Question

7. Have you ever observed galls in nature? Examine closely stems and leaves of the very large trees on Kissena Boulevard (Pin Oaks) and on 150th Street (English Planes or Sycamores). Do you think these galls are caused by Agrobacterium? Look up "plant galls" or "lant gall types" on the internet to discover alternate causative agents and mechanisms of formation. I

Answer 1

Yes, galls are frequently seen on a variety of plansta nd trees in nature.

The galls formed on pin oaks are caused by cynipid wasps and not by Agrobacterium and similarly the sycamore galls are by mites anemly the maple pimple gall mites and the maple felt gall mites and not by Agrobacterium.

The alternative causative agents are bacteria, fungi, viruses, nematodes, insects and mites

The mechanism in general is the causative agent identifyies a spot on the plant where it can manifest itself, its usually a place which cannot be seen easily and also a place where rapid cell growth occurs. Initialally after coming to contact with the plant cell the causative agent in case of fungi its spores, and bacteria and viruses directly or through a carrier insect afffects the plants, neamatodes, insects and mites eggs are the source of infection try to establish its presence. THey secrete substance which causes the formation of a gall, this is further covered by plant cells surrounding it and forming a pocket or chamber. And the nutrients from the plant cells are absorbed to keep the gal alive. and slowly it invadeds the nutritous parts of the plant.