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931.
We present evidence that plant growth at elevated atmospheric CO2 increases the high‐temperature tolerance of photosynthesis in a wide variety of plant species under both greenhouse and field conditions. We grew plants at ambient CO2 (~ 360 μ mol mol ? 1) and elevated CO2 (550–1000 μ mol mol ? 1) in three separate growth facilities, including the Nevada Desert Free‐Air Carbon Dioxide Enrichment (FACE) facility. Excised leaves from both the ambient and elevated CO2 treatments were exposed to temperatures ranging from 28 to 48 °C. In more than half the species examined (4 of 7, 3 of 5, and 3 of 5 species in the three facilities), leaves from elevated CO2‐grown plants maintained PSII efficiency (Fv/Fm) to significantly higher temperatures than ambient‐grown leaves. This enhanced PSII thermotolerance was found in both woody and herbaceous species and in both monocots and dicots. Detailed experiments conducted with Cucumis sativus showed that the greater Fv/Fm in elevated versus ambient CO2‐grown leaves following heat stress was due to both a higher Fm and a lower Fo, and that Fv/Fm differences between elevated and ambient CO2‐grown leaves persisted for at least 20 h following heat shock. Cucumis sativus leaves from elevated CO2‐grown plants had a critical temperature for the rapid rise in Fo that averaged 2·9 °C higher than leaves from ambient CO2‐grown plants, and maintained a higher maximal rate of net CO2 assimilation following heat shock. Given that photosynthesis is considered to be the physiological process most sensitive to high‐temperature damage and that rising atmospheric CO2 content will drive temperature increases in many already stressful environments, this CO2‐induced increase in plant high‐temperature tolerance may have a substantial impact on both the productivity and distribution of many plant species in the 21st century. 相似文献
932.
The presented work was conducted on seedlings of spring barley and meadow fescue which differ in the degree of sensitivity
to leaf spot pathogen Bipolaris sorokiniana (Sacc.) Shoem. The seedling reaction to inoculation with mycelium and conidia was examined in glasshouse conditions on the
basis of respiration intensity and heat production. The leaf respiration was measured using Clark-type electrode, while heat
emission was evaluated by means of isotermic microcalorimeter. The measurements were performed after 1, 3, 6, 10, 24, 48,
72, 168 and 240 hours since the inoculation moment.
Leaves of meadow fescue were characterized by the most intense respiration at the 6th hour, while barley leaves at the 24th and 72nd hour after inoculation. In the case of meadow fescue the greatest heat production was noted in the period between 24 and
168 hours after inoculation. Simultaneously, at the 48th hour the smallest rate of respiration was observed. Barley leaves emitted the greatest amount of heat only in the first 3
hours of the pathogenesis. In these hours the smallest respiration rate was noted. The observed, opposing reaction of respiration
intensity and heat emission in the infected seedlings of both species may illustrate a disorder in metabolic processes in
plants during pathogenesis. The plants studied differed in the time of their reaction to pathogen attack: barley responded
earlier in heat production, while fescue extended respiration rate in the first hours after inoculation. This is clearly observable,
when coefficients of metabolic inefficiency (heat rates per mole O2) are compared. In the case of barley the highest rates were noticed just after inoculation, whereas in fescue at the 48th hour. In both species attack of pathogen caused high metabolic efficiency. 相似文献
933.
不同活力玉米种子胚萌发期间热激蛋白的合成 总被引:8,自引:0,他引:8
玉米(Zea mays L.)种子在萌发期间热激处理(42℃)时蛋白质合成率低于对照(25℃);高活力种子胚热激蛋白的合成率最高。在42℃热激处理时玉米种胚子合成的热激蛋白的分子量分别为73、65、62、54、18kD等5种。高活力种胚合成的热激蛋白在最上高于低活力种子,高活力种胚合成的特异性热激蛋白56kD可以作为衡量种子活力的指标。双向电泳表明高低活力种子间热激蛋白的合成有更多质上的差异。 相似文献
934.
935.
激光热疗中,激光与生物组织相互作用研究主要包含两方面:光子在生物组织中的迁移规律,以及光生扫热在生物组织在的传导。对前者的描述主要为,基于传输理论的解析法和Monte ̄Carlo模拟,生物组织中光子迁移规律的研究能定量描述组织中的光分布,并进一步获得生物组织中的热分布;考虑到了生物组织特性,所建立了生物组织中温度场分布及变化规律。光子迁移与生物传热理论是研究激光热序不可分割的传热模型,全面描述了生 相似文献
936.
The effect of different osmolytes on the viability and the effect of osmotic pressure on the induction of a dormant state similar to that caused by a slow desiccation rate were evaluated in the entomopathogenic nematode Steinernema carpocapsae ‘All’. For both experiments, a high-temperature (45°C) assay (HTA) was employed. Exposing fresh infective juveniles to the HTA resulted in a drastic reduction in viability. Using the same assay, the mortality of desiccated nematodes was gradual, showing an enhanced ability to withstand high-temperature conditions. The patterns of decline in viability in the evaporatively dehydrated and the osmotically desiccated nematodes were similar. Most of the salts tested in the screening assay caused high mortality levels among the nematodes within the first 24 h of exposure. In contrast, the nonionic solutes tested did not hamper the viability of the infective juveniles. In these nonionic solutions, all nematodes were completely shrunk after 48 h. Furthermore, 72-h exposure to these solutions resulted in an increase in heat tolerance similar to that of the evaporatively dehydrated nematodes. A substantial increase in heat tolerance was recorded in the treatments with glycerol solutions at concentrations from 2.2 to 3.8 M. A similar effect was obtained by polyethylene glycol (PEG) 300 MW at concentrations ranging from 1.2 to 1.6 M. PEG 600 MW induced enhancement of heat tolerance at a concentration of 0.8 M. A high level of viability was attained among nematodes that were stored for 72 days following a gradual increase in glycerol concentrations. Exposure of these nematodes to 45°C in the HTA resulted in 87.3 ± 4.7 and 49.2 ± 3.9% survival after 4 and 8 h, respectively. Reduction in viability was observed among nematodes that were directly exposed to the glycerol solution over a 19-day storage period. With this treatment, survival levels of 72.7 ± 3.9 and 26.5 ± 4.7% after 4 and 8 h, respectively, were recorded in the HTA. Reduction in viability among nematodes stored in distilled water was noted after 36 days of storage. Evaluation of nematode infectivity by two criteria (insect mortality and invasion rate) indicated that infectivity of nematodes desiccated by gradual osmotic pressure induced by glycerol was similar to that of fresh nematodes after 54 days in storage at 25°C. In comparison, infectivity of nematodes stored in distilled water declined significantly compared to that of fresh nematodes. 相似文献
937.
In the published reports concerning the design of laboratory experiments examining signals that might trigger seed germination, there is currently a misunderstanding of what might constitute correct replication of the experimental treatment. This is particularly true for the study of dry heat, smoke and charcoal, where either an individual seed or a batch of seeds in a Petri dish or tray is being treated as the unit of replication of the experimental treatment, irrespective of whether or not those seeds were all subjected to the experimental manipulation simultaneously. Under these circumstances, the application of the treatment is unreplicated, while samples nested within that single application have been replicated, and the Petri dishes/trays are functioning solely as independent replicates of the variability in germination response within the seed batch used and variation within the pretreatment and post‐treatment environments. Thus any observed difference in germination may be due to the germination treatment but, potentially, it could also be due to any chance event affecting the treated sample. There are a number of alternative experimental designs that avoid this problem. The essential point with these designs is that the application of the experimental manipulation to each replicate should be separated in space by the use of separate experimental equipment and/or in time by the repeated use of the same experimental apparatus. 相似文献
938.
钙-钙调素与小麦苗中热激蛋白的诱导 总被引:1,自引:0,他引:1
在 34℃热激条件下 ,种子经钙预处理的小麦苗中的钙调素含量随着热激时间的延长而增加 ,热激 90min时达最大值 ,而种子用钙离子螯合剂EGTA预处理的小麦苗中钙调素含量无明显增加。种子用EGTA及钙调素拮抗剂CPZ和TFP预处理的小麦幼苗在 34℃热激时 ,热激蛋白的合成量减少。 4d的小麦幼苗在34℃或 37℃热激条件下 ,能诱导耐热性的获得 ,分别用EGTA、钙离子通道阻断剂易博定、钙调素拮抗剂TFP或CPZ预处理种子后 ,所得幼苗热诱导的耐热性的提高程度有所下降 相似文献
939.
A. Dell'Aquila 《Biologia Plantarum》2000,43(4):591-594
The germination of lentil seeds was gradually reduced when seeds were exposed to temperature of 30 or 40 °C, either alone or combined with 0.1, 0.2 or 0.3 M NaCl or 34.1 % (m/v) PEG 8000, during 6 –12 h imbibition. [35S]-methionine incorporation in 12 h imbibed lentil axes also decreased with increasing NaCl concentration at 20 and 40 °C, whereas at 30 °C only 0.3 M NaCl treatment partially inhibited protein synthesis. An analysis of newly synthesized proteins by 1-D SDS PAGE, showed that the expression of most polypeptides decreased following increasing stress. Among these, low molecular mass heat-shock proteins declining, higher in 40 °C treated axes than those treated at 30 °C, supports the hypothesis that at this temperature maximal level of expression of these proteins was achieved. 相似文献
940.
Polymerase chain reaction (PCR) has been used extensively in the construction of linkage maps for many cultivated crops including soybean, [Glycine max (L.) Merr]. In this study, four sets of oligonucleotide primer pairs of known genes (pearl millet Adh 1, nodule specific proline-rich protein, Drosophila homeobox, heat shock protein), several different combinations from kits A, D, E, and J of arbitrary primers and five primer pairs of soybean simple sequence repeats of varying length (Satt 9, Satt 20, Satt 42, Satt 64, and Satt 30) were utilized in PCR to identify molecular markers which were then used to construct a genetic linkage map. DNA for the PCR reactions was isolated from 65 recombinant inbred soybean lines resulting from crossing PI 290,136 and BARC-2 (Rj
4
), followed by self-pollination for seven generations without selection. Mapmaker 3.0, a computer package, was used for construction of the linkage map. A total of 43 polymorphic markers were identified; 30 markers were linked and distributed among 5 linkage groups while 13 markers were unlinked. Arbitrary primers revealed more polymorphisms than specific primers. A combination of arbitrary primers A5 and A18 revealed the maximum number of polymorphic bands. Five observed linkage groups can be expanded in future soybean research by using additional markers. 相似文献