Method for treatment and control of plant disease
The present invention provides methods for development of a virulent bacteriophage-based treatment for the control of plant diseases caused by Xylella fastidiosa . The invention further provides methods of isolating and propagating bacteriophage virulent to X. fastidiosa in a Xanthomonas bacterial host and for treating or reducing symptoms of X. fastidiosa infection in a plant. The invention further provides methods of isolating and propagating bacteriophage virulent to Xanthomonas axonopodis pv. citri and for treating or reducing symptoms of Xanthomonas axonopodis pv. citri infection in a plant.
1. A method of preventing or reducing symptoms or disease associated with Xylella fastidiosa or Xanthomonas in a plant, comprising contacting said plant with particles of at least one virulent bacteriophage, wherein Xylella fastidiosa and/or Xanthomonas axonopodis are hosts of the bacteriophage, wherein the bacteriophage is a Xfas 300-type bacteriophage and displays the following characteristics:
(a) the bacteriophage is capable of lysing said Xylella fastidiosa and/or Xanthomonas bacteria;
(b) the bacteriophage infects a cell by binding to a Type IV pilus;
(c) the bacteriophage comprises a non-contractile tail with a capsid size ranging from 58-68 nm in diameter and belongs to the Podoviridae family;
(d) the genomic size of the bacteriophage is about 43300 bp to 44600 bp; and
(e) the bacteriophage prevents or reduces symptoms associated with Pierce's disease in a plant or plants.
2. The method of claim 1 , wherein contacting comprises introducing the bacteriophage particles into the plant.
3. The method of claim 1 , wherein the plant is selected from the group consisting of a grapevine plant, a citrus plant, almond, coffee, alfalfa, oleander, oak, sweetgum, redbud, elm, peach, apricot, plum, blackberry, mulberry, and Chitalpa tashkentensis.
4. The method of claim 1 , wherein the bacteriophages are introduced into the plant by injection, by an insect vector, via the root system, by spray, by mist, or by dust on the plant.
5. The method of claim 4 , wherein the insect vector is a glassy winged sharpshooter.
6. The method of claim 4 , wherein the number of said bacteriophage to be introduced into said plant is from 1 to 10 12 PFU/ml.
7. The method of claim 4 , wherein the number of said bacteriophage to be introduced into said plant is from 10 4 to 10 11 PFU/ml.
8. The method of claim 4 , wherein the number of said bacteriophage to be introduced into said plant is from 10 7 to 10 10 PFU/ml.
9. The method of any one of claims 1 to 2 , wherein said bacteriophage virulent to Xylella fastidiosa and Xanthomonas species are introduced simultaneously or sequentially to the plant by a combination of two, three, four, five, or six virulent bacteriophage strains.
10. The method of claim 1 , defined as comprising contacting a population of plants with the bacteriophage particles to prevent or reduce symptoms associated with X. fastidiosa and subspecies thereof in the population.
11. The method of claim 1 , wherein said virulent bacteriophage comprises at least one bacteriophage strain which is a member of the Xfas300 phage type; wherein the phage is selected from the group consisting of: Xfas302, Xfas303, Xfas304, and Xfas306; wherein representative samples of said phage have been deposited under ATCC Accession Numbers PTA-13098, PTA-13099, PTA-13100, and PTA-13097, respectively, for phages Xfas302, Xfas303, Xfas304, and Xfas306.
12. The method of claim 1 , further comprising contacting said plant with particles of at least one virulent bacteriophage, wherein Xylella fastidiosa and/or Xanthomonas axonopodis are hosts of the bacteriophage, wherein the bacteriophage is a Xfas 100-type bacteriophage and displays the following characteristics:
(a) the bacteriophage is capable of lysing said Xylella fastidiosa and/or Xanthomonas bacteria;
(b) the bacteriophage infects a cell by binding to a Type IV pilus;
(c) the bacteriophage comprises a non-contractile tail with a capsid size ranging from 55-77 nm in diameter and belongs to the Siphoviridae family;
(d) the genomic size of the bacteriophage is about 55500 bp to 56200 bp; and
(e) the bacteriophage prevents or reduces symptoms associated with Pierce's disease in a plant or plants.
13. The method of claim 12 , wherein said virulent bacteriophage comprises at least one bacteriophage strain which is a member of the Xfas 100 phage type; wherein the phage is selected from the group consisting of: Xfas 103 and Xfas 106, and wherein representative samples of said phage have been deposited under ATCC Accession Numbers PTA-13096 and PTA-13095, respectively, for phages Xfas 103 and Xfas 106.