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Keywords = Macrozamia

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25 pages, 18135 KB  
Article
Discovery of Cyanobacteria Associated with Cycads and Description of Three Novel Species in Desmonostoc (Nostocaceae)
by Melissa H. Pecundo, Tao Chen, Thomas Edison E. dela Cruz, M. Patrick Griffith, Zhangli Hu, Huirong Chen and Nan Li
Diversity 2023, 15(11), 1132; https://doi.org/10.3390/d15111132 - 6 Nov 2023
Cited by 6 | Viewed by 5143
Abstract
Heterocyte-forming cyanobacteria form symbiotic relationships with several lineages of plants. Here, twenty (20) strains of endosymbiotic cyanobacteria (cyanobionts) with Nostoc-like morphologies were isolated from the highly specialized coralloid roots of five host species in Cycadales—Cycas debaoensis, C. fairylakea, C. [...] Read more.
Heterocyte-forming cyanobacteria form symbiotic relationships with several lineages of plants. Here, twenty (20) strains of endosymbiotic cyanobacteria (cyanobionts) with Nostoc-like morphologies were isolated from the highly specialized coralloid roots of five host species in Cycadales—Cycas debaoensis, C. fairylakea, C. elongata, Ceratozamia robusta, and Macrozamia moorei. Molecular phylogeny based on the 16S rRNA gene placed these strains into seven different taxa within the Nostocaceae, specifically under the genera Desmonostoc and Dendronalium. The percent dissimilarity and unique patterns in the secondary structures of the D1-D1′, Box-B, V2, and V3 helices, which were based on the 16S–23S rRNA internal transcribed spacer (ITS) regions, supported three distinct species in Desmonostoc. These three morphologically distinct novel species are described in this report: Desmonostoc debaoense sp. nov., Desmonostoc meilinense sp. nov., and Desmonostoc xianhuense sp. nov. Other investigated strains were phylogenetically identified as members of the recently discovered genus Dendronalium and represent the first report of association of that genus with cycads. Our findings suggest that the order Cycadales hosts diverse species of cyanobionts in their coralloid roots and that many potential unreported or novel taxa are present in cycads occurring in their natural habitat and await discovery. Full article
(This article belongs to the Special Issue The Phylogenetic Diversity of Cyanobacteria and Algae)
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25 pages, 653 KB  
Review
Chemical Element Concentrations of Cycad Leaves: Do We Know Enough?
by Benjamin E. Deloso, Murukesan V. Krishnapillai, Ulysses F. Ferreras, Anders J. Lindström, Michael Calonje and Thomas E. Marler
Horticulturae 2020, 6(4), 85; https://doi.org/10.3390/horticulturae6040085 - 19 Nov 2020
Cited by 10 | Viewed by 7955
Abstract
The literature containing which chemical elements are found in cycad leaves was reviewed to determine the range in values of concentrations reported for essential and beneficial elements. We found 46 of the 358 described cycad species had at least one element reported to [...] Read more.
The literature containing which chemical elements are found in cycad leaves was reviewed to determine the range in values of concentrations reported for essential and beneficial elements. We found 46 of the 358 described cycad species had at least one element reported to date. The only genus that was missing from the data was Microcycas. Many of the species reports contained concentrations of one to several macronutrients and no other elements. The cycad leaves contained greater nitrogen and phosphorus concentrations than the reported means for plants throughout the world. Magnesium was identified as the macronutrient that has been least studied. Only 14 of the species were represented by data from in situ locations, with most of the data obtained from managed plants in botanic gardens. Leaf element concentrations were influenced by biotic factors such as plant size, leaf age, and leaflet position on the rachis. Leaf element concentrations were influenced by environmental factors such as incident light and soil nutrient concentrations within the root zone. These influential factors were missing from many of the reports, rendering the results ambiguous and comparisons among studies difficult. Future research should include the addition of more taxa, more in situ locations, the influence of season, and the influence of herbivory to more fully understand leaf nutrition for cycads. Full article
(This article belongs to the Special Issue Feature Papers in Horticulturae)
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15 pages, 671 KB  
Article
Climate Predictions Accelerate Decline for Threatened Macrozamia Cycads from Queensland, Australia
by Melinda J. Laidlaw and Paul I. Forster
Biology 2012, 1(3), 880-894; https://doi.org/10.3390/biology1030880 - 14 Dec 2012
Cited by 11 | Viewed by 8061
Abstract
Changes in the potential habitat of five allopatric species of threatened Macrozamia cycads under scenarios of increased ambient temperature were examined. A lack of seed dispersal, poor recruitment, low seedling survival, obligate pollinator mutualisms and continued habitat loss have led to extant populations [...] Read more.
Changes in the potential habitat of five allopatric species of threatened Macrozamia cycads under scenarios of increased ambient temperature were examined. A lack of seed dispersal, poor recruitment, low seedling survival, obligate pollinator mutualisms and continued habitat loss have led to extant populations being largely restricted to refugia. Models predict that the area of suitable habitat will further contract and move upslope, resulting in a reduced incidence within protected areas with increasing annual mean temperature. Areas of potential habitat for all five species are also predicted to become increasingly isolated from one another, further reducing the exchange between metapopulations and subpopulations, exacerbating existing threatening processes. Full article
(This article belongs to the Special Issue Biological Implications of Climate Change)
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