Banana (Musa spp.) is an important nutrient-rich fruit crop cultivated in the tropics and sub-tropics for local consumption and export. Targets for genetic improvement of banana range from improved fruit quality, yield, disease resistance, tolerance to biotic and abiotic stresses, and the biosynthesis of pharmaceutical compounds. Sterility has limited the success of generating new cultivars by conventional breeding. Tissue culture-based technologies that involve embryo rescue, the generation of somaclonal variation, and gene-transfer procedures are a useful adjunct to sexual hybridization, although considerable effort is required to establish robust protoplast-to-plant systems for somatic hybridization. Transformation involving Agrobacterium and biolisticsmediated gene transfer is feasible, underpinned by shoot regeneration from cultured cells and tissues. Molecular characterization of germplasm will facilitate the selection of material most relevant for incorporation into sexual and somatic genetic-improvement programs.
Banana (Musa spp.) is an evergreen perennial, monocotyledonous plant of the family Musaceae. The latter consists of seminiferous and cultivated species with broad biological diversity (Abadie et al. 2003). Currently, about 1,000 banana cultivars and landraces are recognized from 50 or so Musa species (Heslop-Harrison & Schwarzacher 2007). Bananas are grown in the tropics and subtropics at latitudes of 20 degrees above and below the equator, where there is a wide seasonal variation in rainfall and temperature (Pua 2007). Two wild species, M. acuminata and M. balbisiana, are the progenitors of modern edible bananas. The main centers of diversity for M. acuminata and its derivative hybrids are Malaysia and Indonesia (Asif, Mak, & Othman 2001; Daniells et al. 2001), whereas M. balbisiana and its hybrids are presumed to be native to India (Robinson 1996). The distribution of bananas from their centers of origin is probably through planting of vegetative materials transported to other tropical and subtropical regions, such as Africa, the Caribbean, Latin America, Oceania, and the Middle East (Price 1995; Robinson 1996). Banana plants were introduced about 500 years ago into Central and Latin America, where the crop became of major economic importance (van den Houwe, Panis, & Swennen 2000). Distinct centers of secondary genetic diversification may have evolved in the Great Lakes region of East Africa and in the more humid forests of Central and West Africa (van den Houwe, Panis, & Swennen 2000). Currently, bananas are cultivated in 120 countries throughout the humid tropics and subtropics in the Americas, Asia, Africa, Australia (Queensland), and Europe (Canary Islands) (Heslop-Harrison & Schwarzacher 2007). The leading producers of bananas in 2007 were India, China, The Philippines, Brazil, and Ecuador (FAOSTAT 2009). Bananas are multipurpose plants because most of their parts can be used in various ways, depending on the species. The most important part is the edible fruit, which can be eaten either ripe as a dessert, or unripe as boiled, fried or roasted food (Smith et al. 2005). Nutritionally, the fruit is rich in carbohydrates, vitamins A, B, and C, and potassium (Aurore, Parfait, & Fahrasmane 2009). The unripe fruit can be brewed to form beer and wine, or processed into sauce, flour, chips, crisps, smoked products, and confectionary. Unripe fruit is also a source of amylase and starch (van den Houwe, Panis, & Swennen 2000). Male floral buds can be eaten as a boiled vegetable, whereas pseudostems are a source of fiber for the manufacture of rope, paper, and textiles. Banana leaves are used for thatching, in the production of fabric and cordage, and as mulch and animal forage (Smith et al. 2005). Species such as M. ornata and M. veluntina are popular ornamental plants (Heslop-Harrison & Schwarzacher 2007).