Developmental Process
Biological Significance
Mechanistic Level
Plants
100
What is the result of apomixis?
Seeds that are genetic clones of the mother
100
How many tons of rice are produced globally every year?
738 million tons
100
What general cell parts are involved in Apomeiosis?
Ovule which contains megaspore and somatic cells.
100
What plants are known to practice apomixis?
Many different species from several different families. Citruses, Flowers, and grasses are some of the known types of plants that practice this
200
What are the three main developmental components found in all forms of apomixis?
embryo sac formation without meiosis,
development of an embryo without fertilization
and formation of endosperm
200
What are the effects of the creation of new heterozygous hybrid plants that can help crops to improve their fitness?
200
How do the two types of Apomixis differ?
• Sporophytic Apomixis - Uses somatic ovule cells(nucleus and integuments of ovule) for mitosis that will directly form embryo.
• Gametophytic Apomixis - There's two types. Embryo sac formed mitotically from cells in ovule - letting it bypass meiosis(apomeiosis).
For BOTH, they're fertilizatoin-independent, but need fertilization of embryo sac to form endosperm.
200
What are citrus known for?
That they practice sporophytic apomixis
300
What triggers fertilization instead of apomixis in plants that do both?
high stress conditions with environmental fluctuations
300
What’s the benefit if rice becomes an apomixis plant?
The genotype frequency can be passed on, which maintains the heterosis of hybrids rice and thus increases yields.
300
What decides the fate of whether the plant goes through either Sporophytic or Gametophytic Apomixis?
If the cell gives rise to megagametophytes, then that’s when it would go through gametophytic apomixis.
If the cell gives rise to the embryo directly, that is when sporophytic apomixis occurs instead.
300
What are three genera that practice apospory?
Brachiaria (signalgrass), Hieracium (hawkweeds), and Pennisetum (fountain grass)
400
How do the 2 main types of apomixis differ from one another?
In gametophytic apomixis or apomeiosis, the egg sac is formed mitotically, bypassing meiosis entirely while in sporophytic meiosis the egg sac is formed through meiosis and the ovules are formed through mitosis so egg sac must be fertilized for the embryo to germinate
400
What's the function of Arabidopsis MiMe? (Hint: MiMe helps Arabidopsis to reproduce asexually and produce new diploids without fertilization).
Meiosis is turned into a mitotic-like division.
400
How do Diplospory and Apospory differ?
These are the two types of Gametophytic Apomixis
• Diplospory- Megaspore mother cell either starts mitosis immediately or will start meiosis and be disrupted. It will undergo three mitoses events to form an embryo sac.
• Apospory - occurs from nucellar cells/somatic cells (nucellus or integuments). Mitosis of these somatic cells occur and the nuclei cellularize - leading to embryo sac being formed.
At the end of both of these,the eight nuclei embryo sac, an egg, a central cell, and synergids are formed. The embryo in the embryonic sacs will now develop without fertilization - which is called parthenogenesis.
400
What are four plant species that practice diplospory?
Taraxacum officinale (dandelion), Boechera spp. (rockcress), Erigeron annuus (annual fleabane), and Tripsacum dactyloides (eastern gamagrass)
500
Which form of apomixis can end up with multiple embryos inside of one seed and which ones germinate?
In sporophytic apomixis, diploid embryos always germinate while the haploid embryo may or may not germinate.
500
What prevents the rice with the OsMiMe mutation from being put into farming?
Rice lacks the gene that is the homolog of CENH3 in Arabidopsis.
500
What if the plant requires fertilization for something other than the embryo?
The cell will develop a strategy to make up for it.
500
List all of your REFERENCES!!!
Bicknell, Ross A., and Anna M. Koltunow. "Understanding apomixis: recent advances and remaining conundrums." The Plant Cell 16.suppl 1 (2004): S228-S245.
“Breeding Program Management.” 3.4 Hybrid Rice & Seed, www.knowledgebank.irri.org/ricebreedingcourse/Hybrid_Rice_Breeding_&_Seed_Production.htm.
Darrigues, Audrey, et al. Genetic Analysis of Apomixis.faculty.agron.iastate.edu/ madan/Genetics.pdf.
Hand, M. L., & Koltunow, A. M. (2014). The genetic control of apomixis: asexual seed formation. Genetics, 197(2), 441–450. https://doi.org/10.1534/genetics.1 14.163105
Hojsgaard, Diego, and Elvira Hörandl. "The rise of apomixis in natural plant populations." Frontiers in plant science 10 (2019): 358.
Mehta, P. “Polyembryonic Mango Seeds: Mango Seeds That Grow Fruits in 2 to 4 Years.” My Kitchen Garden, My Kitchen Garden, 14 Aug. 2020, www.mykitchengarden.info/2018/07/mango-seeds-that-grow-fruits-quickly.html.
Mieulet, D., Jolivet, S., Rivard, M., Cromer, L., Vernet, A., Mayonove, P., et al. (2016). Turning rice meiosis into mitosis. Cell Res. 26, 1242–1254. doi: 10.1038/cr.2016.117
“Oryza Sativa.” Wikipedia, Wikimedia Foundation, 24 Jan. 2021, en.wikipedia.org/wiki/Oryza_sativa.