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The floral meristem (FM) is self-maintaining at the early stages of flower development, but it is terminated when a fixed number of floral organs are produced. The FLORAL ORGAN NUMBER4 (FON4; also known as FON2) gene, an ortholog of Arabidopsis CLAVATA3 (CLV3), is required for regulating FM size and determinacy in rice. However, its interactions with floral homeotic genes remain unknown. Here, we report the genetic interactions between FON4 and floral homeotic genes OsMADS15 (an A-class gene), OsMADS16 (also called SUPERWOMAN1, SPW1, a B-class gene), OsMADS3 and OsMADS58 (C-class genes), OsMADS13 (a D-class gene), and OsMADS1 (an E-class gene) during flower development. We observed an additive phenotype in the fon4 double mutant with the OsMADS15 mutant allele dep (degenerative palea). The effect on the organ number of whorl 2 was enhanced in fon4 spw1. Double mutant combinations of fon4 with osmads3, osmads58, osmads13, and osmads1 displayed enhanced defects in FM determinacy and identity, respectively, indicating that FON4 and these genes synergistically control FM activity. In addition, the expression patterns of all the genes besides OsMADS13 had no obvious change in the fon4 mutant. This work reveals how the meristem maintenance gene FON4 genetically interacts with C, D, and E floral homeotic genes in specifying FM activity in monocot rice. [ABSTRACT FROM AUTHOR]

Lipid molecules are key structural components of plant male reproductive organs, such as the anther and pollen. Although advances have been made in the understanding of acyl lipids in plant reproduction, the metabolic pathways of other lipid compounds, particularly glycerolipids, are not fully understood. Here we report that an endoplasmic reticulum-localized enzyme, Glycerol-3-Phosphate Acyltransferase 3 (OsGPAT3), plays an indispensable role in anther development and pollen formation in rice. OsGPAT3 is preferentially expressed in the tapetum and microspores of the anther. Compared with wild-type plants, the osgpat3 mutant displays smaller, pale yellow anthers with defective anther cuticle, degenerated pollen with defective exine, and abnormal tapetum development and degeneration. Anthers of the osgpat3 mutant have dramatic reductions of all aliphatic lipid contents. The defective cuticle and pollen phenotype coincide well with the down-regulation of sets of genes involved in lipid metabolism and regulation of anther development. Taking these findings together, this work reveals the indispensable role of a monocot-specific glycerol-3-phosphate acyltransferase in male reproduction in rice. [ABSTRACT FROM AUTHOR]

Ginsenosides, the valuable pharmaceutical compounds in Panax ginseng, are triterpene saponins that occur mainly in ginseng plants. It was shown that in vitro treatment with the phytohormone jasmonic acid (JA) is able to increase ginsenoside production in ginseng plants. To understand the molecular link between JA biosynthesis and ginsenoside biosynthesis, we identified a JA biosynthetic 13-lipoxygenase gene (PgLOX6) in P. ginseng that promotes ginsenoside production. The expression of PgLOX6 was high in vascular bundles, which corresponds with expression of ginsenoside biosynthetic genes. Consistent with the role of PgLOX6 in synthesizing JA and promoting ginsenoside synthesis, transgenic plants overexpressing PgLOX6 in Arabidopsis had increased amounts of JA and methyl jasmonate (MJ), increased expression of triterpene biosynthetic genes such as squalene synthase (AtSS1) and squalene epoxidase (AtSE1), and increased squalene content. Moreover, transgenic ginseng roots overexpressing PgLOX6 had around 1.4-fold increased ginsenoside content and upregulation of ginsenoside biosynthesis-related genes including PgSS1, PgSE1, and dammarenediol synthase (PgDDS), which is similar to that of treatment with MJ. However, MJ treatment of transgenic ginseng significantly enhanced JA and MJ, associated with a 2.8-fold increase of ginsenoside content compared with the non-treated, non-transgenic control plant, which was 1.4 times higher than the MJ treatment effect on non-transgenic plants. These results demonstrate that PgLOX6 is responsible for the biosynthesis of JA and promotion of the production of triterpenoid saponin through up-regulating the expression of ginsenoside biosynthetic genes. This work provides insight into the role of JA in biosynthesizing secondary metabolites and provides a molecular tool for increasing ginsenoside production. [ABSTRACT FROM AUTHOR]

Dissection of the genetic pathways and mechanisms by which anther development occurs in grasses is crucial for both a basic understanding of plant development and for examining traits of agronomic importance such as male sterility. In rice, MULTIPLE SPOROCYTES1 (MSP1), a leucine-rich-repeat receptor kinase, plays an important role in anther development by limiting the number of sporocytes. OsTDL1a (a TPD1-like gene in rice) encodes a small protein that acts as a cofactor of MSP1 in the same regulatory pathway. In this study, we analyzed small RNA and mRNA changes in different stages of spikelets from wild-type rice, and from msp1 and ostdl1a mutants. Analysis of the small RNA data identified miRNAs demonstrating differential abundances. miR2275 was depleted in the two rice mutants; this miRNA is specifically enriched in anthers and functions to trigger the production of 24-nt phased secondary siRNAs (phasiRNAs) from PHAS loci. We observed that the 24-nt phasiRNAs as well as their precursor PHAS mRNAs were also depleted in the two mutants. An analysis of co-expression identified three Argonaute-encoding genes (OsAGO1d, OsAGO2b, and OsAGO18) that accumulate transcripts coordinately with phasiRNAs, suggesting a functional relationship. By mRNA in situ analysis, we demonstrated a strong correlation between the spatiotemporal pattern of these OsAGO transcripts and phasiRNA accumulations. [ABSTRACT FROM AUTHOR]

Moderate leaf rolling maintains the erectness of leaves and minimizes the shadowing between leaves which is helpful to establish ideal plant architecture. Here, we describe a srl2 (semi-rolled leaf2) rice mutant, which has incurved leaves due to the presence of defective sclerenchymatous cells on the abaxial side of the leaf and displays narrow leaves and reduced plant height. Map-based cloning revealed that SRL2 encodes a novel plant-specific protein of unknown biochemical function. SRL2 was mainly expressed in the vascular bundles of leaf blades, leaf sheaths, and roots, especially in their sclerenchymatous cells. The transcriptional activities of several leaf development-related YABBY genes were significantly altered in the srl2 mutant. Double mutant analysis suggested that SRL2 and SHALLOT-LIKE1 (SLL1)/ROLLED LEAF9 (RL9) function in distinct pathways that regulate abaxial-side leaf development. Hence, SRL2 plays an important role in regulating leaf development, particularly during sclerenchymatous cell differentiation. [ABSTRACT FROM AUTHOR]

AGL6 is an ancient subfamily of MADS-box genes found in both gymnosperms and angiosperms. Its functions remained elusive despite the fact that the MADS-box genes and the ABC model have been studied for >20 years. Nevertheless, recent discoveries in petunia, rice, and maize support its involvement in the 'E' function of floral development, very similar to the closely related AGL2 (SEPALLATA) subfamily which has been well characterized. The known functions of AGL6 span from ancient conserved roles to new functions acquired in specific plant families. The AGL6 genes are involved in floral meristem regulation, in floral organs, and ovule (integument) and seed development, and have possible roles in both male and female germline and gametophyte development. In grasses, they are also important for the development of the first whorl of the flower, whereas in Arabidopsis they may play additional roles before floral meristem formation. This review covers these recent insights and some other aspects that are not yet fully elucidated, which deserve more studies in the future. [ABSTRACT FROM AUTHOR]

After meiosis, tapetal cells in the innermost anther wall layer undergo program cell death (PCD)-triggered degradation. This step is essential for microspore development and pollen wall maturation. We identified a key gene, Defective Tapetum Cell Death 1 (DTC1), that controls this degeneration by modulating the dynamics of reactive oxygen species (ROS) during rice male reproduction. Mutants defective in DTC1 exhibit phenotypes of an enlarged tapetum and middle layer with delayed degeneration, causing male sterility. The gene is preferentially expressed in the tapetal cells during early anther development. In dtc1 anthers, expression of genes encoding secretory proteases or lipid transporters is significantly reduced, while transcripts of PCD regulatory genes, e.g. UDT1, TDR1, and EAT1/DTD, are not altered. Moreover, levels of DTC1 transcripts are diminished in udt1, tdr, and eat1 anthers. These results suggest that DTC1 functions downstream of those transcription factor genes and upstream of the genes encoding secretory proteins. DTC1 protein interacts with OsMT2b, a ROS scavenger. Whereas wild-type plants accumulate large amounts of ROS in their anthers at Stage 9 of development, those levels remain low during all stages of development in dtc1 anthers. These findings indicate that DTC1 is a key regulator for tapetum PCD by inhibiting ROS-scavenging activity. [ABSTRACT FROM AUTHOR]

Male reproduction in higher plants requires the support of various metabolites, including lipid molecules produced in the innermost anther wall layer (the tapetum), but how the molecules are allocated among different anther tissues remains largely unknown. Previously, rice (Oryza sativa) ATP binding cassette G15 (ABCG15) and its Arabidopsis (Arabidopsis thaliana) ortholog were shown to be required for pollen exine formation. Here, we report the significant role of OsABCG26 in regulating the development of anther cuticle and pollen exine together with OsABCG15 in rice. Cytological and chemical analyses indicate that osabcg26 shows reduced transport of lipidic molecules from tapetal cells for anther cuticle development. Supportively, the localization of OsABCG26 is on the plasma membrane of the anther wall layers. By contrast, OsABCG15 is polarly localized in tapetal plasma membrane facing anther locules. osabcg26 osabcg15 double mutant displays an almost complete absence of anther cuticle and pollen exine, similar to that of osabcg15 single mutant. Taken together, we propose that OsABCG26 and OsABCG15 collaboratively regulate rice male reproduction: OsABCG26 is mainly responsible for the transport of lipidic molecules from tapetal cells to anther wall layers, whereas OsABCG15 mainly is responsible for the export of lipidic molecules from the tapetal cells to anther locules for pollen exine development. [ABSTRACT FROM AUTHOR]

The pollen wall consists of an exine and an intine. The mechanism underlying its formation is not well understood. Glycosyltransferases catalyze the modification of biological molecules by attaching a single or multiple sugars and play key roles in a wide range of biological processes. We examined the role of GLYCOSYLTRANSFERASE1 (OsGT1) in pollen wall development in rice (Oryza sativa). This gene is highly expressed in mature pollen, and plants containing alleles caused by transfer DNA insertion do not produce homozygous progeny. Reciprocal crosses between OsGT1/osgt1 and the wild type indicated that the mutation leads to a male gametophyte defect. Microscopic analyses revealed that osgt1 pollen developed normally to the pollen mitosis stage but failed to produce mature grains. In osgt1 pollen, intine structure was disrupted. In addition, starch and protein levels were much lower in the mutant grains. Recombinant OsGT1 transferred glucose from UDP-glucose to the third and seventh positions of quercetin, a universal substrate of glycosyltransferases. Consistent with the role of OsGT1, an OsGT1-green fluorescent protein fusion protein was localized to the Golgi apparatus. Taken together, our results suggest that OsGT1 is a Golgi-localized glycosyltransferase essential for intine construction and pollen maturation, providing new insight into male reproductive development. [ABSTRACT FROM AUTHOR]

Protein interactions are fundamental to the molecular processes occurring within an organism and can be utilized in network biology to help organize, simplify, and understand biological complexity. Currently, there are more than 10 publicly available Arabidopsis (Arabidopsis thaliana) protein interaction databases. However, there are limitations with these databases, including different types of interaction evidence, a lack of defined standards for protein identifiers, differing levels of information, and, critically, a lack of integration between them. In this paper, we present an interactive bioinformatics Web tool, ANAP (Arabidopsis Network Analysis Pipeline), which serves to effectively integrate the different data sets and maximize access to available data. ANAP has been developed for Arabidopsis protein interaction integration and network-based study to facilitate functional protein network analysis. ANAP integrates 11 Arabidopsis protein interaction databases, comprising 201,699 unique protein interaction pairs, 15,208 identifiers (including 11,931 The Arabidopsis Information Resource Arabidopsis Genome Initiative codes), 89 interaction detection methods, 73 species that interact with Arabidopsis, and 6,161 references. ANAP can be used as a knowledge base for constructing protein interaction networks based on user input and supports both direct and indirect interaction analysis. It has an intuitive graphical interface allowing easy network visualization and provides extensive detailed evidence for each interaction. In addition, ANAP displays the gene and protein annotation in the generated interactive network with links to The Arabidopsis Information Resource, the AtGenExpress Visualization Tool, the Arabidopsis 1,001 Genomes GBrowse, the Protein Knowledgebase, the Kyoto Encyclopedia of Genes and Genomes, and the Ensembl Genome Browser to significantly aid functional network analysis. The tool is available open access at http://gmdd.shgmo.org/Computational-Biology/ANAP. [ABSTRACT FROM AUTHOR]

The accumulation of a number of small RNAs in plants is affected by abscisic acid (ABA) and abiotic stresses, but the underlying mechanisms are poorly understood. The MIR168-mediated feedback regulatory loop regulates ARGONAUTEI (AGO1) homeostasis, which is crucial for gene expression modulation and plant development. Here, we reveal a transcriptional regulatory mechanism by which MIR168 controls AGO1 homeostasis during ABA treatment and abiotic stress responses in Arabidopsis (Arabidopsis thaliana). Plants overexpressing MIR168a and the AGO1 loss-of-function mutant agol-27 display ABA hypersensitivity and drought tolerance, while the MIR168a-2 mutant shows ABA hyposensitivity and drought hypersensitivity. Both the precursor and mature miR168 were induced under ABA and several abiotic stress treatments, but no obvious decrease for the target of MIR168, AGO1, was shown under the same conditions. However, promoter activity analysis indicated that AGO1 transcription activity was increased under ABA and drought treatments, suggesting that transcriptional elevation of MIR168a is required for maintaining a stable AGO1 transcript level during the stress response. Furthermore, we showed both in vitro and in vivo that the transcription of MIR168a is directly regulated by four abscisic acid-responsive element (ABRE) binding factors, which bind to the ABRE cis-element within the MIR168a promoter. This ABRE motif is also found in the promoter of MIR168a homologs in diverse plant species. Our findings suggest that transcriptional regulation of MIR168 and posttranscriptional control of AGO1 homeostasis may play an important and conserved role in stress response and signal transduction in plants. [ABSTRACT FROM AUTHOR]

Male Sterile2 (MS2) is predicted to encode a fatty acid reductase required for pollen wall development in Arabidopsis (Arabidopsis thaliana). Transient expression of MS2 in tobacco (Nicotiana benthamiana) leaves resulted in the accumulation of significant levels of C16 and C18 fatty alcohols. Expression of MS2 fused with green fluorescent protein revealed that an amino- terminal transit peptide targets the MS2 to plastids. The plastidial localization of MS2 is biologically important because genetic complementation of MS2 in ms2 homozygous plants was dependent on the presence of its amino-terminal transit peptide or that of the Rubisco small subunit protein amino-terminal transit peptide. In addition, two domains, NAD(P)H-binding domain and sterile domain, conserved in MS2 and its homologs were also shown to be essential for MS2 function in pollen exine development by genetic complementation testing. Direct biochemical analysis revealed that purified recombinant MS2 enzyme is able to convert palmitoyl-Acyl Carrier Protein to the corresponding C16:0 alcohol with NAD(P)H as the preferred electron donor. Using optimized reaction conditions (i.e. at pH 6.0 and 30°C), MS2 exhibits a Km for 16:0-Acyl Carrier Protein of 23.3 ± 4.0 µM, a Vmax of 38.3 ± 4.5 nmol mg-1 min-1, and a catalytic efficiency/Km of 1,873 M-1 S-1. Based on the high homology of MS2 to other characterized fatty acid reductases, it was surprising that MS2 showed no activity against palmitoyl- or other acyl-coenzyme A; however, this is consistent with its plastidial localization. In summary, genetic and biochemical evidence demonstrate an MS2-mediated conserved plastidial pathway for the production of fatty alcohols that are essential for pollen wall biosynthesis in Arabidopsis. [ABSTRACT FROM AUTHOR]

In higher plants, timely degradation of tapetal cells, the innermost sporophytic cells of the anther wall layer, is a prerequisite for the development of viable pollen grains. However, relatively little is known about the mechanism underlying programmed tapetal cell development and degradation. Here, we report a key regulator in monocot rice (Oryza sativa), PERSISTANT TAPETAL CELLI (PTC1), which controls programmed tapetal development and functional pollen formation. The evolutionary significance of PTC1 was revealed by partial genetic complementation of the homologous mutation MALE STERILITY1 (MS1) in the dicot Arabidopsis (Arabidopsis thaliana). PTC1 encodes a PHD-finger (for plant homeodomain) protein, which is expressed specifically in tapetal cells and microspores during anther development in stages 8 and 9, when the wild-type tapetal cells initiate a typical apoptosis-like cell death. Even though ptc1 mutants show phenotypic similarity to ms1 in a lack of tapetal DNA fragmentation, delayed tapetal degeneration, as well as abnormal pollen wall formation and aborted microspore development, the ptc1 mutant displays a previously unreported phenotype of uncontrolled tapetal proliferation and subsequent commencement of necrosis-like tapetal death. Microarray analysis indicated that 2,417 tapetum- and microspore-expressed genes, which are principally associated with tapetal development, degeneration, and pollen wall formation, had changed expression in ptc1 anthers. Moreover, the regulatory role of PTC1 in anther development was revealed by comparison with MS1 and other rice anther developmental regulators. These findings suggest a diversified and conserved switch of PTC1/MS1 in regulating programmed male reproductive development in both dicots and monocots, which provides new insights in plant anther development. [ABSTRACT FROM AUTHOR]

Grass plants develop unique floral patterns that determine grain production. However, the molecular mechanism underlying the specification of floral organ identities and meristem determinacy, including the interaction among floral homeotic genes, remains largely unknown in grasses. Here, we report the interactions of rice (Oryza sativa) floral homeotic genes, OsMADS3 (a C-class gene), OsMADS13 (a D-class gene), and DROOPING LEAF (DL), in specifying floral organ identities and floral meristem determinacy. The interaction among these genes was revealed through the analysis of double mutants, osmads13-3 osmads3-4 displayed a loss of floral meristem determinacy and generated abundant carpelloid structures containing severe defective ovules in the flower center, which were not detectable in the single mutant. In addition, in situ hybridization and yeast two-hybrid analyses revealed that OsMADS13 and OsMADS3 did not regulate each other's transcription or interact at the protein level. This indicates that OsMADS3 plays a synergistic role with OsMADS13 in both ovule development and floral meristem termination. Strikingly, osmads3-4 dl-sup6 displayed a severe loss of floral meristem determinacy and produced supernumerary whorls of lodicule-like organs at the forth whorl, suggesting that OsMADS3 and DL synergistically terminate the floral meristem. Furthermore, the defects of osmads13-3 dl-sup6 flowers appeared identical to those of dl-sup6, and the OsMADS13 expression was undetectable in dl-sup6 flowers. These observations suggest that DL and OsMADS13 may function in the same pathway specifying the identity of carpel/ovule and floral meristem. Collectively, we propose a model to illustrate the role of OsMADS3, DL, and OsMADS13 in the specification of flower organ identity and meristem determinacy in rice. [ABSTRACT FROM AUTHOR]

Synthesis of lipidic components in anthers, including of the pollen exine, is essential for plant male reproductive development. Plant lipid transfer proteins (LTPs) are small, abundant lipid-binding proteins that have the ability to exchange lipids between membranes in vitro. However, their biological role in male reproductive development remains less understood. Here, we report the crucial role of OsC6 in regulating postmeiotic anther development in rice (Oryza sativa). Found in monocots, OsC6 belongs to a distinct clade from previously identified LTP1 and LTP2 family members found in both dicots and monocots. OsC6 expression is mainly detectable in tapetal cells and weakly in microspores from stage 9 to stage 11 of anther development. Immunological assays indicated that OsC6 is widely distributed in anther tissues such as the tapetal cytoplasm, the extracellular space between the tapetum and middle layer, and the anther locule and anther cuticle. Biochemical assays indicated that recombinant OsC6 has lipid binding activity. Moreover, plants in which OsC6 was silenced had defective development of orbicules (i.e. Ubisch bodies) and pollen exine and had reduced pollen fertility. Furthermore, additional evidence is provided that the expression of OsC6 is positively regulated by a basic helix-loop-helix transcription factor, Tapetum Degeneration Retardation (TDR). Extra granule-like structures were observed on the inner surface of the tdr tapetal layer when the expression of OsC6 was driven by the TDR promoter compared with the tdr mutant. These data suggest that OsC6 plays a crucial role in the development of lipidic orbicules and pollen exine during anther development in rice. [ABSTRACT FROM AUTHOR]

Grass plants develop distinct inflorescences and spikelets that determine grain yields. However, the mechanisms underlying the specification of inflorescences and spikelets in grasses remain largely unknown. Here, we report the biological role of one SEPALLATA (SEP)-like gene, OsMADS34, in controlling the development of inflorescences and spikelets in rice (Oryza sativa). OsMADS34 encodes a MADS box protein containing a short carboxyl terminus without transcriptional activation activity in yeast cells. We demonstrate the ubiquitous expression of OsMADS34 in roots, leaves, and primordia of inflorescence and spikelet organs. Compared with the wild type, osmads34 mutants developed altered inflorescence morphology, with an increased number of primary branches and a decreased number of secondary branches. In addition, osmads34 mutants displayed a decreased spikelet number and altered spikelet morphology, with lemma/leaf-like elongated sterile lemmas. Moreover, analysis of the double mutant osmads34 osmads1 suggests that OsMADS34 specifies the identities of floral organs, including the lemma/palea, lodicules, stamens, and carpel, in combination with another rice SEP-like gene, OsMADS1. Collectively, our study suggests that the origin and diversification of OsMADS34 and OsMADS1 contribute to the origin of distinct grass inflorescences and spikelets. [ABSTRACT FROM AUTHOR]

To understand the molecular mechanism regulating meristem development in the monocot rice (Oryza sativa), we describe here the isolation and characterization of three floral organ number4 (fon4) alleles and the cloning of the FON4 gene. The fon4 mutants showed abnormal enlargement of the embryonic and vegetative shoot apical meristems (SAMs) and the inflorescence and floral meristems. Likely due to enlarged SAMs, fon4 mutants produced thick culms (stems) and increased numbers of both primary rachis branches and floral organs. We identified FON4 using a map-based cloning approach and found it encodes a small putatively secreted protein, which is the putative ortholog of the Arabidopsis (Arabidopsis thaliana) CLAVATA3 (CLV3) gene. FON4 transcripts mainly accumulated in the small group of cells at the apex of the SAMs, whereas the rice ortholog of CLV1 (FON1) is expressed throughout the SAMs, suggesting that the putative FON4 ligand might be sequestered as a possible mechanism for rice meristem regulation. Exogenous application of the peptides FON4p and CLV3p corresponding to the CLV3/ESR-related (CLE) motifs of FON4 and CLV3, respectively, resulted in termination of SAMs in rice, and treatment with CLV3p caused consumption of both rice and Arabidopsis root meristems, suggesting that the CLV pathway in limiting meristem size is conserved in both rice and Arabidopsis. However, exogenous FON4p did not have an obvious effect on limiting both rice and Arabidopsis root meristems, suggesting that the CLE motifs of Arabidopsis CLV3 and FON4 are potentially functionally divergent. [ABSTRACT FROM AUTHOR]

The basic/helix-loop-helix (bHLH) transcription factors and their homologs form a large family in plant and animal genomes. They are known to play important roles in the specification of tissue types in animals. On the other hand, few plant bHLH proteins have been studied functionally. Recent completion of whole genome sequences of model plants Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa) allows genome-wide analysis and comparison of the bHLH family in flowering plants. We have identified 167 bHLH genes in the rice genome, and their phylogenetic analysis indicates that they form well-supported clades, which are defined as subfamilies. In addition, sequence analysis of potential DNA-binding activity, the sequence motifs outside the bHLH domain, and the conservation of intron/exon structural patterns further support the evolutionary relationships among these proteins. The genome distribution of rice bHLH genes strongly supports the hypothesis that genome-wide and tandem duplication contributed to the expansion of the bHLH gene family, consistent with the birth-and-death theory of gene family evolution. Bioinformatics analysis suggests that rice bHLH proteins can potentially participate in a variety of combinatorial interactions, endowing them with the capacity to regulate a multitude of transcriptional programs. In addition, similar expression patterns suggest functional conservation between some rice bHLH genes and their close Arabidopsis homologs. [ABSTRACT FROM AUTHOR]

The importance of adhesins in pathogenicity has resulted in them being useful targets in the defense against bacterial infections. To produce edible vaccines against piglet diarrhea caused by enterotoxigenic Escherichia coli (ETEC), plants were genetically engineered to produce recombinant fimbrial adhesin FaeG. To evaluate the efficacy of the edible vaccine FaeG in mice, the soluble protein extracts were examined by about 15 μg recombinant FaeG for each oral immunization dose per mouse. After four doses of vaccination, both IgG and IgA antibodies specific to K88ad fimbriae were elicited in serum, and specific IgA antibodies were also evoked in feces of the immunized mice. Moreover, visible K88ad ETEC agglutination by the specific serum from the immunized mice was observed, implying the antibody was highly specific and effective. Results from an in vitro villous-adhesion assay further confirmed that serum antibodies of the immunized mice could inhibit K88ad ETEC from adhering to pig intestinal receptors, further demonstrating the oral immune efficacy of the plant-derived FaeG. This study provides a promising, noninvasive method for vaccinating swine by feeding supplements of transgenic plant. Moreover, the low cost and ease of delivery of this edible ETEC vaccine will facilitate its application in economically disadvantaged regions. [ABSTRACT FROM AUTHOR]

The Arabidopsis thaliana ASYMMETRIC LEAVES1 (AS1) and AS2 genes are important for repressing class I KNOTTED1-like homeobox (KNOX) genes and specifying leaf adaxial identity in leaf development. RNA-dependent RNA polymerases (RdRPs) are critical for posttranscriptional and transcriptional gene silencing in eukaryotes; however, very little is known about their functions in plant development. Here, we show that the Arabidopsis RDR6 gene (also called SDE1 and SGS2) that encodes a putative RdRP, together with AS1 and AS2, regulates leaf development, rdr6 single mutant plants displayed only minor phenotypes, whereas rdr6 as1 and rdr6 as2 double mutants showed dramatically enhanced as1 and as2 phenotypes, with severe defects in the leaf adaxial-abaxial polarity and vascular development. In addition, the double mutant plants produced more lobed leaves than the as1 and as2 single mutants and showed leaf-like structures associated on a proportion of leaf blades. The abnormal leaf morphology of the double mutants was accompanied by an extended ectopic expression of a class I KNOX gene BREVIPEDICELLUS (BP) and high levels of microRNA165/166 that may lead to mRNA degradation of genes in the class III HD-ZIP family. Taken together, our data suggest that the Arabidopsis RDR6-associated epigenetic pathway and the AS1-AS2 pathway synergistically repress BP and MIR165/166 for proper plant development. [ABSTRACT FROM AUTHOR]

The article reports on the results of an interlaboratory trial validation of an event-specific qualitative polymerase chain reaction (PCR)-based detection method for genetically modified RT73 rapeseed. A description of the experimental set-up and measurement method is presented. The study showed that all of the rapeseed endogenous reference high mobility group protein gene, figwort mosaic virus 35S promoter and RT73 event-specific fragment could be detected from rapeseed samples at 0.1 percent.

Studies specific primers for the rapeseed, Brassica napus, high-mobility-group protein I/V (HMG-I/V) single-copy gene used in qualitative and real-time quantitative polymerase chain reaction (PCR)detection of transgenic cultivars. Reliability of PCR methods for qualitative and quantitative detection of genetically modified organisms; Limits of detection and quantitation in qualitative and quantitative PCR systems; Feasibility of the HMG-I/V gene as an endogenous reference gene.