Apomixis Flashcard
Apomixis, a term introduced by the botanist Hans Winkler in 1908, encompasses a fascinating mode of asexual reproduction in plants. Derived from the Greek words apo, meaning “away from,” and mixes, meaning “mixing,” apomixis refers to the formation of seeds or embryos without the need for fertilization. In this process, the typical fusion of male and female gametes does not occur, yet the plant produces viable offspring.
What is apomixis?
Apomixis is a form of asexual reproduction in plants where seeds are produced without fertilization.
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What is apomixis?
Apomixis is a form of asexual reproduction in plants where seeds are produced without fertilization.
How does apomixis differ from sexual reproduction?
Apomixis does not involve the fusion of gametes, resulting in genetically identical offspring, unlike sexual reproduction.
Name a type of apomixis.
Parthenogenesis, diplospory, apospory, and adventitious embryony are types of apomixis.
What is parthenogenesis?
Parthenogenesis is the development of an embryo from an unfertilized gamete.
Define diplospory.
Diplospory involves the embryo sac developing from a megaspore mother cell through mitosis or incomplete meiosis.
What is apospory?
Apospory is the formation of an embryo sac from nucellar cells without meiosis.
Describe adventitious embryony.
Adventitious embryony is the development of embryos from tissues like the nucellus or integuments, not the embryo sac.
What is the advantage of apomixis in agriculture?
Apomixis allows for rapid production of pure lines, retention of hybrid vigour, and easier hybrid seed production.
How does apomixis ensure genetic uniformity?
By producing offspring that are genetically identical to the parent plant, apomixis ensures genetic uniformity.
What is the main disadvantage of apomixis?
Apomixis results in limited genetic variation, which can hinder adaptability to changing environments.
Can apomixis occur without pollination?
Yes, some forms of apomixis can occur without pollination, although in others, pollination is required.
What type of apomixis involves haploid cells?
Non-recurrent apomixis, such as haploid parthenogenesis and haploid apogamy, involves haploid cells.
Name a plant genus known for apomixis.
Examples include Crataegus, Amelanchier, and Rubus.
What is the role of colchicine in apomixis?
Colchicine is used to induce haploid apogamy and parthenogenesis, leading to the production of diploid pure lines.
What is obligate apomixis?
Obligate apomixis is when plants produce offspring exclusively through apomixis.
Define facultative apomixis.
Facultative apomixis allows for both apomixis and sexual reproduction, depending on environmental conditions.
What is the significance of maintaining hybrid vigour in apomixis?
It helps in preserving the advantageous traits of hybrids across generations without segregation.
What is a disadvantage of the accumulation of deleterious mutations in apomixis?
Deleterious mutations may accumulate due to lack of genetic recombination, potentially reducing plant fitness.
How does apomixis contribute to the preservation of maternal traits?
Apomixis allows for the transmission of desirable maternal traits from one generation to the next without genetic alteration.
What is a common application of apomixis in agriculture?
Apomixis is used to produce uniform, high-yielding crop varieties and maintain hybrid vigour in agriculture.