Submitted to: Acta Horticulturae
Publication Type: Proceedings
Publication Acceptance Date: May 26, 2008
Publication Date: December 1, 2010
Citation: Rinehart, T.A., Pounders Jr, C.T. 2010. Estimating Diversity Among Lagerstroemia Species and Hybrids Using SSR Markers. Acta Horticulturae. 885:285-290.2010. Interpretive Summary: Crapemyrtles are small flowering trees that are widely cultivated in landscapes in the southern U.S. Most cultivars selected before the latter part of the twentieth century were chance seedlings chosen for unique color or growth habit. Today, commercial production in the U.S. is primarily by means of asexual propagation of named crapemyrtle clones. Cultivars are now available that vary in ultimate size, growth habit, pest tolerance, and flower color. Over 200 named varieties of crape myrtles exist with at least 120 of those available within the nursery industry. Crapemyrtle breeding has focused on developing hybrids between parents with disease or pest resistance and those with good floral characteristics. Here we use 48 SSR markers to estimate the genetic diversity of 41 crapemyrtle cultivars and created a DNA fingerprint database of crapemyrtle cultivars. We also include the parentage results for Cherry Dazzle, Raspberry Dazzle, and Ruby Dazzle. The same technology can be applied to "true to name" guarantees, plant labeling disputes, and plant patent protection.
Technical Abstract: Crapemyrtles are popular small trees throughout southern U.S. landscapes. The wide assortment of inflorescence colors, forms and sizes, coupled with a rather long flowering period (up to 120 days) have increased the popularity of this genus. Cultivars with a broad range of plant sizes (from miniature 1 meter shrubs to +10 m tall trees), growth habits (broad, upright, weeping), cold hardiness (Zones 6-10), disease resistance, and a range of bark characteristics and foliage fall colorations have been produced by breeding programs over the last 30 years. Lagerstroemia is one of the approximately 31 genera composing the Lythraceae family (Order: Myrtales). There are approximately eighty (80) species in the Lagerstroemia genus, native to SE Asia, but most are valued for commercial timber and medicinal uses and are unknown to gardeners and horticulturists. Lagerstroemia indica, L. fauriei, L. speciosa and L. subcostata have been employed as ornamental plants, but only the first two have been extensively used in the breeding, selection, and development of modern commercial cultivars. Many of the cultivars available today can be traced to L. indica and L. fauriei hybrids. We recently developed SSR markers for cultivar identification, hybrid verification, and marker assisted breeding. Here we demonstrate the utility of these markers by verifying interspecific crosses between L. indica, L. fauriei, and L. speciosa. We also developed DNA fingerprints for over 40 named varieties of crape myrtles to estimate diversity and determined parentage of newly released cultivars. Data consist of allele size variation at 48 SSR loci.