2种多胺对铁皮石斛瓶内开花的影响

以铁皮石斛无根组培苗为试验材料,研究不同浓度的外源腐胺（Put）和精胺（Spm）对铁皮石斛瓶内开花的影响。结果表明：培养基中添加适量的Put和Spm可提高开花率。当Put浓度为0.4 mg/L时,铁皮石斛瓶内开花率最高,为30.47%;Spm浓度为0.2 mg/L时,铁皮石斛瓶内开花率最高,为22.26%;Put浓度为0.2 mg/L时,铁皮石斛始花期最短,为83.33 d,观赏期最长,为43.33 d。Put浓度为0.4 mg/L时,植株可溶性糖和可溶性蛋白含量最高;对照处理下植株全N含量达最高;Spm浓度为0.6 mg/L时,植株C/N比达最大。Put浓度为0.4 mg/L时,有利于铁皮石斛组培苗碳氮化合物的积累,可提高铁皮石斛的开花率;Put浓度为0.2 mg/L时,能使花期提前,延长观赏期。Spm浓度为0.4 mg/L时,有利于铁皮石斛组培苗株高增长和生根,促进铁皮石斛组培苗的营养生长。     

鞭角华扁叶蜂体内多胺的动态

用紫外荧光法测定鞭角华扁叶蜂末龄幼虫及滞育预蛹血淋巴中多胺的动态.结果表明:鞭角华扁叶蜂血淋巴中含有8种多胺,其中腐胺(Put)、亚精胺(Spd)、精胺(Spm)、尸胺(Cad)为普遍存在的多胺,其发育的不同阶段,多胺的种类和含量均发生变化;在滞育预蛹的血淋巴中Spm一直保持较高的含量,并在整个滞育期间存在2个峰值;在滞育的前5个月中血淋巴中不存在Spd,之后Spd突然出现,且含量迅速升高;Cad的代谢较平稳,在化蛹前稍有下降;Put的含量除在滞育后3个月左右有较大的峰值外,其余阶段的含量均较高,并在化蛹前有升高的趋势.总之,多胺可能参与鞭角华扁叶蜂预蛹滞育过程.     

Physiological mechanism underlying spikelet degeneration in rice

The phenomenon of degenerated spikelets is very common in cereals, and considered as a serious physiological defect and a main constraint to grain production. Understanding the physiological mechanism in which spikelet degeneration occurs would have great significance in enhancing yield potential in grain crops. Taking rice as an example, the paper reviewed the physiological mechanism underlying spikelet degeneration, with focus on the roles of phytohormones in regulating the process. There are several hypotheses for the spikelet degeneration, such as resource limitation, self-organization, and primigenic dominance. However, convincing evidences are not enough to support the assumptions. Phytohormones including auxins, cytokinins, gibberellins, abscisic acid, and ethylene are involved in regulating spikelet degeneration in cereals. The new phytohormones of brassinosteroids and polyamines have been observed to suppress spikelet degeneration in rice. The interactions among or between plant hormones may play a more important role in regulating spikelet degeneration. However, the information on such interactions is very limited. Some agronomic practices, especially proper water and nitrogen management, could reduce spikelet degeneration but the mechanism underlying remains unclear. Further research is needed to understand the cross-talk among/between phytohormones on spikelet degeneration, to reveal the physiological and molecular mechanism in which phytohormones and their interactions regulate the degeneration of spikelets, to exploit approaches to decrease spikelet degeneration and to elucidate their mechanism.     

菜豆果实发育过程中多胺氧化酶活性与多胺含量的变化

对菜豆（Phaseolus vulgaris L．）果实发育过程中的多胺氧化酶（Polyamine oxidase，PAO）活性及腐胺（Putrescine，Put）、亚精胺（Spermidine，Spd）和精胺（Spermine，Spm）等3种多胺（Polyamines，PAs）含量的变化动态进行了测定和分析．结果表明，花后果皮PAO活性变化呈明显的下降趋势，但从种子中未能检测到PAO活性；花后第2d果皮中的Spd含量最高，随后Spd和Spm含量变化大致呈“W”型，而Put含量则呈先升后降的趋势；花后第2d，种子中的Put、Spd和Spm含量均显著高于其在果皮中的含量，但在花后第2—8d迅速下降，随后降速趋缓；花后果皮和种子中3种PAs的总含量变化均呈下降趋势，且花后第2～8d种子中的PAs总含量远高于果皮．     

Relationship between Polyamines and Other Cold‐induced Response Mechanisms in Different Cereal Species

To find a connection between polyamines and various protective effectors involved in the development of cold tolerance, eight different cereal genotypes, including wheat, barley and oat species, were investigated during the acclimation phase to low temperature. Exposure to low temperature induced different changes in the levels of polyamines, and other signalling molecules, such as salicylic acid and abscisic acid, and of other protective compounds, namely flavonols, sugars and antioxidant enzyme activity, and in the lipid composition of certain membrane factions. The most remarkable differences were observed in the oat varieties compared to the other cereal genotypes, which was manifested in the lack of spermidine accumulation and of decrease in trans‐Δ³‐hexadecanoic acid content, in lower initial and not cold‐inducible abscisic acid content and guaiacol peroxidase activity after cold treatment. Correlation analysis revealed that spermidine shows strong positive relationship with flavonols, abscisic acid and ascorbate peroxidase, while was in negative relationship with trans‐Δ³‐hexadecanoic acid. These results suggest that spermidine may have a crucial role in the cold acclimation signalling processes in cereals.     

外源多胺拌种对夏玉米抗涝性的影响

为了缓解玉米生产中涝渍胁迫带来的问题,通过小区试验,研究外源多胺拌种对玉米抗涝能力的影响。结果表明,淹水后,多胺拌种植株的丙二醛物质的量浓度均低于不拌种植株,且在恢复期内基本能下降到正常水平;多胺拌种植株的可溶性蛋白和可溶性糖质量分数在处理时期均低于不拌种植株,淹水后均升高,且表现出先升后降的趋势;淹水条件下,百粒质量和产量均大幅度下降,在淹水3、5、7、9d条件下,多胺拌种和不拌种植株百粒质量下降幅度分别为2.94%、14.42%、21.88%、22.11%和16.24%、18.30%、25.59%、27.99%,产量降幅分别为32.10%、43.20%、48.74%、43.94%和35.13%、47.65%、53.67%、48.86%;持续淹水条件下,多胺拌种产量比不拌种产量最高可提高625.11kg/hm2。     

New aspects of soybean somatic embryogenesis

Somatic embryo formation from immature cotyledons was improved in the following ways: by cutting into sections, supplementing culture media with spermine and using solid/liquid/solid type of culture. Cut cotyledons of the eight genotypes examined expressed a higher ability for somatic embryogenesis than whole cotyledons. Of the three polyamines tested, spermine considerably stimulated and putrescine slightly inhibited induction of somatic embryos. The ability of embryoid formation on medium with spermidine depended on the genotype. The solid/liquid/solid type of culture was better than the continuous solid culture. The best nitrogen ion content for the subculture of somatic embryos was 10 mM NH₄NO₃ and 30 mM KNO₃. The possibility of using these modifications in Agrobacterium transformation is discussed.     

Effect of taurine supplementation on the metabolism and body lipid‐to‐protein ratio in juvenile Atlantic salmon (Salmo salar)

Previously, we reported that methionine intake determined the taurine concentration in the liver of on‐growing Atlantic salmon fed plant protein diets. Further, the methionine intake and/or the increased taurine concentration following increased methionine intake affected the liver lipid metabolism. The following study therefore aimed to test whether taurine affected the growth or the type of growth when added in high plant protein diets naturally low in taurine but equal and adequate in dietary methionine. Juvenile Atlantic salmon [initial body weight (BW) of 2 g] were fed plant protein diets (16.5% fishmeal), which were supplemented with taurine or not for a period of 56 days. As a control for growth and normal metabolism, a fishmeal‐based commercial diet (68% fishmeal) was used. Supplementation with taurine to high plant protein diets had a slightly negative effect on weight gain, but the final body weight was not different. Interestingly, the pool of free amino acids in the liver and muscle was significantly higher in fish fed the supplemented diet as compared with fish fed the plant protein diet without taurine supplementation. Liver polyamine concentration was higher in fish fed the supplemented diet than in fish fed the similar diet without supplementation. Additionally, juvenile salmon fed the plant‐based diet supplemented with taurine had a lower body lipid‐to‐protein ratio due to a reduced whole‐body lipid content, while the whole‐body protein content was similar between treatments. Our study thus indicates that the addition of a low concentration of taurine to high plant protein diets interacts with lipid metabolism and storage, concomitantly affecting the general metabolism as the concentrations of the free amino acids and polyamines in the liver were significantly higher. The possible reasons for these changes are discussed.     

外源多胺对苹果幼苗生长及抗旱性的影响

采用盆栽控水的方法研究了干旱条件下3种外源多胺(精胺、亚精胺和腐胺)对苹果树苗抗生长及抗旱性的影响。结果表明,在中度干旱条件下叶面喷施多胺能提高苹果树苗的光合速率和水分利用效率,同时促进游离氨基酸、可溶性糖和脯氨酸等有机渗透调节物质的合成与积累,增强渗透调节能力。实验结果还表明,干旱条件下保护酶活性降低,质膜透性和丙二醛(MDA)含量增高。喷施外源多胺能维持或提高保护酶(SOD、CAT)活性,降低质膜透性和丙二醛(MDA)含量,防止或降低细胞膜脂过氧化作用,由此维持正常代谢水平,促进植物的生长,提高抗旱性。3种外源多胺中精胺(Spm)的效果相对较好,但三者之间对多数抗旱性生理指标及生长的影响差异不显著。     

Changes in Hormonal Balance: A Possible Mechanism of Pre‐Sowing Chilling‐Induced Salt Tolerance in Spring Wheat

There is a lack of knowledge about factors contributing to the chilling‐induced alleviatory effects on growth of plants under salt stress. Thus, the primary objective of the study was to determine whether chilling‐induced changes in endogenous hormones, ionic partitioning within shoots and roots and/or gaseous exchange characteristics is involved in salt tolerance of two genetically diverses of wheat crops. For this purpose, the seeds of two spring wheat (Triticum aestivum) cultivars, MH‐97 (salt intolerant) and Inqlab‐91 (salt tolerant) were chilled at 3°C for 2 weeks. The chilled, hydroprimed and non‐primed (control) seeds of the two wheat cultivars were sown in both Petri dishes in a growth room and in the field after treatment with 15 dS m^?1 NaCl salinity. Chilling was very effective in increasing germination rate and subsequent growth when compared with hydropriming and control under salt stress. Results from field experiments clearly indicated the efficacy of chilling over hydropriming in improving shoot dry biomass and grain yield in either cultivar, particularly under salt stress. This increase in growth and yield was related to increased net photosynthetic rate, greater potential to uptake and accumulate the beneficial mineral elements (K⁺ and Ca²⁺) in the roots and reduced uptake and accumulation of toxic mineral element (Na⁺) in the shoots of both wheat cultivars when grown under salt stress. Salt‐stressed plants of both wheat cultivars raised from chilled seed had greater concentrations of indoleacetic acid, abscisic acid, salicylic acid and spermine when compared with hydropriming and control. Therefore, induction of salt tolerance by pre‐sowing chilling treatment in wheat could be attributed to its beneficial effects on ionic homeostasis and hormonal balance. The results presented are also helpful to understand the chilling‐induced cross adaptation of plants in natural environments. Moreover, efficacy of pre‐sowing chilling treatment over hydropriming suggested its commercial utilization as a low risk priming treatment for better wheat crop production under stressful environments.