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HueyTyng Lee, Agnieszka A Golicz, Philipp E Bayer, Anita Severn-Ellis, Chon-Kit Kenneth Chan, Jacqueline Batley, Gary A Kendrick, David Edwards
Seagrasses are marine angiosperms that live fully submerged in the sea. They evolved from land plant ancestors, with multiple species representing at least three independent return to the sea events. This raises the question whether these marine angiosperms followed the same adaptation pathway to allow them to live and reproduce under the hostile marine conditions. To compare the basis of marine adaptation between seagrass lineages, we generated genomic data for Halophila ovalis and compared this with recently published genomes for two members of Zosteraceae, as well as genomes of five non-marine plant species (Arabidopsis thaliana, Oryza sativa, Phoenix dactylifera, Musa acuminata, and Spirodela polyrhiza)...
April 18, 2018: Journal of Experimental Botany
M C Aime, C D Bell, A W Wilson
The rust fungi ( Pucciniales ) are the most speciose natural group of plant pathogens, members of which possess the most complex lifecycles in Fungi . How natural selection works on the Pucciniales has been the subject of several hypotheses in mycology. This study uses molecular age estimation using sequence data from multiple loci, and cophylogeny reconciliation analyses to test hypotheses regarding how the aecial and telial stages in the lifecycle of rust fungi may have differentially impacted their diversification...
March 2018: Studies in Mycology
Claudio Casola, Tomasz E Koralewski
Gene duplications and gene losses are major determinants of genome evolution and phenotypic diversity. The frequency of gene turnover (gene gains and gene losses combined) is known to vary between organisms. Comparative genomic analyses of gene families can highlight such variation; however, estimates of gene turnover may be biased when using highly fragmented genome assemblies resulting in poor gene annotations. Here, we address potential biases introduced by gene annotation errors in estimates of gene turnover frequencies in a dataset including both well-annotated angiosperm genomes and the incomplete gene sets of four Pinaceae including two pine species, Norway spruce and Douglas-fir...
June 14, 2018: Plant Journal: for Cell and Molecular Biology
Yuriko Carrington, Jia Guo, Cuong H Le, Alexander Fillo, Junsu Kwon, Lan Tran, Jürgen Ehlting
The shikimate pathway synthesizes aromatic amino acids essential for protein biosynthesis. Shikimate dehydrogenase (SDH) is a central enzyme of this primary metabolic pathway, producing shikimate. The structurally similar quinate is a secondary metabolite synthesized by quinate dehydrogenase (QDH). SDH and QDH belong to the same gene family, which diverged into two phylogenetic clades after a defining gene duplication just prior to the angiosperm/gymnosperm split. Non-seed plants that diverged before this duplication harbour only a single gene of this family...
June 12, 2018: Plant Journal: for Cell and Molecular Biology
Adrian Patrut, Stephan Woodborne, Roxana T Patrut, Laszlo Rakosy, Daniel A Lowy, Grant Hall, Karl F von Reden
The African baobab is the biggest and longest-living angiosperm tree. By using radiocarbon dating we identified the stable architectures that enable baobabs to reach large sizes and great ages. We report that 9 of the 13 oldest and 5 of the 6 largest individuals have died, or at least their oldest parts/stems have collapsed and died, over the past 12 years; the cause of the mortalities is still unclear.
June 11, 2018: Nature Plants
Benjamin Laenen, Jairo Patiño, Anders Hagborg, Aurélie Désamoré, Jian Wang, A Jonathan Shaw, Bernard Goffinet, Alain Vanderpoorten
A latitudinal diversity gradient towards the tropics appears as one most recurrent patterns in ecology, but the mechanisms underlying this pattern remain an area of controversy. In angiosperms, the tropical conservatism hypothesis proposes that most groups originated in the tropics and are adapted to a tropical climatic regime, and that relatively few species have evolved physiological adaptations to cold, dry or unpredictable climates. This mechanism is, however, unlikely to apply across land plants, and in particular, to liverworts, a group of about 7500 species, whose ability to withstand cold much better than their tracheophyte counterparts is at odds with the tropical conservatism hypothesis...
June 8, 2018: Molecular Phylogenetics and Evolution
Mark E Olson, Julieta A Rosell, Salvador Muñoz, Matiss Castorena
Background and aims: Corner's rules describe a global spectrum from large-leaved plants with thick, sparingly branched twigs with low-density stem tissues and thick piths to plants with thin, highly branched stems with high-density stem tissues and thin piths. The hypothesis was tested that, if similar crown areas fix similar amounts of carbon regardless of leaf size, then large-leaved species, with their distantly spaced leaves, require higher stem growth rates, lower stem tissue densities and stiffnesses, and therefore thicker twigs...
June 7, 2018: Annals of Botany
Mónica R Carvalho, Robert Turgeon, Thomas Owens, Karl J Niklas
PREMISE OF THE STUDY: The hydraulics of xylem has been widely studied in numerous species and organ types. However, comparatively little is known about how phloem and xylem are hydraulically coupled or about many of the basic structural properties of phloem (such as conducting cell numbers and conductive areas), which nevertheless have direct bearing on understanding phloem loading and unloading. METHODS: Using a combination of light, epifluorescence, confocal, and transmission electron microscopy, we quantified the hydraulic architecture of Ginkgo biloba leaf laminae and examined the scaling relationships between phloem and xylem in five fully mature leaves...
September 2017: American Journal of Botany
Daniel Fink, Elena Dobbelstein, Andreas Barbian, Gertrud Lohaus
Sucrose concentration in phloem sap was several times higher than in the cytosol of mesophyll cells. The results suggest that phloem loading involves active steps in the analyzed tree species. Phloem loading in source leaves is a key step for carbon partitioning and passive symplastic loading has been proposed for several tree species. However, experimental evidence to prove the potential for sucrose diffusion from mesophyll to phloem is rare. Here, we analyzed three tree species (two angiosperms, Fagus sylvatica, Magnolia kobus, and one gymnosperm, Gnetum gnemon) to investigate the proposed phloem loading mechanism...
June 7, 2018: Planta
Anke Hein, Volker Knoop
BACKGROUND: C-to-U RNA editing in mitochondria and chloroplasts and the nuclear-encoded, RNA-binding PPR proteins acting as editing factors present a wide field of co-evolution between the different genetic systems in a plant cell. Recent studies on chloroplast editing factors RARE1 and CRR28 addressing one or two chloroplast editing sites, respectively, found them strictly conserved among 65 flowering plants as long as one of their RNA editing targets remained present. RESULTS: Extending the earlier sampling to 117 angiosperms with high-quality genome or transcriptome data, we find more evidence confirming previous conclusions but now also identify cases for expected evolutionary transition states such as retention of RARE1 despite loss of its editing target or the degeneration of CRR28 truncating its carboxyterminal DYW domain...
June 7, 2018: BMC Evolutionary Biology
Wei-Bing Fan, Ying Wu, Jiao Yang, Khurram Shahzad, Zhong-Hu Li
In general, the chloroplast genomes of angiosperms are considered to be highly conserved and affected little by adaptive evolution. In this study, we tested this hypothesis based on sequence differentiation and adaptive variation in the plastid genomes in the order Dipsacales. We sequenced the plastid genomes of one Adoxaceae species and six Caprifoliaceae species, and together with seven previously released Dipsacales chloroplasts, we determined the sequence variations, evolutionary divergence of the plastid genomes, and phylogeny of Dipsacales species...
2018: Frontiers in Plant Science
Hongxia Zhang, Weibin Li, Henry D Adams, Anzhi Wang, Jiabing Wu, Changjie Jin, Dexin Guan, Fenghui Yuan
Atmospheric nitrogen (N) deposition has been found to significantly affect plant growth and physiological performance in terrestrial ecosystems. Many individual studies have investigated how N addition influences plant functional traits, however these investigations have usually been limited to a single species, and thereby do not allow derivation of general patterns or underlying mechanisms. We synthesized data from 56 papers and conducted a meta-analysis to assess the general responses of 15 variables related to leaf economics, gas exchange, and hydraulic traits to N addition among 61 woody plant species, primarily from temperate and subtropical regions...
2018: Frontiers in Plant Science
Luciano Pereira, Denisele Flores-Borges, Paulo Bittencourt, Juliana Mayer, Eduardo Kiyota, Pedro Araújo, Steven Jansen, Raul Freitas, Rafael Oliveira, Paulo Mazzafera
In the xylem of angiosperm plants, microscopic pits through the secondary cell walls connect the water-conducting vessels. Cellulosic meshes originated from primary walls and middle lamella between adjacent vessels, called pit membrane, separates one conduit from another. The intricate structure of the nano-sized pores in pit membranes enables the passage of water under negative pressure without hydraulic failure due to obstruction by gas bubbles (i.e., embolism) under normal conditions or mild drought stress...
June 5, 2018: Plant Physiology
Jing Lu, Enrico Magnani
Flowering plants display a large spectrum of seed architectures. The volume ratio of maternal versus zygotic seed tissues changes considerably among species and underlies different nutrient-storing strategies. Such diversity arose through the evolution of cell elimination programs that regulate the relative growth of one tissue over another to become the major storage compartment. The elimination of the nucellus maternal tissue is regulated by developmental programs that marked the origin of angiosperms and outlined the most ancient seed architectures...
June 5, 2018: Plant Reproduction
Mario Coiro, Maria Rosaria Barone Lumaga
The family Nymphaeaceae includes most of the diversity among the ANA-grade angiosperms. Among the species of this family, floral structures and pollination strategies are quite varied. The genus Victoria, as well as subgenera Lotos and Hydrocallis in Nymphaea, presents night-blooming, scented flowers pollinated by scarab beetles. Such similar pollination strategies have led to macromorphological similarities among the flowers of these species, which could be interpreted as homologies or convergences based on different phylogenetic hypotheses about the relationships of these groups...
June 5, 2018: Plant Biology
Mengyun Wang, Yibo Teng
Mitochondrial calcium uptake (MICU) plays a vital role in the regulation of mitochondrial calcium homeostasis, and, consequently, influences calcium signaling transduction. Although genes involved in mitochondrial calcium uptake have been well studied in animals, less is known about their ubiquity and function in plants. In this study, we identified 96 MICU genes in land plants. On the basis of phylogenetic analysis of MICU proteins, they were classified into three clades: MICU from eudicots (Clade I), from monocots (Clade II), and from a basal angiosperm, a bryophyte, and a lycophyte (Clade III)...
May 28, 2018: Gene
Anna V Shchennikova, Marya A Slugina, Alexey V Beletsky, Mikhail A Filyushin, Andrey A Mardanov, Olga A Shulga, Elena Z Kochieva, Nikolay V Ravin, Konstantin G Skryabin
Monotropa hypopitys is a mycoheterotrophic, nonphotosynthetic plant acquiring nutrients from the roots of autotrophic trees through mycorrhizal symbiosis, and, similar to other extant plants, forming asymmetrical lateral organs during development. The members of the YABBY family of transcription factors are important players in the establishment of leaf and leaf-like organ polarity in plants. This is the first report on the identification of YABBY genes in a mycoheterotrophic plant devoid of aboveground vegetative organs...
2018: International Journal of Genomics
Ginga Shimakawa, Akio Murakami, Kyosuke Niwa, Yusuke Matsuda, Ayumi Wada, Chikahiro Miyake
While subject to illumination, photosystem I (PSI) has the potential to produce reactive oxygen species (ROS) that can cause photo-oxidative damage in oxygenic photoautotrophs. The reaction center chlorophyll in PSI (P700) is kept oxidized in excess light conditions to limit over-excitation of PSI and alleviate the production of ROS. Oxidation of P700 requires a sufficient electron sink for PSI, which is responsible for flavodiiron proteins (FLV) safely dissipating electrons to O2 in cyanobacteria, green algae, and land plants except for angiosperms during short-pulse light (SP) illumination under which photosynthesis and photorespiration do not occur...
May 29, 2018: Photosynthesis Research
Martin Cheek, Hirokazu Tsukaya, Paula J Rudall, Kenji Suetsugu
Oxygyne Schltr. (Thismiaceae) is a rare and little-known genus of achlorophyllous mycoheterotrophic perennial herbs with one of the most remarkable distributions of all angiosperm plant genera globally, being disjunct between Japan and West-Central Africa. Each species is known only from a single location, and in most cases from a single specimen. This monographic study names, describes and maps two new species, Oxygyne duncanii Cheek from cloud forest in SW Region Cameroon and O. frankei Cheek from gallery forest in the Central African Republic , representing the first new Oxygyne species described from Africa in 112 years, and raising the number of described Oxygyne species from four to six...
2018: PeerJ
Matthias Karnahl, Misoon Park, Cornelia Krause, Ulrike Hiller, Ulrike Mayer, York-Dieter Stierhof, Gerd Jürgens
Sec1/Munc18 (SM) proteins contribute to membrane fusion by interacting with Qa-SNAREs or nascent trans -SNARE complexes. Gymnosperms and the basal angiosperm Amborella have only a single SEC1 gene related to the KEULE gene in Arabidopsis However, the genomes of most angiosperms including Arabidopsis encode three SEC1-related SM proteins of which only KEULE has been functionally characterized as interacting with the cytokinesis-specific Qa-SNARE KNOLLE during cell-plate formation. Here we analyze the closest paralog of KEULE named SEC1B...
May 29, 2018: Proceedings of the National Academy of Sciences of the United States of America
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