0 a system of very small tubes that carries food from the leaves to other parts of a plant -- folem
The phloem carries these sugars to parts of the plant that cannot photosynthesize, like the roots.
The specialist race found its host plant faster, reached the phloem sooner, and spent more time feeding than the generalist one.
Since aphids are specialist herbivores targeting the phloem sieve element, it is reasonable to expect that changes in gene expression may be phloem-specific.
This result contrasts with plant responses to phloem-feeding insects.
It is not known whether disproportionately higher levels of alkaloids in other tissues, principally the phloem, contribute to this aphid resistance.
The sugar-rich phloem is a possible niche for such organisms.
The enlarged cambial cells appeared to crush the phloem and were thus presumed to cause the hopperburn symptom characteristic of the leafhopper damage.
To reach the phloem sieve elements the aphid's stylet mouthparts must pierce a series of plant tissues.
Another open question is whether the transgene product could be transported in the phloem sap.
