Symbiotic Association of Aphids: Biochemical Role of the Procaryotic Endosymbiont

蚜虫的共生关联：原核内共生体的生化作用

• 批准号: 9201285
• 负责人: Paul Baumann
• 金额: $ 15万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-09-01 至 1994-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9201285&HistoricalAwards=false
• 关键词: Symbiotic; Association; Aphids; Biochemical; Role

Aphids are small syringe-like insects which penetrate plants and suck up plant juices for nutrients. Acting like unsterilized needles these insects transmit a variety of agriculturally important plant diseases. Within the body cavity of aphids are specialized cells which contain gram-negative bacteria (endosymbionts) which cannot be cultured outside the host cells. The aphid is dependent on the endosymbionts, their elimination by treatment with antibiotics results in sterility or death of the host. Plant sap is deficient in a variety of amino acids which insects cannot synthesize and evidence suggests that the endosymbionts supply these amino acids for the aphid host. Perhaps the best available evidence is for the overproduction of tryptophan by the endosymbiont; there is also evidence that some endosymbionts may overproduce cysteine. Our study involves the cloning and sequencing of genes coding for enzymes of tryptophan and cysteine biosynthesis, the overproduction of selected key enzymes and a study of their kinetic properties. These results may indicate that the two key amino acids, tryptophan and cysteine are overproduced by the endosymbiont and utilized by the aphid host. This information will establish a function for the endosymbiont and may suggest approaches for the controlling of aphid pests by the elimination of their endosymbionts.

蚜虫是小型注射器样昆虫，可穿透植物并吸收植物汁以获取营养。 这些昆虫像未经斯托的针一样，会传播各种重要的农业植物疾病。 在蚜虫的体腔中是专门的细胞，其中含有革兰氏阴性细菌（内共生菌），无法在宿主细胞外培养。 蚜虫取决于内共生体，通过抗生素治疗消除它们的消除导致宿主的不育或死亡。 植物SAP缺乏各种昆虫无法合成的氨基酸，证据表明，内共生体为蚜虫宿主提供这些氨基酸。 也许最好的证据是内共生体的色氨酸过量生产。 也有证据表明，某些内共生体可能过量生产半胱氨酸。 我们的研究涉及编码色氨酸和半胱氨酸生物合成酶的基因的克隆和测序，对选定关键酶的过量生产以及对其动力学特性的研究。 这些结果可能表明，两种关键的氨基酸，色氨酸和半胱氨酸被内共生菌过量生产，并被蚜虫宿主使用。 该信息将为内共生体建立一个功能，并可能建议通过消除其内共生体来控制蚜虫害虫的方法。