A biologically intensive approach to induce the natural immunity of potatoes against the pathogens inciting Late Blight and Verticillium wilt

CSANR Project 139

Status: Complete

Project Summary

The overall objective of this proposal is to develop a procedure for improving the natural immunity of potato adequately to ward off the destructive pathogens causing Late Blight ad Verticillium wilt.  Our lab’s preliminary research has determined that some yeast-like non-pathogenic fungi can induce a defense response in plants, either with the DNase enzyme they  release or by the presence of the intact fungal cell applied to potato leaves prior to the arrival of the pathogen.  A second agent, a chelating agent, acts by the same mode  (alteration of the plant DNA structure) to also induce immunity.  The immunity response is monitored with an excised leaf assay.  This assay will further screen  immunity- enhancing yeast-like species and determine the optimal levels of these agents that will be both effective and economical.  We expect all the enhancing agents to comply with the regulations of the National Organic Program (NOP).  Following the leaf assay, the benefits will be assessed in intact plants under greenhouse conditions and finally under field conditions.

Annual Entries

2014

Principal Investigator: Lee Hadwiger
Additional Investigator: Dean Glawe
Progress Report: http://csanr.wsu.edu/wp-content/uploads/2014/03/139Hadwiger.pdf
Grant Amount: $19027

Publications

With this grant, adequate data was collected to enable the following manuscripts to be published
in the American Journal of Potato Research, and to an organic chemical journal called
Molecules.

Hadwiger, L. A., McDonel, H., Glawe, D. 2015. Wild Yeast strains as prospective candidates to
induce resistance against potato late blight. Am. J. Potato Res. DOI 10.1007/s12230-015-9443-y

Hadwiger, L. A., Tanaka, K. 2015. EDTA a novel inducer of pisatin, a phytoalexin indicator of
the non-host resistance in peas. Molecules 20, 24-34: doi:10.3390/molecules20010024
Publications related to the response of plants to pathogens releasing elicitors that are not
considered specific for the plant species challenged (non-host resistance) are as follows:

Hadwiger, L. A. 2015. Nonhost resistance: Self-inflicted DNA damage by fungal DNase
accumulation is a major factor in terminating fungal growth in the pea –Fusarium solani f sp.
phaseoli interaction. Physiol. and Molecular Plant Pathology 92:79-87.

Hadwiger, L. A. 2015. Anatomy of a nonhost disease resistance response of pea to Fusarium
solani: PR gene elicitation via DNase, chitosan and chromatin alterations. Frontiers in Plant
Science 6:373-400.

Hadwiger, L. A. 2015. Chitosan: The preliminary research and the host/parasite system that led
to the discovery of its antifungal and gene inducing properties. J. Mol. Genet. Med. 9:158. doi:
10.4172/1747-0862.1000158.

Hadwiger, L. A. 2015. Low level DNA damage occurs as PAMPs, chitin and flg22, activate PR
genes, and increases pisatin and disease resistance in pea endocarp tissue. New Negat. Plant
Sci.1-2:6-15.

Additional Funds Leveraged

I received minimal support from the Washington State Potato Commission and will continue to
apply for funds from this source in the future. To date the commission has funded 3 years at
7,000/per annum.

Impacts and Outcomes

SHORT TERM:
Our data were accepted well by the Northwest Consortium of potato commissions and this
organization will also provide some support for research directed towards the benefits of organic
growers. The data also provides us a start for aggressively pursuing the mechanisms of
immunity induction. The data has been and is currently a basis for obtaining the commission
funding.
INTERMEDIATE-TERM:
The National Organic Program reluctantly allows some copper compounds to be legally used
by organic growers probably since they are not chemically synthesized beyond mining. We
previously developed a successful copper treatment using the natural component, chitosan as a
sticker (Hadwiger and McBride, Plant Health Progress doi:10.1094/PHP-2006-01-RS). Without
any late blight protection, potatoes in some rainy areas simply can not be produced. The
prospect for having protection in the absence of a heavy metal (copper) may result in the NOP
removing their copper allowance. This would of course cause organic growers to seek the biocontrol
methods such as those I am developing.
LONG TERM:
Those pursuing biological controls are aware that developing a control-- that can end up as a
commercial agriculture practice-- is a tall order. In the case of protection from potato Late
Blight, it will be worth the effort if there is to be disease-free organic potatoes available to the
consumer. Researchers also know that what works nicely in the lab is much more of a challenge
to see similar results under field conditions. It will depend on how the field conditions are
worked out as to what the long-term benefit can be. There are some things that have been
worked out, such as concentration of yeast cells required and the methods of their culture and
preservation. The field testing contracted to a very competent private researcher, did not
develop since the environmental conditions were not conducive for a late blight epidemic the
summer of 2015. The potato research locations available to Washington State University can not
allow the dispersal of Late Blight inocula, because of the chance of initiating epidemics effecting
local growers. I am optimistic that this yeast control can be developed to the point where
potatoes can be grown organically and yield reasonable if not bountiful harvests. This yeast
microbe can be reproduced to levels that can economically viable in a very short period of time
and has no environmentally detrimental properties.