eChapters

Abstract: Limoniums, popularly called as statice/ Sea lavender are morphologically diverse and admired for their ornamental value. Perennial annual statice is widely cultivated worldwide for both, garden decoration and indoor decoration. This chapter includes a short overview of the taxonomic and reproductive behaviour of the genus. Majority of the species are triploids and reproduce apomictically. Limoniums exhibit incompatibility linked with pollen and stigma dimorphism, heterostyly and biparental inbreeding and species cross compatibility leading to genetic variability. Many F₁ hybrids are available for commercialization as potted lines. Use of tissue culture, molecular markers, embryo rescue, cryopreservation, super compact transgenic clones has been discussed. No genetic information and trait heritability has been established for this crop. Traits of interest to flower breeders for crop transformation include: plant architecture, panicle length, number of branches per panicle, novel colours of both calyx and corolla, high number of flowers per stem, environmental adaptation to stressful conditions, etc.

Keywords: F₁ cultivars, interspecific hybridization, polyploidization, self incompatibility, potted plants.

Abstract: Snapdragon, a decorative ornamental, is used as model plant for genetic and biochemical study. These are popular flowering potted plants, bedding plants and cut flowers around the world due to their flowering floriferousness, wide range in flower colour, size, and shape with numerous phenotypes (Tall Giant/ Grandiflora, Super Giant, Dwarf, Semi-dwarf, Miniature, etc.) series (Butterfly, Rocket Hybrid, Sweet Heart, Pixie, etc.) and cultivars available in market. Hybrid seed production transformed the crop; continued domestication by flower breeders produced a wide range of flower colours and flower patterns. The increasing knowledge of the inheritance of traits and molecular genetics techniques are valuable tools aiding modern snapdragon breeders. Snapdragons are of the few floriculture crops which have genetic evolutionary race history, precise elucidation of taxonomic relationships between taxa, genomic maps, and advanced molecular genetics. In particular elucidation of the genes involved in control of floral development and in anthocyanin biosynthesis pathway has enabled precision in the creation of new flower colours or modification of floral symmetry and expression.

Keywords: Antirrhinum, taxonomy, flower shape, structural genes, molecular biology.

Abstract: Ornamental salvia, native to Brazil is cultivated as bedding plant in the world. Many species have horticultural, commercial and medicinal values. Continued breeding and improvement of salvia is focused on disease resistance, new flower colours, seed oil content and abiotic stress tolerance. Interspecific hybridization is hampered by genomic differences, heterostyly, self incompatibility and low seed set. Breeders have created polyploid cultivars and mutants which have high ornamental value. Continued use of these and other modern techniques will ensure creation of new phenotypes for the market.

Keywords: Salvia, polyploidization, male sterility, inheritance, seed production.

Abstract: Rose is a popular cut flower and flowering garden plant. Fragrance, wide colour range, plant forms and wide adaptability make it a versatile floriculture crop. The diagnostic traits of the different classes are described with reference to their potential commercial value. Increasing genetic information and trait heritability has been established for this crop and molecular genetic techniques are valuable tools aiding modern rose breeders, cultivars are almost exclusively asexually propagated. A gametophytic self incompatibility is found within this species. Numerous cultivars developed through hybridization and mutation techniques are discussed. Rose breeding efforts have been focused on miniature forms, floral fragrance, recurrent blooming, diverse colours, thornlessness, potential rootstocks, mutilple disease, pest resistance and winter hardiness. Transgenic research is highlighted. The journey of rose is endless and rose breeding may continue forever.

Keywords: Rose, intervarietal hybridization, mutation, inheritance, self incompatibility, rootstock, seed production, genetic transformation.

Abstract: Calendulas, popularly known as pot marigold, are admired for their ornamental value. The leaves, seeds and flowers are source of oil, pigments, dye, flavonoids, and ingredient in cosmetics, human, and animal medicines and dietary composition. Currently, there are intraspecific hybrids in the market. Traits of interest to flower breeders for crop transformation include plant architecture, flowering, flower colour and size, large and bold seed with high oil, pest and virus resistance.

Keywords: Calendula, intraspecific hybridization, mutation, molecular marker.

Abstract: Phlox, garden annual, is used as an ideal crop for cytogenetical study. The modern cultivars are grown for ground cover in beds, borders, rock gardens or as edging in landscaping. Phlox taxa serve as a model for speciation through hybridization and contribute to domestication of wild species through interspecific hybridization which revitalized the crop. Limited fertility, reproductive barriers, germination challenges, low seed set often pose significant challenges to breeders. The increasing knowledge of the inheritance of traits and molecular genetic techniques are valuable tools aiding modern phlox breeders. Breeding objectives with high priority include dwarf stature, novel forms, winter hardiness and disease resistance.

Abstract: Petunias, popular bedding plants, with variety of forms, sizes and shapes are employed for landscape planning, garden designs and container gardening. The numerous phenotypes viz., Grandifloras, Multifloras, Millifloras, Waves, Hedgifloras, etc. are complex hybrids. The outstanding marketable series of P. x hybrida have been developed for upright, spreading and semi-trailing to trailing habits. The leaf colour ranges from light to dark green and also variegated types. Flower colours with charming shades and patterns, picotte, star and pronounced venation of darker colours are available on world market. Petunias are strictly cross pollinated and progeny can segregate widely for traits due to heterozygosity. Increasing knowledge of the inheritance of traits and molecular genetics techniques are valuable tools aiding modern breeders. Numerous genes have been identified in the genus with some sequenced genes being used to create transformants with modified plant morphology, floral structure development, floral scent, and flower shelf life. Genes involved in the flavonoid biosynthesis pathway has enabled precision in the creation of flower colours or modification of pigment production and expression. An exploitation of sterility and incompatibility for production of F₁ hybrid seeds is discusses in detail.

Abstract: Periwinkles are popular seed propagated bedding plants with numerous hybrid varieties and series (First Kiss, Garden leader Splash, etc.) and cultivars available on world market and accepted by landscapers. A continued domestication by flower breeders produced a wide range of flower colours and flower patterns. The breeding objectives with high priority include alkaloid content, plant organs rich in pharmaceutical compounds, blooming potted plants with long display life, novel flower shapes/ form. Research focused on genetics of characters, genetic divergence, intervarietal/ interspecific hybridization and seed production has been discussed.

Abstract: Viola or garden pansy, commonly known as sweet violet or king of annuals, are widely cultivated worldwide for landscape planting, garden design and container gardening. Today, numerous OP varieties, F₁ hybrids (Europa, Toto, Wasa), F₂ strains, series (Waterford, heat tolerant S series) and cultivars introduced by seed companies are available on the world market. Pansy breeding efforts have been focused on F₁ hybrid seed production, heat tolerance, flower colour, flower size and form, double flowers, earliness, disease resistance, floriferous nature and interspecific hybridization. Increasing knowledge of the inheritance of traits and molecular genetics techniques are valuable tools aiding modern pansy breeders. Research is needed to exploit heterosis for productivity and gene transformation to create new genetic variability.

Abstract: Orchids, one of the largest commodities in international cut flowers and ornamental plant market, in which genera Cymbidium, Dendrobium, Phalaenopsis, and Vanda are most traded. Orchids occupy prime position among ornamental plants of the modern world. Both warm and cool temperature cultivars are grown in vitro germinated seeds or clones. Breeders have created polyploid cultivars (amphidiploids, triploids) which have greater flower number/raceme, large flowers and other valuable traits. Numerous genes have been identified in the genus with some sequenced genes being used to create genetic transformants. Genome breeding and wide crosses are routinely used to create new genetic variability. Future crop ideotypes are proposed to continue transformation of this crop during the next millennium.

Abstract: Among the annual flowers, marigold is commercially important loose flower crop in India. Marigold types with odourless foliage with orange to light lemon colour are available in world market. Being cross pollinating and seed propagated, progeny can segregate widely for traits due to heterozygosity. Improvements in marigold as cut flowers, larger flowers, more intense flower colour, an expanded flower colour range, more uniform plant habit, earlier flowering, more xanthophylls and extended bloom time are future breeding objectives. The use of intraand interspecific hybridization, heterosis, polyploidy and genetics of traits have been presented with a focus on creating novel transformations for this crop in future.

Abstract: Lotus, aquatic economic flower, associated with religion, art, and culture, is native to India. Most cultivars are diploid, seed and vegetatively propagated. Lotus is cross pollinated and progeny can segregate widely for traits due to heterozygosity. Low seed set often pose significant challenge to breeders. Breeding efficiency remains unknown. Flower breeders have created new colours with interspecific hybridization including yellow, pink, white and rose colour changing to creamy yellow. Traits of interest for crop transformation include environmental adaptation to stressful condition, low seed tannin, and flowering (colour, size, timing, etc.). Genetics of characters is unknown. Future breeding and genetic studies are needed for further transformation of this crop.

Abstract: Lilium is one of the six major genera of flower bulbs produced worldwide. Species are native to diverse habitat within Northern hemisphere. Liliums have a lengthy association with various world cultures. As a result, flower breeders have created numerous genotypes during the millennia of breeding this crop which has enabled its establishment in the top ten cuts, potted flowering and garden crops worldwide. The crop arises from multiple species. Research has focused on development of late flowering genotypes with forcing ability, improvement of flower form/ shape, pollenless cultivars, disease resistance and floral longevity. The limited genetic information and trait heritability have been established for this crop. Wide crosses are routinely used to create new genetic variability. Breeders have created complex hybrids such as LA, OT, OTO, FA, FAA, FO and OA hybrids through in vitro embryo rescue techniques. Molecular biology is being used to engineer Lilium against LSV and TBV. Crop ideotypes prescribe numerous traits for incorporation by flower breeders and geneticists including short forcing time, late flowering in Asiatic lilies, enhanced shelf life, genetically controlled height, rapid propagation and cultivars requiring no vernalization for flowering.

Abstract: Genus Jasminum contains 90 species to be true in existence and use, range from landscape to hair adornments, and perfumes. It is native to Indo-Malayan region. Morphological variants from different species have been developed in different regions in India. Unfruitfulness, cross incompatibility, pollen and seed sterility, delicate flower parts, peak and active night flowering, endosperm antagonism often pose significant challenge to breeders. Genetic information and trait heritability is almost unknown for this crop. Phenotypic traits requiring future improvement include recurrent flowering for fresh flower market, high concrete recovery, biotic and abiotic stress tolerance. Future breeding and genetic studies are needed for further transform this crop.

Abstract: Hollyhocks are seed propagated garden annuals with numerous hybrid phenotypes, series (single and bicoloured Halo series), Spotlight, Carter’s Double, Double Triumph, Giant Double Powder Puff, Halo Bush (tricoloured), Halo Mixed (eight colours) and cultivars are available in the world market. Unusual plant height, delayed flowering compared to other winter annuals handicap its popularity. While little genetic information and trait heritability has been established for this crop, breeding continues to produce new variants for commercial production. Gene pool of hollyhock exhibits great diversity. Breeding objectives with high priority include dwarf stature (2 feet height), compact growth, double and large flowered inflorescence, precocious flowering and resistance to leaf rust disease.

Abstract: Ornamental hibiscus (shoe flower) is native of Asia, probably China, but now conspicuous in all warm countries. Hibiscus is cross pollinating, evergreen shrub and progeny can segregate widely for traits due to heterozygosity. High polyploid constitution of species predominant vegetative reproduction and rampant hybridization irrespective of chromosome number are features of this crop. The important traits for continuous crop improvement include plant with good growth habit, floriferous nature, desirable flower colour, size, shape and good keeping quality. A variety of flower forms, flower colours and growth forms exist. Very little genetic information and trait heritability has been established for this crop. Use of somatic hybridization, mutation breeding and marker assisted breeding are discussed. The continuous use of these techniques will ensure creation of new phenotypes for the market.

Abstract: Gomphrena, indigenous to India, is popular choice for borders, edging, making crafts and potpourris. Only few species are cultivated under tropical and sub-tropical regions. A little work has been done in its improvement. Research should be focused on varietal development for long photoperiod cultivation, tolerant to high temperature stress and medicinal values of the crop. Prospects of hybridization and mutation breeding need to be explored.

Abstract: Gladiolus, commonly known as ‘sword lily’ is native to South Africa. Most members of genus are heteroploids. It has pivotal place as cut flower with novel phenotypes (Grandifloras, Primulinus, Butterfly, Miniature, Face Ups, Orchideola), cultivars available on world market. Modern types are evolved through conventional breeding and very few through mutation breeding. Their continued popularity has warranted extensive breeding and development of fragrant, winter hardy and disease resistant cultivars. Breeders have reported close linkages in variety of traits. Cross pollinating nature coupled with high heterozygosity makes heredity transmission unpredictable. Future crop idiotypes are proposed to continue transformation of this important crop during the next millennium.

Abstract: Gerberas are popular seed and vegetatively propagated flower crop with numerous phenotypes, series and cultivars available on the world market. Crop improvement is currently focused on bicoloured mini gerbera, semi-double and spider type forms, and hybrid cultivars with expanded colour range to boost productivity and profitability. Application of genetic engineering techniques and tools are aiding in modern gerbera breeding. The need for new cultivars remains strong as production system become more specialized and new markets develop. Breeding objectives with high priority include cut flower cultivars highly resistant to diseases, tolerant to low temperature, and floral longevity.

Abstract: Pelargonium (syn. Geranium), has become mainstay in temperate landscapes because of its ease of production and cultivation, long lasting bloom, range of plant habits and diversity of uses (perfumery, cosmetic, pharmaceutical and food industries). Confusion exists about nomenclature and taxonomic revision has attempted. Pelargoniums are popular seed and vegetatively propagated bedding and pot plants with numerous phenotypes (Fish type, Ivy leaved, Regal, Angels, Fancy leaves, Scented, Oak leaf) and cultivars (Double/ Bar/ Centre/ Ring/ Vein/ Picotee pattern/ Tulip/ Carnation/ Phlox/ Birds egg flowered) available on the world market. Their continued popularity has warranted extensive breeding and development of novel phenotypes particularly trailing growth habit, reduced plant size, compact form, manipulation of flowers (size, number, coloration, longevity, timing) and disease resistant cultivars. Increasing knowledge of the inheritance of traits, molecular genetic techniques and biotechnological applications are valuable tools aiding modern pelargonium breeders. The need of new cultivars remains strong as divergence among pelargonium market types increases, production system becomes more specialized and new market develops.