CELLULAR BIOLOGY AND BIOTECHNOLOGY INCLUDING MUTATION TECHNIQUES FOR CREATION OF NEW USEFUL BANANA GENOTYPES
International Atomic Energy Agency,
FAO/IAEA Joint Division, Room A-2206,
Plant Breeding and Genetics Section, Box 100,
Banana and plantain are among the world's major food crops, and are considered as the poor man's fruit crop in tropical and subtropical countries. The world's total banana and plantain production ranks fifth after cereals, and there is still much scope for yield improvement. They are important plants in the subsistence diet of the poor millions, and bananas are important export commodities of some developing countries in Africa, Latin America, and the Asia and the Pacific regions. In some of these countries bananas are the only significant export commodity. These crops have the potential, along with other major crops, to feed the world. They are a staple food for nearly 400 million people in the tropics. About one billion people eat banana and plantain regularly. In some African countries, daily consumption may exceed one-and-a-half kilograms per person, whereas in North America and Western Europe the consumption is on an average about one banana per week per person.
Banana fruit production is severely limited by several diseases and pests, such as banana bunchy top virus, burrowing nematodes (Radopholus similis and Pratylenchus spp.), weevil (Cosmopolites sordidus), freckle (Cladosporium musae), Phyllostictina musarium, Cordana, Moko disease (Ralstonia solanacearum), black Sigatoka or black leaf streak (Mycosphaerella fijiensis) and Fusarium wilt (Fusarium oxysporum f.sp. cubense). Another problem with Musa germplasm enhancement is its low reproductive fertility and slow propagation rate. Biotechnology and gene technology, together with conventional methods can assist in overcoming these problems in developing new banana cultivars.
Progress in the development of various biotechnologies has greatly contributed to the application of induced mutations in a wide range of plant species. Generally, radiation and especially gamma rays have most often been used to generate desired characters for crop breeding. Today, the FAO/IAEA Mutant Varieties database includes nearly 2300 officially released varieties of 154 plant species (http://www-mvd.iaea.org). These techniques can be used in many crop species, often those with narrow genetic variation, to improve individual or specific characters in local cultivars that are particularly adapted to specific environmental conditions. This is mainly due to: successful applications of in vitro mutation techniques, new opportunities to induce mutations in vegetatively propagated crops by the use of in vitro techniques, the availability of rapid, and often non-destructive, mass-screening methods, application of mutational analysis in genetic investigation of particular biochemical pathways, and use of mutagenesis as a tool for the identification and isolation of plant genes using molecular approaches.
The main objective of this CRP was genetic improvement of bananas and plantains in order to make a more stable and profitable crop by innovative approaches and conventional breeding. In particular: to enhance regional and interregional cooperation among scientists in developing and developed countries; to integrate radiation-induced mutations and in vitro culture methods into conventional breeding of bananas; to promote the development of methods for large-scale rapid multiplication of the resulting mutants/segregants; to develop molecular markers for rapid characterization of genotypes, to develop rapid methods for genome ploidy-level manipulation, in vitro screening of mutants, validate the use of toxins for early selection of banana resistant to black Sigatoka disease, transgenics; and to facilitate field-testing in different climatic conditions and regions.