious effects of multiple correlated traits (pleiotropy). Thus far, systems that demonstrate this capacity include only ancient or artificial morphological diversifications. The Hawaiian Islands, with their linear geological sequence, present a unique environment to study recent, natural radiations. We have focused our research on the Hawaiian endemic mints (Lamiaceae), a large and diverse lineage with paradoxically low genetic variation, in order to test whether a direct relationship between coding-sequence repeat diversity and morphological change can be observed in an actively evolving system. RESULTS: Here we show that in the Hawaiian mints, extensive polyglutamine (CAG codon repeat) polymorphism within a homolog of the pleiotropic flowering time protein and abscisic acid receptor FCA tracks the natural environmental cline of the island chain, consequent with island age, across a period of 5 million years. CAG expansions, perhaps following their natural tendency to elongate, are more frequent in colonists of recently-formed, nutrient-rich islands than in their forebears on older, nutrient-poor islands. Values for several quantitative morphological variables related to reproductive investment, known from Arabidopsis fca mutant studies, weakly though positively correlate with increasing glutamine tract length. Together with protein modeling of FCA, which indicates that longer polyglutamine tracts could induce suboptimally mobile functional domains, we suggest that CAG expansions may form slightly deleterious alleles (with respect to protein function) that become fixed in founder populations. CONCLUSION: In the Hawaiian mint FCA system, we infer that contraction of slightly deleterious CAG repeats occurred because of competition for resources along the natural environmental cline of the island chain. The observed geographical structure of FCA variation and its correlation with morphologies expected from Arabidopsis mutant studies may indicate that developmental pleiotropy played a role in the diversification of the mints. This discovery is important in that it concurs with other suggestions that repetitive amino acid motifs might provide a mechanism for driving morphological evolution, and that variation at such motifs might permit rapid tuning to environmental change.}, keywords = {Alleles, DNA: Plant, Genes: Plant, Hawaii, Mentha, Minisatellite Repeats, Peptides, Phylogeny, Plant Proteins, Selection: Genetic, Sequence Homology: Amino Acid, Species Specificity}, doi = {10.1186/1471-2148-7-105}, author = {Charlotte Lindqvist and Liisa Laakkonen and Victor A Albert} } @article {Zhou:2008p7979, title = {Altered expression patterns of TCP and MYB genes relating to the floral developmental transition from initial zygomorphy to actinomorphy in Bournea (Gesneriaceae)}, journal = {New Phytol}, volume = {178}, number = {3}, year = {2008}, month = {Jan}, pages = {532{\textendash}43}, abstract = {The shift from zygomorphy to actinomorphy has been intensively studied in molecular genetic model organisms. However, it is still a key challenge to explain the great morphological diversity of derived actinomorphy in angiosperms, since different underlying mechanisms may be responsible for similar external morphologies. Bournea (Gesneriaceae) is of particular interest in addressing this question, as it is a representative of primarily derived actinomorphy characteristic of a unique developmental transition from zygomorphy to actinomorphic flowers at anthesis. Using RNA in situ hybridization, the expression patterns were investigated of three different Bournea orthologues of TCP and MYB genes that have been shown to control floral symmetry in model species. Here, it is shown that the initial zygomorphic pattern in Bournea is likely a residual zygomorphy resulting from conserved expression of the adaxial (dorsal) identity gene BlCYC1. As a key novel event, the late downregulation of BlCYC1 and BlRAD and the correlative changes in the late specific expression of the abaxial (ventral) identity gene BlDIV should be responsible for the origin of the derived actinomorphy in Bournea. These results further indicate that there might be diverse pathways in the origin and evolution of derived actinomorphy through modifications of pre-existing zygomorphic developmental programs under dynamics of regulatory networks.}, keywords = {Flowers, Gene Expression Regulation: Plant, Genes: Plant, Lamiaceae, Phylogeny, Plant Proteins}, doi = {10.1111/j.1469-8137.2008.02384.x}, author = {Xiu-Ren Zhou and Yin-Zheng Wang and James F Smith and Rujin Chen} } @article {Iijima:2004p8034, title = {Characterization of geraniol synthase from the peltate glands of sweet basil}, journal = {Plant Physiol}, volume = {134}, number = {1}, year = {2004}, month = {Jan}, pages = {370{\textendash}9}, abstract = {The monoterpene fraction of the lemon-scented sweet basil (Ocimum basilicum) cv Sweet Dani consists mostly of citral (a mixture of geranial and neral), with lower levels of geraniol and nerol. These compounds are stored in the peltate glands found on the leaf epidermis. Younger leaves, which have a higher density of such glands, also have a higher content of monoterpenes than older leaves. Geraniol synthase (GES) activity, generating geraniol from geranyl diphosphate, was shown to be localized exclusively or almost exclusively to glands. GES activity resides in a homodimeric protein that was purified to near homogeneity. Basil GES requires Mn2+ as a divalent metal cofactor for activity and produces only geraniol from geranyl diphosphate. Km values of 21 and 51 microM were obtained for geranyl diphosphate and Mn2+, respectively. In the presence of 18O-labeled water, GES catalyzed the formation of 18O-geraniol from geranyl diphosphate, indicating that the reaction mechanism of GES is similar to that of other monoterpene synthases and is different from the action of phosphatases. A GES cDNA was isolated based on analysis of a glandular trichome expressed sequence tag database, and the sequence of the protein encoded by this cDNA shows some similarity to sequences of other terpene synthases. The expression of the GES cDNA in Escherichia coli resulted in a protein with enzymatic activity essentially identical to that of plant-purified GES. RNA gel-blot analysis indicated that GES is expressed in glands but not in leaves of basil cv Sweet Dani, whose glands contain geraniol and citral, and not in glands or leaves of another basil variety that makes other monoterpenes but not geraniol or citral.}, keywords = {Alkyl and Aryl Transferases, Amino Acid Sequence, DNA: Complementary, DNA: Plant, Gene Expression, Genes: Plant, Molecular Sequence Data, Ocimum basilicum, Phylogeny, Plant Structures, Sequence Homology: Amino Acid, Terpenes}, doi = {10.1104/pp.103.032946}, author = {Yoko Iijima and David R Gang and Eyal Fridman and Efraim Lewinsohn and Eran Pichersky} }