A Reliable Methodology for Quantitative Extraction of Fruit and Vegetable Physiological Amino Acids and Their Subsequent Analysis with Commonly Available HPLC Systems

Many of the extraction and amino acid analysis methodologies currently employed do not provide complete analysis of all the physiological amino acids and biogenic amines. Extraction procedures frequently employ dilute acid which partially converts gln and asn to glu and asp. A commonly used pre-column derivatizing agent, o-phthalaldehyde, does not react with the imino acids, pro and hydroxypro. The purpose of this investigation was to integrate extraction and analysis procedures into a reliable method for measuring the complete physiological amino acid profiles of fruit and vegetables using HPLC instrumentation commonly available to most laboratories. Water extraction of ground, frozen-thawed tissues effected complete recovery of the physiological amino acids as demonstrated by spiking experiments and tissue combination experiments. HPLC of dabsyl derivatives of the free amino acids allowed their quantification in a selection of fruit and vegetables. Physiological amino acid levels were determined for peach, apple, potato, onion, tomato, bell pepper, broccoli, and seven types of cucurbits. The coefficient of variation for estimation of an amino acid level generally fell in the range of 5% to 7%. Because of marked variability in physiological amino acid content as a result of growing conditions, cultural practices, and inherent cultivar differences, comparisons of results with literature values were not possible.

侵染贵州番茄的辣椒褪绿病毒分子鉴定与分析

辣椒褪绿病毒(Capiscum chlorosis virus, CaCV)是正番茄斑萎病毒属(Orthotospovirus)的重要成员,能够侵染辣椒、番茄等作物并造成严重危害。为明确贵州番茄CaCV分离物基因组分子结构特征及其进化起源,本研究通过RT-PCR技术扩增和测定了CaCV的N、NSs和NSm基因的全长片段,分别获得长度约828bp、1 320bp和927bp的目标条带。经过序列比对和进化树构建等方法进行遗传进化分析发现,贵州番茄CaCV分离物的N、NSs和NSm基因与CaCV其他分离物核苷酸的相似性分别在85.5%~99.4%、82.7%~98.9%和83.1%~98.7%之间。根据系统发育树结果,贵州番茄CaCV分离物N基因和NSs基因与中国云南分离物的亲缘关系较近,NSm基因与中国海南和广州分离物的亲缘关系近,推测贵州CaCV可能是由于番茄、辣椒的品种引进,及蓟马带毒传播进入。这是贵州省CaCV侵染番茄的首次报道,对监测CaCV在我国的扩散具有重要意义。