Fig. 1.

Experimental approach for replacement of the native Buchnera symbionts within an A. pisum matriline. The recipient line (LSR1) contains a heat-sensitive Buchnera genotype, and the donor (5AY) contains a heat-tolerant Buchnera genotype. Native Buchnera are depleted by heat in the recipient line, and microinjection is used to flood the hemocoel with donor Buchnera. Most embryos are successfully colonized by the donor symbionts. In some cases, complete replacement occurs in the progeny of injected females. In other cases, progeny have a mixed Buchnera population, which can be shifted completely to the donor type through further heat exposure.