Population structure of Xanthomonas oryzae pv. oryzae from a single rice field in Calauan, Laguna

Date

4-1995

Degree

Bachelor of Science in Biology

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Rebecca J. Nelson

Abstract

Restriction fragment length polymorphism (RFLP) analysis was used to determine the population structure of Xanthomonas oryzae pv oryzae infecting Sinandomeng in a rice field in Calauan, Laguna. An approximately 80 leaves showing typical bacterial blight symptoms were obtained from a researcher who sampled the field systematically. The bacteria were isolated and its genomic DNA extracted. An additional 100 DNA extracts isolated from the bacteria from the same field, already available at IRRI were also used for this study. A total of 162 DNA isolates were digested with EcoRl and analyzed for RFLPs using a repetitive DNA element. IS/113 (formerly pTriX1) as probe. Among the 162 isolates examined, four IS1113-haplotypes designate as B-200, B-004, B-005. and C-002, were identified. Haplotype C-002 was the most frequent haplotype observed (77%). The frequency of the other haplotype ranged from 2% to 11%. The genetic diversity of the total sample population was estimated to be 0.38 based on Net and Tajima's (1981) diversity index. Chi-square test and Fisher's exact test showed that the frequencies of the different haplotypes among the locations do not significantly vary, indicating the uniform distribution of variation in the field. The population of X oryzae were compared with those infecting 1RRB4. Of the six IS1113-haplotypes observed two haplotypes were found to be unique in IRBB4. The predominant IRBB4. The genetic diversity of the population infecting IRBB4 is similarly low as the population in Sinandomeng. The relatively low genetic diversity and the predominance of C-002 haplotype in Sinandomeng could be attributed to two factors; 1) the isolates with the C-002 haploype were more adapted to both cultivars and the environment conditions in this area; and/or 2) these isolates were present in greater abundance in the initial inoculum compared with the isolates with other haplotypes.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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