Date of Award

1-1-2001

Thesis Type

PhD

Document Type

Thesis

Divisions

Faculty of Science

Department

Institute of Biological Sciences

Institution

Universiti Malaya

Abstract

The purpose of this study was to characterize the variation pattern that exists in the wild Musa acuminata (AA) populations. widely distributed in Malaysia. Fourteen populations of Musa acuminata, which included subspecies malaccensis, siamea and truncata were collected from different locations including Selangor, Pahang, Perak, Kelantan, Kedah and Terengganu for studies on variation within and between populations, based on morphological characters, biochemical, ploidy and genomic DNA content. Techniques of numerical taxonomy were employed to determine the variation pattern and these included use of the clustering method and principal component analysis. Ploidy level and genomic DNA content were determined by flow cytometry (FCM). Anthocyanins of different wild banana bracts were determined through high performance liquid chromatography (HPLC). Mum acuminata s.,p. malaccensis suckers were screened in the 'Hot Spot' for Fusarium wilt resistance studies. Similarly seed progenies from five Musa acuminata ssp. malaccensis populations were raised through zygotic embryo culture and screened for resistance to Fusarium wilt disease by using seedlings planted in a double tray technique. Seedlings that appeared to be resistant or susceptible were further characterized by using randomly amplified polymorphic DNA markers (RAPD). Finally a tetraploid was induced by colchicine treatment in Musa acuminata ssp. malaccensis characterized as resistant to Fusarium oxysporum f. sp. cubense Race 4. The fourteen wild M. acuminata populations appeared very variable and morphological characters showed greater variability compared to ploidy, anthocyanin and genomic DNA content. The two main subspecific groups of these fourteen populations are malaccensis (lowland) and truncata (highland). These two groups could further be classified based on anthocyanin composition and genomic DNA content. No variation was observed for ploidy level among Musa acuminata accessions (2n =22). For the most variable M acuminata ssp. malaccensis, further characterization was carried out to check its response to Fusarium wilt Race 4. Screening of the suckers in the Fusarium "Hot Spot" for two years revealed high resistance to Fusarium oxysporum f sp. cubense Race 4. However seed progenies derived from in vitro zygotic culture of the Musa acuminata ssp. malaccensis were found to be segregating for disease resistance. Optimized in vitro zygotic culture resulted in more than 90% germination after 1-2 weeks. Seed progenies showed a large RAPD polymorphism. Four primers OPA-03, primer-24, primer-25 and primer-27 produced specific banding patterns of sizes 500bp, 300bp, l.5Kbp, and 500bp respectively in susceptible plants. Primer-21 produced a band of I .0Kbp consistently present in resistant progenies. Polyploids were induced in seed progenies of M. acuminata ssp. malaccensis resistant to FOC Race 4, using 0.5% (w/v) colchicine with 2.0% (v/v) DMSO. Ploidy of the treated plantlets was detennined through flow cytometry (FCM). Colchicine treatment resulted in 15% tetraploids (2n=4x=44). Tetraploids were further confirmed through chromosomal counting and based on morphological comparison between diploids, tetraploids and mixoploids.

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Additional Information

Thesis (PhD) -- Faculty of Science, Universiti Malaya, 2001.

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