User:Premaldesai05/sandbox

I am a junior at Saint Louis University majoring in Biology and minoring in Health Care Ethics. I hope to contribute to pages on Evolutionary Biology, specifically in regards to genetics.

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Assignment 7: Revised Wikipedia Assignment

Final Article URL: Leymus mollis

Genetic Hybridization

Leymus mollis has been studied for possible usage in the science of wheat breeding. Wide hybridization of wheat and L. mollis has been conducted successfully since the 1960s to generate many hybrids. An important example of L. mollis hybridization with wheat occurred when the AD99 L. mollis line was hybridized with wheat. The AD99 was resistant to powdery mildew, and the resultant wheat hybrid yielded six lines that were also resistant to powdery mildew. This experiment can be used as a basis for L. mollis to be considered as a very useful genetic resource ^[1]. By using Expressed Sequence Tags (ESTs) it was found that wheat has a complex and redundant genome. ESTs serve to identify transcribed parts of the genome. Through a comparative study it was found that L. mollis has some of these genes as well; because they are highly conserved. These genes are more prominent in L. mollis than wheat however, and are used for osmotic and drought stress tolerance. Due to their similarity though, they have the ability to be hybridized into wheat. Overall these ESTs help to provide proper tools for molecular markers to help identify possible introgression of genes into wheat, particularly in regards to osmotic stress tolerance ^[2].

Leymus mollis' relative success with wheat breading can be demonstrated specifically by utilizing the Genetic In-Situ Hybridization (GISH) method. Comparative GISH showed that the genomes in the genus Leymus are fairly diverse. However, it was also found that chromosomes of species within this genus were able to undergo complete meiotic paring in hybridism with each other. Using the GISH technique, it was found that differences in sub-telomeric heterochromatin do not affect meiotic pairing. Because of this it can be understood that the differences between Leymus genus and Triticum (wheat) would not prevent successful hybridization ^[3]. This conclusion results from the fact that Leymus is already able to overcome differences within its own genus in pairing.

Adaptability

Leymus mollis is generally looked at for hybridization due to it being highly adaptable and robust. To determine this adaptable nature of L. mollis, its seedlings were studied in an environment in which there was low nutrient availability. In this environment, the seedlings were very tolerant of the low nutrients and were still able to sprout. Generally, low soil moisture is considered to be an important mortality factor, yet L. mollis seedlings were able to survive successfully. The period of drought that these seedlings were tested in was 5 successive days, and L. mollis had a survival rate of 93% ^[4]. This adaptability of the plant is something that is not seen in wheat seedlings, which is why it is looked at for hybridization. Being a dune grass, L. mollis also has an extensive ability to survive salinity. The viability of these seeds in the salinity was found to be higher than fifty percent following submergence for seven days. This is translatable to L. mollis being able to grow in soil with high salt content. The surrounding soil may not be viable for traditional plants, however L. mollis still retains the ability to grow. This further demonstrates the wide adaptability of L. mollis ^[5].

References

^ Pang Y, Chen X, Zhao J, et al. (2014). Molecular Cytogenetic Characterization of a Wheat - Leymus mollis 3D(3Ns) Substitution Line with Resistance to Leaf Rust. Journal of Genetics and Genomics 41(4): 205-214.
^ Habora M, Eltayeb A, & Tsujimoto H. (2012). Identification of osmotic stress-responsive genes from Leymus mollis, a wild relative of wheat (Triticum aestivum L.). Breeding Science 62(1): 78-86.
^ Kishii M, Wang R, & Tsujimoto H. (2003). Characteristics and behaviour of the chromosomes of Leymus mollis and L. racemosus (Triticeae, Poaceae) during mitosis and meiosis. Chromosome Research 11(1): 741-748.
^ Gagne J & Houle G. (2002). Factors responsible for Honckenya peploides (Caryophyllaceae) and Leymus mollis (Poaceae) spatial segregation on subarctic coastal dunes. American Journal of Botany 89(3): 479-485.
^ Rachel A & Marcel R (2000). The effect of sea-water submergence on rhizome bud viability of the introduced Ammophila arenaria and the native Leymus mollis in California. Journal of Coastal Conservation 6(1): 107-111.

[1] Pang Y, Chen X, Zhao J, et al. (2014). Molecular Cytogenetic Characterization of a Wheat - Leymus mollis 3D(3Ns) Substitution Line with Resistance to Leaf Rust. Journal of Genetics and Genomics 41(4): 205-214.

[2] Habora M, Eltayeb A, & Tsujimoto H. (2012). Identification of osmotic stress-responsive genes from Leymus mollis, a wild relative of wheat (Triticum aestivum L.). Breeding Science 62(1): 78-86.

[3] Kishii M, Wang R, & Tsujimoto H. (2003). Characteristics and behaviour of the chromosomes of Leymus mollis and L. racemosus (Triticeae, Poaceae) during mitosis and meiosis. Chromosome Research 11(1): 741-748.

[4] Gagne J & Houle G. (2002). Factors responsible for Honckenya peploides (Caryophyllaceae) and Leymus mollis (Poaceae) spatial segregation on subarctic coastal dunes. American Journal of Botany 89(3): 479-485.

[5] Rachel A & Marcel R (2000). The effect of sea-water submergence on rhizome bud viability of the introduced Ammophila arenaria and the native Leymus mollis in California. Journal of Coastal Conservation 6(1): 107-111.

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