Determination of optimum ethylmethanesulfonate conditions for chemical mutagenesis of selected vernonia (Centrapalus pauciflorus) accessions

Abstract

Chemical mutagenesis could potentially increase allelic diversity and address genetic erosion in vernonia (Centrapalus pauciflorus) breeding programmes. The objective of this study was to determine an optimum treatment combination, i.e. exposure duration, temperature and ethylmethanesulfonate (EMS) dose that would reduce seed germination by 50%, with minimal reduction in seedling growth and delays in emergence relative to untreated controls. Seeds of four vernonia accessions (Vge–1, Vge–4, Vge–7 and Vge–10) were treated using three EMS concentrations, three temperature regimes and four exposure durations, and thereafter planted in a controlled environment facility for assessment. Parameters recorded were time to 50% emergence, germination percentage and seedling height. The interaction of EMS, accession, time and temperature significantly (p < 0.001) affected all tested parameters. Optimal seed treatment conditions for Vge–1 were 0.372% v/v EMS at 35 °C for 1 h. For Vge–4, optimal seed treatment conditions were 0.372% v/v EMS at 35 °C for 30 min. For Vge–7, optimal seed treatment conditions were 0.372% v/v EMS at 30 °C for 1 h. For Vge–10, optimal seed treatment conditions were 0.372% v/v EMS at 32.5 °C for 30 min. Optimum treatment conditions will be utilised to induce large-scale mutation in vernonia and select target mutants.