Cloning and Sequencing of the Pokeweed Antiviral Protein Gene and Its Expression in E. coli

The total RNA was isolated from pokeweed (Phytolacca americana ) leaves using the method of guanidine isothiocyanite and used as a template to amplify the deleted mutant pokeweed antiviral protein (PAP) gene by RT-PCR and then the gene was cloned into the pGEMR-T vector. The sequencing results showed that the PAP gene consisted of 711nt, which was 99.6% identical to the PAP gene reported by Lin et al (1991). The IPTG-inducible expression vector containing the PAP gene was constructed and transferred into the E. coli strain BL21 (DE3)-plysS. A specific protein was produced after induction with 0.4m mol/L IPTG and its molecular weight was 26ku. The results of the double diffusion on the agar plate and the western blotting test showed that the protein produced in E. coli was highly identical with the PAP extracted by a Frenchman from French pokeweed leaves. These revealed that PAP gene was actually achieved and exactly expressed in E . coli.     

李的大小孢子及雌雄配子体发育研究

以牛心李（ＰｒｕｎｕｓａｍｅｒｉｃａｎａＭａｒｓｈ）为材料，系统地观察了李的大小孢子与雌雄配子体发育，结果表明：①３月末～４月末为小孢子及雄配子体发育时期。小孢子母细胞减数分裂中，胞质分裂为同时型，呈四面体型排列，成熟花粉为２—细胞型，②４月中旬～５月初，为大孢子和雌配子体发育时期。双珠被、厚珠心，胚囊发育属单孢子蓼型。并对其发育的时序性、地域性等问题进行了讨论。     

Chlorophyll meter predicts nitrogen status of tall fescue

The nitrogen (N) status of a crop can be used to predict yield and supplemental N fertilizer requirements, and rapid techniques for evaluating the N status of crops are needed. A study was conducted to determine the feasibility of using a hand held chlorophyll meter (SPAD 502, Minolta Co. Ltd., Japan) to monitor N status of tall fescue (Festuca arundinacea Schreb.). Four diverse tall fescue genotypes were grown at three locations in Alabama and fertilized at four N‐rates from 0 to 336 kg ha^‐1. A similar experiment was conducted in the greenhouse using soil from the same field sites. Chlorophyll meter readings (SPAD) were taken, and extractable chlorophyll content, tissue N concentration and dry matter yield were determined at harvest. SPAD, extractable chlorophyll content, tissue N concentration, and dry matter yield increased quadratically (0.67 < R² < 0.99) with increasing N fertilization in both experiments. All genotypes responded similarly to applied N, with some differences in magnitude. Relationships between SPAD meter readings and extractable chlorophyll and tissue N concentrations were linear with r² > 0.95. An additional independent variable, the square root of the inverse of SPAD, lowered the residual mean square by 11 and 16%, respectively, for tissue‐N and chlorophyll concentrations, but did not increase the R². This would be preferred for predictive purposes. Tissue N concentrations at higher N‐rates were sufficient for maximum yield which occurred at 290 and 248 kg N ha^‐1 for greenhouse and field, respectively, but were lower than previously reported sufficiency values. The chlorophyll meter is an easy and efficient method of detecting tall fescue N status.     

Colletotrichum siamense is the main aetiological agent of anthracnose of avocado in south-eastern Brazil

Anthracnose caused by species of Colletotrichum is considered one of the main postharvest diseases for avocado. In this study, Colletotrichum isolates associated with avocado anthracnose, collected in different states of Brazil, were evaluated through phylogenetic analysis, morphological characterization, and pathogenicity assays. Moreover, the events during pathogen infection of avocados were examined by scanning electron microscopy. To assess the genetic diversity of 54 Colletotrichum isolates, partial sequence analysis of the gene gapdh was performed. According to the generated groupings and the geographical origins of isolates, a subset of 14 strains was selected for performing multilocus phylogeny analysis (using sequences of gapdh, act, tub2, and ApMat). Two species previously described were identified: C. siamense belonging to the C. gloeosporioides species complex and Colletotrichum karstii belonging to the C. boninense species complex. All Colletotrichum strains evaluated caused typical symptoms of anthracnose in avocado fruits. Conidia of the most virulent strain germinated between 6 and 12 hr after inoculation (hai). Penetration through wounds occurred 48 hai, tissue colonization occurred between 144 and 240 hai, and sporulation took place at 240 hai via the production of an acervulus, conidiophores, and conidia. The findings shed light on the aetiology of avocado anthracnose in Brazil and provide a better understanding of the infection process of this pathogen, which may assist in the development of disease management strategies.     

Effect of Application of Sulfuric and Humic Acid in the Mitigation of Root Asphyxiation Stress in Potted Avocado Plants

ABSTRACT

Avocado crop is very sensitive to root asphyxiation. Among the agricultural management techniques, soil applications of humic and sulfuric acids became increasingly popular. In a trial with potted 'Hass' avocado trees grown on a silty-clay soil, different soil treatments were applied to determine their effects on tree physiology and soil characteristics: Control, deionized water; SA, H₂SO₄ application; HA, humic acid application; SA+HA, combination of both treatments. Treatments were applied during a 9-month period. SA reduced soil pH, rised electrical conductivity and reduced saturated soil hydraulic conductivity (Ks) in the upper layers of the potted soil. On the other hand, HA increased electrical conductivity and Ks compared with Control. None of the treatments improved CO₂ assimilation, stomatal conductance, stem water potential, chlorophyll fluorescence, growth or nutrient content. Our findings suggest that a rapid and positive response to the application of acids is unlikely to be observed under conditions of restricted oxygen in the root zone.     

美洲大蠊对肉鸡生产性能、血液生化指标及小肠绒毛高度的影响

将396只1日龄雄性黄羽肉鸡随机分为4个处理,每处理设3个重复,每重复33只。对照组饲喂基础日粮,试验组分别用2.0%、1.0%和0.5%美洲大蠊虫粉等量取代基础日粮中的鱼粉,进行70d的饲养,分别在第42d、70d测定肉鸡的生长性能、血液生化指标及十二指肠绒毛高度。结果表明,各处理日采食量、日增重及死亡率差异均不显著(P>0.05),2%虫粉组的料重比显著低于对照组8.06%(P<0.05);各处理血清尿素氮、尿酸及白蛋白含量差异均不显著(P>0.05),2%虫粉组血清总蛋白、球蛋白含量显著高于对照组(P<0.05);2%虫粉组及1%虫粉组42d,70d十二指肠绒毛高度均显著高于对照组(P<0.05)。     

紫貂、松貂与美洲貂背中部冬季直针毛的结构差异

利用钢直尺、H6303i生物显微镜及配套的图片处理、测量软件系统(重光数码显微系统),测量紫貂(Martes zibellina)、松貂(Martes martes)和美洲貂(Martes americana)的背中部冬季直针毛长度、细度、近毛根细度、髓质细度、毛根无髓段长度及各类型鳞片比例等形态学指标;使用SPSS19.0对比分析测定数据。结果表明:紫貂、松貂和美洲貂的直针毛均呈典型纺锤型,髓质花纹类型均为网格型-B,鳞片类型、排列顺序、主要鳞片类型相近。松貂直针毛的长度、细度、髓质细度、毛根无髓段长度、扁平型鳞片比例显著高于紫貂(P0.05),而瓣状型鳞片比例明显低于紫貂,在其他性状方面二者差异不显著(P0.05);美洲貂的直针毛细度、扁平型鳞片比例显著低于松貂(P0.05),毛长度、髓质细度、近毛根细度、髓质指数等性状方面二者差异不显著(P0.05);紫貂和美洲貂只在直针毛的细度上表现出明显的差异(P0.05)。     

高效液相色谱法定性定量测定油梨果实中的可溶性糖成分

分析油梨果实可溶性糖成分及含量,为以后深入分析、利用其成分提供一定理论基础。对所采集的3份油梨,应用高效液相色谱仪测定其可溶性糖组分及含量。结果显示,3份油梨果肉中的可溶性总糖含量为(13.19±0.32)~(25.94±0.98)(mg/g FW),其可溶性糖由甘露庚酮糖、甘露庚糖醇、果糖及葡萄糖等4个成分组成,以甘露庚酮糖为主;可溶性总糖、甘露庚酮糖、甘露庚糖醇、果糖及葡萄糖含量在3份油梨果肉中差异均显著。3份油梨种子中的可溶性总糖含量为(20.47±0.52)~(29.41±0.60)(mg/g FW),其可溶性糖同样由甘露庚酮糖、甘露庚糖醇、果糖及葡萄糖等4个成分组成,以甘露庚糖醇为主;可溶性总糖、甘露庚酮糖、甘露庚糖醇、果糖及葡萄糖含量在3份油梨种子中差异均显著。3份油梨果肉和种子之间可溶性总糖和各可溶性糖成分平均含量差距大小依次为:甘露庚糖醇果糖甘露庚酮糖葡萄糖可溶性总糖。     

7个油梨品种(系)果肉的脂肪酸含量及其相关性

为油梨果肉油脂开发和品质育种奠定基础,采用索氏提取法和气质联用法对国内油梨品种(系)RN-1、RN-5、RN-11、RN-12、RN-15、RN-16和国外品种Hass等果肉的含油量和脂肪酸成分进行测定,并进行相关性与聚类分析。结果表明:7个油梨品(系)果肉含油量为5.04~8.75g/100g FW,且差异显著(P0.05),其中RN-5的含油量最高,达8.75g/100g;果肉均含有8种脂肪酸成分,在大部分油梨品种(系)间差异显著(P0.05),相对含量为棕榈酸(30.87%)油酸(29.48%)亚油酸(26.58%)棕榈油酸(9.96%)亚麻酸(1.30%)硬脂酸(1.16%)花生酸(1.02%)肉豆蔻酸(0.23%)。不饱和脂肪酸相对含量为62.80%~70.60%,其中油酸相对含量大于30%的品种(系)3个,为RN-1、RN-15和RN-16;亚油酸相对含量大于25%的4个,为RN-1、RN-5、RN-12、RN-15和RN-16;棕榈油酸相对含量大于10%的3个,为RN-5、RN-11和Hass。亚麻酸与花生酸的相对含量呈极显著正相关,肉豆蔻酸与亚油酸呈显著正相关。基于8种脂肪酸成分相对含量聚类,RN-1、RN-5、RN-11、RN-16和Hass聚为一组,RN-12和RN-15各为一组。油梨果肉具有较高含油量和适宜的脂肪酸含量,其中RN-5在油脂开发和品质育种上具有较好的开发利用前景。     

剑麻提取液对台湾青枣采后生理及贮藏效果的影响

探讨剑麻提取液在台湾青枣果实贮藏保鲜上的作用。以剑麻提取液为材料,浸泡处理台湾青枣采后果实,然后在常温条件下贮藏,研究剑麻提取液处理对台湾青枣果实采后生理及品质的影响。结果表明:剑麻提取液处理可有效降低果实失重率和腐烂率,延缓果实硬度、可溶性固形物含量、维生素C、可滴定酸的下降,保持了果实的品质;同时,剑麻提取液处理还提高了采后贮藏台湾青枣果实POD、CAT活性,减轻了台湾青枣细胞膜脂过氧化程度,从而有效延缓果实的衰老;剑麻提取液在台湾青枣贮藏保鲜上有良好的保鲜效果。