Effect of Non-Rubber Constituents on Guayule and Hevea Rubber Intrinsic Properties

To meet the increasing demand for natural rubber (NR), currently sourced from the tropical rubber tree Hevea brasiliensis, and address price volatility and steadily increasing labor costs, alternate rubber-producing species are in commercial development. One of these, guayule (Parthenium argentatum), has emerged on the market as a commercial source of high quality rubber. Non-rubber constituents play an important role in the physical properties of NR products. The intrinsic composition of the two NR materials differs and these differences may be a principal cause of the performance differences between them.We have compared the effect of non-rubber constituents, such as protein, lipids, resin and rubber particle membranes. Firstly, a film casting method was developed to obtain rubber films with a uniform thickness. Secondly, the glass transition temperature of different rubbers was determined by dynamic mechanical analysis, and tensile properties were tested for uncompounded materials. Guayule natural rubber (GNR), from which most of the membranes were removed while in latex form (MRGNR) was found to have higher intrinsic strength than GNR or gel-free NR (FNR). An acetone extraction was performed to quantify the resin and free lipids in the rubber samples

Chloroplast genome resources and molecular markers differentiate rubber dandelion species from weedy relatives

Rubisco large subunit genes (rbcL) from the Asteraceae. (DOCX 29 kb

Molecular identification and characterization of two rubber dandelion amalgaviruses

The Amalgaviridae family is composed of persistent viruses that share the genome architecture of Totiviridae and gene evolutionary resemblance to Partitiviridae. A single Amalgavirus genus has been assigned to this family, presenting only four recognized species, corresponding to plant infecting viruses with dsRNA monopartite genomes of ca. 3.4 kb. Here, we present the genomic identification and characterization of two novel viruses detected in rubber dandelion (Taraxacum kok-saghyz). The sequenced isolates presented genomes of 3,409 and 3,413 nt long, including two partially overlapping ORFs encoding a putative coat protein and an RNA-dependent RNA polymerase (RdRP). Phylogenetic insights based on the detected virus sequences suggest them to be members of two new species within the Amalgavirus genus. Multiple independent RNAseq data suggest that the identified viruses have a dynamic distribution and low relative RNA levels in infected plants. Virus presence was not associated with any apparent symptoms on the plant hosts. We propose the names rubber dandelion latent virus 1 & 2 to the detected amalgaviruses; the first viruses to be associated to this emergent and sustainable natural rubber crop.Fil: Debat, Humberto Julio. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Patología Vegetal; ArgentinaFil: Zinan Luo. Ohio State University. Department of Horticulture and Crop Science; Estados UnidosFil: Iaffaldano, Brian J. Ohio State University. Department of Horticulture and Crop Science; Estados UnidosFil: Xiaofeng Zhuang. Ohio State University. Department of Horticulture and Crop Science; Estados UnidosFil: Cornish, Katrina. Ohio State University. Department of Horticulture and Crop Science; Estados Unido

Comparative analysis of the complete sequence of the plastid genome of Parthenium argentatum and identification of DNA barcodes to differentiate Parthenium species and lines

<p>Abstract</p> <p>Background</p> <p><it>Parthenium argentatum </it>(guayule) is an industrial crop that produces latex, which was recently commercialized as a source of latex rubber safe for people with Type I latex allergy. The complete plastid genome of <it>P. argentatum </it>was sequenced. The sequence provides important information useful for genetic engineering strategies. Comparison to the sequences of plastid genomes from three other members of the Asteraceae, <it>Lactuca sativa, Guitozia abyssinica </it>and <it>Helianthus annuus </it>revealed details of the evolution of the four genomes. Chloroplast-specific DNA barcodes were developed for identification of <it>Parthenium </it>species and lines.</p> <p>Results</p> <p>The complete plastid genome of <it>P. argentatum </it>is 152,803 bp. Based on the overall comparison of individual protein coding genes with those in <it>L. sativa, G. abyssinica </it>and <it>H. annuus</it>, we demonstrate that the <it>P. argentatum </it>chloroplast genome sequence is most closely related to that of <it>H. annuus</it>. Similar to chloroplast genomes in <it>G. abyssinica, L. sativa </it>and <it>H. annuus</it>, the plastid genome of <it>P. argentatum </it>has a large 23 kb inversion with a smaller 3.4 kb inversion, within the large inversion. Using the <it>mat</it>K and <it>psb</it>A-<it>trn</it>H spacer chloroplast DNA barcodes, three of the four <it>Parthenium </it>species tested, <it>P. tomentosum</it>, <it>P. hysterophorus </it>and P. <it>schottii</it>, can be differentiated from <it>P. argentatum</it>. In addition, we identified lines within <it>P. argentatum</it>.</p> <p>Conclusion</p> <p>The genome sequence of the <it>P. argentatum </it>chloroplast will enrich the sequence resources of plastid genomes in commercial crops. The availability of the complete plastid genome sequence may facilitate transformation efficiency by using the precise sequence of endogenous flanking sequences and regulatory elements in chloroplast transformation vectors. The DNA barcoding study forms the foundation for genetic identification of commercially significant lines of <it>P</it>. <it>argentatum </it>that are important for producing latex.</p

Carbon Monoxide Alleviates Salt-Induced Oxidative Damage in Sorghum bicolor by Inducing the Expression of Proline Biosynthesis and Antioxidant Genes

Crop growth and yield are affected by salinity, which causes oxidative damage to plant cells. Plants respond to salinity by maintaining cellular osmotic balance, regulating ion transport, and enhancing the expression of stress-responsive genes, thereby inducing tolerance. As a byproduct of heme oxygenase (HO)-mediated degradation of heme, carbon monoxide (CO) regulates plant responses to salinity. This study investigated a CO-mediated salt stress tolerance mechanism in sorghum seedlings during germination. Sorghum seeds were germinated in the presence of 250 mM NaCl only, or in combination with a CO donor (1 and 1.5 μM hematin), HO inhibitor (5 and 10 μM zinc protoporphyrin IX; ZnPPIX), and hemoglobin (0.1 g/L Hb). Salt stress decreased the germination index (47.73%) and root length (74.31%), while hydrogen peroxide (H2O2) (193.5%), and proline (475%) contents increased. This increase correlated with induced HO (137.68%) activity and transcripts of ion-exchanger and antioxidant genes. Salt stress modified vascular bundle structure, increased metaxylem pit size (42.2%) and the Na+/K+ ratio (2.06) and altered primary and secondary metabolites. However, exogenous CO (1 μM hematin) increased the germination index (63.01%) and root length (150.59%), while H2O2 (21.94%) content decreased under salt stress. Carbon monoxide further increased proline (147.62%), restored the vascular bundle structure, decreased the metaxylem pit size (31.2%) and Na+/K+ ratio (1.46), and attenuated changes observed on primary and secondary metabolites under salt stress. Carbon monoxide increased HO activity (30.49%), protein content, and antioxidant gene transcripts. The alleviatory role of CO was abolished by Hb, whereas HO activity was slightly inhibited by ZnPPIX under salt stress. These results suggest that CO elicited salt stress tolerance by reducing oxidative damage through osmotic adjustment and by regulating the expression of HO1 and the ion exchanger and antioxidant transcripts

Compartmentalized Metabolic Engineering for Artemisinin Biosynthesis and Effective Malaria Treatment by Oral Delivery of Plant Cells

Artemisinin is highly effective against drug-resistant malarial parasites, which affects nearly half of the global population and kills \u3e500 000 people each year. The primary cost of artemisinin is the very expensive process used to extract and purify the drug from Artemisia annua. Elimination of this apparently unnecessary step will make this potent antimalarial drug affordable to the global population living in endemic regions. Here we reported the oral delivery of a non-protein drug artemisinin biosynthesized (~0.8 mg/g dry weight) at clinically meaningful levels in tobacco by engineering two metabolic pathways targeted to three different cellular compartments (chloroplast, nucleus, and mitochondria). The doubly transgenic lines showed a three-fold enhancement of isopentenyl pyrophosphate, and targeting AACPR, DBR2, and CYP71AV1 to chloroplasts resulted in higher expression and an efficient photo-oxidation of dihydroartemisinic acid to artemisinin. Partially purified extracts from the leaves of transgenic tobacco plants inhibited in vitro growth progression of Plasmodium falciparum-infected red blood cells. Oral feeding of whole intact plant cells bioencapsulating the artemisinin reduced the parasitemia levels in challenged mice in comparison with commercial drug. Such novel synergistic approaches should facilitate low-cost production and delivery of artemisinin and other drugs through metabolic engineering of edible plants

Study Protocol - Accurate assessment of kidney function in Indigenous Australians: aims and methods of the eGFR Study

Background: There is an overwhelming burden of cardiovascular disease, type 2 diabetes and chronic kidney disease among Indigenous Australians. In this high risk population, it is vital that we are able to measure accurately kidney function. Glomerular filtration rate is the best overall marker of kidney function. However, differences in body build and body composition between Indigenous and non-Indigenous Australians suggest that creatinine-based estimates of glomerular filtration rate derived for European populations may not be appropriate for Indigenous Australians. The burden of kidney disease is borne disproportionately by Indigenous Australians in central and northern Australia, and there is significant heterogeneity in body build and composition within and amongst these groups. This heterogeneity might differentially affect the accuracy of estimation of glomerular filtration rate between different Indigenous groups. By assessing kidney function in Indigenous Australians from Northern Queensland, Northern Territory and Western Australia, we aim to determine a validated and practical measure of glomerular filtration rate suitable for use in all Indigenous Australians

The Commercialization of Guayle (Power Point Presentation)

Replaced with revised version of paper 05/12/08Crop Production/Industries,