抗氧化酶和植物螯合肽对苎麻重金属Cd胁迫的应答

为了探究抗氧化酶和植物螯合肽在苎麻耐镉生理机制中的作用,本研究以苎麻耐性品种‘川苎8号'为实验材料,对其进行5、25、50 mg/L的镉处理,7 d后分别测定其生物量、镉含量、抗氧化酶活性、植物螯合肽含量以及相关基因表达量。结果表明5 mg/L镉处理‘川苎8号'的株高、根长与生物量受到促进,25、50 mg/L镉处理下‘川苎8号'的株高、根长与生物量受到抑制,‘川苎8号'主要将镉积累在根部,不同镉处理下转运系数均小于1,25 mg/L镉处理时镉积累量与转运系数均显著高于其他处理;镉胁迫后‘川苎8号'地上部和地下部超氧化物歧化酶（SOD）活性显著升高,丙二醛（MAD）活性显著降低,过氧化氢（H₂O₂）含量显著上升;5、25 mg/L镉处理时地下部植物螯合肽（PCs）与谷胱甘肽（GSH）含量显著低于对照,50 mg/L镉处理时高于对照但未达到显著差异;PCs和GSH在地上部和地下部承担着不同的解毒作用;各浓度处理的地上部BnPCS1相对表达量均与镉含量呈极显著正相关（P<0.01）,高浓度（25、50 mg/L）处理的地上部BnGCL1相对表达量与镉含量呈正相关（P<0.01）;低浓度（5 mg/L）处理下SOD活性显著高于对照,与各部位镉含量均呈极显著正相关（P<0.01）,高浓度镉处理时地下部SOD活性与镉含量呈极显著负相关（P<0.01）,地下部PCs含量与镉含量呈极显著正相关（P<0.01）。综合分析说明,‘川苎8号'在低浓度镉胁迫时主要通过激活抗氧化酶活性消除细胞中自由基的毒害,高浓度镉胁迫时通过调节抗氧化酶活性和PCs与GSH合成解除镉的毒害。     

Increase in phosphorylase activity during cold-induced sugar accumulation in potato tubers

Summary The accumulation of reducing sugars, sucrose and hexose phosphates in cv. Bintje and genotype KW77-2916 during storage at 2, 4, or 8°C was studied in relation to several catalytic activities. Bintje tubers accumulated sugars during storage at 2 or 4°C, whereas KW77-2916 showed reduced cold-sweetening at 2°C. The increase in glucose 6-phosphate and sucrose occurred concurrently and preceded the increase in reducing sugar concentration. Phosphorylase activity showed a strong interaction with temperature, storage duration and sugar accumulation in both genotypes. Invertase activity increased in Bintje concomitantly with the increase in reducing sugars, but this effect was less obvious in KW77-2916. The activities of other glycolytic and Krebs cycle enzymes showed no obvious correlation with sugar accumulation. It is suggested that the increase in phosphorylase activity acts as a triggering event in the sweetening of potato tubers during cold storage.     

杂交稻不同抗性组合感染白叶枯病菌后几种酶活性的变化

选用4个对白叶枯病具有不同抗性级别的杂交组合，即抗病组合威优6号（V6）、中抗组合Ⅱ优46（Ⅱ－U46）、感病组合威优64（V64）和高感组合汕优63（S63）为材料，研究了其3叶期幼苗感染白叶枯病菌后体内苯丙氨酸解氨酸（PAL）、过氧化物酶（POX）、多酚氧化酶（PPO）和超氧物歧化酶（SOD）活性的变化。结果表明，各组合上述酶活性在接种白叶枯病菌后均明显增强，在接种36－96h内活性曲线有2个峰值，各组合稻株的抗病性与酶活性呈一定的正相关，抗病组合V6的4种酶活性变化幅度明显大于感病组合S63。可以认为杂交稻的抗白叶枯病特性与体内酚类物质代谢防御酶系活性密切相关。     

Effect of distillery effluents on plant and soil enzymatic activities and groundnut quality

A field experiment was conducted during the rainy season 2000 to examine the effect of distillery effluents, i.e., biomethanated spent wash (BSW), raw spent wash (RSW), and lagoon sludge (LS) versus recommended NPK+FYM (farmyard manure) on nutritional quality of groundnut (Arachis hypogaea L.) and enzyme activities of plant and soil. The distillery effluents did not affect the oil content (%), crude and true protein contents (%) in groundnut but increased the seed yield and the contents of methionine by 44 % (1.15 g (16 g N)^–1 vs. 0.80 g (16 g N)^–1 in control) and of cysteine by 24 % (1.36 g (16 g N)^–1 vs. 1.10 g (16 g N)^–1 in control). BSW produced the highest seed yield (619 kg ha^–1) followed by RSW (557 kg ha^–1) and LS (472 kg ha^–1). LS recorded the highest total chlorophyll content (2.94 mg (g FW)^–1) in groundnut leaves. Application of BSW and RSW significantly increased the activity of plant peroxidase whereas the plant polyphenol oxidase was higher in BSW only. The application of distillery effluents did not affect the nitrate reductase activity but BSW significantly increased the nitrate content in the rhizosphere soil. The three effluents significantly increased the dehydrogenase and alkaline phosphatase activity more than recommended NPK+FYM.     

不同培肥措施对藏东南土壤酶活性的影响

对进行不同培肥措施后土壤进行理化性状和酶活性测定 ,结果表明 :土壤中的脲酶、转化酶、碱性磷酸酶活性与土壤肥力有良好的相关性。不同培肥措施中 ,以有机肥 (厩肥、秸秆 )配施化肥对脲酶、转化酶、碱性磷酸酶活性影响最大 ,分别是单施化肥处理的酶活性的 1 .47、3 .3 1、1 .0 7倍。各培肥措施中 ,以有机肥 (厩肥、秸秆 )配施化肥效果最好 ,有机无机结合中厩肥 化肥又优于秸秆 化肥。建议藏东南地区采用有机无机结合方式培肥土壤。     

小麦抗赤霉病突变体的选育及其变异研究

利用辐射与离体培养,细胞筛选相结合的方法进行抗病突变体的筛选,选育出４个抗赤霉病的突变体,经多年田间接种鉴定和考察,突变体的抗病能力较亲本提高１～２级,株高,穗长和小穗数等主要农艺性状也发生了变异。突变体与其亲本相比,醇溶蛋白电泳和过氧化物同工酶酶谱带数,谱带强度和谱带位置都有差异,超氧化物歧化酶的活性分析表明,在毒素作用下,突变体的酶活性比亲本高８．６１％～２４．１４％,突变体具有较高的超氧化物     

Recovery of topsoil characteristics after landslip erosion in dry hill country of New Zealand, and a test of the space-for-time hypothesis

The rate of development of topsoil is an important characteristic for soil resilience and sustainable use. We located a chronosequence (1-59 yr) of recovering landslip scars in erodible siltstone hill country under permanent pasture for sheep farming in New Zealand. We measured the rates of recovery in microbial C, respiration, catabolic diversity, phosphatase, sulphatase and invertase activities, pH, total C, total N, C/N ratio, potentially mineralizable N, total P, Olsen P, cation-exchange capacity, bulk density, particle density, porosity, available water and aggregate stability (0-10 cm depth). A subset of the same sites was sampled again after a 14-yr interval, enabling us to test whether rates of change estimated by resampling the same sites were the same as those estimated from a single time sample from the chronosequence (the space-for-time hypothesis).Most topsoil characteristics had recovered to 71-85% of those in the non-slipped sites after 59 yr. Exceptions were soil respiration, invertase and sulphatase activities, and bulk density, which recovered to 94-110% of the values of the non-slipped sites. There was little change in soil pH, total P, Olsen P, exchangeable cations and water storage along the chronosequence. An asymptote model fitted the patterns of recovery in biochemical characteristics, organic matter, bulk density and particle density. Recovery (to 90% of the asymptote value) was most rapid for the C/N ratio (5 yr) and longest for particle density (79 yr); most other characteristics fell in an 18-50 yr range. Overall, a single sampling of a chronosequence of matched landslip scars was as reliable to estimate rates of recovery as was resampling individual sites through time. Total C and N were as effective as more complicated biochemical measures to monitor the recovery of topsoil.     

Soil biochemical and microbial indices in wet tropical forests: Effects of deforestation and cultivation

Little information is available about the long‐term effects of deforestation and cultivation on biochemical and microbial properties in wet tropical forest soils. In this study, we evaluated the general and specific biochemical properties of soils under evergreen, semi‐evergreen, and moist deciduous forests and adjacent plantations of coconut, arecanut, and rubber, established by clear felling portions of these forests. We also examined the effects of change in land use on microbial indices and their interrelationships in soils. Significant differences between the sites occurred for the biochemical properties reflecting soil microbial activity. Microbial biomass C, biomass N, soil respiration, N mineralization capacity, ergosterol, levels of adenylates (ATP, AMP, ADP), and activities of dehydrogenase and catalase were, in general, significantly higher under the forests than under the plantations. Likewise, the activities of various hydrolytic enzymes such as acid phosphomonoesterase, phosphodiesterase, casein‐protease, BAA‐protease, β‐glucosidase, CM‐cellulase, invertase, urease, and arylsulfatase were significantly higher in the forest soils which suggested that deforestation and cultivation markedly reduced microbial activity, enzyme synthesis and accumulation due to decreased C turnover and nutrient availability. While the ratios of microbial biomass C : N and microbial biomass C : organic C did not vary significantly between the sites, the ratios of ergosterol : biomass C and ATP : biomass C, qCO2 and AEC (Adenylate Energy Charge) levels were significantly higher in the forest sites indicating high energy requirements of soil microbes at these sites.     

超高压技术对果蔬汁微生物和品质影响的研究进展

对近年来国内外发表的超高压技术应用于果蔬汁加工方面的研究论文进行了分析,综述了超高压技术对果蔬汁中微生物、酶活性、理化特性、色泽、风味及生物活性物质等的影响。通过分析超高压技术在果蔬汁加工方面的优势及存在的问题,为该技术更好地应用于果蔬汁生产加工提供参考借鉴。     

低温胁迫对2种主要砧穗组合砂糖橘幼树抗寒性的影响北大核心CSCD

【目的】探究广东肇庆主要使用的2种砧木对砂糖橘(Citrus reticulata‘Shatangju’)抗寒性的影响,为优化其引种栽培和苗木繁育提供科学支撑。【方法】以枳壳[Poncirus trifoliata(L.)Raf.]砧、酸橘(C.sunki Hort.exTanaka)砧3年生砂糖橘为试材,在人工气候室中48 h内从10℃梯次降温至(3±0.5)℃、(-3±0.5)℃分别胁迫24 h,然后,经48 h梯次升温至10℃,24 h后转移至塑料温室中常规栽培90 d,期间调查测定落叶量、生长量、生物量,定期测试分析抗寒生理特性。【结果】在(3±0.5)℃、(-3±0.5)℃胁迫后栽培的90 d中,砂糖橘酸橘砧植株单株落叶数量减小幅度较枳壳砧植株分别大412.2%、134.5%,落叶质量减小幅度较枳壳砧植株分别大546.6%、1098.0%;胁迫后90 d酸橘砧植株株高降低幅度较枳壳砧植株分别大5.0%、16.3%,地径减小幅度较枳壳砧植株分别大75.0%、8.8%,冠幅减小幅度较枳壳砧植株分别大231.6%、52.2%,全株生物量减小幅度较枳壳砧植株分别大465.4%、45.6%。(3±0.5)℃、(-3±0.5)℃胁迫后90 d,酸橘砧植株叶片叶绿素含量(Chl c)降低幅度较枳壳砧植株分别大101.1%、27.0%,光合速率(Pn)降低幅度分别大65.8%、52.2%,叶片蒸腾速率(Tr)升高幅度较枳壳砧植株分别大44.1%、99.9%,叶片气孔导度(Gs)升高幅度较枳壳砧植株分别大41.3%、39.7%。低温胁迫导致砂糖橘叶片碳同化关键酶(Rubisco)、FBP、Ald及PEPC的活性均较同期对照显著降低,叶片水分饱和亏缺(WSD)显著加重、丙二醛(MDA)含量显著升高,枳壳砧植株的变化幅度显著小于酸橘砧植株。【结论】砂糖橘枳壳砧植株抗寒性显著强于酸橘砧植株,其机制主要在于低温胁迫下落叶程度轻,根系较发达,叶片较厚重,光合效率较高,叶片抗脱水、抗膜脂过氧化能力强。