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Open Access Publications from the University of California

The Regulation and Epigenetic Patterns of Aphid Tissues That are Involved in Symbiosis and Insect-Plant Interactions

  • Author(s): Kim, Dohyup
  • Advisor(s): Hansen, Allison K
  • et al.
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Creative Commons 'BY-NC' version 4.0 license

In this dissertation, the integrated metabolism of three aphid species (Acyrthosiphon pisum, Aphis glycines, and Myzus persicae) and their specialized endosymbionts was explored. In the first chapter, tissue- and host plant-specific profiles of gene expression and CpG methylation of A. pisum were analyzed. Through RNA-Seq and whole genome bisulfite sequencing, I identified key metabolic genes that are differentially expressed and methylated between bacteriocytes and body cells. Moreover, I demonstrated for the first time that key aphid genes involved in the regulation of aphid-Buchnera symbiosis are differentially expressed and methylated depending on the aphid’s host plant diet, suggesting that DNA methylation may be a key regulatory factor that induces phenotypic variation depending on the host plant diet. In the second aphid system, I empirically and computationally confirmed the functional CpG methylation system in Aphis glycines. Also, I showed that lineage-specific genes in A. glycines have significantly lower CpG methylation levels compared to evolutionarily conserved genes. Moreover, five aphid-specific genes were identified to play key roles in insect-plant interactions at the epigenetic level. In the last aphid system, I identified differentially expressed genes in bacteriocytes of Myzus persicae compared to its body cells. I demonstrated overall up-regulation of the genes that are involved in amino acid biosynthesis as well as key genes in aphid-Buchnera integrated metabolism. I then compared gene expression patterns of M. persicae bacteriocytes to those of A. pisum bacteriocytes. I found that the two closely related species have very similar gene expression profiles in their bacteriocytes while there are lineage-specific expression signatures in some metabolic genes.

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This item is under embargo until July 22, 2021.