白背飞虱中的Wolbachia和Cardinium双重感染特性

Double infection of Wolbachia and Cardinium in the whitebacked planthopper, Sogatella furcifera (Hemiptera: Delphacidae)

为了明确自然种群白背飞虱Sogatella furcifera中Wolbachia和Cardinium的感染情况以及Wolbachia与其特有的WO噬菌体之间的关系,以采自中国7个省区9个地点的白背飞虱为研究材料,运用PCR检测的方法调查了Wolbachia,Cardinium以及WO噬菌体在各飞虱种群中的感染率和组织分布特点。结果表明:白背飞虱广泛双重感染Wolbachia和Cardinium,并且都表现出很高的感染率。白背飞虱各种群Cardinium的感染率几乎均为100%;Wolbachia的感染率也较高,但雌雄虫感染率差异较大,雌虫的感染率几乎均为100%,而雄虫的感染率从22.2%～95.0%不等。另外,通过不同DNA聚合酶、不同提取方法的对比,揭示了DNA粗提样品在基于PCR技术的胞内共生菌检测中的不足之处。对白背飞虱头部、胸部、腹部、足和翅5个不同部位组织的检测结果表明,不仅在含有生殖组织的腹部有这两类共生菌的感染,在其他非生殖组织中同样也感染了这两类共生菌;虽然Wolbachia和Cardinium在寄主的各个组织中均有分布,但是两者在白背飞虱成虫(尤其是雄虫)阶段的动态变化有明显的差异。进一步对Wolbachia宿主特异性WO噬菌体的检测结果表明,自然种群雄虫中Wolbachia的感染率与不感染个体中WO噬菌体的比率呈明显的负相关。因此推测,雄虫中Wolbachia感染率相对较低的原因可能是由于Wolbachia基因组中溶原性的WO噬菌体受到某种因素的诱导已转化为裂解性噬菌体。研究结果为进一步揭示Wolbachia和Cardinium双重感染条件下对寄主的生殖调控作用及其机制、垂直传播规律、两者之间的相互关系以及进一步的应用研究等方面提供了重要的理论基础。

In order to reveal the infection characteristics of bacterial endosymbionts Wolbachia and Cardinium in natural populations of Sogatella furcifera （Horváth） and the relationship between Wolbachia and bacteriophage WO, we used PCR method to detect the infection rates and tissue distribution of these bacteria and phage in various S. furcifera populations which were collected from nine localities in seven provinces and regions of China. The results revealed that the double infection of Wolbachia and Cardinium was a common event in this insect with each population tested having a high infection rate. For Cardinium, the infection rate was nearly 100%, but for Wolbachia, the infection rates of females and males were quite different, nearly 100% in females while ranged from 22.2%-95.0% in male adults. In addition, by comparing the detection results using different DNA extraction methods and DNA polymerase, we found that the rough DNA extraction method has evident disadvantages in surveying the endosymbiont infection. Wolbachia and Cardinium existed not only in the germinal tissues of S. furcifera but also in non-reproductive tissues/parts such as head, thorax, legs and wings. Meanwhile, these two endosymbionts exhibited different change patterns during the adult stage, particularly in males. There existed an obvious negative correlation between the infection rates of Wolbachia and the rates of bacteriophage WO detected from uninfected individuals in males. The lower Wolbachia infection rate in males might be caused by the transition of WO phage from lysogenic to lytic type under the induction of certain factors. The results of this study will shed light on further understanding of the reproductive manipulation and underlying mechanisms of Wolbachia and Cardinium, their vertical transfer, interrelationship and their potential utilization.