Plant genetics
[1][2] It is generally considered a field of biology and botany, but intersects frequently with many other life sciences and is strongly linked with the study of information systems.
The study of plant genetics has major economic impacts: many staple crops are genetically modified to increase yields, confer pest and disease resistance, provide resistance to herbicides, or to increase their nutritional value.
The earliest evidence of plant domestication found has been dated to 11,000 years before present in ancestral wheat.
While initially selection may have happened unintentionally, it is very likely that by 5,000 years ago farmers had a basic understanding of heredity and inheritance.
He worked at the Abbey of St. Thomas in Brünn (now Brno, Czech Republic), where his organism of choice for studying inheritance and traits was the pea plant.
Mendel's work tracked many phenotypic traits of pea plants, such as their height, flower color, and seed characteristics.
His seminal work on genetics, “Versuche über Pflanzen-Hybriden” (Experiments on Plant Hybrids), was published in 1866, but went almost entirely unnoticed until 1900 when prominent botanists in the UK, like Sir Gavin de Beer, recognized its importance and re-published an English translation.
Castle discovered that while individual traits may segregate and change over time with selection, that when selection is stopped and environmental effects are taken into account, the genetic ratio stops changing and reach a sort of stasis, the foundation of Population Genetics.
[5] This was independently discovered by G. H. Hardy and W. Weinberg, which ultimately gave rise to the concept of Hardy–Weinberg equilibrium published in 1908.
By the early 1920s, Donald Forsha Jones had invented a method that led to the first hybrid maize seed that were available commercially.
The strict requirements for producing hybrid seed led to the development of careful population and inbred line maintenance, keeping plants isolated and unable to out-cross, which produced plants that better allowed researchers to tease out different genetic concepts.
The structure of these populations allowed scientist such a T. Dobzhansky, S. Wright, and R.A. Fisher to develop evolutionary biology concepts as well as explore speciation over time and the statistics underlying plant genetics.
[11] While breeding experiments were taking place, other scientists such as Nikolai Vavilov[12] were interested in wild progenitor species of modern crop plants.
Understanding and manipulating of plant genetics was in its heyday during the Green Revolution brought about by Norman Borlaug.
During this time, the molecule of heredity, DNA, was also discovered, which allowed scientists to actually examine and manipulate genetic information directly.
DNA is often compared to a set of blueprints or a recipe, or a code, since it contains the instructions needed to construct other components of cells, such as proteins and RNA molecules.
For example, the yield of Maize has increased nearly five-fold in the past century due in part to the discovery and proliferation of hybrid varieties.
[17] In animals, inheritable germline polyploidy is less common, and spontaneous chromosome increases may not even survive past fertilization.
Polyploid individuals that are capable of self-fertilizing can give rise to a new, genetically distinct lineage, which can be the start of a new species.
Because its broad leaves are easily transiently transformed with Agrobacterium tumefaciens, it is used to study both the expression of pathogen genes introduced into a plant or test new genetic cassette effects.
Other models include the alga Chlamydomonas reinhardtii, the moss Physcomitrella patens, the clover Medicago truncatula, Antirrhinum majus (snapdragon), the C4 grass Setaria viridis, and maize (corn).
An important side effect of GM crops has been decreased land requirements,[24] Commercial sale of genetically modified foods began in 1994, when Calgene first marketed its unsuccessful Flavr Savr delayed-ripening tomato.
[25][26] Most food modifications have primarily focused on cash crops in high demand by farmers such as soybean, corn, canola, and cotton.
[40][41][42][43] The legal and regulatory status of GM foods varies by country, with some nations banning or restricting them, and others permitting them with widely differing degrees of regulation.
[44][45][46][47] There are still ongoing public concerns related to food safety, regulation, labeling, environmental impact, research methods, and the fact that some GM seeds are subject to intellectual property rights owned by corporations.
The particles are propelled at high velocity using a short pulse of high pressure helium gas, and hit a fine mesh baffle placed above the tissue while the DNA coating continues into any target cell or tissue.
Transformation via Agrobacterium has been successfully practiced in dicots, i.e. broadleaf plants, such as soybeans and tomatoes, for many years.
In general, the Agrobacterium method is considered preferable to the gene gun, because of a greater frequency of single-site insertions of the foreign DNA, which allows for easier monitoring.
In this method, the tumor inducing (Ti) region is removed from the T-DNA (transfer DNA) and replaced with the desired gene and a marker, which is then inserted into the organism.
"AAAS Board of Directors: Legally Mandating GM Food Labels Could "Mislead and Falsely Alarm Consumers"".
