Laboratory for Genomics and Development, College of Bio-Resources and Agriculture, Department of Entomology, National Taiwan University (NTU), No. 1, Sec. 4, Roosevelt Rd., Taipei, 10617, Taiwan.
Department of Biochemistry and Molecular Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan.
Dev Genes Evol. 2022 Aug;232(2-4):51-65. doi: 10.1007/s00427-022-00690-7. Epub 2022 Jun 9.
Aphids are hemimetabolous insects that undergo incomplete metamorphosis without pupation. The annual life cycle of most aphids includes both an asexual (viviparous) and a sexual (oviparous) phase. Sexual reproduction only occurs once per year and is followed by many generations of asexual reproduction, during which aphids propagate exponentially with telescopic development. Here, we discuss the potential links between viviparous embryogenesis and derived developmental features in the pea aphid Acyrthosiphon pisum, particularly focusing on germline specification and axis determination, both of which are key events of early development in insects. We also discuss potential evolutionary paths through which both viviparous and oviparous females might have come to utilize maternal germ plasm to drive germline specification. This developmental strategy, as defined by germline markers, has not been reported in other hemimetabolous insects. In viviparous females, furthermore, we discuss whether molecules that in other insects characterize germ plasm, like Vasa, also participate in posterior determination and how the anterior localization of the hunchback orthologue Ap-hb establishes the anterior-posterior axis. We propose that the linked chain of developing oocytes and embryos within each ovariole and the special morphology of early embryos might have driven the formation of evolutionary novelties in germline specification and axis determination in the viviparous aphids. Moreover, based upon the finding that the endosymbiont Buchnera aphidicola is closely associated with germ cells throughout embryogenesis, we propose presumptive roles for B. aphidicola in aphid development, discussing how it might regulate germline migration in both reproductive modes of pea aphids. In summary, we expect that this review will shed light on viviparous as well as oviparous development in aphids.
蚜虫是半变态昆虫，经历不完全变态而没有蛹期。大多数蚜虫的年生活史包括无性（胎生）和有性（卵生）两个阶段。有性生殖每年仅发生一次，随后是多代无性生殖，在此期间蚜虫以指数方式繁殖，并且具有伸缩式发育。在这里，我们讨论了胎生胚胎发生与豌豆蚜 Acyrthosiphon pisum 中衍生的发育特征之间的潜在联系，特别是重点关注生殖细胞的特化和轴的确定，这两个都是昆虫早期发育的关键事件。我们还讨论了有性和胎生雌性可能利用母体生殖质来驱动生殖细胞特化的潜在进化途径。这种发育策略，如生殖细胞标记所定义的，在其他半变态昆虫中尚未报道。此外，在胎生雌性中，我们讨论了在其他昆虫中表征生殖质的分子，如 Vasa，是否也参与了后极的确定，以及 Ap-hb 的同源物 hunchback 如何在前部定位建立前后轴。我们提出，每个卵巢中的卵母细胞和胚胎的发育链以及早期胚胎的特殊形态可能推动了胎生蚜虫生殖细胞特化和轴确定的进化创新。此外，基于共生菌 Buchnera aphidicola 在胚胎发生过程中与生殖细胞密切相关的发现，我们提出了 Buchnera aphidicola 在蚜虫发育中的假定作用，讨论了它如何调节豌豆蚜两种生殖模式中的生殖细胞迁移。总之，我们希望本综述将阐明蚜虫的胎生和卵生发育。
