ARCHIVED Sb 3.1 – Xanthomonas axonopodis pv glycines – soybean
|PATHOGEN: Xanthomonas axonopodis pv. glycines (syn: Xanthomonas campestris pv. glycines)|
|HOST: Soybean (Glycine max)|
|COMMON NAME: bacterial pustule|
|METHOD: Sb 3.1 MXG selective media (Prathuangwong et al., 1997)|
|METHOD CLASS: TEMPORARY STANDARD (B)|
|SAMPLE: 5000 seeds|
- Seeds are surfaced sterilized with 95% ethyl alcohol for 30 sec.
- Seeds are plated on MXG selective medium amended with 1 ml of a 50 mg/ml stock solution of polymixin B sulfate/ liter.
- Plates are incubated at room temperature for 2 weeks.
- Presumptive colonies of X. campestris pv glycines are distinguished by morphological characteristics including color and size.
- Subcultures on plates of nutrient glucose agar are identified by a range of biochemical tests including oxidase reaction, acid and gas production from carbon sources, gram staining, and production of indoleacetic acid.
- Cultures are grown on nutrient glucose broth overnight and adjusted to a concentration of 107 cfu/ml.
- Leaves of a 3-5 day old soybean plant (cultivar SJ14 or other susceptible variety) are inoculated.
- Plants are evaluated for symptom development after 7-10 days at 30-34oC and 79-95% relative humidity.
Prepared MXP agar
Distilled water 1000 ml
K2HPO4 0.8 g
KH2HPO4 0.6 g
Yeast extract 0.7 g
Soluble starch 0.8 g
Glucose 1.0 g
Agar 15.0 g
1 ml methyl green (1% in 20% ETOH)=1 ml per liter of MXP, pH = 7.2-7.4 and autoclaved.
After cooling add filter sterilized:
Cycloheximide (50 mg/ml in 12.5% methanol) 1 ml
Cephalexin (50 mg/ml aqueous) 1 ml
Bacitran (10 mg/ml aqueous) 1 ml
Kasugamycin (50 mg/ml aqueous) 1 ml
Prathuangwong, S., Khandej, K., and Goto, M. 1997. Development of new methods for ecological study of soybean bacterial pustule: A semiselective medium for detecting Xanthomonas campestris pv. glycines in contaminated soybean seed. pp 197-202 in: Banpot Napompeth (ed). Proceedings of World Soybean Research Conf. V, Chiangma, Thailand 1994.