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1.
Temperature response curves of chlorophyll a fluorescence parameters were used to assess minimum sub-zero temperature assuring functioning of photosynthetic photochemical
processes in photosystem II (PS II) of Antarctic lichens. Umbilicaria Antarctica and Xanthoria elegans were measured within the temperature range from −20 to +10°C by a fluorometric imaging system. For potential (F
V/F
M) and actual (Φ
II) quantum yields of photochemical processes the minimum temperature was found to be between −10 and −20°C. Non-photochemical
quenching (NPQ) of absorbed excitation energy increased with temperature drop reaching maximum NPQ at −15°C. Image analysis
revealed intrathalline heterogeneity of chlorophyll a fluorescence parameters with temperature drop. Temperature response of Φ
II exhibited an S-curve with pronounced intrathalline differences in X. elegans. The same relation was linear with only limited intrathalline difference in U. antarctica. The results showed that Antarctic lichen species were well adapted to sub-zero temperatures and capable of performing primary
photosynthesis at −15°C. 相似文献
2.
Wen-Jun Wang Fei-Jiu Wang Jian-Yi Zhu Xiu-Tao Sun Chun-Yan Yao Pu Xu 《Journal of applied phycology》2011,23(6):1017-1022
In January and February 2010, heavy sea ice formed along the coast of the Bohai Sea and the northern Yellow Sea, China. Intertidal
organisms were subjected to serious freezing stress. In this study, we investigated the freezing tolerance of the upper intertidal
economic seaweed Porphyra yezoensis. The maximum photochemical efficiency of PS II (F
v/F
m) in undehydrated thalli remained high after 24 h at −2°C and that in dehydrated thalli decreased in a proportion to thallial
water loss. F
v/F
m dropped sharply after 24 h at −20°C, regardless of absolute cellular water content (AWC). The F
v/F
m in frozen thalli recovered rapidly at 0–20°C. A wide range of water loss in the thalli enhanced their tolerance to freezing.
F
v/F
m values in undehydrated thalli dropped sharply after 3 d at −2°C or 10 d at −20°C while those in dehydrated thalli (20–53%
AWCs) remained at high levels after 9 d at −2°C or 30 d at −20°C. These results indicate that P. yezoensis has high freezing tolerance by means of dehydration during the ebb tide and rapid recovery of F
v/F
m from freezing. A strategy of P. yezoensis industry to avoid heavy loss during freezing season is discussed based on these findings. 相似文献
3.
M. Gomathy M. Thangaraju S. Gunasekaran N. O. Gopal 《Indian journal of microbiology》2007,47(3):259-262
Sporulation in Bacillus megaterium var phosphaticum (PB — 1) was induced using modified nutrient media. This modified medium induced sporulation within 36 h. After spore induction
the spores were kept under refrigerated (5°C) and room temperature (32°C) for five months and survival of spores was studied
at 15 days intervals by plating them in nutrient agar medium. It was observed that there was not much variation in the storage
temperature (5°C & 32°C). The spore cells of Bacillus megaterium var phosphaticum (PB — 1) were observed up to five months of storage under refrigerated (5°C) and room temperature (32°C). Regeneration of
spore cells into vegetative cells was studied in tap water, rice gruel, nutrient broth, sterile lignite and sterile water
at different concentrations of spore inoculum. The multiplication of sporulated Bacillus megaterium var phosphaticum culture was fast and reached its maximum (29.5 × 108 cfu ml−1) in nutrient broth containing 5 per cent inoculum level. 相似文献
4.
Four temperature treatments were studied in the climate controlled growth chambers of the Georgia Envirotron: 25/20, 30/25,
35/30, and 40/35 °C during 14/10 h light/dark cycle. For the first growth stage (V3-5), the highest net photosynthetic rate
(P
N) of sweet corn was found for the lowest temperature of 28–34 μmol m−2 s−1 while the P
N for the highest temperature treatment was 50–60 % lower. We detected a gradual decline of about 1 P
N unit per 1 °C increase in temperature. Maximum transpiration rate (E) fluctuated between 0.36 and 0.54 mm h−1 (≈5.0–6.5 mm d−1) for the high temperature treatment and the minimum E fluctuated between 0.25 and 0.36 mm h−1 (≈3.5–5.0 mm d−1) for the low temperature treatment. Cumulative CO2 fixation of the 40/35 °C treatment was 33.7 g m−2 d−1 and it increased by about 50 % as temperature declined. The corresponding water use efficiency (WUE) decreased from 14 to
5 g(CO2) kg−1(H2O) for the lowest and highest temperature treatments, respectively. Three main factors affected WUE, P
N, and E of Zea: the high temperature which reduced P
N, vapor pressure deficit (VPD) that was directly related to E but did not affect P
N, and quasi stem conductance (QC) that was directly related to P
N but did not affect E. As a result, WUE of the 25/20 °C temperature treatment was almost three times larger than that of 40/35 °C temperature treatment. 相似文献
5.
Luana Quassinti Daniela Pellegrino Filippo Garofalo Ennio Maccari Massimo Bramucci 《Polar Biology》2009,32(5):673-677
Biochemical parameters of the angiotensin converting enzyme-like activity (ACELA) in the gills of two Antarctic teleosts,
Chionodraco hamatus and Trematomus bernacchii were characterized. Enzymatic activity was revealed following hydrolysis of a specific substrate of angiotensin-converting
enzyme N-[3-(2-furyl)acryloyl]l-phenylalanyl-glycyl-glycine (FAPGG) and metabolites were separated by reverse phase HPLC analysis. The results showed similar
Km values for the substrate FAPGG at 5°C for the two species with an increase of Km value for T. bernacchii at 25°C. The optimum pH value was 8.5 at 25°C and optimum chloride concentrations were about 300 mM. In T. bernacchii the optimum temperature for maximum enzyme activity was 50°C, while maximum activity in C. hamatus occurred at 35°C. Lisinopril was more efficient in inhibiting ACELA in C. hamatus with an I
50 value of 16.83 ± 5.11 nM, compared to an I
50 value of 30.66 ± 5.19 nM in T. bernacchii. In conclusion, it appears that some biochemical parameters of ACELA in C. hamatus differ from those in T. bernacchii, probably due to different ways that the enzyme adapts to the constantly cold temperatures of the animal’s environment. 相似文献
6.
Jin Zhou Ju Chu Yong-Hong Wang Si-Liang Zhang Ying-Ping Zhuang Zhong-Yi Yuan 《World journal of microbiology & biotechnology》2008,24(6):789-796
An intracellular S-adenosylmethionine synthetase (SAM-s) was purified from the fermentation broth of Pichia pastoris GS115 by a sequence chromatography column. It was purified to apparent homogeneity by (NH4)2SO4 fractionation (30–60%), anion exchange, hydrophobic interaction, anion exchange and gel filtration chromatography. HPLC showed
the purity of purified SAM-s was 91.2%. The enzyme was purified up to 49.5-fold with a final yield of 20.3%. The molecular
weight of the homogeneous enzyme was 43.6 KDa, as determined by electro-spray ionization mass spectrometry (ESI-MS). Its isoelectric
point was approximately 4.7, indicating an acidic character. The optimum pH and temperature for the enzyme reaction were 8.5
and 35 °C, respectively. The enzyme was stable at pH 7.0–9.0 and was easy to inactivate in acid solution (pH ≤ 5.0). The temperature
stability was up to 45 °C. Metal ions, such as, Mn2+ and K+ at the concentration of 5 mM had a slight activation effect on the enzyme activity and the Mg2+ activated the enzyme significantly. The enzyme activity was strongly inhibited by heavy metal ions (Cu2+ and Ag2+) and EDTA. The purified enzyme from the transformed Pichia pastoris synthesized S-adenosylmethionine (SAM) from ATP and l-methionine in vitro with a K
m of 120 and 330 μM and V
max of 8.1 and 23.2 μmol/mg/min for l-methionine and ATP, respectively. 相似文献
7.
Ling Zhao Yongming Bao Jingyun Wang Boshi Liu Lijia An 《World journal of microbiology & biotechnology》2009,25(1):57-64
A mutant designated as UV-3 was obtained from wild-type Enterobacter aerogenes 10293 through u.v. radiation. The activities of α-acetolactate decarboxylase (Ald), lactate dehydrogenase (Ldh) and diacetyl
reductase (Dr) in UV-3 were strongly attenuated, with the lowest activities at pH 7.0–7.5, and temperature between 36 and
39°C. Compared to the wild-type, the yield of diacetyl by UV-3 was increased 18.7-fold, up to 1.05 ± 0.01 g l−1. Acetoin and ethanol productions were decreased by 48.4 and 71.4%, respectively, but acetate yield was increased by 34.6%.
Optimum medium for diacetyl production by UV-3 contained 10% glucose, 0.5% peptone, 0.5% yeast extract powder, 0.01% (NH4)2SO4, 0.1% citric acid, 0.2% MnSO4 and 0.2% MgSO4, and this was determined by one-factor-at-a-time approach. Data from the five level central composite designs demonstrated
that initial pH of 7.0, temperature of 37°C and rotational speed of 180 rev/min were optimum processing parameters for diacetyl
production. The maximum yield of diacetyl could reach 1.35 g l−1 in a 5-l bioreactor. These results showed an enhancement of the non-enzymatic oxidative decarboxylation of α-acetolactate
and a decrease in the activities of Ald, Ldh and Dr as a consequence of diacetyl accumulation in UV-3. 相似文献
8.
Two experiments were performed to determine how application of the cytokinin benzyladenine (BA) influenced flowering in Doritaenopsis and Phalaenopsis orchid clones. In the first experiment, two vegetative orchid clones growing in 15-cm pots were transferred from a 28°C greenhouse
that inhibited flowering to a 23°C greenhouse for flower induction (day 0). A foliar spray (0.2 L m−2) containing BA at 100, 200, or 400 mg L−1 or 25, 50, or 100 mg L−1 each of BA and gibberellins A4 + A7 (BA+GA) was applied on days 0, 7, and 14. Plants treated with BA alone at 200 or 400 mg L−1 had a visible inflorescence 3–9 days earlier and had a mean of 0.7–3.5 more inflorescences and 3–8 more flowers per plant
than nontreated plants. The application of BA+GA had no effect on inflorescence number and total flower number at the rates
tested. In the second experiment, three orchid clones received a single foliar spray of BA at 200 mg L−1 at six time points relative to time of transfer from 29°C to 23°C (−1, 0, +1, +2, +4, or +6 weeks). A separate group of plants
received a BA application at week 0 but was maintained at 29°C. Inflorescence number was greatest in all three orchid clones
when plants were treated with BA 1 week after the temperature transfer. Plants that were sprayed with BA and maintained at
29°C did not initiate inflorescences. The promotion of flowering by the application of BA suggests that cytokinins at least
partially regulate inflorescence initiation of Doritaenopsis and Phalaenopsis, but its promotion is conditional and BA application cannot completely substitute for an inductive low temperature. 相似文献
9.
Involvement of betacyanin in chilling-induced photoinhibition in leaves of <Emphasis Type="Italic">Suaeda salsa</Emphasis> 总被引:1,自引:0,他引:1
Seeds of Suaeda salsa were cultured in dark for 3 d and betacyanin accumulation in seedlings was promoted significantly. Then the seedlings with
accumulated betacyanin (C+B) were transferred to 14/10 h light/dark and used for chilling treatment 15 d later. Photosystem
2 (PS2) photochemistry, D1 protein content, and xanthophyll cycle during the chilling-induced photoinhibition (exposed to
5 °C at a moderate photon flux density of 500 μmol m−2 s−1 for 3 h) and the subsequent restoration were compared between the C+B seedlings and the control (C) ones. The maximal efficiency
of PS2 photochemistry (Fv/Fm), the efficiency of excitation energy capture by open PS2 centres (Fv′/Fm′), and the yield of PS2 electron transport (ΦPS2) of the C+B and C leaves both decreased during photoinhibition. However, smaller decreases in Fv/Fm, Fv′/Fm′, and ΦPS2 were observed in the C+B leaves than in C ones. At the same time, the deepoxidation state of xanthophyll cycle, indicated
by (A+Z)/(V+A+Z) ratio, increased rapidly but the D1 protein content decreased considerably during the photoinhibition. The
increase in rate of (A+Z)/(V+A+Z) was higher but the D1 protein turnover was slower in C+B than C leaves. After photoinhibition
treatment, the plants were transferred to a dim irradiation (10 μmol m−2 s−1) at 25 °C for restoration. During restoration, the chlorophyll (Chl) fluorescence parameters, D1 protein content, and xanthophyll
cycle components relaxed gradually, but the rate and level of restoration in the C+B leaves was greater than those in the
C leaves. The addition of betacyanins to the thylakoid solution in vitro resulted in similar changes of Fv/Fm, D1 protein content, and (A+Z)/(V+A+Z) ratio during the chilling process. Therefore, betacyanin accumulation in S. salsa seedlings may result in higher resistance to photoinhibition, larger slowing down of D1 protein turnover, and enhancement
of non-radiative energy dissipation associated with xanthophyll cycle, as well as in greater restoration after photoinhibition
than in the control when subjected to chilling at moderate irradiance. 相似文献
10.
The cytochrome b
6
f (Cyt b
6
f) complex, which functions as a plastoquinol-plastocyanin oxidoreductase and mediates the linear electron flow between photosystem
II (PSII) and photosystem I (PSI) and the cyclic electron flow around PSI, was isolated from spinach (Spinacia oleracea L.) chloroplasts using n-octyl-β-D-glucopyranoside (β-OG). The preparation was also able to catalyze the peroxidase-like reaction in the presence
of hydrogen peroxide (H2O2) and guaiacol. The optimal conditions for peroxidase activity of the preparation included: pH 3.6, ionic strength 0.1, and
temperature 35°C. The apparent Michaelis constant (K
m) values for H2O2 and guaiacol were 50 mM and 2 mM, respectively. The bimolecular rate constant (k
obs) was about 26 M−1 s−1 and the turnover number (K
cat) was about 60 min−1 (20 mM guaiacol, 100 mM sodium phosphate, pH 3.6, 25°C, [H2O2]<100mM). These parameters were similar to those of several other heme-containing proteins, such as myoglobin and Cyt c. 相似文献
11.
The present paper reports a protocol for minimum growth conservation of Drosophyllum lusitanicum (L.) Link. in vitro. Double-node cuttings were maintained for 4, 8 and 12 months at 5 or 25 °C in the dark. The effects of sucrose either alone
at 5, 20, 30, 40 and 60 g dm−3 or at 20, 40 and 60 g dm−3 in combination with 20 g dm−3 mannitol, on survival and post-storage shoot multiplication efficiency were investigated. The cultures could effectively
be conserved under minimum growth at 5 °C for 8 months on Murashige and Skoog’s medium supplemented with 60 g dm−3 sucrose, 20 g dm−3 mannitol and 0.91 μM zeatin. Following extended conservation, the cultures could be successfully regenerated into new shoots,
and they were morphologically similar to those of non-stored controls. 相似文献
12.
Double d-amino acid oxidases (dRtDAO and dTvDAO) were previously genetically constructed by linking the C-terminus of one subunit
of their corresponding native DAOs from Rhodosporidium toruloides and Trigonopsis variabilis (RtDAO and TvDAO) to the N-terminus of the other identical subunit. We have now immobilized these double DAOs and their native
counterparts onto streptavidin-coated magnetic beads through the interaction between biotin and streptavidin. The catalytic
efficiencies (kcat/KM) of immobilized DAOs toward d-alanine and cepharosporin C remained similar to those of their soluble forms, except the catalytic efficiency of immobilized
TvDAO toward d-alanine was decreased by 56%. After immobilization, the Tm value for RtDAO was shifted 15°C higher to 60°C, while those for dRtDAO, TvDAO and dTvDAO were increased by 5–8°C to 56,
60 and 60°C, respectively. In the presence of 10 mM H2O2, immobilized RtDAO, dRtDAO, TvDAO and dTvDAO exhibited half-lives of about 8, 10, 3 and 5 h, respectively, giving 16-, 10-,
6- and 7-fold greater stability than their soluble forms, respectively. Therefore, immobilization through biotin–streptavidin
affinity binding enhances the thermal and oxidative stability of native and double DAOs studied, especially RtDAO. The additive
stabilizing effect of subunit fusion and immobilization was more pronounced in the case of RtDAO than TvDAO. 相似文献
13.
An SJ Pandeya D Park SW Li J Kwon JK Koeda S Hosokawa M Paek NC Choi D Kang BC 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2011,122(3):459-470
A temperature-sensitive mutant of Capsicum chinense, sy-2, shows a normal developmental phenotype when grown above 24°C. However, when grown at 20°C, sy-2 exhibits developmental defects, such as chlorophyll deficiency and shrunken leaves. To understand the underlying mechanism
of this temperature-dependent response, phenotypic characterization and genetic analysis were performed. The results revealed
abnormal chloroplast structures and cell collapse in leaves of the sy-2 plants grown at 20°C. Moreover, an excessive accumulation of reactive oxygen species (ROS) resulting in cell death was detected
in the chlorophyll-deficient sectors of the leaves. However, the expression profile of the ROS scavenging genes did not alter
in sy-2 plants grown at 20°C. A further analysis of fatty acid content in the leaves showed the impaired pathway of linoleic acid
(18:2) to linolenic acid (18:3). Additionally, the Cafad7 gene was downregulated in sy-2 plants. This change may lead to dramatic physiological disorder and alteration of leaf morphology in sy-2 plants by losing low-temperature tolerance. Genetic analysis of an F2 population from a cross between C. chinense ‘sy-2’ and wild-type C. chinense ‘No. 3341’ showed that the sy-2 phenotype is controlled by a single recessive gene. Molecular mapping revealed that the sy-2 gene is located at a genomic region of the pepper linkage group 1, corresponding to the 300 kb region of the Ch1_scaffold
00106 in tomato chromosome 1. Candidate genes in this region will reveal the identity of sy-2 and the underlying mechanism of the temperature-dependent plant response. 相似文献
14.
Martin Bačkor Jozef Kováčik Alexander Dzubaj Miriam Bačkorová 《Plant Growth Regulation》2009,58(3):279-286
Peltigera rufescens (Weis) Humb. with a prokaryotic photobiont Nostoc sp. and Cladina arbuscula subsp. mitis (Sandst.) Ruoss with a eukaryotic photobiont Trebouxia sp. were studied to determine the copper sensitivity of lichens with different algal symbionts. Samples growing on historic
copper mine-spoil heaps at Ľubietová–Podlipa, Slovakia were assessed for physiological parameters, including total and intracellular
uptake of copper, assimilation pigmentation, activity of photosystem II, ergosterol levels, thiobarbituric acid reactive substances
and water-soluble protein content. Our results indicate that P. rufescens was more sensitive to copper exposure than C. arbuscula subsp. mitis. 相似文献
15.
The marcoalga Ulva pertusa was cultured under (20 ± 2)°C, (20 ± 4)°C, (20 ± 6)°C, (20 ± 8)°C and (20 ± 10)°C circadian rhythms of fluctuating temperature
conditions, and constant temperature of 20°C was used as the control. The growth rate of macroalga at (20 ± 2)°C, (20 ± 4)°C
and (20 ± 6)°C were significantly higher than that at constant temperature of 20°C, while growth rate at (20 ± 8)°C and (20
± 10)°C were significantly lower than that at constant temperature of 20°C. The growth rate of macroalga was a quadratic function
of the thermal amplitude. Such a growth model can be described by G = β
0 + β
1(TA) + β
2(TA)2, where G represents the relative growth rate, TA is thermal amplitude in degree Celsius, β
0 is the intercept on the G axis, and β
1 and β
2 are the regression coefficients. The optimal thermal amplitude for the growth of thallus at mean temperature of 20°C was
estimated to be ± 3.69°C. Analysis of biochemical composition at the final stages of thaulls growth revealed that diel fluctuating
temperature caused various influences (P < 0.05). The content of chlorophyll, protein and total solute carbohydrate at (20 ± 2)°C and (20 ± 4)°C were slightly higher
than those at constant temperature of 20°C, however no statistically significant differences were found among them (P > 0.05). While osmolytes (total solute carbohydrate and free proline) at (20 ± 10)°C were significantly higher than that at
20°C (P < 0.05). Therefore, more chlorophyll and carbohydrate production might account for the enhancement in the growth of macroalga
at the diel fluctuating temperatures in the present study.
Handling editor: S. M. Thomaz 相似文献
16.
Qi LL Pumphrey MO Friebe B Zhang P Qian C Bowden RL Rouse MN Jin Y Gill BS 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2011,123(1):159-167
Stem rust (Puccinia graminis f. sp. tritici Eriks. & E. Henn.) (the causal agent of wheat stem rust) race Ug99 (also designated TTKSK) and its derivatives have defeated
several important stem rust resistance genes widely used in wheat (Triticum aestivum L.) production, rendering much of the worldwide wheat acreage susceptible. In order to identify new resistance sources, a
large collection of wheat relatives and genetic stocks maintained at the Wheat Genetic and Genomic Resources Center was screened.
The results revealed that most accessions of the diploid relative Dasypyrum villosum (L.) Candargy were highly resistant. The screening of a set of wheat–D. villosum chromosome addition lines revealed that the wheat–D. villosum disomic addition line DA6V#3 was moderately resistant to race Ug99. The objective of the present study was to produce and
characterize compensating wheat–D. villosum whole arm Robertsonian translocations (RobTs) involving chromosomes 6D of wheat and 6V#3 of D. villosum through the mechanism of centric breakage-fusion. Seven 6V#3-specific EST–STS markers were developed for screening F2 progeny derived from plants double-monosomic for chromosomes 6D and 6V#3. Surprisingly, although 6D was the target chromosome,
all recovered RobTs involved chromosome 6A implying a novel mechanism for the origin of RobTs. Homozygous translocations (T6AS·6V#3L
and T6AL·6V#3S) with good plant vigor and full fertility were selected from F3 families. A stem rust resistance gene was mapped to the long arm 6V#3L in T6AS·6V#3L and was designated as Sr52. Sr52 is temperature-sensitive and is most effective at 16°C, partially effective at 24°C, and ineffective at 28°C. The T6AS·6V#3L
stock is a new source of resistance to Ug99, is cytogenetically stable, and may be useful in wheat improvement. 相似文献
17.
18.
Using two different inbred lines of Momordica charantia (bitter gourd), Y-106-5 and Z-1-4, the cell membrane stability, leaf water potential, pigment contents and the chlorophyll
a fluorescence were investigated with different low night temperature (LNT) treatments over a 7 day time period and the sequent
a 7 day recovery. Under LNT treatments, electrolyte leakage increased in both inbred lines and it increased more significantly
in Y-106-5 plants than that in Z-1-4. The content of Chl b and total Chl decreased, while the Chl a/b ratio increased in stressed plants of the two lines. Almost all LNT treatments induced little change in Chl a content in Z-1-4 whereas obvious decreases in 5 and 8°C treated Y-106-5 plants were observed. Chilling changed the water
status of plants and induced decreases of leaf water potential (LWP) in 5 and 8°C treated plants. LNT treatments also resulted
in changes in the chlorophyll fluorescence parameters in bitter gourd leaves. The potential PSII activity (F
v/F
o) was reduced obviously by LNT stress and showed more sensitive to LNT than the maximum quantum efficiency of PSII primary
photochemistry (F
v/F
m). The efficiency of open PSII centers exhibited a slight decrease whereas the photochemical quenching efficient (q
P) was affected more seriously by LNT stress in both two inbred lines. The allocation of energy was rearranged by LNT stress.
The light fraction used for PSII photochemistry (P) was reduced, while that used for heat dissipation (D) and the third fraction
of absorbed light defines excess energy (E) increased due to the chilling stress. The impacts of LNT stress on bitter gourd
generally increased with the number of LNT chilling and the severe night chilling. Plants were little affected by 12°C night
chilling and the most acute damage was found in 5°C night chilling treatments. A 7 day recovery mitigated the adverse effects
of LNT for both lines and almost all LNT treated plants restored to control levels except 5°C night chilling treated Y-106-5
plants. The two lines have a variance in tolerance to LNT stress and display obvious differences of phenotypes under extreme
conditions. 相似文献
19.
The rpiB gene, encoding ribose-5-phosphate isomerase (RpiB) from Clostridium thermocellum, was cloned and expressed in Escherichia coli. RpiB converted d-psicose into d-allose but it did not convert d-xylose, l-rhamnose, d-altrose or d-galactose. The production of d-allose by RpiB was maximal at pH 7.5 and 65°C for 30 min. The half-lives of the enzyme at 50°C and 65°C were 96 h and 4.7 h,
respectively. Under stable conditions of pH 7.5 and 50°C, 165 g d-allose l−1
was produced without by-products from 500 g d-psicose l−1 after 6 h. 相似文献
20.
Twenty-three isolates of Metarhizium anisopliae (Metschnikoff) Sokorin and three isolates of Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales: Clavicipitaceae) were assessed for their virulence against the two-spotted
spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). Based on the screening results, nine isolates of M. anisopliae and two isolates of B. bassiana were tested for their virulence against young adult (1- to 2-day-old) female T. urticae at constant temperatures of 20, 25, 30 and 35°C. At all temperatures tested, all the fungal isolates were pathogenic to T. urticae but mortality varied with isolates and temperatures. Fungal isolates were more virulent at 25, 30 and 35°C than at 20°C.
The lethal time to 50% mortality (LT50) and lethal time to 90% mortality (LT90) values decreased with increased temperature. There were no significant differences in virulence between fungal isolates
at 30 and 35°C; however, significant differences were observed at 20 and 25°C. 相似文献