A Leaf Inoculation Method for Detection of Xanthomonas oryzae pv. oryzicola from Rice Seed

Area of Science:

• Plant Pathology
• Bacteriology
• Agricultural Science

Background:

• Xanthomonas oryzae pv. oryzicola causes leaf streak disease in rice.
• Accurate detection in seeds is crucial for disease management.
• Existing detection methods can be complex or require specialized equipment.

Purpose of the Study:

• To develop and validate a simple, reliable leaf-inoculation method for detecting Xanthomonas oryzae pv. oryzicola in rice seed.
• To compare the efficacy of the new method with existing techniques.

Main Methods:

• Developed a detached-leaf inoculation technique using seed washings on agar plates.
• Maintained leaf segment viability with benzimidazole.
• Determined minimum inoculum concentration (10^3 CFU/ml) and incubation periods (3.5 days to lesion, 5 days to ooze).
• Confirmed bacterial identity using bacteriological, serological, and Biolog tests.

Main Results:

• The detached-leaf method successfully induced typical leaf streak lesions and bacterial ooze from infected rice seeds.
• Detection sensitivity varied with mother plant disease severity.
• The method proved as simple and reliable as immuno-radiometric assay and greenhouse inoculation.

Conclusions:

• The developed detached-leaf inoculation method is a practical and effective tool for detecting Xanthomonas oryzae pv. oryzicola in rice seed.
• This method provides a valuable alternative for routine diagnostics and seed health testing.
• Further research could optimize seed amount and incubation conditions for varying disease levels.