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1.
Elena Cassani Daniele Villa Massimo Durante Michela Landoni Roberto Pilu 《Plant Growth Regulation》2011,64(2):185-192
In maize there are three types of brachytic mutants (br1, br2 and br3) showing short stature and a gibberellins-insensitive phenotype. So far only the brachytic 2 gene has been cloned and it encodes for a putative protein of the Multidrug Resistant (MDR) class of P-glycoproteins (PGPs)
that could be involved in polar movement of auxins: in fact the br2 mutant is insensitive to treatment with auxins and gibberellins. We have isolated a new recessive mutation of br2 gene (named br2-23) and with the aim of study its interactions with the other brachytic mutations we produced a br2 br3 double mutant that showed an additive effect on the stature with respect to the single mutants br2 and br3 and abnormal growth. In the progeny of the selfed double mutant we observed various defective seedlings, mirroring an altered
embryo development and growth, which also suggested a role for the br3 gene in auxin transport. Expression analysis of the auxin efflux transporters codified by ZmPIN1 genes supports this finding, showing the up-regulation of the ZmPIN1a gene in the br3 mutant. To our knowledge this is the first report showing the involvement of Br2 and Br3 genes in embryo development. These single and double mutants appear to be useful tools to study the genetics of plant height
and to investigate auxin transport in plants. 相似文献
2.
Kamiel Spoelstra Serge Daan 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2008,194(3):235-242
Mutations in each of the genes mPer1, mPer2, mCry1 and mCry2 separately cause deviations from the wild type circadian system. Differences between these mutant strains have inspired the
hypothesis that the duality of circadian genes (two mPer and two mCry genes involved) is related to the existence of two components in the circadian oscillator (Daan et al., J Biol Rhythms 16:105–116,
2001). We tested the predictions from this theory that the circadian period (τ) lengthens under constant illumination (LL)
in mCry1 and mPer1 mutant mice, while it shortens in mCry2 and mPer2 mutants. mCry1
−/−
and mCry2
−/−
knockout mice both consistently increased τ with increasing light intensity, as did wild type mice. With increasing illumination,
rhythmicity is reduced in mCry1, mCry2 and mPer1, but not in mPer2 deficient mice. Results for mPer mutant mice are in agreement with data reported on these strains earlier by Steinlechner et al. (J Biol Rhythms 17:202–209,
2002), and also with the predictions from the model. The increase in cycle length of the circadian system by light in the
mCry2 deficient mice violates the predictions. The model is thereby rejected: the mCry genes do not play a differential role, although the opposite responses of mPer mutants to light remain consistent with a functional Evening–Morning differentiation. 相似文献
3.
Symptoms of fairy rings caused by Lepista sordida have been reported on Zoysiagrass (Zoysia spp.) turf maintained at fairway height (2 cm), but not on bentgrass (Agrostis spp.) maintained at putting green height (0.5 cm). The mycelia of this fungus inhabit primarily the upper 0–2 cm layer of
the soil extending into the thatch. To compare conditions for the mycelial growth in Z. matrella turf to those in A. palustris turf, we examined the effects of nutrients, temperature, water potential, and pH in the field as well as in the laboratory.
Greater growth of the mycelia was observed in medium that included hot water extracts from soil of the 0–1 cm zone in Z. matrella turf compared to that from A. palustris. The upper soil layer in Z. matrella turf contained more organic matter from clippings than that in A. palustris. The temperature and water potential of the 0–2 cm soil zone in Z. matrella turf were also more favorable for the mycelial growth. The soil pH values of this zone in Z. matrella turf were less favorable compared to A. palustris but within the range for accelerating mycelial growth.
Part of this study was presented orally at the 46th meeting of the Mycological Society of Japan in 2002 相似文献
4.
Elena Cassani Edoardo Bertolini Francesco Cerino Badone Michela Landoni Dario Gavina Alberto Sirizzotti Roberto Pilu 《Molecular breeding : new strategies in plant improvement》2009,24(4):375-385
The “green revolution” involving mainly wheat and rice was based on the use by breeders of semidominant mutations involved
in the signal transduction pathway of Gibberellin (GA). In particular, mutations in the Reduced height (Rht) gene of wheat have been used to reduce plant height and consequently to avoid storm damage and lodging. These genes have
been cloned and they encode for DELLA proteins which contain an N-terminal DELLA and a VHYNP domain essential for GA-dependent
degradation of these proteins. In maize several mutations have been isolated which affect gibberellin biosynthesis and perception
and in particular, mutations in Dwarf8 (D8) gene cause a severe dwarfing phenotype. D8 gene has been identified as an orthologue of Rht (Reduced height), Slr1(Slender rice 1) and Gibberellic Acid Insensitive (GAI) genes, this latter is a negative regulator of GA response in Arabidopsis. In this work, for the first time, we isolated and characterized a single amino acid insertion in the VHYNP domain of D8 maize gene causing the appearance of a dominant dwarf mutation. This spontaneous mutation, named D8-1023, showed a phenotype which is less severe in comparison with the other D8 mutants previously isolated which have modifications
in the DELLA domain. This mutant appears to be an useful tool either to study the mechanism of GA-modulated growth in plants
or to lower the height of maize tropical germplasm for breeding purposes. 相似文献
5.
S. Haque A. H. A. Farooqi M. M. Gupta R. S. Sangwan A. Khan 《Plant Growth Regulation》2007,51(3):263-269
Pyrethrins and flower yield of pyrethrum (Chrysanthemum
cinerariaefolium Viz.) plants were determined after application of ethrel, chlormequat chloride and paclobutrazol. Ethrel at 50, 100, 250
and 500 mg l−l produced a significant positive effect on pyrethrins level, decreased plant height, while 50 and 100 mg l−l significantly increased fresh and dry flower yield. Chlormequat chloride at 1000 and 2000 mg l−l and paclobutrazol (80 and 160 mg l−l) increased pyrethrins level, single flower weight and decreased plant height and flower yield. 14C-acetate incorporation studies further substantiated positive effect of growth retardants on pyrethrins biosynthesis. The
effect of growth retardants on pyrethrins seems to be mediated through its effect on biosynthesis. 相似文献
6.
Pratiksha Bhadauriya Radha Gupta Surendra Singh Prakash Singh Bisen 《World journal of microbiology & biotechnology》2008,24(1):139-141
n-Alkanes pattern in response to NaCl stress has been studied in the cyanobacterium Anabaena cylindrica. Saturated hydrocarbons were separated and identified by gas chromatography-mass spectrometry (GC-MS) using serially coupled
capillary column. Light chain n-alkanes in the range of C9–C17 (43%) and heavy chain n-alkanes in range of C17–C23 (34%) and C23–C31 (23%) were identified as the major components of total hydrocarbons in the NaCl adapted cells of A. cylindrica. In contrast, NaCl-untreated cells of A. cylindrica had dominance of only long chain n-alkanes in the range of C23–C31 comprising about 94% of its total n-alkanes. The persistence of high level (43%) of short chain n-alkanes (C9–C17) in NaCl adapted cells of A. cylindrica as compared to its negligible level (0.2%) in NaCl untreated counterpart clearly indicates that NaCl stress causes the A. cylindrica to shift towards the synthesis of short chain n-alkanes. 相似文献
7.
The objectives of this research were first to isolate plastid gene sequences from cabbage (Brassica oleracea L. var. capitata L.), and to establish the chloroplast transformation technology of Brassica. A universal transformation vector (pASCC201) for Brassica chloroplast was constructed with trnV–rrn16S (left) and trnI–trnA–rrn23S (right) of the IRA region as a recombination site for the transformed gene. In transforming plasmid pASCC201, a chimeric aadA gene was cloned between the rrn16S and rrn23S plastid gene borders. Expression of aadA confers resistance to spectinomycin and streptomycin antibiotics. The uidA gene was also inserted into the pASCC201 and transferred into the leaf cells of cabbage via particle gun mediated transformation.
Regenerated plantlets were selected by 200 mg/l spectinomycin and streptomycin. After antibiotic selection, the regeneration
percentage of the two cabbage cultivars was about 2.7–3.3%. The results of PCR testing and Southern blot analysis confirmed
that the uidA and aadA genes were present in the chloroplast genome via homologously recombined. Northern blot hybridizations, immunoblotting and
GUS histochemical assays indicated that the uidA gene were stable integrated into the chloroplast genome. Foreign protein was accumulated at 3.2–5.2% of the total soluble
protein in transgenic mature leaves. These results suggest that the expression of a variety of foreign genes in the chloroplast
genome will be a powerful tool for use in future studies. 相似文献
8.
Optimization of <Emphasis Type="Italic">Agrobacterium</Emphasis>-mediated transformation conditions in mature embryos of elite wheat 总被引:1,自引:0,他引:1
Immature embryos have been used frequently as target tissues in the genetical transformation of wheat. However, obtaining
a large number of high quality immature embryos throughout the year is a laborious and delicate process, because of the need
to cultivate the plants under controlled conditions. To circumvent this, we have employed mature embryos rather than immature
ones as starter explants for Agrobacterium-mediated transformation of an elite wheat (Triticum aestivum L.) cultivar EM12. The neomycin phosphotransferase ІІ (npt ІІ) and β-glucuronidase (gus) genes were used as selectable and screenable marker genes, respectively, to assess and optimize the performance of T-DNA
delivery. With the aid of an orthogonal design, the effect of four factors in combination on transfer DNA (T-DNA) delivery
was studied. These factors were preculture duration, different kinds of inoculation, length of inoculation and co-culture
condition. Optimal conditions for T-DNA delivery were obtained for mature embryos precultured for 14 days, followed by immersing
in inoculation suspension with full strength Murashige and Skoog (MS) salts in darkness at 23–25°C for 3 h, and then co-culturing
with Agrobacterium under desiccating condition in the dark at 23–24°C for 2–3 days. Complete analysis of transgene insertion demonstrated that
the optimized method for Agrobacterium-mediated transformation of mature embryos of wheat was efficient and practicable. 相似文献
9.
Erhard E. Pfündel 《Photosynthesis research》2009,100(3):163-177
The F
0 and F
M level fluorescence from a wild-type barley, a Chl b-less mutant barley, and a maize leaf was determined from 430 to 685 nm at 10 nm intervals using pulse amplitude-modulated
(PAM) fluorimetry. Variable wavelengths of the pulsed excitation light were achieved by passing the broadband emission of
a Xe flash lamp through a birefringent tunable optical filter. For the three leaf types, spectra of F
V/F
M (=(F
M − F
0)/F
M) have been derived: within each of the three spectra of F
V/F
M, statistically meaningful variations were detected. Also, at distinct wavelength regions, the F
V/F
M differed significantly between leaf types. From spectra of F
V/F
M, excitation spectra of PS I and PS II fluorescence were calculated using a model that considers PS I fluorescence to be constant
but variable PS II fluorescence. The photosystem spectra suggest that LHC II absorption results in high values of F
V/F
M between 470 and 490 nm in the two wild-type leaves but the absence of LHC II in the Chl b-less mutant barley leaf decreases the F
V/F
M at these wavelengths. All three leaves exhibited low values of F
V/F
M around 520 nm which was tentatively ascribed to light absorption by PS I-associated carotenoids. In the 550–650 nm region,
the F
V/F
M in the maize leaf was lower than in the barley wild-type leaf which is explained with higher light absorption by PS I in
maize, which is a NADP-ME C4 species, than in barley, a C3 species. Finally, low values of F
V/F
M at 685 in maize leaf and in the Chl b-less mutant barley leaf are in agreement with preferential PS I absorption at this wavelength. The potential use of spectra
of the F
V/F
M ratio to derive information on spectral absorption properties of PS I and PS II is discussed. 相似文献
10.
C. Douglas Boyette Mark A. Weaver Robert E. Hoagland Kenneth C. Stetina 《World journal of microbiology & biotechnology》2008,24(11):2721-2726
A mycelial formulation of the fungus Myrothecium verrucaria (IMI 361690) containing 0.20% Silwet L-77 surfactant was found to be highly efficacious in controlling the exotic invasive
weed kudzu. The mycelium can be rapidly (48–72 h) produced in several media, including an inexpensive soy flour–corn meal
medium. Mycelial yields were 2, 10, and 25 g dry weight l−1 in Czapek-Dox, Richard’s V-8, and soy flour–corn meal media, respectively. Scale-up production in soy flour–corn meal medium
using laboratory fermenters (10–25 l), resulted in a mycelial formulation that caused 90% mortality of naturally-occurring
mature (0.9–1.0 m in height) kudzu within 48 h after application in field experiments. HPLC analyses revealed that the mycelium
produced in this liquid culture contained no detectable amounts of the trichothecene mycotoxins roridin A and verrucarin A
(limit of detection 2 μg ml−1). This has resulted in a safer, yet effective bioherbicidal product. We anticipate that these findings should improve the
probability of EPA registration and subsequent commercial development of this bioherbicide. 相似文献
11.
Rhitu Rai Prasanta K. Dash B. M. Prasanna Aqbal Singh 《World journal of microbiology & biotechnology》2007,23(6):853-858
The genotypic diversity of indigenous bacterial endophytes within stem of tropical maize (Zea mays L.) was determined in field and greenhouse experiments. Strains were isolated from stem tissues of a tropical maize cultivar
(PEHM-1) by trituration and surface disinfestation and their population dynamics was determined. Endophytes were found in
most of the growing season at populations ranging from 1.36–6.12 × 105 colony-forming units per gram fresh weight (c.f.u./gm fw) of stem. Analysis of these bacterial endophytes using Gas Chromatography—Fatty
Acid Methyl Ester (GC-FAME) led to the identification of Bacillus pumilus, B. subtilis, Pseudomonas aeruginosa and P. fluorescens as the relatively more predominant group of bacterial species residing in maize stem. When the maize seedlings grown in a
greenhouse were inoculated with these four isolates individually, their population densities decreased (1.6–3.1 × 105 c.f.u./gm fw of stem) as compared to the field-grown maize (1.8–3.8 × 105 c.f.u./gm fw of stem). The highest persistence, however, was recovered in the case of B. subtilis with a population density of 3.1 × 105 c.f.u./gm fw of stem tissue on 28 days after emergence (DAE). This is the first report on population dynamics of bacterial
endophytes from tropical maize and the results establish that symptomless populations of bacteria exist in the maize stem. 相似文献
12.
Ardisia crenata, an evergreen shrub native to East Asia, has been a serious invasive plant to the southeastern USA. Here 13 polymorphic microsatellite
loci were isolated and characterized from an enrichment genomic library of A. crenata. The average allele number of these microsatellites was four per locus, ranging from two to seven. The ranges of observed
and expected heterozygosity were 0.000–1.000 and 0.239–0.789, respectively. These microsatellite markers will be useful for
investigating population genetics and reproductive ecology of A. crenata. 相似文献
13.
Effects of zinc and soil moisture on photosynthetic rate and chlorophyll fluorescence parameters of maize 总被引:1,自引:0,他引:1
Effects of zinc [0 and 5.0 mg Zn kg−1 (soil)] on photosynthetic rate (PN), and chlorophyll fluorescence in leaves of maize (Zea mays L.) cv. Zhongdan 9409 seedlings grown under different soil moisture regimes (40–45 % and 70–75 % of soil saturated water
content) were studied. Zn application did not enhance maize plant adaptation to drought stress. The relative water content
and the water potential of leaves were not affected by Zn treatment. Moreover, The PN of drought-stressed plants was not improved by Zn supply. The increases of plant biomass, stomatal conductance and quantum
yield of photosystem 2 due to Zn addition were notable in well-watered plants. 相似文献
14.
Hao-Wei Fu You-Fa Li Qing-Yao Shu 《Molecular breeding : new strategies in plant improvement》2008,22(2):281-288
Mutation techniques have been used for generating genetic variation and breeding new varieties during the past decades. However,
the skepticism has also persisted during the course on the sole mutational origin of genetic variation in mutated populations.
We addressed this issue using three unique rice genetic lines in this study. First, we confirmed that gamma rays had significant
effect on the growth of M1 plants, leading to significant reduction of fertility, seed set and plant height at doses 200 Gy and above. Second, we proved
that out-crossing derived genetic variants existed in M2 population (0.8%) and among selected putative mutants (0–33.3%), in addition to induced mutants. Third, we demonstrated that
true induced mutant lines had identical microsatellite haplotypes to their parents. We proposed microsatellite assay as a
method to exclude any genetic contaminants from induced mutants, with appropriate numbers for different levels of power based
on reported microsatellite mutation rate and microsatellite polymorphic index. 相似文献
15.
Fawzeia H. Elmhalli Katinka Pålsson Jan Örberg Thomas G. T. Jaenson 《Experimental & applied acarology》2009,48(3):251-262
The toxicity of para-menthane-3,8-diol (PMD), the main arthropod-repellent compound in the oil of the lemon eucalyptus, Corymbia citriodora, was evaluated against nymphs of Ixodes ricinus using five methods (A–E) of a contact toxicity bioassay. Mortality rates were estimated by recording numbers of dead nymphs
at 30 min intervals during the first 5 h after the start of exposure and at longer intervals thereafter. The mortality rate
increased with increasing concentration of PMD and duration of exposure with a distinct effect after 3.5 h. From the results
obtained by methods A, C and E, the LC50 range was 0.035–0.037 mg PMD/cm2 and the LC95 range was 0.095–0.097 mg PMD/cm2 at 4 h of exposure; the LT50 range was 2.1–2.8 h and the LT95 range was 3.9–4.2 h at 0.1 mg PMD/cm2. To determine the duration of toxic activity of PMD, different concentrations (0.002, 0.01, 0.1 mg PMD/cm2) were tested and mortality was recorded at each concentration after 1 h; thereafter new ticks were tested. This test revealed
that the lethal activity of PMD remained for 24 h but appeared absent after 48 h. The overall results show that PMD is toxic
to nymphs of I. ricinus and may be useful for tick control. 相似文献
16.
17.
Oscillations with a period of 1–2 min in the rate of photosynthesis have been found in leaves of C3 and C4 land plants under invariant, saturating, light and carbon dioxide. This article reports the occurrence of similar oscillations
with a period of 2–2.5 min in individual cells of the marine diatom Coscinodiscus wailesii. These oscillations were determined by measurements of both oxygen (oxygen microelectrode) and carbon dioxide (pH microelectrode)
just outside the plasmalemma. These oscillations were found in less than 1% of the cells examined. The occurrence of oscillations
in unicelluar diatoms rules out for these organisms hypotheses as to the origin of oscillations in land plant leaves that
are based on cell–cell interactions. 相似文献
18.
Simultaneous measurements of chlorophyll (Chl) fluorescence and CO2 assimilation (A) in Vicia faba leaves were taken during the first weeks of growth to evaluate the protective effect of 24-epibrassinolide (EBR) against
damage caused by the application of the herbicide terbutryn (Terb) at pre-emergence. V. faba seeds were incubated for 24 h in EBR solutions (2 × 10−6 or 2 × 10−5 mM) and immediately sown. Terb was applied at recommended doses (1.47 or 1.96 kg ha−1) at pre-emergence. The highest dose of Terb strongly decreased CO2 assimilation, the maximum quantum yield of PSII photochemistry in the dark-adapted state (F
V/F
M), the nonphotochemical quenching (NPQ), and the effective quantum yield (ΔF/F′M) during the first 3–4 weeks after plant emergence. Moreover, Terb increased the basal quantum yield of nonphotochemical processes
(F
0/F
M), the degree of reaction center closure (1 − q
p), and the fraction of light absorbed in PSII antennae that was dissipated via thermal energy dissipation in the antennae
(1 − F′V/F′M). The herbicide also significantly reduced plant growth at the end of the experiment as well as plant length, dry weight,
and number of leaves. The application of EBR to V. faba seeds before sowing strongly diminished the effect of Terb on fluorescence parameters and CO2 assimilation, which recovered 13 days after plant emergence and showed values similar to those of control plants. The protective
effect of EBR on CO2 assimilation was detected at a photosynthetic photon flux density (PFD) of 650 μmol m−2 s−1 and the effect on ΔF/F′M and photosynthetic electron transport (J) was detected under actinic lightings up to 1750 μmol m−2 s−1. The highest dose of EBR also counteracted the decrease in plant growth caused by Terb, and plants registered the same growth
values as controls. 相似文献
19.
Alien chromosome addition lines have been widely used for identifying gene linkage groups, assigning species-specific characters
to a particular chromosome and comparing gene synteny between related species. In plant breeding, their utilization lies in
introgressing characters of agronomic value. The present investigation reports the production of intergeneric somatic hybrids
Brassica
napus (2n = 38) + Orychophragmus violaceus (2n = 24) through asymmetric fusions of mesophyll protoplasts and subsequent development of B. napus-O. violaceous chromosome addition lines. Somatic hybrids showed variations in morphology and fertility and were mixoploids (2n = 51–67) with a range of 19–28 O. violaceus chromosomes identified by genomic in situ hybridization (GISH). After pollinated with B. napus parent and following embryo rescue, 20 BC1 plants were obtained from one hybrid. These exhibited typical serrated leaves of O. violaceus or B. napus-type leaves. All BC1 plants were partially male fertile but female sterile because of abnormal ovules. These were mixoploids (2n = 41–54) with 9–16 chromosomes from O. violaceus. BC2 plants showed segregations for female fertility, leaf shape and still some chromosome variation (2n = 39–43) with 2–5 O. violaceus chromosomes, but mainly containing the whole complement from B. napus. Among the selfed progenies of BC2 plants, monosomic addition lines (2n = 39, AACC + 1O) with or without the serrated leaves of O. violaceus or female sterility were established. The complete set of additions is expected from this investigation. In addition, O. violaceus plants at diploid and tetraploid levels with some variations in morphology and chromosome numbers were regenerated from the
pretreated protoplasts by iodoacetate and UV-irradiation.
Z. Zhao and T. Hu make equal contributions to this work. 相似文献
20.
Subramanian Mohan Raj Chelladurai Rathnasingh Woo-Chel Jung Sunghoon Park 《Applied microbiology and biotechnology》2009,84(4):649-657
The stability and specific activity of endo-β-1,4-glucanase III from Trichoderma reesei QM9414 was enhanced, and the expression efficiency of its encoding gene, egl3, was optimized by directed evolution using error-prone PCR and activity screening in Escherichia coli RosettaBlue (DE3) pLacI as a host. Relationship between increase in yield of active enzyme in the clones and improvement
in its stability was observed among the mutants obtained in the present study. The clone harboring the best mutant 2R4 (G41E/T110P/K173M/Y195F/P201S/N218I)
selected in via second-round mutagenesis after optimal recombinating of first-round mutations produced 130-fold higher amount
of mutant enzyme than the transformant with wild-type EG III. Mutant 2R4 produced by the clone showed broad pH stability (4.4–8.8)
and thermotolerance (entirely active at 55°C for 30 min) compared with those of the wild-type EG III (pH stability, 4.4–5.2;
thermostability, inactive at 55°C for 30 min). k
cat of 2R4 against carboxymethyl-cellulose was about 1.4-fold higher than that of the wild type, though the K
m became twice of that of the wild type. 相似文献