In vitro induction of polyploidy in Nepenthes gracilis

Sun, Wan Fong (2008) In vitro induction of polyploidy in Nepenthes gracilis. Masters thesis, University of Malaya.

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The present study aims to determine the 2C nuclear DNA content of Nepenthes gracilis via flow cytometry as well as to investigate in vitro polyploidy induction in this plant. The 2C DNA content of N. gracilis was found to be 1.60 ± 0.02 pg based on Glycine max cv. Polanka (2C = 2.50 pg) as the internal standard. Polyploidy induction was conducted by treating nodal segments (explants) from in vitro-grown plants with liquid solution of colchicine (1.25, 2.5, 5 and 10 mM) and oryzalin (20, 40, 60 and 80 μM) for different durations (24, 48, 72 and 96 hours). The first visible effect of polyploidization treatments was delayed growth of shoot buds and aberrant morphology of the treated explants. Flow cytometry was used to screen for tetraploids. Tetraploids were obtained from two treatments: 10 mM colchicine for 72 hours and 40 μM oryzalin for 24 hours. Overall, the percentage of tetraploid induction was low: 1.39% and 0.70% in colchicine and oryzalin treatments, respectively. However, oryzalin treatments produced significantly more mixoploids than colchicine treatments as inferred by Duncan’s Multiple Range Test at P≤0.05, where oryzalin and colchicine treatments produced 79.86% and 45.14% mixoploids, respectively. Stomata studies (stomata length, stomata width and stomata frequency) demonstrated a significant difference between diploid and tetraploid plants, as inferred by two-sample t-test at P≤0.05. The stomata size (length and width) of tetraploids were significantly larger than those of diploids, while the stomata frequency was lower in tetraploids than diploids. Root induction medium (WPM + 0.5 mg/l IBA + 0.3% gelrite) was formulated to induce suitable roots (thick with obvious root tip regions) to facilitate root tip squashing for chromosome studies. The chromosomes of N. gracilis were found to be small in size but in large number (near to 80). Chromosome studies also revealed the chimeric nature of the tetraploid plants produced.

Item Type: Thesis (Masters)
Subjects: Q Science > Q Science (General)
Date Deposited: 31 Jul 2013 03:16
Last Modified: 31 Jul 2013 03:16

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