质型多角体病毒(Cytoplasmic polyhedrosis virus,CPV)隶属呼肠孤病毒科Reoviridae质型多角体病毒属Cypovirus,通常基因组由10个节段双链RNA构成。RNA分子量为3～27u。根据病毒基因组dsRNA片段在聚丙烯酰胺或琼脂糖凝胶中电泳图谱的差异,目前CPV已被分为19个电泳型。不同于呼肠孤病毒科其它成员,CPV为单层衣壳,而不是常见的双层衣壳结构,衣壳蛋白主要由衣壳蛋白、大突起蛋白及塔式突起蛋白组成。大部分质型多角体病毒引起昆虫慢性疾病,造成寄主死亡或适应性降低。随着RNA病毒基因序列测定技术的成熟,质型多角体病毒的序列测定方面取得较大进展,目前GenBank核苷酸序列数据库中已经公布了家蚕Bombyx mori CPV电泳型1两个株系(H株和I株)、舞毒蛾Lymantria dispar CPV电泳型1、舞毒蛾CPV电泳型14及粉纹夜蛾Trichoplusia ni CPV电泳型全基因组序列,为该病毒的进化与起源的研究提供更多的遗传信息。本文从结构功能、侵染特点、基因组特点及应用前景等方面综述了昆虫质型多角体病毒的研究进展。
Plant allocation to defensive compounds by elevated CO2-grown nontransgenic and transgenic Bt cotton in response to infestation by cotton aphid, Aphis gossypii （Glover） in open-top chambers under elevated CO2 were studied. The results showed that significantly lower foliar nitrogen concentration and Bt toxin protein occurred in transgenic Bt cotton with and without cotton aphid infestation under elevated CO2. However, significantly higher carbon/nitrogen ratio, condensed tannin and gossypol were observed in transgenic Bt cotton ＂GK-12＂ and non-transgenic Bt cotton ＇Simian-3＇ under elevated CO2. The CO2 level and cotton variety significantly influenced the foliar nitrogen, condensed tannin and gossypol concentrations in the plant leaves after feeding by A. gossypii. The interaction between CO2 level x infestation time （24 h, 48 h and 72 h） showed a significant increase in cotton condensed tannin concentrations, while the interaction between CO2 level x cotton variety significantly decreased the true choline esterase （TChE） concentration in the body ofA. gossypi. This study exemplified the complexities of predicting how transgenic and non-transgenic plants will allocate defensive compounds in response to herbivorous insects under differing climatic conditions. Plant defensive compound allocation patterns and aphid enzyme changes observed in this study appear to be broadly applicable across a range of plant and herbivorous insect interactions as CO2 atmosphere rises.
Effects of CO2 level （ambient vs. elevated） on the interactions among three cotton （Gossypium hirsutum） genotypes, the cotton aphid （Aphis gossypii Glover）, and its hymenoptera parasitoid （Lysiphlebiajaponica Ashrnead） were quantified. It was hypothesized that aphid-parasitoid interactions in crop systems may be altered by elevated CO2, and that the degree of change is influenced by plant genotype. The cotton genotypes had high （M9101）, medium （HZ401） and low （ZMS13） gossypol contents, and the response to elevated CO2 was genotype-specific. Elevated C02 increased the ratio of total non-structural carbohydrates to nitrogen （TNC ： N） in the high-gossypol genotype and the mediumgossypol genotype. For all three genotypes, elevated CO2 had no effect on concentrations of gossypol and condensed tannins. A. gossypii fitness declined when aphids were reared on the high-gossypol genotype versus the low-gossypol genotype under elevated CO2. Furthermore, elevated CO2 decreased the developmental time of L. japonica associated with the high-gossypol genotype and the low-gossypol genotype, but did not affect parasitism or emergence rates. Our study suggests that the abundance of A. gossypii on cotton will not be directly affected by increases in atmospheric CO2. We speculate that A. gossypii may diminish in pest status in elevated COz and high-gossypol genotype environments because of reduced fitness to the high-gossypol genotype and shorter developmental time of L. japonica.
