Genetic variation is the mainstay which plant breeders require to produce new and improved cultivars. The opportunity of obtaining novel traits exists through induction of mutations. Induced mutations have played a significant role in meeting challenges related to world food and nutritional security by way of mutant germplasm enhancement and their utilisation for the development of new mutant varieties. A wide range of genetic variability has been induced by physical and chemical mutagens. In the past several decades, induced mutations have contributed immensely to the development of improved varieties in several crop plants. Cellular and molecular biology tools have led to enhanced efficiency of induction, detection and deployment of mutations. Till date, 3,218 mutant varieties have been released worldwide. More than 60 % of officially released mutant varieties are from Asia with China, India and Japan topping the list. The mutant varieties developed and released in major crops have been cultivated by farmers in large areas and have resulted in increased food production, thus contributing to food security. In this chapter, various aspects of mutation induction, applications and examples of successful use of induced mutants in crop improvement programmes are presented.

Induced Mutations and Crop Improvement

Recent trends in the biotechnology of Chrysanthemum: a critical review

In an attempt to develop a system for producing transformed plants from explants ofDendranthema grandiflora, the susceptibility of the cultivar Super White to various wild-type strains ofAgrobacterium tumefaciens andA. rhizogenes was investigated. Tumour formation was not a reliable indicator of the ability of a related disarmed strain to mediate transformation. Following inoculation of explants with disarmedAgrobacterium strains, a number of shoots developed on selective media. However, none of these shoots were transformed. By co-cultivating stem internode explants with a mixed inoculum of wild-type and disarmed strains, it was possible to obtain a callus stably transformed withAgrobacterium carrying a disarmed T-DNA. Histological analysis of explants revealed that shoot regeneration initially occurred from the cells of the epidermis and subsequently from the cortex. However, the cells which were susceptible to T-DNA transfer were confined to the vascular tissue.

A study of some factors affecting Agrobacterium transformation and plant regeneration of Dendranthema grandiflora Tzvelev (syn. Chrysanthemum morifolium Ramat.)

Chrysanthemum (Chrysanthemum morifolium) is an economically important ornamental crop across the globe. As floral color is the major factor determining customer selection, manipulation of floral color has been a major objective for breeders. Anthocyanins are one of the main pigments contributing to a broad variety of colors in the ray florets of chrysanthemum. Manipulating petal pigments has resulted in the development of a vast range of floral colors. Although the candidate genes involved in anthocyanin biosynthesis have been well studied, the genetic and transcriptional control of floral color remains unclear. Despite advances in multi-omics technology, these methods remain in their infancy in chrysanthemum, owing to its large complex genome and hexaploidy. Hence, there is a need to further elucidate and better understand the genetic and molecular regulatory mechanisms in chrysanthemum, which can provide a basis for future advances in breeding for novel and diverse floral colors in this commercially beneficial crop. Therefore, this review describes the significance of anthocyanins in chrysanthemum flowers, and the mechanism of anthocyanin biosynthesis under genetic and environmental factors, providing insight into the development of novel colored ray florets. Genetic and molecular regulatory mechanisms that control anthocyanin biosynthesis and the various breeding efforts to modify floral color in chrysanthemum are detailed.

https://www.mdpi.com/1422-0067/21/18/6537/pdf

Anthocyanins in Floral Colors: Biosynthesis and Regulation in Chrysanthemum Flowers.

Genome engineering in ornamental plants: Current status and future prospects.

Radiation-induced sports in Chrysanthemum morifolium Ram. have been reported for several years. It has become an everyday practice to produce flower-colour mutants from outstanding cross-breeding products, even before they are distributed for the commercial production of cut flowers.

A mutant of a mutant of a mutant of a...: Irradiation of progressive radiation-induced mutants in a mutation-breeding programme with Chrysanthemum morifolium Ram.

C. Broertjes

Papers

A mutant of a mutant of a mutant of a...: Irradiation of progressive radiation-induced mutants in a mutation-breeding programme with Chrysanthemum morifolium Ram.