Alyssum Flower Mutagenesis: Ornamental Crop Improvement

Alyssum (Lobularia) is a common ornamental flower used in urban and commercial landscapes in many parts of the United States. The white umbuliferous flowers are aesthetically appealing and produced all season. Unfortunately, the flowers are small and stems can be long and gangly. Improvements through increased flower size with a more compact plant growth are desirable and possible through mutation breeding. In this study, four triflurilin treatments (0.0086%, 0.086%, 0.86%, and 1.63%) were applied topically to the meristimatic tissues of 260 young Alyssum cuttings. Plants treated with 0.86% and 1.63% triflurilin showed greater tissue damage and stunted growth but did not die, while those treated with 0.0086% and 0.086% had little tissue damage or stunting. Two weeks following triflurilin treatments, plants in the 0.086% and 0.86% treatments began to show new tissue growth. Within another week, new growth on the 0.086% and 0.86% treatments showed phenotypic signs of mutation and ploidy doubling that included larger and darker green leaves. Cuttings of new (suspected polyploid) growth from 0.86% and 0.086% treatments were taken and re-rooted one month after original treatment. Two months after treatment polyploid mutants were identified through flow cytometry and had twice the amount of DNA when compared to nontreated plants. Treatment with 0.86% produced the most polyploid plants. Three months after treatment polyploid flowers were cut and measured for diameter and pedal width. Nontreated flowers were also measured and the mutant flowers were 0.835 mm (9.43%) larger than their control equivalents. To reduce stem length, Alyssum calli were induced and then treated with ethyl methanesulfonate (EMS). Plantlets from EMS treated calli were separated and grown in the greenhouse.