Genealogy of Alfalfa

Genealogy of Alfalfa
In this paper on the genealogy of alfalfa I will begin by telling you about the background and history of alfalfa in the United States. Secondly, I will tell you about the different sources of alfalfa germplasm. Next, I will talk about different studies and experiments that have been done to diversify the breeds of alfalfa. Finally, I will tell you about the genetic makeup of alfalfa and what distinguishes it from other popular plants. Alfalfa otherwise known today as the ?Queen of Forage? is thought to have originated in Iran over 2,400 years ago. It was the only forage crop that was cultivated before recorded history therefore the history of its origin isn?t one-hundred percent accurate. The first attempt to grow alfalfa in the United States was recorded in Georgia in the year 1736. The introduction of alfalfa to California came first by Spanish settlers and later by Europeans. The Europeans were headed to California during the gold rush. They obtained alfalfa seed when sailing around South America. Alfalfa flourished in the western states because of its favorable climate. Because alfalfa has a good yield, is palatable, and has a high value of nutrition. Word spread and so did the planting. Alfalfa then spread eastward to the Midwestern states. The distribution of alfalfa to states east of the Mississippi river was a failure due to its acid soils, plant disease, and humidity.
Most of the genetic diversities of alfalfa come from nine germplasm sources. These nine germplasm sources are M. falcate, M. varia, Turkistan, Flemish, Chilean, Peruvian, Indian, and African.According to Barnes, Bingham, Murphy, Hunt, Beard, Skrdla, and Teubar ?M. falcata has orange-yellow flowers and an early fall dormancy therefore it is known to have a heavy first cutting and a light second cutting. It also has some bacterial wilt and foliar disease resistances. Strains were usually classified as M. varia because they had variegated flower colors and variable pod shapes. M. varia sources were introduced to South Dakota in 1907 as seed from a single hybrid plant found in Russia. These sources are winter hardy, more vigorous than M. falcata and are susceptible to bacterial wilt. Turkistan alfalfas have been described as poor seed producers, susceptible to leaf diseases, and resistant to many insects and crown and root disease. They vary in winter hardiness from moderately hardy to hardy. Chilean sources generally lacked winter hardiness and were susceptible to the spotted alfalfa aphid. Peruvian sources are characterized as being pubescent, nondormant, susceptible to the spotted alfalfa aphid, and containing only M. sativa germplasm. Indian germplasm is characterized as being nondormant, susceptible to the spotted alfalfa aphid, and containing only M. sativa germplasm. African is nondormant and generally susceptible to the spotted alfalfa aphid.? (Alfalfa germplasm in the United States: Genetic vulnerability, use, improvement, and maintenance)

There are over one-hundred-sixty different introductions of alfalfa plants being grown in the United States and Canada today. These have been bread on farms, in scientists? labs, and at different schools all over the world. One in particular is the North Central Regional Plant introduction Station at Ames, Iowa. In Ames they grow different types of alfalfa combined in one single row. The plants are scored for flower color, winter injury, and several other characteristics. In alfalfa each trait is determined in by genes residing in four chromosomes instead of two like corn and soybeans. Alfalfa is made up of thirty-two chromosomes that house the legume?s genes. The chromosomes in alfalfa are much smaller than chromosomes in other plants which make them hard to see even in a microscope. Two scientists Bauchan and Hossain figured out that if they converted the microscope?s images into pixels it would enlarge the image. Making it much easier to identify what they were looking for. In doing so, scientists have made many discoveries about the complex genome of alfalfa. ?For example, along the ?arms? of certain alfalfa chromosomes scientists identified thick bands of dna and protein material called heterochromatin.?(A Gene Map for Alfalfa p.15) The bands would block the exchange of genes between parent plants or different alfalfa species. As stated by Bauchan ?what we?ve discovered, is that some yellow-flowered (Falcata) alfalfas, which carry genes for winter hardiness, stand persistence, and resistance to bacterial wilt, have a lower amount of heterochromatin than some of the standard, purple-flowered alfalfas.?(A Gene Map for Alfalfa p.15) Scientists are hoping to use these bands as a way to mark genes. This is called gene mapping.

A study conducted on the breeding of cultivated alfalfa was conducted to improve breeding methods of the crop. This was done to enhance forage yields and quality. Since cultivated alfalfa is an open-pollinated species it is characterized with multiple plants and inbreeding. Because of this many breeding methods are usually focused on multiple combinations of genes.

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