When I was researching a solution for Elm Phloem Necrosis I found a paper written by M. Ćurković Perica that outlined success in curing periwinkle of a phytoplasma bacteria. This solution should be used for Flavescence dorée.
Periwinkle and IAA
Prof. Ćurković Perica saw that some plants would spontaneously recover from the diseases by themselves. An investigation was then carried out to find out why the plants recovered. The conclusion was that plant hormones were likely responsible for the recovery.
An experiment was conducted and test several hormones on infected periwinkle. The results, IAA, an Auxin compound had the biggest impact. The conclusion was that IAA changes the expression of the plant’s genes by demethylation. Genetic tests confirmed that IAA was causing expression of genes in the periwinkle and in the phytoplasma bacteria. In plants, some of these genes then cause an increase concentration of peroxide in the plant. The peroxide then kills the phytoplasma. In the bacteria, the genes were likely genes to increase the likelihood of survival. This solution could be applied to Flavescence dorée.
The solution of using IAA to produce peroxide in plants should be applied elsewhere. What plants would make the most sense? Well it would be ones that have high economic value. Plants that live for a long time. And plants that we can apply IAA can easily such as a foliar (leaf) application. Grapes meet all these requirements and Flavescence dorée would be an ideal disease to solve.
What is Flavescence dorée? It is a disease that impacts grapes in France and neighboring countries. Currently, there are two solutions to deal with the diseases: Removal of the vines, and a heat treatment. IAA treatment would be a cheaper alternative than both of these current solutions.
We should test IAA to see the effects on Flavescence dorée. After testing we could improve the treatment further. Future development of an IAA treatment could alter IAA or apply IAA with an additional compound. The goal would be to make it more effective at killing the bacteria and to decrease the impact on normal growth. One way to better kill the bacteria after a treatment of IAA is to prevent the phytoplasma bacteria from adapting. For the normal growth of the grapes a second hormone, such as cytokinin could be applied after the plant is clear of the infection.
Before we remove the plant or try a heat treatment maybe apply a treatment of IAA. If you do document how it works. This development could help vineyards around the world from the development of another solution to Flavescence dorée.
Ćurković Perica, M. (2008), Auxin-treatment induces recovery of phytoplasma-infected periwinkle. Journal of Applied Microbiology, 105: 1826–1834. doi:10.1111/j.1365-2672.2008.03946.x