How do aphids obtain their obligate endosymbiont Buchnera aphidicola?

How do aphids obtain their obligate endosymbiont Buchnera aphidicola?

• A. Horizontal transmission via feeding on plant phloem.
• B. Vertical transmission, where bacteria are incorporated into embryos during reproduction.
• C. Acquired from the environment.
• D. Through pollen.

Answer: (B)

Aphids keep Buchnera aphidicola because the symbiont is passed directly from mother to offspring, a process called vertical transmission. Buchnera resides in specialized cells called bacteriocytes within a shared organ (the bacteriome). During reproduction, the bacteria are moved from the mother’s bacteriocytes into the developing embryos, so every new aphid inherits the endosymbiont from its mother. This tight, maternal inheritance fits the obligate nature of Buchnera, which cannot survive long outside aphid cells or be acquired from the environment. Therefore, transmission through the germ line during reproduction is the reliable way aphids maintain their essential symbiont.

Aphids keep Buchnera aphidicola because the symbiont is passed directly from mother to offspring, a process called vertical transmission. Buchnera resides in specialized cells called bacteriocytes within a shared organ (the bacteriome). During reproduction, the bacteria are moved from the mother’s bacteriocytes into the developing embryos, so every new aphid inherits the endosymbiont from its mother. This tight, maternal inheritance fits the obligate nature of Buchnera, which cannot survive long outside aphid cells or be acquired from the environment. Therefore, transmission through the germ line during reproduction is the reliable way aphids maintain their essential symbiont.