Current Status of Genetically Modified Ornamentals

Abstract

Biotechnology offers new means of improving ornamental crops by the addition of desirable traits to existing horticulturally-adapted cultivars. Traditional plant breeding involves the exchange of many hundreds or thousands of genes between related species to create novel combinations, and improved genotypes must be selected from thousands of segregating progeny over multiple c y cles of selection. Introgression of a single desirable new character, such as disease resistance, from an unadapted relative of a crop species may require multiple backcross generations to regain the horticultural or ornamental qualities of the original cultivar, often resulting in reduced intensity of expression of the back-crossed character. In the case of many ornamental species, related germplasm with the desired disease resistance has not been identified. This is particularly true in the case of viruses, where few sources of resistance are known among ornamentals and related species. However, it has been demonstrated that effective resistance against many plant viruses can be obtained, in model systems and in some field crops, by introduction of virus-derived sequences or various anti-viral genes. Viral infection is a significant problem in many ornamentals, and especially floral crops, because so many ornamentals are vegetatively propagated. Virus infection frequently reduces floral quality and value as well as y ield. Transformation of crop species with one or more gene constructs can lead to addition of desirable traits, typically with minimal effects on other desirable characteristics. Transformation systems have currently been developed for over 30 species of herbaceous ornamentals and several woody species, and efforts continue in man y laboratories around the world. Several groups are working to introduce virus resistance into various ornamentals, including lilies, gladiolus, chrysanthemums, and various orchids. Other traits of interest include plant architecture, floral longevity, flower color, and resistance to other environmental stresses including drought, pests, and fungal and bacterial diseases. A few genetically modified ornamental crops have been commercialized, notably carnations with altered flower color, and there is future expectation of the introduction of effective virus resistance into commercial floral crops.

Agrobacterium tumefaciens-mediated transformation of poinsettia, Euphorbia pulcherrima, with virus-derived hairpin RNA constructs confers resistance to Poinsettia mosaic virus

“…The application of genetic engineering in the floriculture industry has clearly become instrumental and rewarding in meeting the demand for novel desirable traits. A number of genetic engineering approaches have been developed for ornamental plants (Griesbach 1994 ; Kamo et al 1995 ; Deroles et al 1997 ; Zuker et al 1998 ; Kamo et al 2000 ; Kishimoto et al 2002 ; Kim et al 2004 ; Teixeira da Silva 2004 ; Hammond 2006 and the current study) to facilitate the improvement of ornamental crops with better quality and enhanced resistance against diseases and pests. Effective resistance against viruses conferred by transgenes has shown significant potential because no chemical can be applied for control of virus diseases.…”

“…Genetic engineering is an important tool for breeding ornamental plants with addition of desirable traits such as novel colour, better quality and resistance to pathogens and insects (Mol et al 1995 ; Deroles et al 2002 ; Hammond 2006 ; Hammond et al 2006 ). This technology has been successfully utilized in the production of a number of important ornamental crops e.g.…”

“…blue roses (Yoshikazu 2004 ), novel carnations ( http://www.florigene.com ), transgenic gladiolus (Kamo et al 1997 ) and improvement of chrysanthemums (Teixeira da Silva 2004 ). To date, transgenic ornamentals of over 30 genera have been produced by different transformation approaches (Hammond 2006 ; Hammond et al 2006 ). However, there are only a few reports describing genetic transformation of poinsettia: one was the US patent 7119262 (Smith et al 1997 ) using the biolistic transformation approach, while the other two were electrophoresis-based transformation attempts (Vik et al 2001 ; Clarke et al 2006 ).…”

Breeding of Ornamentals:Tuberose (<i>Polianthes tuberosa</i> L.)

“…Quantitative trait loci analysis and marker assisted selection techniques are the present interest in genomics for crop improvement. Biotechnology has been successfully used in development of transgenic plants in more than 32 ornamentals [89][90][91][92][93] .  Scientists/breeders working on tuberose should collect available germplasm with different flower colour.…”

Breeding for Disease Resistance in Florists’ Crops

“…A number of transgenic plants with increased resistance to fungal and viral pathogens have been created in florists' crops (Hammond 2006). Transgenic technologies have greatly expanded the pool of genes that can be used for improving disease resistance in florists' crops.…”