Detecting method for the seeds contaminated with plant pathogens
A method of easily detecting a slight percentage of seeds contaminated with a seed-transmissible pathogen as mixed in among a large number of seeds is provided. The method comprises placing a substratum for germination with seeds disposed thereon in a hermetic container, adding an extractant to the hermetic container after germination of the seeds, mixing up the seedlings resulting from germination of the seeds, the germination substratum and the extractant with stirring and/or pressing, and using the mixed liquid derived therefrom as a test material for detecting pathogenic bacteria possibly occurring therein.
1. A method of testing seeds possibly bearing a seed-transmissible plant pathogen, comprising;
a) placing a substratum for germination with seeds disposed uniformly thereon in a hermetic container;
b) allowing the germination substratum with seeds to stand for a period of time necessary for the seed-transmissible plant pathogen to multiply sufficiently;
c) periodically discharging air from the hermetic container while avoiding destruction of seedlings resulting from germination of the seeds;
d) feeding fresh outside air into the hermetic container;
e) after the period of standing, adding an extractant to the hermetic container;
f) mixing up the seedlings, the germination substratum, and the extractant with stirring and/or pressing, to thereby obtain a mixed liquid;
g) removing the mixed liquid from the hermetic container; and
h) testing for seed-transmissible plant pathogens possibly occurring within said removed mixed liquid.
2. A method of testing seeds as claimed in claim 1 , wherein the germination substratum comprises a highly water-absorbing paper and/or a nonwoven fabric and/or cut pieces of a highly water-absorbing paper and/or a nonwoven fabric.
3. A method of testing seeds as claimed in claim 1 , wherein during the discharge of air and feeding in of the fresh air, the hermetic container inside air is forcedly replaced with the outside air during the period of seed germination and seedling growth.
4. A method of testing seeds as claimed in claim 1 , wherein the seed germination and seedling growth are realized by causing the germination substratum to absorb water or 0.01-0.03 M phosphate buffer.
5. A method of testing seeds as claimed in claim 1 , wherein the extractant is water or 0.01-0.03 M phosphate buffer.
6. A method of testing seeds as claimed in claim 1 , wherein the pathogen detection using the test material is carried out by identification of colonies grown on medium and/or by a serological method and/or by a genetic diagnosis.
7. A method of testing seeds as claimed in claim 1 , wherein the seeds to be tested are seeds of a cucurbitaceous plant.
8. A method of testing seeds as claimed in claim 1 , wherein the seeds to be tested are seeds of a poaceous plant.
9. A method of testing seeds as claimed in claim 1 , wherein the hermetic container is made of a flexible resin and comprises a hermetic zipper operative to be opened and closed, such that an inside of the hermetic container is ordinarily shut off from outside air by closing the hermetic zipper and is maintained under environmental conditions such that a high temperature and a high humidity are attained for the multiplication of the pathogen.
10. A method of testing seeds as claimed in claim 9 , wherein during the period of seed germination and seedling growth, the feeding of fresh outside air further comprises periodically feeding fresh outside air into the hermetic container for the promotion of the growth of seeds after germination and for the prevention of putrefaction.
11. A method of testing as claimed in claim 1 , wherein the period of time necessary for the plant pathogen to multiply sufficiently is up to the time of cotyledon development.