Seeds of Coreopsis leavenworthii Torr. & Gray (Asteraceae) are being commercially produced but the lack of genetic diversity information has hindered growers and end users from addressing several critical issues affecting wild collection, commercial production, distribution, and the use of seeds. In this study, the genetic diversity and differentiation among natural, production, and introduced populations were analyzed at the molecular level using 320 amplified fragment length polymorphism (AFLP) markers. A high level of diversity [68.6% average polymorphism; total genetic diversity (H t) = 0.309] and a moderate level of genetic differentiation [total genetic diversity residing among populations (G st) = 0.226; Φst = 0.244; Bayesian analog of Nei's G st (G st-B) = 0.197] was detected among six natural populations—two each from northern, central, and southern Florida. Two distance-based clustering analyses, based on an individual's AFLP phenotypes or a population's allele frequencies, grouped natural populations into three clusters, concordant with our previous results from a common garden study of phenotypic variation. Clustering of populations was mostly according to their respective geographical origin within Florida. The correlation between geographical distances and pairwise F st values between populations was very significant (r = 0.855, P < 0.0001). Two central Florida natural populations were divergent and grouped into separate clusters, indicating that the existence of factors other than physical distance alone were contributing to genetic isolation. Three production populations maintained a level of genetic diversity comparable to that in the natural populations and were grouped with the natural populations from which the production populations were derived, suggesting that the genetic identity of the seed origin was maintained under production practices. The genetic diversity of the introduced population was comparable to that of the source populations (central Florida natural populations), but genetic shift seems to have occurred, causing the introduced population to cluster with local (northern Florida) populations where planted. The observed genetic differentiation among natural populations may indicate a need to develop appropriate zones within Florida for preservation of genetic diversity during seed collection, increase, and distribution. This high level of population differentiation also suggests a need to collect and analyze more natural populations across Florida and from Alabama for a better understanding of the species' genetic diversity and population structure across its distribution range.
David M. Czarnecki II, Madhugiri Nageswara Rao, Jeffrey G. Norcini, Frederick G. Gmitter Jr, and Zhanao Deng
Sandra B. Wilson, Carlee Steppe, Zhanao Deng, Keri Druffel, Gary W. Knox, and Edzard van Santen
Trailing lantana [Lantana montevidensis (Spreng.) Briq.] is a low-growing, woody ornamental valued for its heat and drought tolerance and repeat blooming of purple or white flowers throughout much of the year. In 2011, trailing lantana was predicted to have high invasion risk by the UF-IFAS’s assessment of non-native plants in Florida, and therefore it was no longer recommended for use. All cultivars fall under this designation unless proven otherwise. Eight trailing lantana varieties were obtained from wholesale growers or naturalized populations found in Texas and Australia. Plants were propagated vegetatively, finished in 4-inch pots, and planted in field trials located in central (Balm) and northern (Citra) Florida. Throughout the 24-week study from June to November, mean plant quality was between 4.4 and 4.7 (on a 1 to 5 scale) for U.S. varieties and 3.9 for the Australian form. Mean flowering was between 4.1 and 4.5 (on a 1 to 5 scale) for U.S. trailing lantana varieties and 3.5 for Australian trailing lantana. Australian trailing lantana differed from other U.S. varieties tested, being smaller in size, more sensitive to cold, and having a high female fertility index (producing abundant fruit with viable seed per peduncle). Our findings indicate that some U.S. varieties of trailing lantana are unlikely to present an ecological threat and merit consideration for production and use.
Renjuan Qian, S. Brooks Parrish, Sandra B. Wilson, Gary W. Knox, and Zhanao Deng
Porterweed (Stachytarpheta spp.), a member of the verbena family, is frequently used in pollinator gardens to attract butterflies. This study was conducted to assess the morphological features, pollen stainability and morphology, nuclear DNA content, and chromosome number of five porterweed selections. Coral porterweed (S. mutabilis), ‘Naples Lilac’ porterweed (S. cayennensis × S. mutabilis ‘Violacea’), and nettleleaf porterweed (S. cayennensis) had the largest plant heights. Flower number was significantly higher in nettleleaf porterweed, jamaican porterweed (S. jamaicensis), and U*J3-2 porterweed (S. cayennensis × S. jamaicensis), with an average of 65–72 flowers per inflorescence. Internode length and flower width of jamaican porterweed had much lower values than the other selections. Coral porterweed recorded the lowest pollen stainability with only 10.6% stainability, but it had the largest relative pollen production. ‘Naples Lilac’ porterweed had the highest DNA content with an average of 3.79 pg/2C, like jamaican porterweed with 3.73 pg/2C. Ploidy levels varied between selections, and the basic chromosome number was x = 28. Coral, jamaican, and ‘Naples Lilac’ porterweed had 2n = 6x = 168 chromosomes, first reported in this genus. These results provide a guide and a new tool to distinguish native and non-native porterweed and may aid future breeding toward the production of noninvasive cultivars.
Sandra B. Wilson, Julia Rycyna, Zhanao Deng, and Gary Knox
Over the course of nearly 2 decades, the resident or wild-type form of heavenly bamboo (Nandina domestica) and 25 additional selections have been evaluated for landscape performance and invasive potential in various trial locations in Florida. Overall, in northern Florida (Quincy and Citra), ‘Royal Princess’, ‘Umpqua Chief’, ‘Gulf Stream’, ‘Monfar’ (Sienna Sunrise®), ‘Emerald Sea’, ‘Greray’ (Sunray®), ‘Lemon-Lime’, ‘Murasaki’ (Flirt™), ‘SEIKA’ (Obsession™), and ‘Twilight’ performed well throughout much of the study with average ratings between 3.0 and 4.9 (1 to 5 scale). In southern Florida (Balm and Fort Pierce), ‘AKA’ (Blush Pink™), ‘Compacta’, ‘Emerald Sea’, ‘Firestorm’™, ‘Greray’, ‘Gulf Stream’, ‘Harbour Dwarf’, ‘Jaytee’ (Harbor Belle™), ‘Lemon-Lime’, ‘Monum’ (Plum Passion®), ‘Murasaki’, and ‘SEIKA’ performed well with average ratings between 3.0 and 5.0. Among selections evaluated, plant sizes were categorized as small, medium, or large, where the final plant height ranged from 20 to 129 cm, and the plant perpendicular width ranged from 15 to 100 cm. Almost three-fourths of the selections evaluated had little to no fruiting when compared with the wild-type form. ‘AKA’, ‘Chime’, ‘Filamentosa’, ‘Firehouse’, ‘Firepower’, ‘Firestorm’, ‘Greray’, ‘Lemon- Lime’, ‘Moon Bay’, and ‘SEIKA’ did not fruit at any of the trial sites. In northern Florida, small amounts of fruit (94% to 99.9% reduction) were observed for ‘Gulf Stream’, ‘Harbour Dwarf’, ‘Jaytee’, ‘Monfar’, ‘Murasaki’, ‘Royal Princess’, ‘Twilight’, and the twisted leaf selection. Moderate amounts of fruit (62% to 83% reduction) were observed for ‘Alba’, ‘Emerald Sea’, ‘Lowboy’, ‘Moyer’s Red’, and ‘Umpqua Chief’. Heavy fruiting comparable or greater than the wild type was observed for ‘Compacta’ and ‘Monum’. Pregermination seed viability ranged from 67% to 100% among fruiting selections with 5.5% to 32.0% germination in 60 days. Germination was considerably higher (58% to 82%) when the germination time was extended to 168 days. Nuclear DNA content of selections were comparable to the wild type suggesting they are diploid. Thus, ploidy level does not appear to be associated with female infertility of those little-fruiting heavenly bamboo selections. Overall, our findings revealed certain selections of heavenly bamboo that have little potential to present an ecological threat and thus merit consideration for production and use. As a result, the University of Florida(UF)/Institute of Food and Agricultural Sciences’ (IFAS) Status Assessment on Non-native Plants in Florida’s Natural Areas infraspecific taxon protocol has concluded that ‘Firepower’ and ‘Harbour Dwarf’ are noninvasive and can be recommended for production and use in Florida. In addition, due to acceptable plant performance and low to no fruiting capacity, our research supports that ‘Firehouse’, ‘AKA’, ‘Firestorm’, ‘Gulfstream’, ‘Jaytee’, ‘Monfar’, ‘Royal Princess’, ‘Greray’, ‘Lemon-Lime’, ‘Murasaki’, and ‘SEIKA’ be considered for future noninvasive status approval.
Zhanao Deng, Sandra B. Wilson, Xiaobao Ying, Chunxian Chen, Rosanna Freyre, Victor Zayas, and David M. Czarnecki II
David M. Czarnecki II, Zhanao Deng, Madguhuri N. Rao, Frederick G. Gmitter Jr., Young A. Choi, Jeffrey G. Norcini, and David G. Clark
As one of the Florida's state wildflowers, Coreopsis leavenworthii is highly desirable for roadside plantings in all parts of the state. Seeds of this species are being produced by growers. Where should seed be produced for different ecotypes? Where can the seed be used? These are among questions that have arisen in commercial seed production and distribution. To address these questions, it was necessary to assess the levels of genetic diversity. Eleven populations (242 total individuals) were collected from different parts of Florida, grown at one location in central Florida, and observed for morphological variations. North Florida natural populations had more complex leaves, while south Florida natural populations had smaller flowers. Principal component analyses revealed that two of the seven characteristics studied accounted for as much as 88% of the morphological variations observed. Molecular diversity was analyzed by using the fluorescent amplified fragment length polymorphism (AFLP) technique and the capillary sequencing system. Four primer combinations detected 320 AFLP fragments, of which 90.6% were polymorphic. The overall genetic diversity in the species was 0.2206 (estimated using AMOVA), of which 77.9% was within populations and 22.1% was among populations. The genetic distance among populations seemed to be loosely correlated with geographical distances. A high level of gene flow was found in several populations. Based on the results, a model has been developed to describe the genetic relationship of Coreopsis leavenworthii populations.