1,720,977 research outputs found
seed oil
No full textSeed oil composed of wax esters with long-chain monoenoic acyl moieties represents a high-value commodity for industry. Such plant-derived sperm oil-like liquid wax esters are biodegradable and can have excellent properties for lubrication. In addition, wax ester oil may represent a superior substrate for biodiesel production. In this study, we demonstrate that the low-input oil seed crop Camelina sativa can serve as a biotechnological platform for environmentally benign wax ester production. Two biosynthetic steps catalysed by a fatty alcohol-forming acyl-CoA reductase (FAR) and a wax ester synthase (WS) are sufficient to achieve wax ester accumulation from acyl-CoA substrates. To produce plant-derived sperm oil-like liquid wax esters, the WS from Mus musculus (MmWS) or Simmondsia chinensis (ScWS) were expressed in combination with the FAR from Mus musculus (MmFAR1) or Marinobacter aquaeolei (MaFAR) in seeds of Arabidopsis thaliana and Camelina sativa. The three analysed enzyme combinations Oleo3:mCherry:MmFAR1 Delta c/Oleo3:EYFP:MmWS, Oleo3:mCherry:MmFAR1 Delta c/ScWS and MaFAR/ScWS showed differences in the wax ester molecular species profiles and overall biosynthetic performance. By expressing MaFAR/ScWS in Arabidopsis or Camelina up to 59% or 21% of the seed oil TAGs were replaced by wax esters, respectively. This combination also yielded wax ester molecular species with highest content of monounsaturated acyl moieties. Expression of the enzyme combinations in the Arabidopsis fae1 fad2 mutant background high in oleic acid resulted in wax ester accumulation enriched in oleyl oleate (18:1/18:1 > 60%), suggesting that similar values may be obtained with a Camelina high oleic acid line.EU [FP7-KBBE-2007-1
Nuclear accumulation of the ankyrin repeat protein ANK1 enhances the auxin‐mediated transcription accomplished by the bZIP transcription factors BZI‐1 and BZI‐2
No full textP>The tobacco (Nicotiana tabacum) basic leucine zipper (bZIP) transcription factor BZI-1 has been implicated in auxin-mediated gene regulation. Yeast two-hybrid analysis has led to the identification of two BZI-1 protein interaction partners: the heterodimerizing bZIP factor BZI-2 and an ankyrin repeat domain protein, ANK1. Analysis in transgenic plants confirms that low levels of functional BZI-1, BZI-2 and ANK1 result in reduced auxin responses. This finding indicates that the three proteins act in the same functional context. The in vivo interaction of ANK1 and BZI-1 has been confirmed by protoplast two-hybrid analysis, as well as by bimolecular fluorescence complementation (BiFC) studies. Whereas YFP-BZI-1 has been found to be localized in the nucleus, YFP-ANK1 resides in the cytosol. Nevertheless, the inhibition of nuclear export with the inhibitor leptomycin B (LMB) and the co-expression with BZI-1, as well as treatment with auxin, results in the accumulation of YFP-ANK1 in the nucleus. Whereas BZI-1 is a weak activator, BZI-1/BZI-2 heterodimers efficiently support transcription. Importantly, conditions that lead to the accumulation of ANK1 in the nucleus, such as the expression of an ANK1 protein fused to a nuclear localization sequence (NLS) or auxin treatment, lead to a significant enhancement of BZI-1/BZI-2-mediated transcription. We therefore propose a mechanism in which the nuclear accumulation of ANK1 enhances BZI-1/BZI-2-mediated transcription in an auxin-dependent manner, presumably facilitated by protein-protein interaction. In summary, this study defines novel components in auxin-dependent signalling and transcriptional control.DF
The Vascular Pathogen Verticillium longisporum Requires a Jasmonic Acid-Independent COI1 Function in Roots to Elicit Disease Symptoms in Arabidopsis Shoots
No full textVerticillium longisporum is a soil-borne vascular pathogen that causes reduced shoot growth and early senescence in Arabidopsis (Arabidopsis thaliana). Here, we report that these disease symptoms are less pronounced in plants that lack the receptor of the plant defense hormone jasmonic acid (JA), CORONATINE INSENSITIVE1 (COI1). Initial colonization of the roots was comparable in wild-type and coi1 plants, and fungal DNA accumulated to almost similar levels in petioles of wild-type and coi1 plants at 10 d post infection. Completion of the fungal life cycle was impaired in coi1, as indicated by the reduced number of plants with microsclerotia, which are detected on dead plant material at late stages of the disease. Contrary to the expectation that the hormone receptor mutant coi1 should display the same phenotype as the corresponding hormone biosynthesis mutant delayed dehiscence2 (dde2), dde2 plants developed wild-type-like disease symptoms. Marker genes of the JA and the JA/ethylene defense pathway were induced in petioles of wild-type plants but not in petioles of dde2 plants, indicating that fungal compounds that would activate the known COI1-dependent signal transduction chain were absent. Grafting experiments revealed that the susceptibility-enhancing COI1 function acts in the roots. Moreover, we show that the coi1-mediated tolerance is not due to the hyperactivation of the salicylic acid pathway. Together, our results have unraveled a novel COI1 function in the roots that acts independently from JA-isoleucine or any JA-isoleucine mimic. This COI1 activity is required for a yet unknown root-to-shoot signaling process that enables V. longisporum to elicit disease symptoms in Arabidopsis
Xenobiotic- and Jasmonic Acid-Inducible Signal Transduction Pathways Have Become Interdependent at the Arabidopsis CYP81D11 Promoter
No full textPlants modify harmful substances through an inducible detoxification system. In Arabidopsis (Arabidopsis thaliana), chemical induction of the cytochrome P450 gene CYP81D11 and other genes linked to the detoxification program depends on class II TGA transcription factors. CYP81D11 expression is also induced by the phytohormone jasmonic acid (JA) through the established pathway requiring the JA receptor CORONATINE INSENSITIVE1 (COI1) and the JA-regulated transcription factor MYC2. Here, we report that the xenobiotic-and the JA-dependent signal cascades have become interdependent at the CYP81D11 promoter. On the one hand, MYC2 can only activate the expression of CYP81D11 when both the MYC2- and the TGA-binding sites are present in the promoter. On the other hand, the xenobiotic-regulated class II TGA transcription factors can only mediate maximal promoter activity if TGA and MYC2 binding motifs, MYC2, and the JA-isoleucine biosynthesis enzymes DDE2/AOS and JAR1 are functional. Since JA levels and degradation of JAZ1, a repressor of the JA response, are not affected by reactive chemicals, we hypothesize that basal JA signaling amplifies the response to chemical stress. Remarkably, stress-induced expression levels were 3-fold lower in coi1 than in the JA biosynthesis mutant dede2-2, revealing that COI1 can contribute to the activation of the promoter in the absence of JA. Moreover, we show that deletion of the MYC2 binding motifs abolishes the JA responsiveness of the promoter but not the responsiveness to COI1. These findings suggest that yet unknown cis-element(s) can mediate COI1-dependent transcriptional activation in the absence of JA.Deutsche Forschungsgemeinschaft [GA330/20-1
Production of wax esters in plant seed oils by oleosomal cotargeting of biosynthetic enzymes
No full textWax esters are neutral lipids exhibiting desirable properties for lubrication. Natural sources have traditionally been whales. Additionally some plants produce wax esters in their seed oil. Currently there is no biological source available for long chain length monounsaturated wax esters that are most suited for industrial applications. This study aimed to identify enzymatic requirements enabling their production in oilseed plants. Wax esters are generated by the action of fatty acyl-CoA reductase (FAR), generating fatty alcohols and wax synthases (WS) that esterify fatty alcohols and acyl-CoAs to wax esters. Based on their substrate preference, a FAR and a WS from Mus musculus were selected for this study (MmFAR1 and Mm WS). Mm WS resides in the endoplasmic reticulum (ER), whereas MmFAR1 associates with peroxisomes. The elimination of a targeting signal and the fusion to an oil body protein yielded variants of MmFAR1 and Mm WS that were cotargeted and enabled wax ester production when coexpressed in yeast or Arabidopsis. In the fae1 fad2 double mutant, rich in oleate, the cotargeted variants of MmFAR1 and Mm WS enabled formation of wax esters containing >65% oleyl-oleate. The data suggest that cotargeting of unusual biosynthetic enzymes can result in functional interplay of heterologous partners in transgenic plants.-Heilmann, M., T. Iven, K. Ahmann, E. Hornung, S. Stymne, and I. Feussner. Production of wax esters in plant seed oils by oleosomal cotargeting of biosynthetic enzymes. J. Lipid Res. 2012. 53: 2153-2161
MOESM2 of High-level accumulation of oleyl oleate in plant seed oil by abundant supply of oleic acid substrates to efficient wax ester synthesis enzymes
No full textAdditional file 2: Table S1. Raw data obtained by GC-FID to quantify the wax ester content in seeds of transgenic Arabidopsis transformed with MaFAR/ScWS, ScWS-MaFAR, ScWS-MaFAR/ScWS-MaFAR, ScWS-MaFAR/MaFAR, MaFAR/AbWSD1, MaFAR/PCOAbWSD1, MaFAR/TMMmAWAT2-AbWSD1 and MaFAR/MaWS2 shown in Figs. 1 and 3
In planta ORFeome analysis by large-scale over-expression of GATEWAY (R)-compatible cDNA clones: screening of ERF transcription factors involved in abiotic stress defense
No full textGenomic approaches have generated large Arabidopsis thaliana open reading frame (ORF) collections. However, tools are required to functionally characterize this ORFeome. Here we describe a batch procedure to simultaneously recombine a population of GATEWAY((R))-tagged full-length cDNAs into a plant expression vector. A pool of agrobacteria carrying these constructs has been used in flower-dip transformation experiments to obtain a collection of transgenic lines that over-express HA-tagged ORFs. This AtTORF-Ex library can be used in various screening approaches to identify particular gene family members involved in plant development or stress responses. The feasibility of the approach was studied using a near-complete collection of the Arabidopsis ethylene response factor (ERF) transcription factor (TF) family. Quality control performed at each step of the procedure revealed that the complexity of the population is maintained, and that almost all members of the ORF collection are covered by the plant library. The frequency of multiple transformation events has been determined as approximately 4%. Significant transgene expression was detected at the RNA and protein level in more than 60% and 30% of the transgenic plants, respectively. Striking phenotypic alterations were observed in approximately 4% of the plants. Many ERF TFs have been shown to participate in plant stress responses. As a proof of principle, the AtTORF-Ex library has been used in a selection procedure to isolate TFs involved in enhanced abiotic stress tolerance. The corresponding TF gene can be easily polymerase chain reaction-amplified using GATEWAY((R))att site-specific primers. In summary, we describe here a method that can be generally applied for functional analysis of ORFeomes in planta
Sporisorium reilianum Infection Changes Inflorescence and Branching Architectures of Maize
No full textAbstractSporisorium reilianum is a biotrophic maize (Zea mays) pathogen of increasing economic importance. Symptoms become obvious at flowering time, when the fungus causes spore formation and phyllody in the inflorescences. To understand how S. reilianum changes the inflorescence and floral developmental program of its host plant, we investigated the induced morphological and transcriptional alterations. S. reilianum infection promoted the outgrowth of subapical ears, suggesting that fungal presence suppressed apical dominance. Female inflorescences showed two distinct morphologies, here termed “leafy ear” and “eary ear.” In leafy ears, all floral organs were replaced by vegetative organs. In eary ears, modified carpels enclosed a new female inflorescence harboring additional female inflorescences at every spikelet position. Similar changes in meristem fate and organ identity were observed in the tassel of infected plants, which formed male inflorescences at spikelet positions. Thus, S. reilianum triggered a loss of organ and meristem identity and a loss of meristem determinacy in male and female inflorescences and flowers. Microarray analysis showed that these developmental changes were accompanied by transcriptional regulation of genes proposed to regulate floral organ and meristem identity as well as meristem determinacy in maize. S. reilianum colonization also led to a 30% increase in the total auxin content of the inflorescence as well as a dramatic accumulation of reactive oxygen species. We propose a model describing the architectural changes of infected inflorescence as a consequence of transcriptional, hormonal, and redox modulation, which will be the basis for further molecular investigation of the underlying mechanism of S. reilianum-induced alteration of floral development.</jats:p
Tissue-Specific Accumulation and Regulation of Zeaxanthin Epoxidase in Arabidopsis Reflect the Multiple Functions of the Enzyme in Plastids
No full textThe enzyme zeaxanthin epoxidase (ZEP) catalyzes the conversion of zeaxanthin to violaxanthin, a key reaction for ABA biosynthesis and the xanthophyll cycle. Both processes are important for acclimation to environmental stress conditions, in particular drought (ABA biosynthesis) and light (xanthophyll cycle) stress. Hence, both ZEP functions may require differential regulation to optimize plant fitness. The key to understanding the function of ZEP in both stress responses might lie in its spatial and temporal distribution in plant tissues. Therefore, we analyzed the distribution of ZEP in plant tissues and plastids under drought and light stress by use of a ZEP-specific antibody. In addition, we determined the pigment composition of the plant tissues and chloroplast membrane subcompartments in response to these stresses. The ZEP protein was detected in all plant tissues (except flowers) concomitant with xanthophylls. The highest levels of ZEP were present in leaf chloroplasts and root plastids. Within chloroplasts, ZEP was localized predominantly in the thylakoid membrane and stroma, while only a small fraction was bound by the envelope membrane. Light stress affected neither the accumulation nor the relative distribution of ZEP in chloroplasts, while drought stress led to an increase of ZEP in roots and to a degradation of ZEP in leaves. However, drought stress-induced increases in ABA were similar in both tissues. These data support a tissue- and stress-specific accumulation of the ZEP protein in accordance with its different functions in ABA biosynthesis and the xanthophyll cycle
- …
