Galtonia candicans (syn. Ornithogalum candicans), cape hyacinth, is an herbaceous perennial geophyte native to elevations of 1350 to 2150 m in the Drakensberg region of the Great Escarpment in South Africa (Hilliard and Burtt, 1988). It is naturally self-pollinating and can be clonally propagated by bulb division or twin-scaling. White flowers are borne on racemes that emerge from a crown of strap-like foliage from August to September in the Northern Hemisphere (Armitage, 2008). Inflorescences of G. candicans can grow up to 1.2 m, which can result in lodging due to the length of the peduncle and lack of sufficient support (personal observation). Cape hyacinth has been shown to be hardy for gardens of North America (Armitage, 2008) but there has been little cultivar development. The only cultivar that has been described is the double-flowered Moonbeam, discovered in a New Zealand garden in 1982 (Hammett and Murray, 1993). The species shows promise as a low-input option for landscapes due to its pest resistance and low water use, but its issue with lodging requires improvement. However, there is a narrow genetic base, and we are unaware of sources of diversity with which to breed.
Mutagenesis is a common method used by plant breeders to induce genetic variation in plants and can be particularly useful for naturally self-pollinating plants (Waugh et al., 2006). EMS is a preferred method due to ease of access, its chemical mode of action, and cost compared with methods such as exposure to radiation. EMS treatments result in point mutations in plants by attaching an ethyl group to the oxygen atom of guanine. The direct result of this mutation is the transition from a G/C pairing to an A/T pairing in the genome (Waugh et al., 2006). Prior studies have demonstrated varying effects on germination and survival rates relative to varying concentrations of EMS treatment, as well as changes in seed dormancy (Greer and Rinehart, 2009; Hoskins and Contreras, 2019; Talebi et al., 2012).
Weigle and Butler (1983) reported hereditary dwarfing effects after EMS treatment of Impatiens platypeta seeds and in Capsicum annuum, Jabeen and Mirza (2004) demonstrated that EMS was effective in inducing dwarf mutations and sterility. These results, if observed in cape hyacinth, would result in improved cultivars with potential as containerized summer-flowering perennials for retail sales, reduced lodging to improve landscape performance, and reduced fertility to prevent escape from cultivation. The objective of this study was to evaluate the effects of increasing concentrations of EMS on G. candicans for these traits.
Armitage, A.M. 2008 Herbaceous perennial plants: A treatise on their identification, culture, and garden attributes. 3rd ed. Stipes Publishing, Champaign, IL
Greer, S.P. & Rinehart, T.A. 2009 In vitro germination and dormancy responses of Hydrangea macrophylla and Hydrangea paniculata seeds to ethyl methane sulfonate and cold treatment HortScience 44 764 769
Hoskins, T. & Contreras, R.N. 2019 Exposing seeds of Sarcococca confusa to increased concentration and duration of ethyl methanesulfonate reduced seed germination, twinning, and plant size HortScience 54 1902 1906
Talebi, A.B., Talebi, A.B. & Shahrokhifar, B. 2012 Ethyl methane sulphonate (EMS) induced mutagenesis in Malaysian rice (cv. MR219) for lethal dose determination Amer. J. Plant Sci. 3 1661 1665