Determination of pathogenicity and analysis of genetic diversity of isolates of Mycosphaerella fijiensis Morelet, the causal organism of black sigatoka of banana, from Visayas

Date

6-2016

Degree

Bachelor of Science in Agricultural Biotechnology

College

College of Agriculture and Food Science (CAFS)

Adviser/Committee Chair

Edna Y. Ardales

Restrictions

Restricted: Not available to the general public. Access is available only after consultation with author/thesis adviser and only to those bound by the confidentiality agreement.

Abstract

Sa A total of 104 M. fijiensis isolates were collected from different collection sites and host varieties in four different provinces in the Visayas. Pathogenicity test was done on 10 of the isolates by attaching mycelial agar plugs of M. fijiensis on abraded and unabraded banana leaf portions using adhesive tape. Symptom development was observed and the presence of conidial structures in the leaves was observed microscopically. Pathogenicity test results show that the isolates infest much faster in abraded leaf portions than in unabraded leaf portions. All six stages of the Black Sigatoka was observed in the abraded leaf portions. The genetic diversity of the M. fijiensis isolates was analyzed and evaluated by DNA fingerprinting using 10 microsatellite markers and 5 Variable Number of Tandem Repeat (VNTR) markers. The microsatellite and VNTR markers were all highly informative with an average PIC value of 0.69. Band data from gel electrophoresis was used in estimating diversity thru Powermarker v3.25. Gene diversity per marker ranged from 0.34 to 0.83. Within provinces, highest gene diversity was observed in Southern Leyte (0.70). Within collection sites and host varieties, highest gene diversity was observed in Sto. Niño I, Hinunangan, Southern Leyte (0.64), and Latundan (0.71), respectively. Highest genetic differentiation was observed in Leyte and Southern Leyte (FST = 0.12) which are located in one island, compared to other provinces which are located in distant islands. Phylogenetic analysis showed that the isolates from Cebu were closely related to isolates from other provinces. Moreover, the results of both genetic differentiation and phylogenetic analysis showed that geographical and varietal origin do not have any relationship with clustering of the isolates. AMOVA revealed that 80-97% of the total variation can be found within subpopulations (provinces, collection sites, host varieties).

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2016 A127 /R39

Notes

Major in Crop Protection Biotechnology

Document Type

Thesis

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