The Experts below are selected from a list of 531 Experts worldwide ranked by ideXlab platform

Hugh D. Wilson - One of the best experts on this subject based on the ideXlab platform.

James R. Manhart - One of the best experts on this subject based on the ideXlab platform.

Bruce G Baldwin - One of the best experts on this subject based on the ideXlab platform.

  • pleistocene radiation of the serpentine adapted genus hesperolinon and other divergence times in Linaceae malpighiales
    American Journal of Botany, 2016
    Co-Authors: Adam C Schneider, William A Freyman, Matt C Guilliams, Yuri P Springer, Bruce G Baldwin
    Abstract:

    Author(s): Schneider, Adam C; Freyman, William A; Guilliams, C Matt; Springer, Yuri P; Baldwin, Bruce G | Abstract: Premise of the studyHesperolinon (western flax; Linaceae) is endemic to the western United States, where it is notable for its high and geographically concentrated species diversity on serpentine-derived soils and for its use as a model system in disease ecology. We used a phylogenetic framework to test a long-standing hypothesis that Hesperolinon is a neoendemic radiation.MethodsFive plastid and two ribosomal nuclear DNA gene regions were sampled from 105 populations of Hesperolinon, including all 13 recently recognized species across their known ranges. We used these data to generate population-level phylogenies of Hesperolinon. We also generated a robustly sampled chronogram of Linaceae using an eight-gene, 100-taxon supermatrix calibrated using fossil Linum pollen and a published chronogram of Malpighiales.Key resultsMost diversification in Hesperolinon has taken place in the past 1-2 million yr, much more recently than previous estimates. Only the earliest-diverging species, H. drymarioides, was resolved as a clade. Denser taxon and gene sampling generally support previously proposed relationships within Linaceae, but with more recent diversification of key clades.ConclusionsHesperolinon is an excellent example of edaphic neoendemism, in support of Raven and Axelrod's hypothesis for the genus. Dense population-level sampling reveals a complex of incipient species, with clades poorly aligned with traditional morphological circumscriptions, likely due in part to continued gene flow. The diversification of Linaceae is more recent than previously estimated, and other recent radiations (e.g., Hugonia) warrant further study.

Wilhelm A Alfermann - One of the best experts on this subject based on the ideXlab platform.

  • lignans in flowering aerial parts of linum species chemodiversity in the light of systematics and phylogeny
    Phytochemistry, 2010
    Co-Authors: Thomas J Schmidt, Shiva Hemmati, M Klaes, Belma Konuklugil, Abdolali Mohagheghzadeh, Iliana Ionkova, Elisabeth Fuss, Wilhelm A Alfermann
    Abstract:

    The aerial parts of 54 accessions representing 41 Linum species and four species of related genera were analysed for lignans by means of HPLC-ESI/MS-MS-UV/DAD. In total, 64 different lignans of the aryltetralin-, arylnaphthalene-, aryldihydronaphthalene-, dibenzylbutyrolactone-, and furofuran type were identified. According to their lignan profile, the Linum species can be divided in two groups accumulating as major lignan types either cyclolignans of the aryltetralin-series on one hand, or aryldihydronaphthalenes/arylnaphthalenes, on the other. Five of the investigated Linum species did not contain any detectable amounts of these lignans under the chosen analytical conditions. Furthermore, none of the lignans identified in Linum species was detectable in representatives of three related genera, namely, Reinwardtia (Linaceae, Linoideae), Hugonia and Indorouchera (Linaceae, Hugonioideae). The two species groups differing in the types of the dominating cyclolignans comprise representatives of the major taxonomic sections. Representatives of sections Syllinum, Cathartolinum and Linopsis accumulate mainly aryltetralins while those of sections Linum and Dasylinum were found to contain mainly aryldihydronaphthalenes/-naphthalenes. These phytochemical data correlate very well with a recent study on the molecular phylogeny of Linum/Linaceae, where a subdivision of Linum into two major clades comprising representatives of the two mentioned groups was found. Thus, the distribution of lignans apparently reflecting phylogenetic interrelations at the infrageneric level, a plausible scenario for the evolution of lignan biosynthesis in the genus Linum can now be presented.

  • linum persicum lignans and placement in Linaceae
    Phytochemistry Reviews, 2003
    Co-Authors: Abdolali Mohagheghzadeh, Shiva Hemmati, Iraj Mehregan, Wilhelm A Alfermann
    Abstract:

    Aryltetralin lignans (podophyllotoxin type) are the main lignan constituents of species belonging to Linum section Syllinum (Linaceae). Linum persicum, a perennial plant native to Iran closely related to L. album, has not yet been studied. To evaluate the lignan profile, fresh plants of L. persicumwere collected and divided into different parts and analyzed by HPLC. The main aryltetralin lignans found inL. persicumplant parts, callus and cell cultures were podophyllotoxin (PTOX), 6-methoxypodophyllotoxin (MPTOX) and α- and β-peltatin. Furthermore, the systematic relationship between L. persicum and other Linum species are discussed in the light of morphological and phytochemical aspects.

Matt C Guilliams - One of the best experts on this subject based on the ideXlab platform.

  • pleistocene radiation of the serpentine adapted genus hesperolinon and other divergence times in Linaceae malpighiales
    American Journal of Botany, 2016
    Co-Authors: Adam C Schneider, William A Freyman, Matt C Guilliams, Yuri P Springer, Bruce G Baldwin
    Abstract:

    Author(s): Schneider, Adam C; Freyman, William A; Guilliams, C Matt; Springer, Yuri P; Baldwin, Bruce G | Abstract: Premise of the studyHesperolinon (western flax; Linaceae) is endemic to the western United States, where it is notable for its high and geographically concentrated species diversity on serpentine-derived soils and for its use as a model system in disease ecology. We used a phylogenetic framework to test a long-standing hypothesis that Hesperolinon is a neoendemic radiation.MethodsFive plastid and two ribosomal nuclear DNA gene regions were sampled from 105 populations of Hesperolinon, including all 13 recently recognized species across their known ranges. We used these data to generate population-level phylogenies of Hesperolinon. We also generated a robustly sampled chronogram of Linaceae using an eight-gene, 100-taxon supermatrix calibrated using fossil Linum pollen and a published chronogram of Malpighiales.Key resultsMost diversification in Hesperolinon has taken place in the past 1-2 million yr, much more recently than previous estimates. Only the earliest-diverging species, H. drymarioides, was resolved as a clade. Denser taxon and gene sampling generally support previously proposed relationships within Linaceae, but with more recent diversification of key clades.ConclusionsHesperolinon is an excellent example of edaphic neoendemism, in support of Raven and Axelrod's hypothesis for the genus. Dense population-level sampling reveals a complex of incipient species, with clades poorly aligned with traditional morphological circumscriptions, likely due in part to continued gene flow. The diversification of Linaceae is more recent than previously estimated, and other recent radiations (e.g., Hugonia) warrant further study.