The Biology of Musa L. (Banana)
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The Biology of Musa L. (banana) [Photo credit: Janet Gorst, OGTR] Version 1: January 2008 This document provides an overview of baseline biological information relevant to risk assessment of genetically modified forms of the species that may be released into the Australian environment. For information on the Australian Government Office of the Gene Technology Regulator visit http://www.ogtr.gov.au [THIS PAGE HAS BEEN LEFT INTENTIONALLY BLANK ii The Biology of Musa L. (banana) Office of the Gene Technology Regulator TABLE OF CONTENTS PREAMBLE ...........................................................................................................................................1 SECTION 1 TAXONOMY .............................................................................................................1 SECTION 2 ORIGIN AND CULTIVATION ...............................................................................6 2.1 CENTRE OF DIVERSITY AND DOMESTICATION .............................................................. 6 2.2 COMMERCIAL USES...................................................................................................... 7 2.3 CULTIVATION IN AUSTRALIA....................................................................................... 9 2.3.1 Commercial propagation ...............................................................................................11 2.3.2 Scale of cultivation.........................................................................................................13 2.3.3 Cultivation practices ......................................................................................................14 2.4 CROP IMPROVEMENT ................................................................................................. 21 2.4.1 Breeding.........................................................................................................................23 2.4.2 Genetic modification......................................................................................................25 SECTION 3 MORPHOLOGY .....................................................................................................27 3.1 PLANT MORPHOLOGY ................................................................................................ 27 3.2 REPRODUCTIVE MORPHOLOGY .................................................................................. 28 SECTION 4 DEVELOPMENT ....................................................................................................31 4.1 REPRODUCTION ......................................................................................................... 31 4.1.1 Asexual reproduction.....................................................................................................31 4.1.2 Sexual reproduction.......................................................................................................31 4.2 POLLINATION AND POLLEN DISPERSAL ...................................................................... 32 4.3 FRUIT/SEED DEVELOPMENT AND SEED DISPERSAL ..................................................... 33 4.4 SEED DORMANCY AND GERMINATION........................................................................ 34 4.5 VEGETATIVE GROWTH ............................................................................................... 35 SECTION 5 BIOCHEMISTRY....................................................................................................36 5.1 TOXINS ...................................................................................................................... 37 5.2 ALLERGENS ............................................................................................................... 37 5.3 OTHER UNDESIRABLE PHYTOCHEMICALS................................................................... 38 5.4 BENEFICIAL PHYTOCHEMICALS.................................................................................. 38 SECTION 6 ABIOTIC INTERACTIONS ..................................................................................39 6.1 ABIOTIC STRESSES ..................................................................................................... 39 6.1.1 Nutrient stress ................................................................................................................39 6.1.2 Temperature stress.........................................................................................................40 6.1.3 Water stress ....................................................................................................................40 6.1.4 Other stresses .................................................................................................................40 6.2 ABIOTIC TOLERANCES ............................................................................................... 41 SECTION 7 BIOTIC INTERACTIONS .....................................................................................41 7.1 WEEDS....................................................................................................................... 41 7.2 PESTS AND DISEASES ................................................................................................. 42 7.2.1 Pests................................................................................................................................42 7.2.2 Diseases..........................................................................................................................45 SECTION 8 WEEDINESS............................................................................................................49 8.1 WEEDINESS STATUS ON A GLOBAL SCALE.................................................................. 49 8.2 WEEDINESS STATUS IN AUSTRALIA ........................................................................... 50 8.3 WEEDINESS IN AGRICULTURAL ECOSYSTEMS ............................................................ 50 8.4 WEEDINESS IN NATURAL ECOSYSTEMS ...................................................................... 51 8.5 CONTROL MEASURES ................................................................................................. 51 SECTION 9 POTENTIAL FOR VERTICAL GENE TRANSFER..........................................51 iii The Biology of Musa L. (banana) Office of the Gene Technology Regulator 9.1 INTRASPECIFIC CROSSING .......................................................................................... 51 9.2 NATURAL INTERSPECIFIC CROSSING .......................................................................... 52 9.3 CROSSING UNDER EXPERIMENTAL CONDITIONS ......................................................... 53 REFERENCES .....................................................................................................................................54 APPENDICES ......................................................................................................................................69 iv The Biology of Musa L. (banana) Office of the Gene Technology Regulator PREAMBLE This document describes the biology of Musa L. with particular reference to the Australian environment, cultivation and use. Information included relates to the taxonomy and origins of cultivated Musa spp., general descriptions of their morphology, reproductive biology, biochemistry, and biotic and abiotic interactions. This document also addresses the potential for gene transfer to occur to closely related species. The purpose of this document is to provide baseline information about the parent organism for use in risk assessments of genetically modified (GM) Musa spp. that may be released into the Australian environment. In this document, the general term ‘banana’ is used to encompass cultivated varieties of the genus Musa that fall into one of two sub-groups (Pillay et al. 2004): the sweet or dessert banana which makes up approximately 43% of world production, and the cooking banana which makes up approximately 57%. The general term ‘plantain; is applied to a specific subgroup of cooking bananas (Valmayor et al. 2000). The yellow sweet banana cultivars most commonly found in western greengrocers are the focus of this Biology document. Sweet bananas in general, however, show enormous diversity in terms of plant stature and fruit size, and fruit colour extends from yellow and green to red and orange (Ploetz et al. 2007). Bananas are a major food crop globally and are grown and consumed in more than 100 countries throughout the tropics and sub-tropics (INIBAP 2000). In developing countries they are the fourth most important food crop after rice, wheat and maize (INIBAP 2000). Worldwide, over 1,000 banana cultivars or landraces are recognized (Heslop-Harrison & Schwarzacher 2007). The banana plant is a tall arborescent monocotyledon with a false stem (pseudostem) consisting of leaf sheaths and an underground true stem (corm) that is able to produce suckers by which the plant can reproduce vegetatively. Each pseudostem produces a single inflorescence the female flowers of which give rise (either parthenocarpically1 or following fertilization) to the banana fruits. SECTION 1 TAXONOMY The genus name Musa is thought to be derived from the Arabic name for the plant (mouz) which, in turn, may have been applied in honour of Antonius Musa (63 – 14 BC), physician to Octavius Augustus, first emperor of Rome (Hyam & Pankhurst 1995). The name ‘banana’ is derived from the Arabic banan = finger (Boning 2006) and was thought to be used in Guinea