Progress 10/01/03 to 09/30/04
Outputs
Objectives of this project include determination of invasive potential of cultivated Lantana camara cultivars and establishment of taxonomic relationships, including origin of the cultivars, using traditional and molecular techniques. Data for 62 cultivars and four Florida native and five Jamaican species suggest a direct correspondence between high pollen count and viable seed production. In L. camara cultivars the higher the number of viable pollen the higher the fruit/seed set. This is the result of self- as well as cross-pollination. Pollen fertility ranges from less than 5% (as in Patriot `Sunburst') to more than 80% (as in `Professor Raoux'). Production of viable seed may range from zero to 20 or more per inflorescence in cultivars `Radiation' and Pink Caprice'. These two cultivars have a pantropical-warm temperate distribution and are the most invasive of all known cultivated lantana. Pollen fertility in L. montevidensis and its cultivars range from 1.6% to
32%, but have zero fruit production, hence they are female sterile. The Florida native species L. depressa appears to be self-incompatible but hybridizes freely with L. camara cultivars, resulting in loss of species identity, a fact that has been well documented in the wild. Lantana involucrata, another Florida species, is not cross-compatible with other taxa. Cross-incompatibility is reflected by lack of viable seed. Seed germination data is available for most cultivars. The Caribbean species, L. trifolia, has 82% pollen viability, 204 flowers per inflorescence, and 30 fruit and seed per inflorescence. Flowers are often pollinated by thrips prior to anthesis, but butterflies and bees are the most frequent visitors and play a large role in pollination. Cultivars with pure white flowers are completely or nearly sterile probably because they are not visible to diurnal insects and there is no fragrance to attract moths at night. Bees, however, commonly visit white flowers with yellow
centers. Plants with pink to red flowers are usually the most visited, hence they are most prolific seed producers and most invasive. Molecular studies of taxa in the trade and those collected in Florida and Jamaica in concert with morphological and cytological results as well as reproductive data have provided significant information on reproductive biology, taxonomic relationships, and invasiveness of the taxa. None of the Caribbean indigenous species appear to be involved in production of L. camara cultivars despite the widespread presence of L. camara throughout that region. Diversity in growth habit and flower color of L. camara seems to be the result of mutations and subsequent cross pollination. Results of studies with flow cytometry have indicated diploid and polyploid taxa as well as probable aneuploids, giving further credence to adaptive radiation of this taxon.
Impacts
Planned publication of an article, specifically intended for nursery growers, outlining findings of this project and more specifically listing the sterile/fertile taxa should assist in production of sterile cultivars and directly impact spread of these invasive plants. Despite existence of a large number of publications on Lantana invasiveness none have actually addressed this issue.
Publications
- No publications reported this period
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Progress 09/15/01 to 09/30/04
Outputs
Invasive potential of cultivated Lantana camara cultivars and establishment of taxonomic relationships, including their origin, using traditional and molecular techniques were among the objectives of this project. Data for 62 cultivars and four Florida native and five Jamaican species suggested a direct correspondence between high pollen count and viable seed production. For L. camara cultivars the higher the number of viable pollen the higher the fruit/seed set. This was the result of self- as well as cross-pollination. Pollen fertility ranged from less than 5% to more than 80%. Production of viable seed ranged from zero to 20 or more per inflorescence in cultivars `Radiation' and Pink Caprice'. With a pantropical-warm temperate distribution they are the most invasive of all known lantana. Pollen fertility in L. montevidensis cultivars ranged from 1.6% to 32%, but had zero fruit production. The Florida native species L. depressa appears to be self-incompatible but
hybridizes freely with L. camara cultivars when grown or occur sympatrically. Lantana involucrata, another Florida species, is not cross-compatible with other taxa. Seed germination data was collected for most cultivars. The Caribbean species, L. trifolia, has 82% pollen viability, 204 flowers, and 30 fruit and seed per inflorescence. This species is common throughout American tropics. Although not known to hybridize with other taxa it showed a tendency towards becoming weedy in cultivation. Lantana flowers are often pollinated by thrips prior to anthesis, but butterflies and bees are the most frequent visitors and play a significant role in pollination. Cultivars with pure white flowers are completely or nearly sterile probably because they are not visible to diurnal insects and there is no fragrance to attract moths at night. Bees, however, commonly visit white flowers with yellow centers. Plants with pink to red flowers are usually the most visited, hence they are most prolific
seed producers and most invasive. Molecular studies of taxa in the trade and those collected in Florida and Jamaica in concert with morphological, cytological, and reproductive data provided noteworthy information on reproductive biology, taxonomic relationships, and invasiveness of the taxa. None of the indigenous Caribbean species appear to be involved in creation of L. camara cultivars. Diversity in growth habit and flower color of L. camara seems to be the result of mutations and subsequent cross pollination. Scanning electron microscopy (SEM) of most taxa was of significant help in determination of relationships among the many cultivars. Recent observations of Bolivian species indicated a strong possibility that some of the many cultivated taxa may have their origin in South America as well as the Caribbean Region. Flow cytometry studies have indicated diploid and polyploid taxa as well as probable aneuploids, giving further credence to adaptive radiation of the genus. Given the
two most prolific weedy cultivars, `Radiation' and `Pink Caprice', have long been established in the Caribbean, perhaps they should be considered indigenous to the area.
Impacts
Planned publication of an article, specifically intended for nursery growers, outlining findings of this project and more specifically listing the sterile/fertile taxa should encourage production of sterile cultivars and directly impact spread of these invasive plants. Despite existence of a large number of publications on Lantana and their invasiveness none have actually addressed either probable origin or the existence of sterile cultivars.
Publications
- No publications reported this period
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Progress 10/01/02 to 10/01/03
Outputs
High quality high molecular weight DNA was obtained from more than 50 accessions. The DNA was used in a modified AFLP method known as TE-AFLP to assess genetic diversity in five species and in more than 45 cultivars. TE-AFLP was supposed to provide a high discriminatory power, but give a reduction in the number of bands. The expected advantage of the TE-AFLP procedure was that fingerprints can be obtained in less than half the time and at reduced costs compared to a typical AFLP. While different species can be recognized by unique TE-AFLP banding patterns, this method has proved to be not effective in distinguishing cultivars do to the lack of polymorphic banding and lack of repeatability. We tested a number different modifications to the method to increase the number of amplification products in an effort to generate diagnostic fingerprints for every cultivar in the collection, however all modifications failed to produce the desired polymorphic banding patterns
required for genetic analysis. Since TE-AFLP has not worked we have arranged for an AFLP service laboratory to provide the AFLP reactions and gel banding pattern results for 46 species and cultivars. However, material collected in Jamaica in 2002 were successfully propagated and examined for pollen viability (ranging from 65% to 90%), with taxa collected at Irish Town having the highest count of any taxon examined thus far. Although the resulting seedlings from hand pollination proved to be dubious because of strong probability of selfing, significant seed production and considerable morphological variation was observed from open pollination. We have since determined that cultivars having pollen viability of less than 5% are essentially male sterile and generally produce very few to no fruit. Examination of chromosome ploidy is planned for the near future.
Impacts
Planned publication of an article, specifically intended for nursery growers, outlining findings of this project and more specifically listing the sterile/fertile taxa should assist in production of sterile cultivars and directly impact spread of these invasive plants. Despite existence of a large number of publications on Lantana invasiveness none have actually addressed this issue.
Publications
- No publications reported this period
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Progress 10/01/01 to 10/01/02
Outputs
Objectives of this project are to determine invasive potential of cultivated Lantana camara cultivars and establish taxonomic relationships including origin of the cultivars using traditional methods and molecular techniques. Data for 62 cultivars and four species suggest a direct correspondence between high pollen count and viable seed production in L. camara cultivars: the higher the number of viable pollen the higher the fruit/seed set. This is the result of self- as well as cross-pollination. Pollen fertility ranges from less than 5% (as in Patriot `Sunburst') to more than 80% (as in `Professor Raoux'). Production of viable seed may range from zero to 20 or more per inflorescence in cultivars `Radiation' and Pink Caprice', among others. These two cultivars have a pantropical-warm temperate distribution and are the most invasive of all known cultivated lantanas. Pollen fertility in L. montevidensis and its cultivars range from 1.6% to 32% but have zero viable seed
production, hence they are female sterile. The Florida native species L. depressa appears to be self-incompatible but hybridizes freely with L. camara cultivars, resulting in loss of species identity, a fact that has been well documented in the wild. Lantana involucrata, another Florida species, is not cross compatible with other taxa. Cross-incompatibility is reflected by lack of viable seed. A recently introduced Caribbean species, L. trifolia, has 82% pollen viability, 204 flowers per inflorescence, and 30 fruit and seed per inflorescence. Seed germination data is available for most cultivars. Flowers are often pollinated by thrips prior to anthesis but butterflies and bees are also involved in pollination. Cultivars with pure white flowers are generally nearly sterile probably because they are not visible to diurnal insects and there is no fragrance to attract moths at night. Bees, however, commonly visit white flowers with yellow centers. Plants with pink to white flowers are
usually the most visited, hence they are most prolific seed producers and most invasive. Molecular studies of taxa in the trade and wild species recently collected in Jamaica are in progress.
Impacts
Findings of this research will ultimately result in selection and nursery production of reproductively sterile cultivars of this popular landascape plant. It will also make a significant contribution to invasiveness causes and taxonomy of the genus Lantana.
Publications
- Bijan Dehgan, Charles L. Guy, Fe Almira, and Alan W. Meerow. 2002. Reproductive Biology and Invasive Potential of Lantana camara Cultivars. In Abstract of Reports of International Scientific conference, Devoted to the 25-Aniversary of Botany Department, Syvtyvkar State University. September 18-21.
- Bijan Dehgan, Charles L. Guy, Fe Almira, and Alan W. Meerow. 2002. Reproductive Biology and Invasive Potential of Lantana camara Cultivars. The 7th Annual Janet Meakin Poor Research Symposium - Invasive Plants - Global Issues, Local Challenges. October 27-30, Chocago Botanical Garden.
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