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At least 811 records · Page 45Linked to original sources
PubMed2005

A rationally assembled microbial community for growing Tagetes patula L. in a lunar greenhouse.

Well-defined plant-associated bacteria were used for growing French marigolds (Tagetes patula L.) in anorthosite, a substrate of low bioavailability, analogous to a lunar rock. The consortium was composed mainly of plant growth-promoting rhizobacteria and biocontrol agents that were used for seed inoculation. Simultaneously, the sterile substrate was inoculated with the siliceous bacterium Paenibacillus sp. IMBG156. The plant benefited from bacterial activity which resulted in stimulation of seed germination, better plant development, and finally in flowering of inoculated tagetes. In contrast, control plants grew poorly in sterile anorthosite and never flowered. Analysis of bacterial community composition showed that both species colonized plant roots, and there were no shifts in the consortium structure in the rhizosphere of French marigolds within 6 weeks. Paenibacillus sp. IMBG156 was able to release some elements (Ca, Fe, Si) from substrate anorthosite. It was assumed that a rationally assembled consortium of bacterial strains supported growth and development of the model plant under growth-limiting conditions, at least by means of bioleaching and delivering of essential nutritional elements to the plants, and by promoting plant growth.

Bacillaceae↗
PubMed2000

Prediction of colonization by macrophytes in the Yaciretá reservoir of the Paraná River (Argentina and Paraguay).

The potential colonization by anchored plants (PCAP) and the potential areas for initial colonization of free floating plants were estimated during the early filling phase for the Yaciretá reservoir. In order to obtain the PCAP, the observed maximum depth of colonization of the anchored macrophytes before impoundment and the hypsographic curves were used. The species inhabiting the pre-impoundment area were classified according to the different bioforms before the inclussion in the analysis. The areal extent of PCAP (from depths between 0-4 m) could reach 275 km2 at 76 m above sea level (current water level), whereas at 82 m above sea level (final filling level) the littoral zone will be increased by about 21.5%. The potential area for geophytes was estimated to be 99 km2; 131 km2 for root-floating leaved plants and 120 km2 for submerged plants, at 76 m above sea level. At 82 m above sea level, the geophytes could reach 271 km2. The data for wind frequency, velocity and fetch, together with depth were used to calculate shallow and sheltered areas in which free floating plants could find favourable conditions to initial colonization. Physical and chemical features recorded at eight stations during the early filling phase are discussed in relation to potential plant development.

Argentina↗
PubMed1989

Developmental regulation and the influence of plant sinks on vegetative storage protein gene expression in soybean leaves.

Soybeans (Glycine max L.) accumulate a storage glycoprotein which is abundant in vegetative tissues, but is only a minor component of seeds. Changes in vegetative storage protein gene expression in leaves of control and depodded plants were monitored throughout plant development. Western and Northern blot hybridization analysis of protein and mRNA levels, respectively, showed that expression of these genes was highly regulated during development. Expression correlated with periods when expected demand for mobilized leaf reserves by other plant sinks was low. Vegetative storage protein mRNA comprised about 0.5% of the total mRNA in immature leaves and declined at least 20-fold by flowering. Depodding or blockage of leaf petiole phloem transport increased these mRNAs to about 16% of the total mRNA. Transcript levels also increased dramatically after seed maturation, just before leaf senescence. Protein levels followed a similar pattern and were inversely related to the number of seed pods allowed to develop on the plants. The results support the role for these proteins as temporary storage molecules which can be rapidly synthesized or degraded according to the need for nutrients by other plant tissues.

Journal Article↗
PubMed2002

The OsEBP-89 gene of rice encodes a putative EREBP transcription factor and is temporally expressed in developing endosperm and intercalary meristem.

The AP2/EREBP transcription factors play important roles in plant development and in the responses of plants to biotic and abiotic stresses. All members of the EREBP subfamily described to date are from dicotyledonous plants. In this paper, we describe the cloning and characterization of a rice gene, OsEBP-89, encoding a protein 326 amino acids long with a typical EREBP domain; this is the first report of an EREBP transcription factor in a monocotyledonous plant. Except for the EREBP domain, the OsEBP-89 protein does not have substantial sequence similarities to other members of the subfamily. The DNA-binding activity of the EREBP domain was confirmed by electrophoretic mobility-shift assays. An activation domain rich in acidic amino acids was identified by using a yeast one-hybrid system. Two putative nuclear-localization signals were also identified. The results of northern blot hybridization experiments showed that the transcript of the OsEBP-89 gene accumulates primarily in immature seeds, roots, and leaves (low levels). More detailed information about the pattern of OsEBP-89 gene expression was obtained by histochemical studies of transgenic rice plants carrying an OsEBP-89 5'/GUS reporter gene. The reporter gene was expressed in the endosperm starting at 7 days after pollination and in the intercalary meristem of plants. Expression of OsEBP-89 was induced in roots of rice seedlings by treatment with ACC, NaCl, or 2,4-D. Two cis-acting elements, an endosperm motif and a primary PERE, are present upstream of the OsEBP-89 coding region and may be involved in regulating its expression. Collectively, these results suggest that the OsEBP-89 gene is a new member of the EREBP subfamily and may be involved in ethylene-dependent seed maturation and shoot development of rice.

5' Flanking Region↗
PubMed2005

Quantitative trait loci analysis for the developmental behavior of Soybean (Glycine max L. Merr.).

Quantitative trait loci (QTLs) identified so far in soybean were mainly derived in the final stage of plant development, which did not apply to the exploitation of genetic effects that were expressed during a specific developmental stage. Thus, the aim of this study was to identify conditional QTLs associated with yield traits at a specific developmental interval of soybean plant. The 143 recombinant inbred lines developed from the cross of soybean cultivars 'Charleston' and 'Dongnong 594' were used for the developmental QTLs analysis of pod number in the main stem and plant height by composite interval mapping method combined with mixed genetic model. The results indicated that the number and type of QTLs and their genetic effects for the two agronomic traits were different in a series of measuring stages. A total of 10 unconditional QTLs in 6 linkage groups and 5 conditional QTLs in 3 linkage groups were identified for the pod number of the main stem, while 13 unconditional QTLs in 7 linkage groups and 12 conditional QTLs in 6 linkage groups were identified for plant height. Many QTLs that were detected in the early stages were different from those detected at the later stages. Some QTLs existed only at one stage and others existed across two or three stages. Five marker intervals (satt509-satt251, sat_099-sat_113, sat_113-OPAW19_4, satt457-OPC10_85, sat_095-OPBA08_5) were proven to be associated both with the development of pod number in the main stem and the development of plant height. The present study suggested that the development of pods and plant height in soybean were governed by time-dependent gene expression.

Chromosome Mapping↗
PubMed1998

Cell fate in plants. Lessons from the Arabidopsis root.

Classical studies in plant development have indicated that the fate of plant cells is fixed late, after cell division has ceased. Earlier commitment events are therefore considered reversible. To gain a mechanisatic understanding of the processes involved in specification and fixation of cell fate in plants, we are using the Arabidopsis root epidermis as a model system. The Arabidopsis root epidermis is composed of two cell types whose pattern of differentiation is directed by positional cues during development. Examination of mutations has identified genes involved in the establishment of cell fate specification in this tissue. TRANSPARENT TESTA GLABRA (TTG) and GLABRA2 (GL2) are positive regulators of non-hair fate and are active during the early differentiation of the epidermis in the meristem. GL2 encodes a homeobox protein which is expressed in non-hair cells in the meristem and is positively regulated by TTG. Mutations in genes involved in the regulation of ethylene biosynthesis and signal transduction indicate that ethylene is a positive regulator of hair cell fate. Treatment of ttg and gl2 plants with modulators of ethylene biosynthesis indicate that ethylene acts down stream of TTG and GL2 during the fate specification process. The relationship between meristem organisation and the mechanism underpinning the establishment of cell fate in other systems is also discussed.

Arabidopsis↗
PubMed2006

Isolation of 151 mutants that have developmental defects from T-DNA tagging.

In order to understand the mechanisms underlying plant development, a necessary first step involves the elucidation of the functions of the genes, via the analysis of mutants that exhibit developmental defects. In this study, an activation tagging mutant library harboring 80,650 independent Arabidopsis transformants was generated in order to screen for developmental mutants. A total of 129 mutants manifesting dominant developmental abnormalities were isolated, and their T-DNA insertion loci were mapped. The activation of one or more genes adjacent to a T-DNA insertion locus was confirmed in eight dominant mutants. A gene adjacent to the right border was usually activated by the 35S enhancers. Interestingly, the transcriptional activation of multiple genes within a broad range was observed in one of the mutants, which raises the possibility that activation by the 35S enhancers was not limited strictly to a single gene. In order to gain a better understanding of sexual reproduction in higher plants, we isolated 22 mutants exhibiting defects in female gametophyte development, and determined their T-DNA insertion loci. We propose that this mutant population may prove useful in the further determination of the functions of genes that play important roles in plant development.

Base Sequence↗
PubMed2005

Involvement of the small GTPase Rac in the defense responses of tobacco to pathogens.

During the hypersensitive response (HR), plants accumulate reactive oxygen species (ROS) that are likely generated at least in part by an NADPH oxidase similar to that found in mammalian neutrophils. An essential regulator of mammalian NADPH oxidase is the small GTP-binding protein Rac. To investigate whether Rac also regulates the pathogen-induced oxidative burst in plants, a dominant negative form of the rice OsRac1 gene was overexpressed in tobacco carrying the N resistance gene. Following infection with Tobacco mosaic virus (TMV), DN-OsRacl plants developed smaller lesions than wild-type plants, accumulated lower levels of lipid peroxidation products, and failed to activate expression of antioxidant genes. These results, combined with the demonstration that superoxide and hydrogen peroxide levels were reduced in DN-OsRacl tobacco developing a synchronous HR triggered by transient expression of the TMV p50 helicase domain or the Pto and AvrPto proteins, suggest that ROS production is impaired. The dominant negative effect of DN-OsRacl could be rescued by transiently overexpressing the wild-type OsRac1 protein. TMV-induced salicylic acid accumulation also was compromised in DN-OsRacl tobacco. Interestingly, while systemic acquired resistance to TMV was not impaired, nonhost resistance to Pseudomonas syringae pv. maculicola ES4326 was suppressed. Thus, the effect DN-OsRac1 expression exerts on the resistance signaling pathway appears to vary depending on the identity of the inoculated pathogen.

Gene Expression Regulation, Plant↗
PubMed2002

Induction of protection against the necrotrophic pathogens Phytophthora citrophthora and Alternaria solani in Lycopersicon esculentum Mill. by a novel synthetic glycoside combined with amines.

1,2,3,4-tetra-O-acetyl-6-ethyladipate-beta- D-glucopyranose (TOGE), a glycoside derivative of adipic acid monoethyl ester and 1,2,3,4-tetra-O-acetyl-beta- D-glucopyranose, was synthesized and the resistance-inducing activity shown by TOGE-1 (TOGE plus furfurylamine) and TOGE-2 (TOGE plus 1,3-diaminepropane) was assayed. TOGE-1 and TOGE-2 protected tomato plants against two different fungal pathogens Phytophthora citrophthora and Alternaria solani. Foliar treatments at very low concentrations (2.5 mg l(-1) TOGE, 0.5 mg l(-1) amine) clearly reduced the disease incidence for both pathogens. TOGE-2 application was the most effective on intact plants as well as on detached leaves, reducing fungal growth by more than 46% with respect to control plants. On the other hand TOGE-1 treatment reduced fungal advance by 21%. These results demonstrate a high protective effect against fungal infections for both chemicals. A possible direct antimicrobial effect was discounted due to the weak activity observed in vitro against these pathogens at the low concentrations used in plants. TOGE-2 treatment clearly activates resistance against both pathogens and improves the protective effect previously shown by FGA mixture (adipic acid monoethyl ester, 1,2,3,4-tetra-O-acetyl-beta- D-glucopyranose and furfurylamine) [V. Flors et al. (2001) J Agric Food Chem 49:2569-2575]. The obtained results indicate that TOGE-1 and TOGE-2 act as resistance inducers. Although their mode of action is still unknown, pre-challenge studies have demonstrated the induction of the phenylpropanoid pathway and antioxidant activities. Both chemicals have demonstrated a beneficial effect on plant development, increasing chlorophyll and protein contents, photosynthetic rate and water-use efficiency. The improvement of plant growth and development produced by these treatments suggests crop tolerance to these chemicals, although effective formulations that are safe to humans must be developed before this technology can be used commercially.

Adipates↗
PubMed2003

Genetic control of developmental changes induced by disruption of Arabidopsis histone deacetylase 1 (AtHD1) expression.

Little is known about the role of genetic and epigenetic control in the spatial and temporal regulation of plant development. Overexpressing antisense Arabidopsis thaliana HD1 (AtHD1) encoding a putative major histone deacetylase induces pleiotropic effects on plant growth and development. It is unclear whether the developmental abnormalities are caused by a defective AtHD1 or related homologs and are heritable in selfing progeny. We isolated a stable antisense AtHD1 (CASH) transgenic line and a T-DNA insertion line in exon 2 of AtHD1, resulting in a null allele (athd1-t1). Both athd1-t1 and CASH lines display increased levels of histone acetylation and similar developmental abnormalities, which are heritable in the presence of antisense AtHD1 or in the progeny of homozygous (athd1-t1/athd1-t1) plants. Furthermore, when the athd1-t1/athd1-t1 plants are crossed to wild-type plants, the pleiotropic developmental abnormalities are immediately restored in the F(1) hybrids, which correlates with AtHD1 expression and reduction of histone H4 Lys12 acetylation. Unlike the situation with the stable code of DNA and histone methylation, developmental changes induced by histone deacetylase defects are immediately reversible, probably through the restoration of a reversible histone acetylation code needed for the normal control of gene regulation and development.

Arabidopsis↗
PubMed2006

A new CULLIN 1 mutant has altered responses to hormones and light in Arabidopsis.

Regulated protein degradation contributes to plant development by mediating signaling events in many hormone, light, and developmental pathways. Ubiquitin ligases recognize and ubiquitinate target proteins for subsequent degradation by the 26S proteasome. The multisubunit SCF is the best-studied class of ubiquitin ligases in Arabidopsis (Arabidopsis thaliana). However, the extent of SCF participation in signaling networks is unclear. SCFs are composed of four subunits: CULLIN 1 (CUL1), ASK, RBX1, and an F-box protein. Null mutations in CUL1 are embryo lethal, limiting insight into the role of CUL1 and SCFs in later stages of development. Here, we describe a viable and fertile weak allele of CUL1, called cul1-6. cul1-6 plants have defects in seedling and adult morphology. In addition to reduced auxin sensitivity, cul1-6 seedlings are hyposensitive to ethylene, red, and blue light conditions. An analysis of protein interactions with the cul1-6 gene product suggests that both RUB (related to ubiquitin) modification and interaction with the SCF regulatory protein CAND1 (cullin associated and neddylation dissociated) are disrupted. These findings suggest that the morphological defects observed in cul1-6 plants are caused by defective SCF complex formation. Characterization of weak cul1 mutants provides insight into the role of SCFs throughout plant growth and development.

Arabidopsis↗