Polyploidy refers to the individual with presence of more than two sets of chromosomes (3n, 4n, 5n, etc.) (Soltis et al., 2009) as sporophyte. Polyploids may have arisen as the result of nondisjunction during meiosis or may be generated when chromosomes are dividing properly in mitosis and meiosis, but the cytokinesis does not follow. Polyploidy can be classified into two: polysomic polyploidy (autopolyploidy) and disomic polyploidy (allopolyploidy) (Stebbins, 1951). Autopolyploidy comes from doubling of chromosome number within in individual organisms resulting the formation of new species, while allopolyploidy comes from different genome or from two different species producing interspecific hybrid.
Polyploidy is important as it has been …show more content…
The most common effect of polyploidy in plants is the gigas effect. Gigas effect was explained by Stebbins (1950) as increase in cell size causing larger organs such as roots, leaves, tubercles, fruits, flowers and seeds. However, this is not always exhibited by polyploid plants as the number of cell divisions in polyploidy is often reduced (Stebbins, 1971). Polyploid plants tend to have lower growth rates and flower later or in longer period than their diploid ancestors, making them desirable for ornamental breeding (Levin, 2002). The third characteristic is the reduction in fertility caused by autopolyploidy. Autopolyploidy breeding is usually restricted to crops cultivated for their vegetative organs and propagation due to low rates of viable seed production (Paterson, 2005). This however, is exceptional for seedless fruits such as the triploid watermelon as low number of seeds is the desirable characteristic (Crow, 1994). Despite the disadvantages, autopolyploidy may affect plant tolerance to some stresses such as drought, extreme temperature, pests and pathogens (Levin, 2002). Allopolyploidy or interspecific hybridization is an important evolutionary force for adaptation and speciation in plant groups (Barton, 2001). Allopolyploid plants often showed superior healthy feature compared to its two ancestors; this feature is known as …show more content…
Salt-marsh grass (Spartina sp.) is one of the well-known polyploid plants. This genus commonly grown in salt marsh habitats along the coasts of North America and Europe as it often binds mud flats. Bread wheat (Triticum aestivum L.) is an example of natural allopolyploid species, with AABBDD chromosomes originated from the hybridization between Aegilops tauschii Coss. (DD) and the tetraploid pasta wheat (AABB) (Haider, 2013). Pasta wheat or durum wheat (Triticum turgidum L.) is an example of tetraploid allopolyploid. T. aestivum exhibits desirable features for bread making is the most cultivated wheat, followed by T. turgidum which is the most suitable wheat for pasta-making (Pauly et al., 2013). Another examples of well-known polyploid plants are the tetraploid upland cotton (Gossypium hirsutum L.) and Egyptian cotton (Gossypium barbadense L.). The two allotetraploid species possess AADD-genome, exhibiting high quality spinnable fibers, superior than their diploid parents (Renny-Byfield & Wendel,
Polyploidy is important as it has been …show more content…
The most common effect of polyploidy in plants is the gigas effect. Gigas effect was explained by Stebbins (1950) as increase in cell size causing larger organs such as roots, leaves, tubercles, fruits, flowers and seeds. However, this is not always exhibited by polyploid plants as the number of cell divisions in polyploidy is often reduced (Stebbins, 1971). Polyploid plants tend to have lower growth rates and flower later or in longer period than their diploid ancestors, making them desirable for ornamental breeding (Levin, 2002). The third characteristic is the reduction in fertility caused by autopolyploidy. Autopolyploidy breeding is usually restricted to crops cultivated for their vegetative organs and propagation due to low rates of viable seed production (Paterson, 2005). This however, is exceptional for seedless fruits such as the triploid watermelon as low number of seeds is the desirable characteristic (Crow, 1994). Despite the disadvantages, autopolyploidy may affect plant tolerance to some stresses such as drought, extreme temperature, pests and pathogens (Levin, 2002). Allopolyploidy or interspecific hybridization is an important evolutionary force for adaptation and speciation in plant groups (Barton, 2001). Allopolyploid plants often showed superior healthy feature compared to its two ancestors; this feature is known as …show more content…
Salt-marsh grass (Spartina sp.) is one of the well-known polyploid plants. This genus commonly grown in salt marsh habitats along the coasts of North America and Europe as it often binds mud flats. Bread wheat (Triticum aestivum L.) is an example of natural allopolyploid species, with AABBDD chromosomes originated from the hybridization between Aegilops tauschii Coss. (DD) and the tetraploid pasta wheat (AABB) (Haider, 2013). Pasta wheat or durum wheat (Triticum turgidum L.) is an example of tetraploid allopolyploid. T. aestivum exhibits desirable features for bread making is the most cultivated wheat, followed by T. turgidum which is the most suitable wheat for pasta-making (Pauly et al., 2013). Another examples of well-known polyploid plants are the tetraploid upland cotton (Gossypium hirsutum L.) and Egyptian cotton (Gossypium barbadense L.). The two allotetraploid species possess AADD-genome, exhibiting high quality spinnable fibers, superior than their diploid parents (Renny-Byfield & Wendel,