思茅松人工林生长与立地条件的关系研究

对思茅松人工林生长与地形因子和土壤理化之间的关系进行了分析研究。单因子分析结果表明,思茅松树高生长指标与海拔呈显著负相关,而与坡度、土壤厚度 、有效磷之间呈显著或极显著的正相关;逐步回归分析结果表明,海拔、全钾、有效磷及其组合是影响思茅松生长的主要因子。缺磷少氮是思茅松人工林土壤的共同特点,在选择造林或制定营林措施应当引起足够的重视。     

微量必需元素硒的作用探析

硒在有机体的生命活动过程中具有重要的生物学作用,不断有研究发现硒缺乏与许多疾病的发生有密切关系。本文主要对硒的生物学功能、过量补硒的毒性、我国硒资源及产品开发状况等方面做了综述,同时对硒资源开发利用存在问题和前景进行了展望,以期对硒进行较全面的认识。     

不同种类相思树试管苗内源激素的HPLC测定

本试验以不同种类相思树试管苗为材料,对相思树试管苗内源激素进行提取,并建立了相思树内源激素的HPLC测定方法。研究结果表明不同种类相思树试管苗内源激素测定方法存在差异,不同种类相思树试管苗内源激素含量差异较大。     

花生AhLEA18蛋白基因的克隆与表达分析

LEA蛋白家族是一类在种子胚胎发育晚期丰富表达的蛋白,在种子的正常发育过程中大量积累,同时在植物处于干旱、寒冷、盐胁迫等逆境条件下高水平表达,推测该类蛋白在缺水条件下具有一定的生理保护功能。根据蛋白序列特点,该蛋白家族分为多个组,LEA18蛋白属于其中一组蛋白。PvLEA18蛋白在干燥种子、花粉粒中大量积累,也参与到对水分缺失、ABA处理的生理应答过程过程。本研究从栽培种花生鲁花14中克隆得到一个LEA18基因,命名为AhLEA18。对其序列的生物信息学分析表明,AhLEA18具有典型LEA18蛋白序列特征。通过半定量RT-PCR的方法对该基因在花生植株不同组织及不同发育时期的种子中的表达情况进行了分析。     

基于BP神经网络的橡胶苗叶片磷含量高光谱预测

为验证高光谱技术在橡胶苗叶片磷素营养诊断方面的可行性,该文以砂培橡胶苗为研究对象,利用高光谱仪测得不同磷处理水平下橡胶苗叶片光谱反射率,并应用微分技术求取去噪后光谱反射率一阶和二阶导数,以叶片磷含量和光谱变量相关性分析为基础,选择出叶片磷含量敏感波段,最后以敏感波段为输入变量,结合多重线性回归、偏最小二乘回归和反向传播神经网络模型对叶片磷含量进行预测。结果表明:原始光谱反射率555和722 nm、一阶导数674、710、855、1 091、1 197、1 275、1 718、2 181和2 228 nm以及二阶导数816、890、1 339、1 357和2 201 nm为叶片磷含量敏感波段;反向传播神经网络模型预测精度最高,训练集和验证集中预测值和实测值之间的相关系数r分别为0.964和0.967,均方根误差RMSE分别为0.0139和0.00856,模型性能指数(ratio of performance to deviation,RPD)分别为3.71和3.23,证明高光谱技术可以快速、准确诊断橡胶苗叶片磷含量。     

A molecular diagnosis method using real-time PCR for quantification and detection of Fusarium oxysporum f. sp. cubense race 4

The Fusarium genus causes devastating plant diseases worldwide, in which Fusarium oxysporum is the most serious crop pathogen. Disease monitoring is the basis of integrated pest management of any disease. The lack of rapid, accurate, and reliable device to detect and identify plant pathogens is one of the main limitations in integrated disease management. This study describes an efficient and quantifiable diagnosis method for the specific detection of F. oxysporum f. sp. cubense (Foc) race 4 in field-infected banana. With the optimized PCR parameters using the SCAR (sequence characterized amplified region) primers FocSc-1/FocSc-2 and a real-time PCR strategy, the developed method showed high reproducibility and was very sensitive to detect extremely low quantities of Foc genomic DNA (gDNA). We also found that Foc gDNA in severely symptomatic banana pseudostems and leaves were 6946-fold and 26.69-fold more than in those of mild-symptomatic banana, respectively.     

Molecular characterization and phylogenetic analysis of Citrus viroid V isolates from Pakistan

Citrus viroid V (CVd-V) was recently characterized and belongs to the genus Apscaviroid within the family Pospiviroidae. 334 CVd-V isolates were identified from Punjab, Pakistan, where CVd-V had not been reported. A total of 68 independent cDNA clones were sequenced from 11 infected trees of different cultivars, ranging from 292 to 295 nucleotides. The nucleotide diversity estimated from the nucleotide distances of the CVd-V Pakistan population was similar to that reported from other countries. Based on genetic diversity and phylogenetic analysis, two main CVd-V groups were identified indicating that Pakistan might be one of the geographic origins of CVd-V worldwide. We demonstrated that this viroid has not emerged recently and it is more widespread than previously expected.     

基于光能利用率模型估算大兴安岭北部火烧迹地生产力

以大兴安岭火后不同强度(轻度、中度、重度)及未火烧区森林为研究对象,利用光能利用率模型和ETM+影像,结合植被资料,估算了火烧结束12 a后(1999年8月)过火区的针叶林、阔叶林、针阔混交林的净初级生产力(Net primary productivity,NP,P),分析了1987年"5.6"大火不同强度火烧对森林分布和生产力的影响。结果表明:轻度和中度过火区林地面积的比重与未过火区相近,且NP,P比未过火区高;重度过火区部分林地的比重降低,森林退化成非林地,但林地NP,P与未过火区相近。     

拉美解决粮食问题的典范——以委内瑞拉粮食主权运动为考察对象

粮食主权作为一种宗旨,正成为发展中国家解决粮食问题的指导思想,委内瑞拉查维斯政府在土地改革基础上推行的粮食主权运动是最早实践粮食主权宗旨的国家之一。通过对委内瑞拉粮食主权运动推行的背景、过程、措施的分析阐述,认为拉美各国只要在政府层面制定一个清晰的规划和农业发展战略,能够适应粮食市场的发展规律,提高小农的生产力水平,同时能最大限度地减少发达国家廉价粮食的冲击就可以真正解决粮食匮乏所带来社会、经济等问题。     

Purification, cloning, and immunological characterization of arginine kinase, a novel allergen of Octopus fangsiao

Arginine kinase (AK) is an important enzyme participating in energy metabolism in invertebrates, but, to date, there have been no reports that AK from octopus is an allergen. In this study, octopus AK was purified, and its molecular biological, immunological, and physicochemical characterizations were analyzed. The results showed that octopus AK was purified and confirmed by mass spectrometry for the first time, and its molecular mass was 38 kDa. The full-length gene sequence of octopus AK encompassed 1209 bp and was predicted to encode a protein with 348 amino acid residues. The homology of octopus AK and crustacean AK was about 54%, but the similarity between their three-dimensional structures was high. Octopus AK could react with mouse anti-shrimp AK and rabbit anti-crab AK polyclonal antibody singly. Octopus AK could also react with specific IgE of the sera from octopus-allergic patients effectively, whereas crab AK could inhibit the reaction between them. Finally, the IgE-binding activity of octopus AK could be reduced in the processes of thermal or acid-alkali treatment. In summary, AK was identified as a novel allergen in octopus, which had a sensitizing ability similar to that of crustacean AK. This is significant in allergy diagnosis and the treatment of octopus-allergic disorders.