Review
Páginas: 48 (11841 palabras)
Publicado: 21 de junio de 2011
Journal of Experimental Botany, Vol. 59, No. 12, pp. 3215–3228, 2008 doi:10.1093/jxb/ern188 Advance Access publication 24 July, 2008
REVIEW ARTICLE
Regulation of floral initiation in horticultural trees
John D. Wilkie1,2,*, Margaret Sedgley1 and Trevor Olesen2
2
Faculty of Arts and Sciences, The University of New England, Armidale, NSW 2351, Australia Centre for Tropical Horticulture,New South Wales Department of Primary Industries, Alstonville, NSW 2477, Australia
1
Received 11 November 2007; Revised 23 June 2008; Accepted 25 June 2008
Abstract
The intention of this review is to discuss floral initiation of horticultural trees. Floral initiation is best understood for herbaceous species, especially at the molecular level, so a brief overview of the control of floralinitiation of Arabidopsis (Arabidopsis thaliana (L.) Heynh.) precedes the discussion of trees. Four major pathways to flowering have been characterized in Arabidopsis, including environmental induction through photoperiod and temperature, autonomous floral initiation, and regulation by gibberellins. Tropical trees are generally induced to flower through environmental cues, whereas floral initiation oftemperate deciduous trees is often autonomous. In the tropical evergreen tree mango, Mangifera indica L., cool temperature is the only factor known to induce flowering, but does not ensure floral initiation will occur because there are important interactions with vegetative growth. The temperate deciduous tree apple, Malus domestica Borkh., flowers autonomously, with floral initiation dependent onaspects of vegetative development in the growing season before anthesis, although with respect to the floral initiation of trees in general: the effect of the environment, interactions with vegetative growth, the roles of plant growth regulators and carbohydrates, and recent advances in molecular biology, are discussed.
Key words: Apple, Arabidopsis, floral induction, floral initiation, mango, trees.Introduction Floral initiation includes all of the developments necessary for the irreversible commitment by the meristem to
produce an inflorescence (Kinet, 1993). Control of floral initiation is not restricted to the developing meristem, but may involve signals from other areas of the plant. Autonomous flowering is where internal developmental cues lead to floral initiation. Floral induction iswhere an environmental stimulus, most commonly photoperiod or temperature, leads to floral initiation. Often, interactions between environmental stimuli and endogenous developmental cues exert some control over floral initiation. Some aspects of flowering in trees make them especially challenging for physiologists, breeders, and growers; first, the juvenile phase, which lasts for several years duringwhich time no flowering or fruiting occurs; second, interactions between vegetative growth, flowers, and fruit of the previous year on floral initiation in the current year, affect growers through phenomena such as biennial bearing, and make interpretation of research data difficult for scientists. The purpose of this review is to discuss floral initiation in horticultural trees. However, floralinitiation is best understood for herbaceous species, so the herbaceous literature will be reviewed briefly first, to serve as a framework for the discussion of trees. Several extensive reviews of the genetic or physiological control of floral initiation of herbaceous species have been undertaken, including Bernier et al. (1993), Kinet (1993), Boss et al. (2004), Corbesier and Coupland (2005), and Bernierand Perilleux (2005). Case studies on floral initiation in apple (Malus domestica Borkh.) and mango (Mangifera indica L.) are then presented, because considerable research has been done on these species and they exemplify the differences between temperate deciduous and tropical evergreen tree flowering systems. Finally, floral initiation in horticultural trees as a whole is discussed.
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REVIEW ARTICLE
Regulation of floral initiation in horticultural trees
John D. Wilkie1,2,*, Margaret Sedgley1 and Trevor Olesen2
2
Faculty of Arts and Sciences, The University of New England, Armidale, NSW 2351, Australia Centre for Tropical Horticulture,New South Wales Department of Primary Industries, Alstonville, NSW 2477, Australia
1
Received 11 November 2007; Revised 23 June 2008; Accepted 25 June 2008
Abstract
The intention of this review is to discuss floral initiation of horticultural trees. Floral initiation is best understood for herbaceous species, especially at the molecular level, so a brief overview of the control of floralinitiation of Arabidopsis (Arabidopsis thaliana (L.) Heynh.) precedes the discussion of trees. Four major pathways to flowering have been characterized in Arabidopsis, including environmental induction through photoperiod and temperature, autonomous floral initiation, and regulation by gibberellins. Tropical trees are generally induced to flower through environmental cues, whereas floral initiation oftemperate deciduous trees is often autonomous. In the tropical evergreen tree mango, Mangifera indica L., cool temperature is the only factor known to induce flowering, but does not ensure floral initiation will occur because there are important interactions with vegetative growth. The temperate deciduous tree apple, Malus domestica Borkh., flowers autonomously, with floral initiation dependent onaspects of vegetative development in the growing season before anthesis, although with respect to the floral initiation of trees in general: the effect of the environment, interactions with vegetative growth, the roles of plant growth regulators and carbohydrates, and recent advances in molecular biology, are discussed.
Key words: Apple, Arabidopsis, floral induction, floral initiation, mango, trees.Introduction Floral initiation includes all of the developments necessary for the irreversible commitment by the meristem to
produce an inflorescence (Kinet, 1993). Control of floral initiation is not restricted to the developing meristem, but may involve signals from other areas of the plant. Autonomous flowering is where internal developmental cues lead to floral initiation. Floral induction iswhere an environmental stimulus, most commonly photoperiod or temperature, leads to floral initiation. Often, interactions between environmental stimuli and endogenous developmental cues exert some control over floral initiation. Some aspects of flowering in trees make them especially challenging for physiologists, breeders, and growers; first, the juvenile phase, which lasts for several years duringwhich time no flowering or fruiting occurs; second, interactions between vegetative growth, flowers, and fruit of the previous year on floral initiation in the current year, affect growers through phenomena such as biennial bearing, and make interpretation of research data difficult for scientists. The purpose of this review is to discuss floral initiation in horticultural trees. However, floralinitiation is best understood for herbaceous species, so the herbaceous literature will be reviewed briefly first, to serve as a framework for the discussion of trees. Several extensive reviews of the genetic or physiological control of floral initiation of herbaceous species have been undertaken, including Bernier et al. (1993), Kinet (1993), Boss et al. (2004), Corbesier and Coupland (2005), and Bernierand Perilleux (2005). Case studies on floral initiation in apple (Malus domestica Borkh.) and mango (Mangifera indica L.) are then presented, because considerable research has been done on these species and they exemplify the differences between temperate deciduous and tropical evergreen tree flowering systems. Finally, floral initiation in horticultural trees as a whole is discussed.
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