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941.
A hybrid-specific expressed cDNA fragment, designated as AG5, has been identified in wheat seedling leaves using differential
mRNA display. AG5 contains an open reading frame (ORF) encoding 183 amino acid residues. Comparison with amino acid sequences
in GenBank revealed that the AG5 protein is homologous to a group of Gly-rich proteins with consensus sequence-type RNA-binding
domains (CS-RBD). Structural analysis showed that AG5 protein contains five motifs, including a consensus sequence-type RNA-binding
domain near its N-terminus, arginine/aspartic acid repeats and a Gly-rich region in its center, a Cys-X2-Cys-X4-His-X4-Cys (CCHC) zinc finger motif in the Gly-rich region, and TrySer2ArgAsp2Arg repeats towards its C-terminus. Of all previously described RNA-binding proteins, only RZ-1 from tobacco has a similar
structure to the AG5 protein, but RZ-1 lacks a TrySer2ArgAsp2Arg repeat motif, indicating that the two proteins may belong
to a family of closely related proteins in plants. The possible role of AG5 and its relation to wheat heterosis are discussed.
Received: 21 November 1999 / Accepted: 20 March 2000 相似文献
942.
Vágújfalvi A Crosatti C Galiba G Dubcovsky J Cattivelli L 《Molecular & general genetics : MGG》2000,263(2):194-200
Although cold acclimation in cereals involves the expression of many cold-regulated genes, genetic studies have shown that
only very few chromosomal regions carry loci that play an important role in frost tolerance. To investigate the genetic relationship
between frost tolerance and the expression of cold-regulated genes, the expression and regulation of the wheat homolog of
the barley cold-regulated gene cor14b was studied at various temperatures in frost-sensitive and frost-tolerant wheat genotypes. At 18/15 °C (day/night temperatures)
frost-tolerant plants accumulated cor14b mRNAs and expressed COR14b proteins, whereas the sensitive plants did not. This result indicates that the threshold temperature
for induction of the wheat cor14b homolog is higher in frost-resistant plants, and allowed us to use this polymorphism in a mapping approach. Studies made
with chromosome substitution lines showed that the polymorphism for the threshold induction temperature of the wheat cor14b homolog is controlled by a locus(i) located on chromosome 5A of wheat, while the cor14b gene was mapped in Triticum monococcum on the long arm of chromosome 2Am. The analysis of single chromosome recombinant lines derived from a cross between Chinese Spring/Triticum spelta 5A and Chinese Spring/Cheyenne 5A identified two loci with additive effects that are involved in the genetic control of cor14b mRNA accumulation. The first locus was tightly linked to the marker psr911, while the second one was located between the marker Xpsr2021 and Frost resistance 1 (Fr1).
Received: 20 July 1999 / Accepted: 15 November 1999 相似文献
943.
Genes active in developing wheat endosperm 总被引:3,自引:0,他引:3
This paper describes the construction and characterisation of a cDNA library from wheat endosperm tissue during the early
stages of grain filling. Developing wheat endosperm tissue was characterised with respect to standard measures including dry
weight, cytological appearance and timing of expression of major sources of mRNA such as the seed storage protein genes. In
addition, the full complement of proteins present at mid-endosperm development was examined using 2D-electrophoretic techniques.
Based on this characterisation, endosperm from the developing grain 8–12 days post-anthesis was chosen for isolating mRNA
and preparing cDNA. At this stage in development the mRNA population is not yet dominated by the accumulation of mRNA from
seed storage protein genes. A cDNA library, not normalised, containing a high percentage of full length cDNA clones was constructed
and 4,319 clones sequenced ("single-pass"). Partitioning of the cDNA sequences into gene families and singletons provided
the basis for quantifying the accumulation of sequence classes relative to the total number of sequences determined. The accumulation
of gene families/singletons was not linear. However, mathematical modeling of the data suggested that the maximum number of
different genes expressed is within the range of 4,500–8,000 (detailed in the Appendix). If an average is taken of these extremes,
approximately 27% of the gene products were visible as proteins in the 2D-electrophoretic analysis. Analysis of a functional
class of genes relevant to wheat grain end-use, namely the glutenin/gliadin seed storage protein class of genes, revealed
a new category of gene characterised by a distinctive N-terminal domain and a reduced central repetitive domain.
Electronic Publication 相似文献
944.
The population dynamics, genotypic diversity and activity of naturally-occurring 2,4-diacetylphloroglucinol (DAPG)-producing Pseudomonas spp. was investigated for four plant species (wheat, sugar beet, potato, lily) grown in two different soils. All four plant species tested, except lily and in some cases wheat, supported relatively high rhizosphere populations (5 x 10(4) to 1 x 10(6) CFU/g root) of indigenous DAPG-producing Pseudomonas spp. during successive cultivation in both a take-all suppressive and a take-all conducive soil. Although lily supported on average the highest population densities of fluorescent Pseudomonas spp., it was the least supportive of DAPG-producing Pseudomonas spp. of all four plant species. The genotypic diversity of 492 DAPG-producing Pseudomonas isolates, assessed by Denaturing Gradient Gel Electrophoresis (DGGE) analysis of the phlD gene, revealed a total of 7 genotypes. Some of the genotypes were found only in the rhizosphere of a specific plant, whereas the predominant genotypes were found at significantly higher frequencies in the rhizosphere of three plant species (wheat, sugar beet and potato). Statistical analysis of the phlD(+) genotype frequencies showed that the diversity of the phlD(+) isolates from lily was significantly lower than the diversity of phlD(+) isolates found on wheat, sugar beet or potato. Additionally, soil type had a significant effect on both the phlD(+) population density and the phlD(+) genotype frequencies, with the take-all suppressive soil being the most supportive. HPLC analysis further showed that the plant species had a significant effect on DAPG-production by the indigenous phlD(+) population: the wheat and potato rhizospheres supported significantly higher amounts of DAPG produced per cell basis than the rhizospheres of sugar beet and lily. Collectively, the results of this study showed that the host plant species has a significant influence on the dynamics, composition and activity of specific indigenous antagonistic Pseudomonas spp. 相似文献
945.
Nascimento RP d'Avila-Levy CM Souza RF Branquinha MH Bon EP Pereira-Jr N Coelho RR 《Archives of microbiology》2005,184(3):194-198
Streptomyces malaysiensis AMT-3, isolated from a Brazilian cerrado soil, showed proteolytic activities detected by gelatin–sodium dodecyl sulfate-polyacrylamide
gel electrophoresis. The optimum proteinase production was obtained when using 2.5% wheat bran and 0.1% yeast extract in the
culture medium, after 5 days incubation at 30°C. The enzymatic complex degraded gelatin optimally at pH 7.0, and under these
conditions eight proteolytic bands (four serine-proteinases and four metaloproteinases), ranging from 20 to 212 kDa, were
detected on the culture supernatant filtrates. In addition, a 35-kDa proteinase was thermostable at 60°C for 120 min. These
results point out to the applicability of gelatin zymograms in the characterization of crude enzymatic complexes. According
to our results, this enzymatic complex could be used for biotechnological applications. 相似文献
946.
Schloter M Winkler JB Aneja M Koch N Fleischmann F Pritsch K Heller W Stich S Grams TE Göttlein A Matyssek R Munch JC 《Plant biology (Stuttgart, Germany)》2005,7(6):728-736
Plant growth largely depends on microbial community structure and function in the rhizosphere. In turn, microbial communities in the rhizosphere rely on carbohydrates provided by the host plant. This paper presents the first study on ozone effects in the plant-rhizosphere-bulk soil system of 4-year-old beech trees using outdoor lysimeters as a research platform. The lysimeters were filled with homogenized soil from the corresponding horizons of a forest site, thus minimizing field heterogeneity. Four lysimeters were treated with ambient ozone (1 x O3) and four with double ambient ozone concentrations (2 x O3; restricted to 150 ppb). In contrast to senescence, which was almost unaffected by ozone treatment, both the photochemical quantum yield of photosystem II (PSII) and leaf gas exchange were reduced (11 - 45 %) under the elevated O3 regime. However, due to large variation between the plants, no statistically significant O3 effect was found. Even though the amount of primary metabolites, such as sugar and starch, was not influenced by elevated O3 concentrations, the reduced photosynthetic performance was reflected in leaf biochemistry in the form of a reduction in soluble phenolic metabolites. The rhizosphere microbial community also responded to the O3 treatment. Both community structure and function were affected, with a tendency towards a lower diversity and a significant reduction in the potential nutrient turnover. In contrast, litter degradation was unaffected by the fumigation, indicating that in situ microbial functionality of the bulk soil did not change. 相似文献
947.
948.
The stimulatory role of lumichrome, a rhizosphere metabolite, was assessed on the growth of legume and cereal seedlings. At a very low nanomolar concentration (5 nm), lumichrome elicited growth promotion in cowpea, soybean, sorghum, millet and maize, but not in common bean, Bambara groundnut and Sudan grass. In soybean and cowpea only, 5 nm lumichrome caused early initiation of trifoliate leaf development, expansion in unifoliate and trifoliate leaves, increased stem elongation and, as a result, an increase in shoot and plant total biomass relative to control. Lumichrome (5 nm) also increased leaf area in maize and sorghum, and thus raised shoot and total biomass but there was no effect on the leaf area of the other cereals. Root growth was also stimulated in sorghum and millet by the supply of 5 nm lumichrome. By contrast, the application of a higher dose of lumichrome (50 nm) depressed development of unifoliate leaves in soybean, the second trifoliate leaf in cowpea, and shoot biomass in soybean. The 50 nm concentration also consistently decreased root development in cowpea and millet, but had no effect on the other species. These data show that lumichrome is a rhizosphere signal molecule that affects seedling development in both monocots and dicots. 相似文献
949.
Microgravity does not alter plant stand gas exchange of wheat at moderate light levels and saturating CO<Subscript>2</Subscript> concentration 总被引:2,自引:0,他引:2
Plant stand gas exchange was measured nondestructively in microgravity during the Photosynthesis Experiment Subsystem Testing and Operations experiment conducted onboard the International Space Station. Rates of evapotranspiration and photosynthesis measured in space were compared with ground controls to determine if microgravity directly affects whole-stand gas exchange of Triticum aestivum. During six 21-day experiment cycles, evapotranspiration was determined continuously from water addition rates to the nutrient delivery system, and photosynthesis was determined from the amount of CO2 added to maintain the chamber CO2 concentration setpoint. Plant stand evapotranspiration, net photosynthesis, and water use efficiency were not altered by microgravity. Although leaf area was significantly reduced in microgravity-grown plants compared to ground control plants, leaf area distribution was not affected enough to cause significant differences in the amounts of light absorbed by the flight and ground control plant stands. Microgravity also did not affect the response of evapotranspiration to changes in chamber vapor pressure difference of 12-day-old wheat plant stands. These results suggest that gravity naïve plants grown at moderate light levels (300 mol m–2 s–1) behave the same as ground control plants. This implies that future plant-based regenerative life support systems can be sized using 1 g data because water purification and food production rates operate at nearly the same rates as in 1 g at moderate light levels. However, it remains to be verified whether the present results are reproducible in plants grown under stronger light levels. 相似文献
950.
Phytoremediation is often discussed as a means of extracting trace metals in excess in the soil, but to increase its efficiency a better understanding of the factors controlling plant uptake is required. The main objective of this study was to examine the effect of origin (anthropogenic vs. geogenic) and mobility of thallium (Tl) in the rhizosphere on Tl uptake. Two Tl-hyperaccumulating Brassicaceae species, kale (Brassica oleracea acephala L. cv. Winterbor F1) and candytuft (Iberis intermedia Guers.), were grown in a rhizobox system to investigate the dynamics of Tl in the rhizosphere soil. Four different soils were used. Two soils contained high Tl amounts due to anthropogenic sources (emissions from a cement plant and mining activities). High Tl content in the two other soils was due to a high rock content (geogenic origin). On completion of growth in the rhizoboxes, the depletion of Tl in seven different chemical fractions, determined by sequential extraction, was compared to the plant uptake. Most of the Tl taken up was derived from the so-called "easily accessible" fractions in both soils with geogenic Tl as well as in the soils polluted by mining activities. Due to the small amounts of easily accessible Tl in the geogenic soils, Tl uptake by Brassicaceae was low. On the other hand, for the air emission-polluted soil, a high depletion of Tl from "less accessible" fractions was observed in addition to depletion of the easily accessible fractions. Hence, the latter soil demonstrated the highest potential for effective soil decontamination by phytoextraction within an appropriate time frame. 相似文献