Life Sciences Commons^™

An Endocannabinoid Catabolic Enzyme Faah And Its Paralogs In An Early Land Plant Reveal Evolutionary And Functional Relationship With Eukaryotic Orthologs, Imdadul Haq, Aruna Kilaru

ETSU Faculty Works

Endocannabinoids were known to exist only among Animalia but recent report of their occurrence in early land plants prompted us to study its function and metabolism. In mammals, anandamide, as an endocannabinoid ligand, mediates several neurological and physiological processes, which are terminated by fatty acid amide hydrolase (FAAH). We identified nine orthologs of FAAH in the moss Physcomitrella patens (PpFAAH1 to PpFAAH9) with amidase signature and catalytic triad. The optimal amidase activity for PpFAAH1 was at 37 °C and pH 8.0, with higher specificity to anandamide. Further, the phylogeny and predicted structural analyses of the nine paralogs revealed that PpFAAH1 …

Tree Peony Species As An Efficient Source For Α-Linolenic Acid Production, Lihang H. Xie, Qingyu Zhang, Aruna Kilaru, Yanlong Zhang

ETSU Faculty Works

The increasing need for healthy edible oil has driven us to identify α-linolenic acid (ALA)-rich species and identify key biochemical steps in ALA synthesis. Seeds of tree peony species are rich in unsaturated fatty acid content with > 40% ALA in the total fatty acid. However, fatty acid content and composition is variable among the tree peony germplasm. To this extent, a comparative study was carried out to identify the key genes responsible for differential oil accumulation among nine wild tree peony species. Subsequent to analyzing fatty acid content and composition of the seeds from nine tree peony species, a high- …

Tree Peony Species Are A Novel Resource For Production Of Α-Linolenic Acid, Aruna Kilaru, Lihang H. Xie, Qingyu Zhang, Yanlong Zhang

ETSU Faculty Works

Tree peony is known worldwide for its excellent ornamental and medical values, but recent reports that their seeds contain over 40% α-linolenic acid (ALA), an essential fatty acid for humans drew additional interest of biochemists. To understand the key factors that contribute to this rich accumulation of ALA, we carried out a comprehensive study of oil accumulation in developing seeds of nine wild tree peony species. The fatty acid content and composition was highly variable among the nine species; however, we selected a high- (P. rockii) and low-oil (P. lutea) accumulating species for a comparative transcriptome analysis. Similar to other …

Comparative Transcriptome Analysis Reveals An Efficient Mechanism For Α-Linolenic Acid Synthesis In Tree Peony Seeds, Qingyu Zhang, Rui Yu, Daoyang Sun, Mahbubur Rahman, Lihang Xie, Jiayuan Hu, Lixia He, Aruna Kilaru, Lixin Niu, Yanlong Zhang

ETSU Faculty Works

Tree peony (Paeonia section Moutan DC.) species are woody oil crops with high unsaturated fatty acid content, including α-linolenic acid (ALA/18:3; >40% of the total fatty acid). Comparative transcriptome analyses were carried out to uncover the underlying mechanisms responsible for high and low ALA content in the developing seeds of P. rockii and P. lutea, respectively. Expression analysis of acyl lipid metabolism genes revealed upregulation of select genes involved in plastidial fatty acid synthesis, acyl editing, desaturation, and triacylglycerol assembly in seeds of P. rockiirelative to P. lutea. Also, in association with ALA content in seeds, …

Establishment Of An Efficient In Vitro Propagation System For Iris Sanguinea, Ling Wang, Yu Du, Mahbubur Rahman, Biao Tang, Li-Juan Fan, Aruna Kilaru

ETSU Faculty Works

Iris sanguinea is a perennial flowering plant that is typically cultivated through seeds or bulbs. However, due to limitations in conventional propagation, an alternate regeneration system using seeds was developed. The protocol included optimization of sterilization, stratification and scarification methods as iris seeds exhibit physiological dormancy. In addition to chlorine-based disinfection, alkaline or heat treatment was used to break seed dormancy and reduce contamination. When seeds were soaked in water at 80 °C overnight, and sterilized with 75% EtOH for 30 s and 4% NaOCl solution for 20 minutes, contamination was reduced to 10% and a 73.3% germination was achieved. …

Fatty Acid And Associated Gene Expression Analyses Of Three Tree Peony Species Reveal Key Genes For Α-Linolenic Acid Synthesis In Seeds, Qing-Yu Zhang, Rui Yu, Li-Hang Xie, Mahbubur Rahman, Aruna Kilaru, Li-Xin Niu, Yan-Long Zhang

ETSU Faculty Works

The increasing demand for healthy edible oil has generated the need to identify promising oil crops. Tree peony (Paeonia section Moutan DC.) is a woody oil crop with α-linolenic acid contributing for 45% of the total fatty acid (FA) content in seeds. Molecular and genetic differences that contribute to varied FA content and composition among the wild peony species are however, poorly understood. Analyses of FA content and composition during seed development in three tree peony species (P. rockii, P. potaninii, and P. lutea) showed varied FA content in the three species with highest in P. rockii, followed by P. …

Vascular Flora Of The Rocky Fork Tract, Tennessee, Usa, And Its Use In Conservation And Management, Foster Levy, Elaine S. Walker

ETSU Faculty Works

A flora of the 3800 ha Rocky Fork Tract in northeast Tennessee produced 749 species of which 19 were on the Tennessee Rare Plant List and 34 were on the Cherokee National Forest Species Viability List with 87 county records from Greene County and 217 from Unicoi County. Rare species were particularly numerous in the Cyperaceae and Orchidaceae. The tract serves as a refuge for several regionally uncommon species by supporting either large populations or metapopulations of these species. Exotic species comprised 15% of the flora and were most common in the Fabaceae and Poaceae. The most unique habitat was …

Deidamia Inscriptum (Lettered Sphinx Moth) Caterpillars Feeding On Oxydendrum Arboreum (Sourwood) And Their Predation By Black Bears In Northeast Tennessee, Foster Levy, David L. Wagner, Elaine S. Walker

ETSU Faculty Works

An outbreak of Deidamia inscriptum (Lettered Sphinx Moth) caterpillars was noted in northeast Tennessee where Oxydendrum arboreum (Sourwood) trees were defoliated. Nearly all published literature and online resources list only plants in the grape family (Vitaceae) as larval food plants. Food-plant preference trials using fresh leaves of 3 woody plant species showed that Deidamiacaterpillars from this region had a preference for Sourwood over Parthenocissus quinquefolia(Virginia Creeper), and rejected Acer rubrum (Red Maple), a non-host species. Ursus americanus(Black Bear) were feeding on the caterpillars as evidenced by bent and broken Sourwood saplings bearing claw marks and by abundant …

Oil Biosynthesis In A Basal Angiosperm: Transcriptome Analysis Of Persea Americana Mesocarp, Aruna Kilaru, Xia Cao, Parker B. Dabbs, Ha-Jung Sung, Mahbubur Rahman, Nicholas Thrower, Greg Zynda, Ram Podicheti, Enrique Ibarra-Laclette, Luis Herrera-Estrella, Keithanne Mockaitis, John B. Ohlrogge

ETSU Faculty Works

The mechanism by which plants synthesize and store high amounts of triacylglycerols (TAG) in tissues other than seeds is not well understood. The comprehension of controls for carbon partitioning and oil accumulation in nonseed tissues is essential to generate oil-rich biomass in perennial bioenergy crops. Persea americana (avocado), a basal angiosperm with unique features that are ancestral to most flowering plants, stores ~ 70 % TAG per dry weight in its mesocarp, a nonseed tissue. Transcriptome analyses of select pathways, from generation of pyruvate and leading up to TAG accumulation, in mesocarp tissues of avocado was conducted and compared with …

Deep Sequencing Of The Mexican Avocado Transcriptome, An Ancient Angiosperm With A High Content Of Fatty Acids, Enrique Ibarra-Laclette, Alfonso Méndez-Bravo, Claudia Anahí Pérez-Torres, Victor A. Albert, Keithanne Mockaitis, Aruna Kilaru, Rodolfo López-Gómez, Jacob Israel Cervantes-Luevano, Luis Herrera-Estrella

ETSU Faculty Works

Background: Avocado (Persea americana) is an economically important tropical fruit considered to be a good source of fatty acids. Despite its importance, the molecular and cellular characterization of biochemical and developmental processes in avocado is limited due to the lack of transcriptome and genomic information.

Results: The transcriptomes of seeds, roots, stems, leaves, aerial buds and flowers were determined using different sequencing platforms. Additionally, the transcriptomes of three different stages of fruit ripening (pre-climacteric, climacteric and post-climacteric) were also analyzed. The analysis of the RNAseqatlas presented here reveals strong differences in gene expression patterns between different organs, …

Pattern And Rate Of Decline Of A Population Of Carolina Hemlock (Tsuga Caroliniana Engelm.) In North Carolina, Foster Levy, Elaine S. Walker

ETSU Faculty Works

We monitored a population of Carolina Hemlocks in northwestern North Carolina for four years to examine the rate and pattern of decline in response to infestation by Adelges tsugae (Hemlock Woolly Adelgid). Our yearly census of hemlock condition and severity of the adelgid infestation included trees of all sizes. We estimated declines in condition as the portions of the leaf canopy that were lost. Initially, infestation occurred throughout the population but was severe in only a small cluster of individuals. Within 1 year, the area of severe infestation increased in size to encompass 48% of the population. In another region …

Surface-Soil Properties Of Alder Balds With Respect To Grassy And Rhododendron Balds On Roan Mountain, North Carolina—Tennessee, James T. Donaldson, Zachary C. Dinkins, Foster Levy, Arpita Nandi

ETSU Faculty Works

We analyzed soils in Alder Bald, Grassy Bald, and Rhododendron Bald communities on Roan Mountain to infer the influence of vegetation on soil and to help guide management strategies. In all vegetation types, soils were acid (pH = 4–5) sandy loams. We found vegetation-associated differences for organic content, cation exchange capacity, acidity, two plant macronutrients (K, Mg), and three cations (Fe, Na, Zn). We predicted that nitrogen compounds would be highest in the Alder Bald because Alnus viridis ssp. crispa (Green Alder) can harbor nitrogen-fixing bacteria. Organic content was highest at the alder-bald sites, ammonium was similar among vegetation types, …

Identification Of A New Class Of Lipid Droplet-Associated Proteins In Plants, Patrick J. Horn, Christopher N. James, Satinder K. Gidda, Aruna Kilaru, John M. Dyer, Robert T. Mullen, John B. Ohlrogge, Kent D. Chapman

ETSU Faculty Works

Lipid droplets in plants (also known as oil bodies, lipid bodies, or oleosomes) are well characterized in seeds, and oleosins, the major proteins associated with their surface, were shown to be important for stabilizing lipid droplets during seed desiccation and rehydration. However, lipid droplets occur in essentially all plant cell types, many of which may not require oleosin-mediated stabilization. The proteins associated with the surface of nonseed lipid droplets, which are likely to influence the formation, stability, and turnover of this compartment, remain to be elucidated. Here, we have combined lipidomic, proteomic, and transcriptomic studies of avocado (Persea americana) mesocarp …

Wrinkled1, A Ubiquitous Regulator In Oil Accumulating Tissues From Arabidopsis Embryos To Oil Palm Mesocarp, Wei Ma, Que Kong, Vincent Arondel, Aruna Kilaru, Philip D. Bates, Nicholas A. Thrower, Christoph Benning, John B. Ohlrogge

ETSU Faculty Works

WRINKLED1 (AtWRI1) is a key transcription factor in the regulation of plant oil synthesis in seed and non-seed tissues. The structural features of WRI1 important for its function are not well understood. Comparison of WRI1 orthologs across many diverse plant species revealed a conserved 9 bp exon encoding the amino acids “VYL”. Site-directed mutagenesis of amino acids within the ‘VYL’ exon of AtWRI1 failed to restore the full oil content of wri1-1 seeds, providing direct evidence for an essential role of this small exon in AtWRI1 function. Arabidopsis WRI1 is predicted to have three alternative splice …

Overexpression Of Fatty Acid Amide Hydrolase Induces Early Flowering In Arabidopsis Thaliana, Neal D. Teaster, Jantana Keereetaweep, Aruna Kilaru, Yuh-Shuh Wang, Yuhong Tang, Christopher N.-Q. Tran, Brian G. Ayre, Kent D. Chapman, Elison B. Blancaflor

ETSU Faculty Works

N-Acylethanolamines (NAEs) are bioactive lipids derived from the hydrolysis of the membrane phospholipid N-acylphosphatidylethanolamine (NAPE). In animal systems this reaction is part of the “endocannabinoid” signaling pathway, which regulates a variety of physiological processes. The signaling function of NAE is terminated by fatty acid amide hydrolase (FAAH), which hydrolyzes NAE to ethanolamine and free fatty acid. Our previous work in Arabidopsis thaliana showed that overexpression of AtFAAH (At5g64440) lowered endogenous levels of NAEs in seeds, consistent with its role in NAE signal termination. Reduced NAE levels were accompanied by an accelerated growth phenotype, increased sensitivity to abscisic acid (ABA), enhanced …