Use of In Vitro Breeding Strategies in the Development of Australian Native Plants

Plant biotechnology has emerged as a powerful tool of crop improvement and has aroused a great deal of interest in many countries because of its application to agriculture and horticulture. We report here the application of a number of in vitro plant breeding techniques such as micropropagation, in vitro flowering, in vitro pollination and fertilisation, anther culture, somatic embryogenesis, and gene technology in the development of Australian native plants. The report covers an overview of our experience working with Australian plants in the past 25 or so years. Many of these plants have the potential to become future floricultural products. INTRODUCTION Plant tissue culture is a technique that exploits the ability of many plant cells to revert to a meristematic state. Although originally developed for botanical research, plant tissue culture has now evolved into important commercial practices and has become a significant research tool in agriculture, horticulture and in many other areas of plant science. Plant tissue culture is the sterile culture of plant cells, tissues or organs under aseptic conditions leading to cell multiplication or regeneration of organs or whole plants. The steps required to develop reliable systems for plant regeneration and their application in plant biotechnology have been reviewed in countless books. Some of the major landmarks in the evolution of in vitro techniques are summarised in Table 1. In this paper the current applications of this technology to agriculture, horticulture, forestry and plant breeding is briefly described with specific examples from Australian plants where applicable. RAPID CLONAL PROPAGATION AND PATHOGEN ELIMINATION THROUGH MICROPROPAGATION A major commercial application of plant tissue culture methods has been rapid clonal propagation of many plants. Micropropagation has changed from a laboratory curiosity to a commercial industry, and offers many advantages over the conventional methods of plant propagation. In vitro multiplication involves three main pathways: (i) Axillary shoot formation is the true-to-type multiplication of plants from pre-existing meristems (axillary and apical). (ii) Adventitious shoot prodcution is de novo bud formation on structures without a preexisting meristem, for example leaf segments of Begonia rex, leaf petiole of Saintpaulia sp. or root segments of many species. In this system some off-types may be produced. (iii) Callus production and somatic embryogenesis. Although much more productive than the previous two systems it often results in the production of "somaclonal variation" (Larkin and Scowcroft, 1981). This de novo pathway has enormous potential in the area of plant breeding, artificial seeds and genetic engineering. Proc. V IS on New Flor. Crops Eds.: A.F.C. Tombolato and G.M. Dias-Tagliacozzo Acta Hort. 683, ISHS 2005