鲜黄梨果实糖积累及山梨醇转化相关酶活性的变化

对鲜黄梨果实发育中糖积累及山梨醇转化相关酶活性的变化进行了研究。结果表明:果实发育前期以积累山梨醇和淀粉为主,后期以积累果糖为主。果实整个发育过程中,葡萄糖、果糖、蔗糖、可溶性总糖含量逐渐增加,山梨醇和淀粉含量先增加后降低。山梨醇脱氢酶和山梨醇氧化酶在果实发育早中期活性逐渐增高,后期活性降低,但较前期高,两者共同对山梨醇的转化起调控作用。     

葡萄霜霉菌候选效应子RXLR5信号肽的鉴定

利用Getorf、SignalP 3.0、BLASTP等生物信息学软件和PERL语言从葡萄霜霉菌基因组中预测到一条编码RXLR-EER结构域的效应蛋白候选基因,将该基因编码的蛋白命名为RXLR5。将RXLR5信号肽SP5编码序列连接到pSUC2T7M13ORI载体并转化到酵母蔗糖酶缺陷菌株YTK12后,重组菌株能成功分泌蔗糖酶,促使棉籽糖分解成单糖,因此,能在YPRAA培养基上正常生长;同时生成的单糖能与TTC反应产生红色不溶于水的氯化三苯基四氮唑。由此推测,SP5具有信号肽活性,可能在RXLR5从葡萄霜霉菌细胞内泌到胞外的过程中起重要作用。     

蔗糖转化酶家族基因进化、表达及对草莓果实糖分积累的影响

在草莓蔗糖碱性/中性转化酶家族基因(Fa.A/N-Inv)成员序列分析的基础上,以‘申阳’和‘红颜’草莓为材料,利用实时定量PCR技术分析了Fa.A/N-Inv家族基因在不同条件下的表达模式,利用分光光度法测定了果实发育过程中A/N-Inv酶活性,利用高效液相色谱法分析了果实发育阶段糖分积累规律。结果表明:(1)Fa.A/N-Inv是由8个成员组成的多基因家族;(2)4个Fa.A/N-Invs不仅具有组织特异性,还具有果实发育阶段特异性和品种特异性表达特点;(3)4个Fa.A/N-Invs的表达受细胞分裂素(BA)、赤霉素(GA)和生长素(IAA)诱导;(4)蔗糖和葡萄糖作为A/N-Inv酶促反应的底物和产物,分别对4个Fa.A/N-Invs转录表达起正、负反馈调节作用,此外蔗糖还可作为一种信号分子诱导Fa.A/N-Invs表达;(5)‘申阳’草莓A/N-Inv酶活性在绿果阶段低于‘红颜’,其余阶段均高于‘红颜’;(6)成熟果实中蔗糖含量‘红颜’(50.7 mg·g~(-1) FW)约为‘申阳’(23.2 mg·g~(-1) FW)的2倍。     

赤霉素对发育的大豆种子中同化物卸出和积累的影响

用微注射法将不同浓度的赤霉素 (GA3 )引入开花后 30 d的大豆种子幼胚的 2片子叶中间的质外体空间 ,同时给叶片饲喂 14 CO2 ,以种皮和子叶中放射性强度来比较分析 GA3 对同化物卸出的影响。分析了种皮和子叶中的酸性转化酶活性 ,发现 GA3 1× 10 -5mol.L-1使种皮中酸性转化酶活性提高而子叶中酶活性降低 ,从而促进种皮同化物的卸出和向子叶的分配。实验结果还表明 ,引入 GA3 影响了种子内源脱落酸 (ABA)水平 ,而且子叶中的 ABA含量变化和同化物积累相关 ,GA3 1× 10 -5mol.L-1使子叶中 ABA水平上升 ,伴随总糖、蔗糖和蛋白质的积累增加 ,GA3 1× 10 -4 mol.L-1却使 ABA水平下降 ,而且物质积累也减少     

三氯生与镉单一及复合污染对土壤呼吸和酶活性的影响

为了解典型药品和个人护理品(PPCPs)——三氯生与镉复合污染的生态效应,采用室内培养实验和联合毒性预测模型,首次评价了三氯生与镉单一及复合污染对土壤呼吸及参与土壤碳氮循环的相关酶活性的生态毒性。结果表明:三氯生与镉单一及复合污染对土壤呼吸呈现激活—抑制—激活的生态效应;刺激了蛋白酶活性,激活率先降低后升高,56 d时达到最大。整个实验期间均抑制了蔗糖酶活性,镉(10.0 mg kg-1)单一污染培养14 d抑制率达到最大值(81%),三氯生单一胁迫呈现负的剂量效应关系,两者复合污染无显著的剂量效应关系。联合效应评价模型预测表明,相比三氯生或镉单一污染,两者的复合胁迫对土壤呼吸呈现随时间变化的拮抗—协同—加和效应,对土壤蛋白酶呈现协同—加和—协同的联合效应,而对土壤蔗糖酶活性则主要为协同效应。     

Comparison of Salt and Drought‐Stress Effects on Maize Growth and Yield Formation with Regard to Acid Invertase Activity in the Kernels

The long‐term effects of salt stress (11 dS m^?1) and drought stress (35 % WHC) were investigated for two maize genotypes, focusing on the relation between metabolic changes around the time of pollination and the impact on yield determinants at maturity. The relatively salt‐resistant hybrid Pioneer 3906 and the relatively drought‐resistant hybrid Fabregas were compared. The experiments were conducted in large plastic containers in a vegetation hall in two consecutive years (2011 and 2012). Plant height and leaf area were significantly reduced under both stress conditions. The transpiration rate was only slightly reduced under drought stress; but under salt stress, a significant reduction occurred 40–53 days after sowing. As a significant increase in sucrose concentrations was observed in the salt‐treated maize kernels 2 days after pollination, the availability of assimilates was not limiting and the plants could afford to save water by reduced stomatal opening. Although under both stress conditions the soluble acid invertase activity was reduced 2 days after pollination, concomitantly, an increase in hexose concentrations was observed. Thus, in these experiments, the delivery of hexoses by acid invertase activity did not limit kernel development. Differences in grain yield at maturity between salt and drought stress were most likely caused by salt‐specific effects (Na⁺ toxicity), Fabregas being more affected than Pioneer 3906.     

多效唑对高羊茅叶片糖酶活性的影响

高羊茅草坪草施用多效唑后，叶片的垂直生长受抑，叶片光合同化物向根系运输增强，叶片和根系中淀粉及可溶性糖含量升高。数据表明：叶片中淀粉含量与淀粉酶活性呈正相关（r=0.88)。，另外，叶片中酸性转化酶活性增加，但中性转化酶活性降低，且叶片中可溶性碳水化合物含量一直维持在较高水平，说明酸性转化酶在多效唑对草坪草叶片垂直生长的调节中起重要作用。草坪草生长动态的变化与多效唑改变碳水化合物代谢酶活性有关。可溶性糖的积累有利于增强草坪草抗逆性，促进新器官的发生。     

银杏幼苗叶片转化酶活性及其动力学

采用波钦诺克XH法研究了田间和室内栽培的银杏幼苗叶片转化酶的活性及其动力学性质。结果表明:银杏幼苗叶片转化酶在pH值5.0、温度55℃时活性最强;该酶的米氏常数为3.7×10-2mol·L-1;室内盆栽的银杏幼苗叶片转化酶的活性显著高于田间栽培的同龄银杏幼苗叶片转化酶的活性。     

不同形态氮素对种植大豆土壤中微生物数量及酶活性的影响

采用框栽试验方法,研究6种不同形态氮素[生物固氮(N0)、硝态氮(N1)、铵态氮(N2)、氨基酸态氮(N3)、蛋白态氮(N4)和酰胺态氮(N5)]对种植大豆土壤中微生物数量及土壤酶活性动态变化的影响。结果表明:各大豆生育期内真菌、细菌、放线菌数量和土壤脲酶、蔗糖酶活性对不同形态氮素的反应不同;三大菌群在组成上以细菌数量占绝对优势,数量上均在花期时达到峰值,即均随着大豆生育期的推进呈单峰曲线变化;花期不同形态氮处理下的土壤微生物总数量有差异,具体表现为N5N3N2N1N4N0。土壤多样性指数的变化趋势随着生育期的推进呈缓慢下降趋势,与土壤微生物数量的变化趋势不一致,因此,评价土壤生物多样性指数应将两者结合起来。土壤脲酶和蔗糖酶活性随着生育期的推进亦为单峰曲线变化趋势,但脲酶与蔗糖酶活性的变化趋势不同,其高峰期出现在鼓粒期。     

间作作物及其还田时间对土壤碳素状况和相关酶活性的影响

Catch crops that are cultivated for green manure play an important role in improving soil properties. A 3-year field experiment was conducted to investigate the effect of catch crop(pea, Pisum sativum L.) management, i.e., incorporation of catch crop in October/November(autumn) and March(spring), and without catch crop(control), on soil organic carbon(SOC), microbial biomass carbon(MBC) and the activities of carbon(C)-cycle enzymes, including cellulase(Cel), β-glucosidase(Glu) and invertase(Inv). Additionally, soil total nitrogen(TN) and p HKClwere investigated. The catch crop was cultivated from August to October each year during 2008–2010. Soil samples were collected from the field of spring barley(Hordeum vulgare L.) that had been grown after the catch crop. Soil samples for microbial activity determination were taken in March, May, June and August in 2009, 2010 and2011, while SOC and TN contents as well as p HKClwere determined in March and August. The chemical properties studied did not show significant changes as influenced by the experimental factors. The use of catch crop significantly increased the MBC content and the activities of C-cycle enzymes compared to the control. When the catch crop was incorporated in spring, a significantly higher MBC content was noted in March and May compared to autumn incorporation. Moreover, the spring incorporation of the catch crop significantly increased the Glu activity(except March), while the activities of Cel and Inv as well as the rate of soil basal respiration were usually unaffected by the time of catch crop incorporation. Greater microbial biomass and higher enzyme activities in the catch crop-treated soil, compared to the control, indicated that the application of the catch crop as a green manure could be recommended as a promising technique to increase the biological activity of the soil. Since there was no significant effect or no consistent results were obtained related to the time of catch crop incorporation, both spring and autumn applications can be recommended as a management tool to improve the status of soil properties during the growth of a subsequent crop.