HORTSCIENCE 55(5):621–624. 2020. https://doi.org/10.21273/HORTSCI14775-19 tive to varying concentrations of EMS treatment, as well as changes in seed dor- Galtonia candicans mancy (Greer and Rinehart, 2009; Hoskins Exposing Seeds of to and Contreras, 2019; Talebi et al., 2012). Weigle and Butler (1983) reported heredi- Ethyl Methanesulfonate Reduced tary dwarfing effects after EMS treatment of Impatiens platypeta seeds and in Capsicum Inflorescence Height, Lodging, annuum, Jabeen and Mirza (2004) demonstrated that EMS was effective in inducing dwarf mutations and sterility. These results, if ob- and Fertility served in cape hyacinth, would result in im- Ryan N. Contreras proved cultivars with potential as containerized Department of Horticulture, Oregon State University, 4017 Agricultural and summer-flowering perennials for retail sales, reduced lodging to improve landscape perfor- Life Sciences, Corvallis, OR 97331 mance, and reduced fertility to prevent escape Kim Shearer from cultivation. The objective of this study was to evaluate the effects of increasing concentra- The Morton Arboretum, 4100 Illinois Route 53, Lisle, IL 60532 tions of EMS on G. candicans for these traits. Additional index words. cape hyacinth, chemical mutagens, Hyacinthaceae, mutagenesis, sterility Materials and Methods Abstract. Cape hyacinth (Galtonia candicans) is a geophytic herbaceous perennial from Mutagenesis and germination. In 2011, South Africa. It produces large inflorescences of pendulous white flowers during mid to seed from landscape plants of G. candicans at late summer, followed by capsules filled with copious amounts of seed. The species has Oregon State University North Willamette potential as a low-water-use landscape plant, but lodging and excessive seed production, Research and Extension Center (Aurora, OR) which pose a risk of escape or invasion, are issues that should be addressed before were collected. An experiment was conduct- marketing. Ethyl methanesulfonate (EMS) is a chemical mutagen known to induce usable ed following a completely randomized de- mutations including dwarfing and sterility. We exposed seeds of cape hyacinth to sign with a factorial arrangement of increasing concentrations of EMS (0%, 0.2%, 0.4%, 0.6%, 0.8%, and 1%). Increased treatments. Treatments originally consisted concentrations of EMS resulted in a linear decrease in seed germination when not of two factors, a presoak factor (presoak in exposed to a presoak treatment in water before exposure to EMS. No seedlings survived water vs. no presoak in water) and an EMS or were viable to field plant at 0.6%, 0.8%, or 1%. Resulting plants were field planted in concentration factor (0% control, 0.2%, 2013 and evaluated during 2014 and 2015. In both years, the inflorescence height at first 0.4%, 0.6%, 0.8%, 1.0%). However, follow- flower, average seed number per capsule, and percent lodging were reduced in EMS- ing poor seed germination in the presoak treated plants compared with controls. In 2015, pollen staining was evaluated and was treatment, subsequent tests did not include reduced from 83% in control to less than 3% in the 0.4% treatment. Our study this treatment. A t test was conducted to demonstrated that EMS is a viable option to reduce height and decrease seed set in cape compare percent seed germination of presoak hyacinth. and no presoak groups within each EMS concentration with no comparison among EMS concentrations. We used the Sat- Galtonia candicans (syn. Ornithogalum can result in lodging due to the length of the terthwaite method (df = 32.7) due to unequal candicans), cape hyacinth, is an herbaceous peduncle and lack of sufficient support (per- variances (F = 1.49; P = 0.42). Each treat- perennial geophyte native to elevations of sonal observation). Cape hyacinth has been ment (two soak treatments · six concentra- 1350 to 2150 m in the Drakensberg region of shown to be hardy for gardens of North tions of EMS) was replicated three times for a the Great Escarpment in South Africa America (Armitage, 2008) but there has been total of 36 experimental units, each of which (Hilliard and Burtt, 1988). It is naturally little cultivar development. The only culti- consisted of lots of 300 seeds. In the presoak self-pollinating and can be clonally propa- var that has been described is the double- treatment, seeds were soaked in water with gated by bulb division or twin-scaling. White flowered Moonbeam, discovered in a New one drop of Tween 20 for 24 h before EMS flowers are borne on racemes that emerge Zealand garden in 1982 (Hammett and Mur- treatment. EMS treatments, including con- from a crown of strap-like foliage from Au- ray, 1993). The species shows promise as a trol, were applied as a 24-h soak by diluting gust to September in the Northern Hemi- low-input option for landscapes due to its EMS in a 0.1 M phosphate buffer. For all sphere (Armitage, 2008). Inflorescences of pest resistance and low water use, but its issue soaks, seeds were incubated in a 0.5-L flask G. candicans can grow up to 1.2 m, which with lodging requires improvement. How- placed on a rotary shaker at 100 rpm. After ever, there is a narrow genetic base, and we treatments, seed lots (experimental units) are unaware of sources of diversity with were rinsed under running tap water for which to breed. 15 min and sown in separate 0.2-L containers Received for publication 4 Dec. 2019. Accepted for Mutagenesis is a common method used by filled with soilless media (Metro-Mix 350; publication 13 Jan. 2020. plant breeders to induce genetic variation in Published online 3 April 2020. Sungro Horticulture Canada Ltd., Agawam, We gratefully acknowledge Mara Friddle for tech- plants and can be particularly useful for MA) for germination in a glasshouse with nical assistance in growing containerized and field naturally self-pollinating plants (Waugh day/night set temperatures of 22/16 °C. Due plants. Funding, in part, was provided through a et al., 2006). EMS is a preferred method to extensive mortality in the presoak treat- cooperation between the Oregon Department of due to ease of access, its chemical mode of ment, regression was used to assess the rela- Agriculture (ODA) Nursery Research and Regula- action, and cost compared with methods such tionship between % EMS in the presoak and tory Advisory Committee and the Oregon Associ- as exposure to radiation. EMS treatments no-soak treatments separately. In the presoak ation of Nurseries (OAN). Financial support is result in point mutations in plants by attach- group, we fit an exponential curve using provided through a research assessment included ing an ethyl group to the oxygen atom of PROC NLIN (SAS 9.4; SAS Institute Inc., as part of ODA’s annual nursery license fee. guanine. The direct result of this mutation is R.N.C. is the corresponding author. E-mail: ryan. Cary, NC) and used linear regression for the [email protected]. the transition from a G/C pairing to an A/T no-soak treatment in a spreadsheet (Excel; This is an open access article distributed under the pairing in the genome (Waugh et al., 2006). Microsoft, Redmond, WA). CC BY-NC-ND license (https://creativecommons. Prior studies have demonstrated varying ef- Growing and field planting of M1 plants. org/licenses/by-nc-nd/4.0/). fects on germination and survival rates rela- In Feb. 2012, germinated seedlings were HORTSCIENCE VOL. 55(5) MAY 2020 621 transplanted to 0.37-L square polypropylene 22/16 °C and grown until May 2013. Plants and average seed set per capsule. Qualitative pots (Kord, Canada) filled with douglas fir– were field planted at the Lewis-Brown farm, data analyzed was for lodging (yes = 1 or no = based soilless substrate and grown in an Corvallis, OR (USDA zone 8b). Only the 0%, 0). The number of plants (observations) was unheated poly-house at the OSU Lewis- 0.2%, and 0.4% treatments from not exposed not consistent from planting and was primar- Brown Farm. In Oct. 2012, plants were to presoak treatment produced enough seed- ily due to plant mortality, but there also were placed in a dark 4 °C cooler for a 90-d lings for field evaluation. No presoak seed- plants that did not flower in 2014 yet flowered vernalization treatment. After the vernaliza- lings were field planted. Additionally, the in 2015. In 2014, the following number of tion treatment, the plants were moved into a numbers of seedlings in each replicate varied plants were evaluated in each treatment: 121 glasshouse with day/night set temperatures of based on surviving seedlings from the ger- in 0% (–39 from planting), 154 in 0.2% (–105 mination study. Treatments were kept to- from planting), and 43 in 0.4% (–104 from gether in rows (not randomized) within the planting). In 2015, the following number of field and the three replicates for each treat- plants were evaluated in each treatment: 122 ment were blocked. The following numbers observations in 0% (–38 from planting and of plants were planted: rep 1 0% 50, 0.2% 83, +1 from 2014), 164 in 0.2% (–95 from 0.4% 56; rep 2 0% 50, 0.2% 96, 0.4% 43; rep planting and +10 from 2014), and 41 in 3 0% 50, 0.2% 80, 0.4% 48. 0.4% (–106 from planting and –2 from 2014). Field evaluation. Over the summers of Pollen staining. Flowers were collected 2014 and 2015, qualitative and quantitative from randomly selected M1 plants (25 con- data were collected as response variables for trol, 26 0.2%, 19 0.4%) in the field for a three EMS treatments (0%, 0.2%, and 0.4%) pollen-staining test as an estimate of viabil- Fig.