In vitro selection for Fusarium oxysporum f. sp. conglutinans resistance in Brassica vegetables

Oushadee Anuththara Jayalath Abeyawardana Mudiyanselage, BSc

Master's thesis

Abstract:

Fusarium wilt is a concerning problem in Brassica vegetable cultivation. As economically and nutritionally important, widely growing Brassica vegetable worldwide, it is important to control the damage cause by Fusarium wilt to the production. As most reliable control is cultivation of Fusarium resistance cultivars, development of new cultivars carrying Fusarium resistance is timely important effort. In this study, development of resistance to Fusarium oxysporum f. Sp. conglutinans in six cultivars of Brassica oleracea var. capitata plants by in vitro chemical mutagenesis and selection, through direct and indirect organogenesis was studied. Regeneration capacity of explants (six days and ten days old hypocotyl, shoot tip and cotyledon) excised from in vitro germinated seedlings, through direct and indirect organogenesis path ways were tested before undergoing chemical mutagenesis for selecting explants having better responses in in vitro environment. Six days and ten days old hypocotyl, shoot tip and calli derived from 6 days old hypocotyl explants on the MS medium supplemented with NAA (0.2 mg/L), BAP (3 mg/L) and AgNO3 (0.5 mg/L), were subjected to chemical mutagenesis treatment (DMSO (4% (v/v)) and EMS (0.3% (v/v)), 2 hours at 28°C). Shoots developed directly from hypocotyl and shoot tip explants (in the MS medium supplemented with NAA (0.2 mg/L), BAP (3 mg/L), GA3 (0.01 mg/L), AgNO3 (0.5 mg/L) for shoot induction and NAA (0.2 mg/L), BAP (3 mg/L), GA3 (0.01 mg/L) for development) after mutagenesis treatment and calli following mutagenesis treatment were screened for Fusarium resistance using Fusarium culture filtrate with 15% and 20% v/v selection strength for 30 and 60 days of selection periods in each strength. All six cultivars tested, developed plantlets which showed resistance to Fusarium culture filtrate in in vitro conditions with different survival frequencies ranging between 12.5% - 84.0 % from hypocotyl and 0.0% - 86.7% from shoot tip explants among cultivars indicating development of resistance to Fusarium by in vitro chemical mutagenesis. Furthermore, study results were indicated indirect organogenesis and 10 days old hypocotyl and 6 days old shoot tips are potential explants for in vitro chemical mutagenesis of B. oleracea var. capitate.

Keywords

Fusarium, Brassica, In vitro mutagenesis and selection, Resistance, Cultivar

Language used: English

Date on which the thesis was submitted / produced: 10. 4. 2017

Thesis defence

• Supervisor: doc. Ing. Bc. Martin Koudela, Ph.D.

Czech University of Life Sciences Prague

Faculty of Agrobiology, Food and Natural Resources

Master programme / field:
Sustainable Agriculture and Food Security / Sustainable Agriculture and Food Security