Ornamental Breeding Research Articles

PRESENT USE OF MOLECULAR MARKERS IN ORNAMENTAL BREEDING

In the past 20 years the use of molecular markers has gradually expanded from the field of scientific genetic analysis towards the implementation in commercial breeding programs. Starting from a historical perspective, the benefits and drawbacks of the use of molecular markers for the breeding of ornamentals are brought forward. Important questions to be handled before starting a molecular breeding effort are addressed. Guidelines are being formulated to come to a structured introduction of molecular markers for a specific breeding objective. Examples from rose breeding are used to illustrate the feasibility of molecular breeding approaches.

CHARACTERIZATION OF VIGNA CARACALLA FRAGRANCE

Traditional breeding of ornamentals has led to a scent reduction of many floricultural varieties due to a negative correlation between flower longevity and fragrance. Vigna caracalla L. Verdc. (Leguminosae: Papilionoideae) produces large flowers with an intense, pleasant fragrance. The objective of this study was to identify, using headspace analysis, the major volatiles present in the floral bouquet of cut flowers. The eluted volatiles were analyzed using a gas chromatograph linked to a mass spectrometer. The volatile profile of V. caracalla flowers consists of a complex mixture, with a total of 29 compounds being detected in quantifiable amounts. Up to now, the studied fragrance related genes come mainly from few plant species; V. caracalla could be used as floral scent research material, and in the future, the genomic approach may be applied to cloning of fragrance related genes.

First Report of Leveillula taurica Causing Powdery Mildew on Pepper in Maryland.

Pepper plants in large experimental plots in Beltsville, MD developed widespread powdery mildew during the late summer of 2008. Infection was observed in a diversity of accessions that included Capsicum annuum, C. baccatum, C. chinense, and C. frutescens (2). The C. annuum accessions included culinary bell pepper cultivars and breeding lines as well as a diverse collection of ornamental breeding lines, heirlooms, and land races. Significant leaf damage occurred and led to partial defoliation. Extensive coverage of the abaxial surface by white patches of conidia was noted, along with chlorotic regions on the adaxial surface. Conidia were borne singly and were apically tapered, measuring 65.2 ± 3.2 × 14.9 ± 1.9 μm. Cleistothecia were not found on infected leaves (3). PCR amplification of the internal transcribed spacer (ITS) region using ITS1-2 primers yielded a band that was cloned and sequenced (4). The pathogen was identified as Leveillula taurica based on 100% homology to GenBank Accession No. AY912077. Multiple chili pepper and bell pepper plants were inoculated with conidia from an infected bell pepper plant by placement in an enclosed spore deposition chamber for 1 week, with the infected plant suspended over the test plants. Signs of powdery mildew appeared only on inoculated plants. DNA samples from these inoculated plants were analyzed and verified as L. taurica (a sequence was deposited as GenBank No. GQ167201). A second set of inoculations using the newly infected plants confirmed results of the first test, with mildew developing only on inoculated pepper plants. This disease is new to the mid-Atlantic Region of the United States. It has been reported in greenhouse peppers growing in Ontario, Canada where it has become a recurring problem requiring fungicide intervention (1). Given the wide host range of L. taurica and the systemic nature of infections, it is likely that the fungus has become established in Maryland on perennial host plants.

Production and molecular characterization of two new Citrus somatic hybrids for scion improvement

Somatic hybridization by protoplast fusion from cell suspension cultures and leaf parent has been a well-established technique holding great potential for citrus variety improvement. In this study, somatic hybrid plants were regenerated from the following two fusion combinations: ‘Murcott’ tangor (Citrus reticulata Blanco × C. sinensis (L.) Osbeck) + Hirado Buntan Pink pummelo (HBP) (C. grandis (L.) Osbeck) and ‘Bingtang’ orange (C. sinensis (L.) Osbeck) + Calamondin (C. microcarpa Bunge). Somatic hybrids were selected at an early stage based on their higher capacity for embryogenesis comparing to non-hybrid cells. Flow cytometry analysis showed that all plants from pre-selected lines of the two combinations were tetraploid. SSR analysis confirmed their hybrid nature, with nuclear DNA from both fusion parents, and absence of parental specific bands was also detected. Cytoplasmic compositions of the recovered plants were further revealed by CAPS and cpSSR analysis. The allotetraploid somatic hybrids from the ‘Murcott’ tangor + HBP combination will be applied to develop triploid seedless cultivars by interploid crossing with diploid seedy citrus cultivars, and those from ‘Bingtang’ orange + Calamondin could be valuable for Asiatic citrus canker-tolerant and ornamental citrus breeding.

Regeneration of begonia plantlets by direct organogenesis

The economic importance of ornamentals worldwide suggests a bright future for ornamental breeding. Rapid progress in plant molecular biology has great potentials to contribute to the breeding of novel ornamental plants utilizing recombinant DNA technology. The plant cell, tissue or organ culture of many ornamental species and their regeneration are essential for providing the material and systems for their genetic manipulation, and this is therefore the first requirement of genetic engineering. In this research, different concentration of BA (0.0, 0.5, 1.0, 2.0 mgl-¹ with NAA (0.0, 0.5, 1.0 mgl-¹) and BA (0.0, 0.5, 1.0, 2.0 mgl-¹) with IAA (0.0, 0.5, 1.0, mgl-¹) were investigated to optimize regeneration of Begonia elatior cv. Toran orange. The best regeneration and growth were obtained from the media containing 2.0 mgl-¹ BA and 1.0 mgl-¹ NAA (70%) followed by 1.0 mgl-¹ BA and 0.5 mgl-¹ NAA (50%), 1.0 mgl-¹ BA and 1.0 mgl-¹ NAA (20%) in BA - NAA combination. The media with BA - IAA combination showed that the best regeneration was 0.5 mgl-¹ BA and 0.5 mgl-¹ IAA (43%) followed by 0.5 mgl-¹ BA and 1.0 mgl-¹ IAA (23%).

Regeneration of begonia plantlets by direct organogenesis

The economic importance of ornamentals worldwide suggests a bright future for ornamental breeding. Rapid progress in plant molecular biology has great potentials to contribute to the breeding of novel ornamental plants utilizing recombinant DNA technology. The plant cell, tissue or organ culture of many ornamental species and their regeneration are essential for providing the material and systems for their genetic manipulation, and this is therefore the first requirement of genetic engineering. In this research, different concentration of BA (0.0, 0.5, 1.0, 2.0 mgl-¹ with NAA (0.0, 0.5, 1.0 mgl-¹) and BA (0.0, 0.5, 1.0, 2.0 mgl-¹) with IAA (0.0, 0.5, 1.0, mgl-¹) were investigated to optimize regeneration of Begonia elatior cv. Toran orange. The best regeneration and growth were obtained from the media containing 2.0 mgl-¹ BA and 1.0 mgl-¹ NAA (70%) followed by 1.0 mgl-¹ BA and 0.5 mgl-¹ NAA (50%), 1.0 mgl-¹ BA and 1.0 mgl-¹ NAA (20%) in BA - NAA combination. The media with BA - IAA combination showed that the best regeneration was 0.5 mgl-¹ BA and 0.5 mgl-¹ IAA (43%) followed by 0.5 mgl-¹ BA and 1.0 mgl-¹ IAA (23%).

‘Raider Azure’ Mealy Blue Sage (Salvia farinacea var. farinacea Benth.)

Native wildflowers provide a rich germplasm resource for continued plant improvement. Over the past 10 years, native accessions of Salvia farinacea var. farinacea Benth. have been collected and introduced into an ornamental breeding program. Texas Tech University announces the release of a new mealy blue sage cultivar named ‘Raider Azure’. ‘Raider Azure’ is intended for use as a drought-tolerant native ornamental for demanding landscapes. It has been trialed for use as a perennial bedding plant where it has displayed attractive violet–blue flowers and a vigorous growth habit, which is common in this species. The extended bloom period for mealy blue sage suggests the cultivar ‘Raider Azure’ is well suited for full sun bedding displays in a variety of locations.

Morphological Characterization of Three Intergeneric Hybrids Among Gloriosa superba ‘Lutea’, Littonia modesta, and Sandersonia aurantiaca (Colchicaceae)

Three intergeneric hybrids among colchicaceous ornamentals, Gloriosa superba ‘Lutea’ (2n = 2x = 22), Littonia modesta (2n = 2x = 22), and Sandersonia aurantiaca (2n = 2x = 24), were subjected to morphological characterization and chromosome observation. Hybrid plants produced flowers 2 to 3 years after transplantation of ovule culture-derived plantlets to the greenhouse. All the hybrid plants, L. modesta × S. aurantiaca, L. modesta × G. superba ‘Lutea’, and S. aurantiaca × G. superba ‘Lutea’, showed a climbing habit like those of L. modesta and G. superba ‘Lutea’. Plants of L. modesta × S. aurantiaca and L. modesta × G. superba ‘Lutea’ were taller and shorter than their respective parents, whereas plant height of S. aurantiaca × G. superba ‘Lutea’ was nearly intermediate between the parents. Leaves of all the hybrids had a tendril at the tip like those of L. modesta and G. superba ‘Lutea’. Flower morphologies of all the hybrids were nearly intermediate between the parents. Flower colors of all the hybrids were similar to the seed or pollen parent. Although hybrids of L. modesta × G. superba ‘Lutea’ showed low pollen fertility as assessed with acetocarmine staining, the other two kinds of hybrids had nondehiscent anthers or no fertile pollen grains. Chromosome observation in root tip cells revealed that all the hybrids had a diploid number of chromosomes: L. modesta × S. aurantiaca (2n = 2x = 23), L. modesta × G. superba ‘Lutea’ (2n = 2x = 22), and S. aurantiaca × G. superba ‘Lutea’ (2n = 2x = 23). Novel morphological characteristics of the hybrids may be valuable for future breeding of colchicaceous ornamentals.

Molecular Marker Use in Tree Fruit and Woody Ornamental Plant Breeding

Fruit and ornamental breeders were surveyed about their use of molecular markers in either their breeding programs or in their related research programs. Responses were obtained from over 100 fruit and ornamental breeding programs from throughout the world. Of these, less than 50% used molecular markers in their programs. The two most common uses of these markers were for studies in plant identification and diversity. These were followed by the use of markers in developing molecular maps, in discovering molecular tags and/or trying to identify the genes for specific plant traits, for marker assisted selection, and finally, for the elucidation of plant taxonomy. In conclusion, although there is much research in this area, few programs are actually using markers in the context of an applied breeding program. The major reason for this situation is the lack of available markers and the cost of using these markers to screen large numbers of progeny. Those that use markers in their breeding tend to use them to verify the genotype of the parents or confirm the genotype of selected seedlings rather than screen unselected seedlings.

Update on the Ornamental Breeding Program at the University of New Hampshire

The Ornamental Breeding Program at the University of New Hampshire (UNH) was initiated in 1998, aiming to develop new or improved vegetatively propagated cultivars. Initially, breeding focused on Anagallis monelli (Pimpernel). At the time, only one blue and one orange cultivar (`Skylover Blue' and `Sunrise') were grown commercially. Main breeding goals were to develop plants with more compact habit and earlier flowering in the spring. In 2002, the first two UNH cultivars were released as Proven Selections™: Anagallis`Wildcat Blue' and `Wildcat Orange'. We have also developed breeding lines with new pink, violet, lilac, and white flower colors that are currently in industry trials. Studies on genetics, biochemistry, and anatomy of flower color in A. monelli have been performed and molecular studies are in progress. Breeding of Nolana and Browallia started in 2000 and UNH lines are currently in industry trials. Nolana is comprised of over 80 species native to desert areas of Peru and Chile. Only two cultivars, N. paradoxa`Bluebird' and `Snowbird', and interspecific hybrid `Blue Eyes' are currently commercially available. We now have several Nolana species at UNH representing a wide germplasm base. Based on ornamental potential, some species have been selected for breeding, aiming to develop sterile interspecific hybrids. Studies to break seed dormancy to optimize germination rates are in progress, as well as research on floral development, which is being conducted in collaboration with Peruvian researchers. Interspecific hybridizations have been used in Browallia to develop breeding lines with new or improved traits than those available from seed cultivars.

(14) Hybrid Azalea (4X) × Rhododendron (2X) `Azaleodendron' Progeny Have an Azalea Phenotype

Genus Rhododendron contains more than 800 species worldwide, currently grouped into eight subgenera. Four of these subgenera—comprising the evergreen azaleas, deciduous azaleas, small scaly-leaved rhododendrons, and large non-scaly leaved rhododendrons—have been the focus of ornamental breeding for over 150 years. As a rule of thumb, species within a subgenus are cross-fertile, and most hybrids are derived from intra-subgeneric crosses. Success with wider (inter-subgeneric) crosses, especially deciduous azaleas × large-leaved rhododendrons, has been occasionally reported in the past, based on the intermediate morphology of the hybrids. I crossed a tetraploid `Ilam group' azalea with R.`Catlalgla' (a selection of the native diploid rhododendron species R. catawbiense) and produced a small population of seedlings that proved to be true `azaleodendron' hybrids, based on shared parental alleles at 2 isozyme loci, Idh-1 and Mdh-3. However, none of the progeny are hybrid in appearance; they share the leaf morphology and deciduous trait of the maternal azalea parent. I attribute this result to a dosage effect in these (probable) triploid hybrids, where the azalea genetic contribution is twice that of the rhododendron parent. Higher copy number can be inferred from stronger band intensities for the azalea gene at diallelic loci (Idh-1), or from triallelic loci (Mdh-3) where the genetic contribution to the hybrid progeny appears to be 2:1, azalea: rhododendron. Previously, azalea-like progeny from azalea × rhododendron crosses were thought to result from parthenogenesis or accidental self-pollination.

(406) A Comprehensive Echinacea Germplasm Collection Located at the North Central Regional Plant Introduction Station, Ames, Iowa

Echinacea is becoming a well-established, high-value crop, both as an ornamental and a dietary supplement. A comprehensive collection of Echinacea germplasm is conserved by the USDA-ARS North Central Regional Plant Introduction Station (NCRPIS) in Ames, Iowa, and is available via seed distribution for research and educational purposes (ars-grin.gov/npgs). Representing all nine species collected throughout their respective North American geographic ranges, the Echinacea collection includes 179 accessions. Extensive morphological characterization data associated with this collection have been compiled and are available to researchers on the Germplasm Resources Information Network (GRIN) database to aid in selection criteria. The collection has been used extensively for various research projects, ranging from ornamental breeding studies to HPLC analyses of metabolites of interest to the phytopharmaceutical industry. This poster will summarize the Echinacea collection conserved at the NCRPIS, including a list of available accessions by species, illustrations of seed, and control-pollinated cage propagation methods; and facilities utilized for seed cleaning, testing, and storage. In addition, instructions on how to use the GRIN database to view evaluation data and acquire germplasm will be provided.

ANCHORED ISSR AS MOLECULAR MARKER TO CHARACTERIZE ACCESSIONS OF JACARANDA MIMOSIFOLIA L. DON.

Anchored inter-simple sequence repeats (ISSR) were used to identify 21 accessions of Jacaranda mimosifolia, collected mainly in Buenos Aires City, and the others in Mendoza, Salta and Jujuy Province and La Plata City, as part of an ornamental breeding program. DNA was extracted and purified from young leaves and amplified by four anchored primers based on dinucleotide repeats with 5' or 3´extension. A total of 42 polymorphic bands, obtained after electrophoresis in agarose gels stained with ethidium bromide, were used to construct a molecular identification matrix. A mean of 12.75 bands per primer were generated, ranging from 140 to 1,400 bp. The genomic relationship of the genotypes was evaluated using Jaccard coefficient, and the dendrogram was constructed using UPGMA linkage method. All the accessions were differentiated by this technique, which showed a range of Resolving Power from 1.2 to 5.721. The anchored microsatellite analysis was shown to be a promising method to identify selected material in a breeding program of J. mimosifolia and with high potential to be applied to other ornamental crops.

DISCRIMINATION OF LILY FRAGRANCE BY USE OF AN ELECTRONIC NOSE

Discrimination of lily fragrance was performed by the use of an electronic nose, Prometheus (Alpha-MOS, France) equipped with a metal oxide sensor (MOS) array and a finger-print mass spectrometer (FMS). Fragrance of some Oriental (O), Asiatic (A), Longiflorum (L) and their interspecifc hybrids were investigated. Principle component analysis of the raw signal data was carried out to show the differences among samples. The fragrance of the three lily groups, O, A and L was clearly discriminated by both MOS and FMS. Interspecific hybrids 'Otomenosugata' (L. x formolongi x L. rubellem) and KU2 (L. x folmolongi x 'Marco Polo') were also discriminated from their parents. E-nose has a great potential to discriminate lily fragrance and would be a useful tool for the fragrance breeding of ornamentals.

HOW TO BREED ORNAMENTALS?

Classical breeding is usually not given enough exposure at a scientific breeding congress. The main focus in this presentation will be on the practical breeding of ornamentals. Prego Rijsenhout B.V. is a breeding company that is specialised in this field. Breeding at Prego Rijsenhout B.V. is confined to four cut flowers; Chrysanthemums, Alstroemerias, Gerberas and Roses. The more important aspects of ornamental breeding will be discussed and illustrated in this presentation with some examples obtained from rose breeding and are based on experience gathered from years of breeding in the four different crops. Some specific issues will be addressed for example; a) What is special about ornamental breeding? b) Planning and carrying out procedures to achieving of set breeding targets. c) Commercial exploitation of the finished products. Many decisions have to be made in order to establish a profitable business.

Florida Red Ruffles and Florida Irish Lace: Two New Lance-leaf Caladium Cultivars

Two lance-leaf caladium cultivars are to be released from the ornamental breeding program at the University of Florida. `Red Ruffles', whose pedigree is Red Frill × (`Red Frill' × `Candidum Jr.'), has elongated medium red leaves with ruffled green margins. Plants are upright with strong petioles, have leaf blades 25 cm long and 14 cm wide, and attain a height of 61 cm when grown in full sun in the field. Plants have more leaves and are more cold tolerant than `Red Frill', the major red lance-leaf cultivar of commerce. Tuber yields of `Red Ruffles' are similar to `Red Frill' but less than `Rosalie', with production indices of 95.0, 97.8, and 121.0, respectively. Foliage of `Red Ruffles' is more upright and less likely to elongate under reduced light than the other cultivars. `Irish Lace', an F2 selection from a cross of “Candidum Jr.' × “Red Frill', has elongated dark green leaves with heavily ruffled margins, which are etched with a thin red border. Leaf blades are 26 cm long and 8 cm wide and have heavy substance. Plant height is 65 cm in the field. Tuber yields of `Irish Lace' are greater than `White Wing', a major green/white cultivar. Use of a green caladium would be as a border or a mixture with red or white lance-leaf cultivars.

Protoplast technology for the breeding of top-fruit trees (Prunus, Pyrus, Malus, Rubus) and woody ornamentals

Protoplast technology for the breeding of top-fruit trees (Prunus, Pyrus, Malus, Rubus) and woody ornamentals

PLANT BREEDING OF ORNAMENTAL CROPS: EVOLUTION TO A BRIGHT FUTURE?!

Plant breeding is evolution conducted by mankind. In ornamental crops breeding by hybridization has resulted in hundreds of new cultivars each year. Breeding and breeding research have contributed to the strong growth of the Dutch horticultural industry, but present sexual breeding has its limitations. New techniques such as in vitro fertilization and methods to overcome crossing barriers, micropropagation and the use of molecular markers directly supply the convential breeding techniques. The first results with genetic modification of ornamental crops are described. It is expected that the introduction of alien genes will attribute strongly to resistance breeding in the future. For brussels sprouts, outdoor tomatoes and strawberries the importance of breeding and selection on mechanisation is demonstrated. In most ornamental crops this selection seems to happen in a indirect way. The relation between mechanisation and breeding of ornamentals is discussed.

Cytology and Morphology of Ovule Culture-derived Interspecific Impatiens Hybrids

Abstract Hybrids among African, Indian, and New Guinea Impatiens were euploids and sterile. All but a few developed into normal mature plants. Classification of certain hybrid traits showed 115 mid-parental, 75 either seed- or pollen-parental, and 17 resembling neither parent. Data from phenotypic analysis of hybrids and parents suggested that the following phylogenetic trends could have been conditioned by dominant or partially dominant genes: from equal to unequal petals, flat to hooded dorsal petal, racemose to epedunculate inflorescence, nearly free to markedly fused lateral petals, and lower sepal and a filiform spur to bucciniform or saccate lower sepal. Spiral phyllotaxy was dominant over whorled. Crosses thought to be useful in ornamental breeding were I. auricoma × I. sultani ‘Elfin White’ or New Guinea species for yellow flowers, I. uguenensis × New Guinea or I. flaccida for drought tolerance, and I. flaccida × I. repens or ‘Elfin White’ for double flowers.

Current Developments in the Breeding of Woody Ornamentals

Abstract Man for centuries has had an appreciation of flowers made use of native plants, cultivated and selected more ornamental and exotic types, and improved food plants. But he has devoted relatively little research to the production of woody ornamentals -- trees and shrubs that have woody stems. The breeding of woody ornamentals, however, has gained momentum as a result of accelerated emphasis on beautification due to the population explosion and the aesthetic needs or urban sprawl.