Characteristics of starch synthesis and grain filling of common buckwheat

The common buckwheat ‘cv. Fengtian 1’ (FT1), ‘cv. Yuqiao 4’ (YQ4), ‘cv. Dingtian 2 (DT2)’, and ‘cv. Tongliao (TL)’ were selected to investigate the characteristics of starch synthesis and grain filling. The chlorophyll and chlorophyll a/b contents of leaves in the third stem showed a steady downward trend with the growth of common buckwheat. Whereas, FT1, YQ4 and DT2 showed higher chlorophyll content than that of TL at 7d and 14d. The activity of soluble starch synthase(SSS) and adenosine diphosphate glucose pyrophosphorylase (ADPGP) in the four tested varieties showed a rapid upward trend until 14 days after heading but then rapidly decreased until 21 days after heading. The average adenosine diphosphate glucose pyrophosphorylase activities of FT1, YQ4 and DT2 were higher than TL, while the average soluble starch synthase activities were similar among the four tested varieties. Consistently, the four tested varieties showed rapid accumulation of starch, amylose, and amylopectin during the prefilling stage, but no difference of starch content was found at maturity. The filling process of the four common buckwheat varieties exhibited an “S” curve. The Richards equation was utilized to evaluate the grain-filling process of common buckwheat. YQ4 showed the largest values of initial growth power (R₀). The time reaching the maximum grain-filling rate (t_max.G) of FT1 was the longest, and the maximum grain-filling rate (G_max) of DT2 was the fastest.     

果蔬籽油生物活性研究进展

果蔬籽油是由果蔬籽经压榨或萃取工艺制得的植物油脂。果蔬籽油含有丰富的维生素、多不饱和脂肪酸、有机酸等活性成分,这些成分赋予了果蔬籽油抗氧化、抗癌、调节血脂和调节免疫系统等生物活性。本文综述了果蔬籽油生物活性的研究进展,旨在为果蔬籽油的综合开发和利用提供理论依据和指导。     

HXKs基因在香蕉果实后熟过程中功能初探

香蕉是世界主要水果之一,对乙烯非常敏感,属于呼吸跃变型果实。目前,香蕉果实后熟机理还未完全探明,后熟过程中己糖激酶(HXK)与乙烯的关系还不清楚。通过BLAST比对从香蕉基因组数据库中发现HXK基因家族的11个成员,经克隆获得这些基因的序列,并研究HXKs基因在香蕉果实自然后熟过程中的转录表达谱,重点研究乙烯利、甘露糖、NAG和1-MCP对HXKs基因表达、HXK酶活和内源乙烯生物合成的影响。结果表明:在香蕉果实后熟过程中HXKs基因呈现差异性表达,乙烯利上调大多数HXKs基因的表达和HXK酶活,1-MCP的作用正好相反,这表明外源乙烯正作用于HXK。另一方面,甘露糖加快内源乙烯生物合成,NAG却推迟内源乙烯生物合成,这说明HXK正作用于内源乙烯生物合成。所以,在香蕉果实后熟过程中乙烯和HXK之间存在相互促进的关系。这将为进一步阐明香蕉果实后熟机制提供理论依据,也将为香蕉果实保鲜新技术的挖掘提供新思路。     

Resistance monitoring and enzyme activity in three field populations of cowpea aphid (Aphis craccivora) from Egypt

The cowpea aphid (Aphis craccivora) is one of the most important sucking insect pests attacking certain legumes in Egypt particularly faba bean, cowpea and pea. In this study we monitored the resistance level of three field populations of A. craccivora to seven insecticides belonging to three different chemical classes (organophosphates, carbamates and neonicotinoids). The three populations were collected from three governorates in Egypt namely Dakahlia, Qalyobia and Beni Suef. Diagnostic concentrations (LC₉₀ values for susceptible strain) for each insecticide were established using a leaf dipping technique. Resistance monitoring showed that the field population from Dakahlia was highly resistant to all the tested insecticides. In a similar manner, the population from Qalyobia was also resistant to all insecticides except for fenitrothion to which only moderate resistance was observed. The field population from Beni Suef exhibited a lower level of resistance to all the seven tested insecticides.Biochemical assay showed that esterase activity in these three field populations was generally higher as the enzyme activity ratio ranged from 4.3 to 7.8 fold more than that for the susceptible strain. The activity of the other measured detoxifying enzymes (glutathione -S- transferase and mixed function oxidases) was moderate in the populations from Qalyobia and Dakahlia. Nevertheless, the enzyme activity in A. craccivora collected from Beni Suef was variable and differed slightly from the activity measured in the susceptible strain. Monitoring insecticide resistance among the three aphid populations was a proactive approach to detect any shift in insecticide efficiency. The possible occurrence of resistance in the cowpea aphid to the tested insecticides may be due to the higher activity of carboxylesterases. Further studies on the resistance mechanism to these insecticides are needed to provide insights in how to manage and delay the onset of the resistance and thus prolong the performance of insecticides against A. craccivora.     

一株大豆内生拮抗细菌XZ-2的分离和分子鉴定

从大豆植株中分离到一株具有广谱抗菌活性的拮抗细菌,命名为XZ-2。抑菌活性测定显示XZ-2对甘薯黑斑病菌、大蒜叶枯病菌等8种植物病原真菌均具有较强的抑菌活性,抑菌直径均在20 mm以上。采用分光光度法绘制了XZ-2的生长曲线,结果显示该菌株在LB液体摇培12 h时基本达到对数生长期,该生长曲线的绘制为后期XZ-2的活性物质发酵条件优化奠定了基础。通过PCR扩增16Sr DNA片段并采用MEGA 6.0构建系统发育进化树,初步将该菌株鉴定为多粘类芽孢杆菌。     

秸秆还田与优化施氮改善烤烟根际土壤碳氮转化及氮素吸收

针对华南沙泥田烟区氮肥过量施用导致烟叶品质下降的问题,拟通过秸秆还田与氮肥优化配施调节烤烟各生育期氮吸收、根际土壤碳氮转化及相关酶的活性。试验采用随机区组设计,设水稻秸秆还田与氮肥两因素,其中3个碳（秸秆还田）水平：C0,无秸秆还田,0 kg/hm ²;C1,中量秸秆还田,4500 kg/hm ²;C2,全部秸秆还田,9000 kg/hm ²;2个氮水平：N1,传统施氮,169.50 kg/hm ²;N2,优化施氮,105.00 kg/hm ²。结果表明,与N1相比,N2处理秸秆还田下烤烟前期烟叶和根系氮吸收和累积正常,而后期有所下降;C1、C2处理时,与现蕾期相比,成熟期时根系氮含量均降低4.2 g/kg,叶片氮含量降低3.8、3.0 g/kg;成熟期时,与N1处理相比,N2处理时C1、C2处理的土壤无机氮含量降低30.4%、20.0%,前期2个氮处理间土壤无机氮含量无差异,优化施氮下中量秸秆还田（C1N2）处理烤烟土壤NH₄ ⁺-N含量在整个生育期内较高且呈降低趋势,而硝态氮和土壤无机氮含量在成熟期最低,表明中量秸秆还田下优化施氮能够维持生育前期土壤无机氮含量,且降低成熟期土壤无机氮含量。2个秸秆还田量处理时,团棵期N2处理的土壤转化酶活性是N1处理的1.30、1.13倍;旺长期土壤转化酶活性是N1处理的1.27、1.10倍;与传统施氮相比,秸秆还田下优化施氮处理增加了整个生育期土壤脲酶、磷酸酶、过氧化氢酶活性。在中量秸秆还田（C1）处理下,与N1水平相比,现蕾期和成熟期的N2处理土壤水溶性碳含量提高11.2%和14.1%;与N1相比,N2处理的土壤微生物量氮含量呈降低趋势。综上所述,优化施氮耦合中量秸秆还田（C1N2）能够提高土壤水溶性碳含量,维持土壤氮素合理供应,稳定烤烟生育前期对氮素吸收与累积,减少生育后期烟叶氮素奢侈吸收,与烤烟吸氮规律比较吻合。     

苯基吡唑类化合物的合成、杀虫活性及对蜜蜂的毒性

【目的】以氟虫腈结构为骨架,寻找具有杀虫活性和对环境友好型的苯基吡唑类化合物。【方法】以不同取代基的苯胺为原料,经2步法合成含有不同取代基的苯基吡唑类化合物1～21;产物结构经1H NMR、13C NMR和ESI-MS分析确定;采用浸液法测定目标产物对小菜蛾Plutella xylostella的生物活性;测定化合物1、5、12和16对中华蜂Apis cerana的急性经口毒性。【结果】化合物1、5、12和16处理小菜蛾24 h的LC50分别为0.26、0.95、0.33和1.10 mg·L~(-1),其中化合物1和12对小菜蛾的活性优于氟虫腈。化合物5、12和16对中华蜂的急性经口毒性比氟虫腈(0.05mg·L~(-1))低,但仍属于剧毒,LC50分别为0.21、0.22和0.09 mg·L~(-1)。构效关系表明,苯环的取代基对苯基吡唑类化合物的活性影响很大,当苯环邻位存在—Cl或—Br、对位为—Cl、—CF3或—OCF3时,化合物对小菜蛾表现出极好的活性。【结论】氟虫腈苯环取代基的替换可以提高对小菜蛾的生物活性、降低对中华蜂的毒性,研究结果对今后芳基吡唑类杀虫剂开发、结构优化具有一定的指导意义。     

河朔荛花根中抑菌活性成分研究

在活性追踪指导下，采用多种分离技术从河朔荛花根甲醇提取物中分离得到12个化合物，经核磁共振波谱、质谱等技术并结合相关文献确定其结构分别为1-己酸-2,3-硬脂酸甘油三酯( 1 )、β-谷甾醇( 2 )、月桂醇( 3 )、顺-十八碳-9-烯酸( 4 )、(2E)-庚基-3-(3, 4-二羟基苯基)丙烯酸酯( 5 )、(–)-pluviatolide( 6 )、1β-hydroxy-10β-H-guaia-4,11-dien-3-one( 7 )、异狼毒素( 8 )、新狼毒素B( 9 )、瑞香酚( 10 )、单棕榈酸甘油酯( 11 )和(+)-去甲络石甙元( 12 )。其中，化合物 3 、 4 和 6 ~ 12 均为首次从河朔荛花中分离得到。抑菌活性测定结果表明:异狼毒素( 8 )和新狼毒素B( 9 )对马铃薯晚疫病菌Phytophthora infestans菌丝生长和孢子萌发均表现出明显的抑制作用，其中对菌丝生长的EC₅₀值分别为68.4 μg/mL和44.9 μg/mL，对孢子萌发的EC₅₀值分别为25.1 μg/mL和14.0 μg/mL。     

Comparative study on the effects of buckwheat by roasting: Antioxidant properties,nutrients, pasting,and thermal properties

The increasing need to prolong the shelf life of buckwheat has prompted the use of roasting techniques in buckwheat processing. For effective roasting, the responses of common buckwheat (CB) and tartary buckwheat (TB) to the process should be explored. Herein, the antioxidant properties, nutrients, pasting, and thermal properties of raw and roasted buckwheat flours (roasted at 200 °C for 50 s) from two CB and three TB varieties were investigated. Results showed that roasting considerably reduced the total flavonoid content (TFC) and total phenolic content (TPC) of TB. The TPC of CB was significantly improved by roasting, whereas the TFC significantly decreased. The total antioxidant capacities were consistent with the TPCs. Additionally, the colour deepened as the amount of antioxidant compounds increased. Unexpectedly, roasting enhanced the protein and fat contents of CB and decreased those of TB. Roasting improved the nutritional quality and antioxidant capacity of CB, and opposite results were obtained in TB. In conclusion, CB was more suitable to the development of roasted specialty products with nutritional applications than TB. We suggest that differences among varieties should be considered first in the buckwheat roasting process.     

链霉菌和壳聚糖对淮山土壤微生物活性与群落的影响

为探究链霉菌30702和壳聚糖对淮山土壤微生物活性与群落的影响,采用比色法和滴定法观测土壤酶活性的变化,采用高通量测序技术和Trimmomatic等软件,分析土壤微生物群落中细菌和真菌的发展变化。结果表明,链霉菌、壳聚糖、土壤原始微生物和培养时间等4个因素对淮山土壤的脲酶和过氧化氢酶活性均有显著影响,壳聚糖浓度在0~10.0 g/kg内,土壤酶活性随壳聚糖浓度的增大而提高;随时间的延长,先升再降;壳聚糖与链霉菌之间存在交互效应。链霉菌和壳聚糖能增加淮山土壤细菌的物种丰度,减少细菌的多样性,增加艾德昂菌属（Ideonella）和纤维弧菌（Cellvibrio）等有益菌属的相对丰度,而对真菌的物种丰度和多样性的影响较小,与对照之间的差异不显著,土壤优势菌属为腐质霉属（Humicola）、枝孢属（Cladosporium）、鞘氨醇单胞菌属（Sphingomonas）和uncultured_bacterium_ c_Subgroup_6。其中,链霉菌与2.5 g/kg壳聚糖复合处理的细菌物种丰度最大,细菌多样性最少。