Rootstocks resistant to Armillaria root rot

The fact that Armillaria root rot (ARR) is relentlessly killing trees and so hard to control with conventional methods makes the development of a resistant rootstock very enticing. There are efforts underway to create resistant rootstocks for peach using traditional breeding and transgenics.

Traditional breeding

Dr. Tom Beckman is running a breeding program at the USDA Station in Byron, GA with the goal to produce ARR resistant rootstocks. He has already developed commercially available plum/peach hybrids:

  • Sharpe rootstock 2009 SEFVC Proceedings;
    HortScience (2008; pdf); this rootstock has not become popular due to horticultural weaknesses
  • MP29; this rootstock has no horticultural weaknesses but as of now cannot be  propagated large scale

Transgenic rootstocks

The recent discovery of a monocot mannose-binding lectin (gastrodia-anitfungal protein ;GAFP) imparts resistance in the orchid Gastrodia elata. Our lab has shown that GAFP confers resistance to Phytophthora species and root knot nematode in transgenic tobacco (pdf) and transgenic plum (pdf). However, resistance to ARR was not observed, perhaps because the protein was not produced at large enough amounts in the roots.