Development of a Model Mutagenesis System for Snapdragon

Snapdragon (Antirrhinum majus) has long been a very popular perennial in the United States due to its unique flower shape with a range of striking colors (Huo and Chen, 2018). Based on their height, snapdragons are typically classified into three categories: dwarf (6-15 inches), medium (1-2 feet), and tall (6-15 feet) . The dwarf variety has a dense, bushy growth pattern, producing numerous flower spikes. They grow on average 6 to 15 inches tall and are ideal plants for use as low borders or in containers. Mid-sized varieties grow 1-2 feet tall and are typically used in borders (either alone or with other bedding plants) and sometimes as cut flowers. Tall varieties range anywhere from 2 to 3 feet in height (Gilman et al. 2018). The magnificent flowers with a wide range of petal colors atop the long green spikes make the tall variety a desirable cut flower for container, bouquets, or gardens. In 2015, fresh-cut snapdragon sales increased 51.7% from 2010 and reached $12.93 million, making it a top ten fresh cut flower in United States（USDA, 2015). With all of their aesthetic attributes and versatility, snapdragons are also an important model system for genetics and molecular studies of various plant processes.   For example, snapdragon pigmentation mutants produced by transposon (a type of mobile DNAs) mutagenesis have provided researchers a good way to study anthocyanin biosynthesis and subsequently aid plant breeders in developing new varieties with novel flower colors (Jackson et al. 1992). Furthermore, snapdragon has a mechanism by which transposable mutations can be regulated into active and inactive states through temperature control (Hashida et al., 2006). Advantages of this elegant transposon mutagenesis system and how it relates to plant breeding are described in this paper.