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The effect of five constant temperatures (16, 20, 24, 28 and 32 °C) on the development, survival and reproduction of Tetranychus cinnabarinus (Boisduval) [=?Tetranychus urticae Koch (red form)] fed on cassava leaves was examined in the laboratory at 85% relative humidity. Development time of various immature stages decreased with increasing temperature, with total egg-to-adult development time varying from 27.7 to 6.7 days. The lower thermal threshold for development was 10.8 °C and the thermal constant from egg to adult was 142.4 degree-days. Pre- and post-oviposition period and female longevity all decreased as temperature increased. The longest oviposition period was observed at 20 °C with 20.4 days. Under different temperatures, mated females laid, on average, 1.0, 2.9, 4.7, 4.7 and 4.9 eggs per day, respectively. The maximum fecundity (81.5 eggs per female) was at 28 °C and the intrinsic rate of increase (r m ) was highest (0.25) at 32 °C. The results of this study indicate that T. cinnabarinus population could increase rapidly when cassava leaves serve as a food source. At the appropriate temperature T. cinnabarinus could seriously threaten growth of cassava.  相似文献   

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A Gram-stain negative, ovoid or short rod-shaped, aerobic and non-motile bacterial strain, designated J82T, was isolated from a seawater sample collected from the coast of Yellow Sea in Qingdao, China. The strain grew at salinities of 1.0–6.0% (w/v) NaCl (optimum, 2.5%). Growth occurred at pH 6.0-8.0 (optimum, pH 7.0) and 10–42 °C (optimum, 28–30 °C). The genomic DNA G + C content was determined to be 57.5 mol%. Q-10 was detected as the respiratory quinone. The major fatty acid (>10%) was Summed feature 8 (C18:1 ω7c and/or C18:1 ω6c). The polar lipids consisted of phosphatidylethanolamine, two unidentified aminolipids and two unidentified polar lipids. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain J82T forms a distinct evolutionary lineage within the family Rhodobacteraceae. On the basis of phenotypic, chemotaxonomic and phylogenetic characteristics, the strain merits recognition as representative of a novel genus and species within the family Rhodobacteraceae for which the name Rubricella aquisinus gen. nov., sp. nov. is proposed. The type strain of Rubricella aquisinus is J82T (= DSM 103377T = CCTCC AB 2016170T).  相似文献   

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A newly isolated Pseudomonas fragi P121 strain in a soil sample taken from the Arctic Circle is able to produce trehalose. The P121 strain was able to grow at temperatures ranging from 4 to 25 °C, had an optimum pH of 6.5, and an optimum salt concentration of 2 %. The P121 strain had a survival rate of 29.1 % after being repeatedly frozen and thawed five times, and a survival rate of 78.9 % when placed in physiological saline for 15 days at 20 °C after cold shock, which is far higher than the type strain Pseudomonas fragi ATCC 4973. The P121 strain could produce 2.89 g/L trehalose, which was 18.6 % of dry cell weight within 52 h in a 25 L fermention tank using the malt extract prepared from barley as medium at 15 °C, while only 11.8 % of dry cell weight at 20 °C. These results suggested that cold stress promoted the strain producing trehalose. It is the first reported cold-tolerant bacterium that produces trehalose, which may protect cells against the cold environment.  相似文献   

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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   

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I examined the effects of growth temperature and winter duration on the leaf phenology of Fauria crista-galli plants, which have an indeterminate growth habit. After a 220-day chilling treatment, the leaf expansion and green periods of plants maintained at 25/20°C were much longer than those of plants maintained at 15/10°C and of plants at the natural habitat obtained in a previous study. The results indicate that early growth cessation and early leaf senescence in the natural habitat are not only due to endogenous rhythm but determined to some extent by cool summer temperatures. When grown at 15/10°C, the green period of individual leaves and plants was much shorter after a long chilling treatment (220 days) than after a short chilling treatment (110 days). The plants sprouted during or immediately after the termination of chilling treatment, suggesting that the decrease in the green period results partly from an advance of endogenous developmental stages during the chilling treatment and that the timing of snowmelt potentially affects the time of leaf senescence in the natural habitat.  相似文献   

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A linear model and three nonlinear models (Logan type III, Lactin and Brière) were applied to Macrolophus pygmaeus (Rambur) (Hemiptera: Miridae) at constant temperatures and validated under diel temperature variation, and field conditions. Complete development from egg to adult, with >80% survivorship, occurred at nine constant temperatures between 15 and 32 °C. Total developmental time decreased from a maximum at 15 °C (68.48 days) to a minimum at 30 °C (18.69 days) and then increased at 32 °C (23.44 days). Optimal survival and the highest developmental rate occurred within the range of 27–30 °C. The adjusted determination coefficients were high for linear and nonlinear models (>0.89). Field validation showed high levels of accuracy in all models (≥93.4%). These valid mathematical models contribute to optimal application, field management, and mass rearing of M. pygmaeus for its applicability to biological control.  相似文献   

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We investigated chilling-induced changes in ethylene levels in Arabidopsis to find plants with distinct patterns of ethylene production in the cold-related biosynthetic pathway. The sensitive mutants identified here includedchs1-2,chs4-2, andchs6-2. Among these, plants of thechs4-2 mutant produced more ethylene than did the wild type after both were transferred from 4°C or 10°C to 22°C. This mutant also showed less freezing tolerance and more electrolyte leakage than the wild-type plants. Our results suggest a relationship between ethylene biosynthesis and chilling sensitivity in the mutant To determine which of the enzymes involved in ethylene biosynthesis were induced by chilling, we tested the activities of ACC synthase and ACC oxidase in both mutant and wild-type plants, and found greater activity by ACC synthase as well as a higher ACC content in the mutants after all the plants were transferred from 10°C to 22°C. However, ACC oxidase activity did not differ between mutant and wild-type plants in response to chilling treatment Therefore, we conclude thatchs4-2 mutants produce more ethylene than do other mutants or the wild type during their recovery from chilling conditions. Furthermore, we believe that ACC synthase is the key enzyme involved in this response.  相似文献   

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Two new species, Talaromyces heiheensis from rotten wood and T. mangshanicus isolated from soil, are illustrated and described as new to science in sections Trachyspermi and Talaromyces. The phylogenetic positions of the two new species inferred from the internal transcribed spacer, beta-tubulin, calmodulin and RNA polymerase II second largest subunit regions were carried out. Talaromyces heiheensis is phylogenetically closely related to T. albobiverticillius, T. rubrifaciens, T. solicola and T. erythromellis, and characterised by slow growth on Czapek yeast autolysate agar at 25 °C, orange conidia en masse on malt extract agar at 25 °C, biverticillate and terverticillate conidiophores, acerose phialides and subglobose to ellipsoidal, smooth-walled conidia. Talaromyces mangshanicus is related to T. kendrickii, T. qii and T. thailandensis, and characterised by slow-growing colonies with absent or sparse sporulation on CYA agar at 25 °C, conidia en masse greyish purple, purplish red soluble pigment on yeast extract agar (YES) at 25 °C, biverticillate conidiophores, ampulliform phialides and subglobose to ellipsoidal conidia with echinulate walls. They are distinguished from the known species in culture characteristics on four standard media, microscopic features and sequence data.  相似文献   

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Many phytopathogenic micro-organisms such as bacteria and fungi produce pectin methylesterases (PME) during plant invasion. Plants and insects also produce PME to degrade plant cell wall. In the present study, a thermostable pectin methylesterase (CtPME) from Clostridium thermocellum belonging to family 8 carbohydrate esterase (CE8) was cloned, expressed and purified. The amino acid sequence of CtPME exhibited similarity with pectin methylesterase from Erwinia chrysanthemi with 38% identity. The gene encoding CtPME was cloned into pET28a(+) vector and expressed using Escherichia coli BL21(DE3) cells. The recombinant CtPME expressed as a soluble protein and exhibited a single band of molecular mass approximately 35.2 kDa on SDS-PAGE gels. The molecular mass, 35.5 kDa of the enzyme, was also confirmed by MALDI-TOF MS analysis. Notably, highest protein concentration (11.4 mg/mL) of CtPME was achieved in auto-induction medium, as compared with LB medium (1.5 mg/mL). CtPME showed maximum activity (18.1 U/mg) against citrus pectin with >85% methyl esterification. The optimum pH and temperature for activity of CtPME were 8.5 and 50 °C, respectively. The enzyme was stable in pH range 8.0–9.0 and thermostable between 45 and 70 °C. CtPME activity was increased by 40% by 5 mM Ca2+ or Mg2+ ions. Protein melting curve of CtPME gave a peak at 80 °C. The peak was shifted to 85 °C in the presence of 5 mM Ca2+ ions, and the addition of 5 mM EDTA shifted back the melting peak to 80 °C. CtPME can be potentially used in food and textile industry applications.  相似文献   

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Seed responses to temperature are often essential to the study of germination ecology, but the ecological role of temperature in orchid seed germination remains uncertain. The response of orchid seeds to cold stratification have been studied, but the exact physiological role remains unclear. No studies exist that compare the effects of either cold stratification or temperature on germination among distant populations of the same species. In two separate experiments, the role of temperature (25, 22/11, 27/15, 29/19, 33/24°C) and chilling at 10°C on in vitro seed germination were investigated using distant populations of Calopogon tuberosus var. tuberosus. Cooler temperatures promoted germination of Michigan seeds; warmer temperatures promoted germination of South Carolina and north central Florida seeds. South Florida seed germination was highest under both warm and cool temperatures. More advanced seedling development generally occurred at higher temperatures with the exception of south Florida seedlings, in which the warmest temperature suppressed development. Fluctuating diurnal temperatures were more beneficial for germination compared to constant temperatures. Cold stratification had a positive effect on germination among all populations, but South Carolina seeds required the longest chilling treatments to obtain maximum germination. Results from the cold stratification experiment indicate that a physiological dormancy is present, but the degree of dormancy varies across the species range. The variable responses among populations may indicate ecotypic differentiation.  相似文献   

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Pink bollworm (Pectinophora gossypiella) is recognized as an important pest of cotton and can damage flowers and bolls of both Bt and non-Bt cultivars. Cry-1Ac in Bt cultivars is considered very effective in controlling lepidopterous larvae; therefore, the present study was carried out to investigate the impact of Cry1-Ac and the earliness index on the natural incidence of P. gossypiella at the Cotton Research Institute, Faisalabad. During 2015–2016, ten cultivars were used to determine the incidence of pink bollworm infestation. The experiment was repeated for 2 years. During the next year, Cry1-Ac and earliness traits of selected cultivars were also observed to determine their impact on pink bollworm. Correlation coefficient results regarding days to first flower (r value = 0.66) as well as the earliness index (r value = ? 0.62) exhibited a strong association with pink bollworm, but Cry1-Ac had a weak association (r value = ? 0.058) with pink bollworm. The coefficient of determination (R 2) explained that variability of pink bollworm due to Cry1-Ac, the earliness index, and days to first flower was 18.0, 38.5, and 43.5%, respectively. Principal component analysis results showed that the first two PCs expressed 87% of the total variability. Clusters made on the basis of the studied parameters revealed that clusters 2 and 3 comprised the cotton cultivars possessing earliness traits compared with cluster 1. Therefore, it can be concluded that the earliness index in cotton is an important component for the sustainable management of pink bollworm infestation, the need for which is endless to evade the pink bollworm problem in the era of climate change.  相似文献   

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The objective of this research was to induce mitotic chromosome doubling in Anemone sylvestris L. The mitosis inhibitor oryzalin was directly added to the induction medium at 1, 2, 5, 10 and 15 μM for 8, 10 or 12 weeks of cultivation. Three tetraploid plants (2n?=?4x?=?32), 0.8% (polyploidization efficiency), were obtained from diploid plants (2n?=?2x?=?16) in three treatments (1 μM for 10 weeks, 5 μM for 8 weeks and 8 μM for 10 weeks). Ploidy level was confirmed by flow cytometry. Morphological characteristics (e.g. flower diameter, total plant height, leaf area) and chlorophyll content differences between diploid and tetraploid A. sylvestris were observed together with polyphenol content and antioxidant activity. The inter primer binding sites markers were used for evaluation of polymorphism. New genotypes with different morphological and biological characteristics were obtained through somatic polyploidization. The tetraploid plants were stronger, more vigorous and had an early flowering, which is essential for its use as an ornamental plant. The iPBS analysis showed unique amplicons that can be used for the purposes of molecular identification of tetraploid plants of A. sylvestris in the future. The results demonstrate the first report of in vitro induction of tetraploids of A. sylvestris.  相似文献   

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Vigna unguiculata (cowpea) is a legume adapted to high temperatures and is sensitive to low temperatures. Temperature is one of the limiting factors of growth and yield for many crops but its effect on cowpea metabolism is not known. We investigated the effect of chilling on activity of vacuolar proton pumps (V-ATPase and V-PPase) and their protein content in tonoplast vesicles of cowpea hypocotyls. Seedlings grown for 7 days at 10 or 4°C were used for experiments. Chilling treatment at 10 or 4°C markedly suppressed growth of cowpea seedlings. Following chilling at 10 and 4°C, activity of both proton pumps and the relative amount of V-PPase and subunit A of V-ATPase were significantly increased. Both substrate hydrolysis and H+ transport activities of V-PPase remained at relatively high levels during chilling treatment. For V-ATPase, treatment at 10°C for 6 days increased the ATP hydrolysis activity. However, the H+ transport activity of the enzyme was increased when treated for 4 days but was markedly decreased when treated for 6 days. Our results provide evidence for different regulation for these vacuolar proton pumps, indicating that V-PPase is the more stable proton pump throughout chilling stress.  相似文献   

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Plectosphaerella cucumerina (Lindf.) W. Gams was evaluated as a bioherbicide for Cirsium arvense L. (Scop.) using a Canadian and a New Zealand isolate. Both isolates defoliated C. arvense when applied at 1013 conidia ha?1 in water volumes ranging from 250 to 6400 l ha?1 with a rapid decline in effect with declining conidial dose. Repeat application and the addition of the adjuvant Pulse® penetrant to the conidial suspension increased the disease severity in C. arvense. Maximum disease occurred at 20 °C with a 48 h post-application dew period. The experiments demonstrate that P. cucumerina can defoliate C. arvense under the environmental conditions of temperate pastures where the weed is problematic. The results also show that modifications to formulation and strategic application may reduce the 48 h dew period requirement and risk to non-target species respectively, supporting the conclusion that the fungus has potential as a bioherbicide for C. arvense.  相似文献   

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Characteristics and gel properties of gelatin from frog skin as influenced by extraction temperatures (45–75 °C) were investigated. Yield of gelatin increased as the extraction temperature increased (P < 0.05). All gelatins contained α- and β-chains as the predominant components and showed a high imino acid content (215 residues/1000 residues). Fourier transform infrared (FTIR) spectra indicated that all gelatin samples had major peaks in amide regions. Gelatin extracted at 55 °C exhibited the highest gel strength (P < 0.05), which was similar to that of commercial bovine gelatin (P > 0.05). Gelling and melting temperatures of frog skin gelatin were 23.47–24.87 and 33.22–34.66 °C, respectively. Gels became more yellowish with increasing extraction temperatures (P < 0.05). All gelatin gels were sponge or coral-like in structure but varied in patterns as visualized by scanning electron microscopy (SEM). Gelatin from frog skin could be used as a replacement for land animal counterpart.  相似文献   

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We previously reported that expression and activity of acid invertases (AI) are increased in peach fruit under chilling stress. In order to determine which AI genes respond to chilling stress, seven AI genes, two vacuolar invertases (VINs) and five cell wall-bound invertases (CWINs), were identified and cloned. The predicted amino acid sequences of the genes contain conserved sites characteristic of plant AIs such as NDPNG/A, the sucrose-binding site, and MWECV/P, a cysteine catalytic motif. Using gene-specific primers, the expression of each gene was measured in ‘Baifeng’ and ‘Yulu’ peach fruits stored at 0, 5, 10 and 20 °C. Of the seven genes, expression of PpVIN2 was the most affected by chilling stress; the largest increases were in fruit stored at 5 °C, up to 17-fold in ‘Baifeng’ fruit, and up to 280-fold in ‘Yulu’ fruit. Overall, VIN activity was much higher than CWIN activity in stored peach fruit. In both cultivars reducing sugar content increased significantly and sucrose content decreased gradually during storage at 5 °C relative to other temperatures, and was accompanied by severe chilling injury symptoms. Thus, PpVIN2 appears to be induced by chilling and may play an important role in sucrose metabolism in peach fruit subjected to cold storage.  相似文献   

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