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Dr. L. Curtis Hannah

Professor, University of Florida

Expert Bio

Dr. L. Curtis Hannah is a Professor of Plant Molecular and Cellular Biology teaching Advanced Genetics at the University of Florida. His areas of research include plant molecular biology, plant genetics, starch biosynthesis and transposable elements. Dr. Hannah’s work focuses on engineering heat labile enzymes that play important roles in maize yield. Some variants give rise to as much as a 68% increase in maize yield in hot environments. He earned his Ph.D. in genetics at the University of Wisconsin after completing bachelor’s and master’s degrees in biochemistry and genetics at Purdue University. He remains active in the family farming operations in Indiana.

Studies, Articles and Answers

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Question

Q: If produce can be modifiedengineered, why should we believe that it cannot be done in the case of climate engineering? What are the ties of weather with food production?

Answered By Dr. L. Curtis Hannah - Jul 15, 2015

A: Your question addresses an active area of present research in plant improvement. As you alluded to, climate change places additional constraints on plant growth and productivity.  Accordingly, many public and private groups around the world are now screening diverse genetic resources or creating genetic variation via biotechnology that will mitigate some of these adverse environmental effects due to climate change.   For example, I am involved in a group that is identifying biochemical steps in corn that become limiting under high temperatures.  We then clone the genes affect [...]

Answered By Dr. L. Curtis Hannah - Jul 15, 2015

A: Your question addresses an active area of present research in plant improvement. As you alluded to, climate change places additional constraints on plant growth and productivity.  Accordingly, many public and private groups around the world are now screening diverse genetic resources or creating genetic variation via biotechnology that will mitigate some of these adverse environmental effects due to climate change.   For example, I am involved in a group that is identifying biochemical steps in corn that become limiting under high temperatures.  We then clone the genes affect [...]

Other

Question

Q: Which is the more common method of mutagenesis chemical or radiation?

Answered By Dr. L. Curtis Hannah - Aug 21, 2015

A: Thanks for the question. I had to do some digging on this one. In terms of which person-directed mutagenesis method is more common among commercial varieties, Ahloowalia et al (Euphytica 135: 187-204, 2004) state that radiation is the most frequently employed method used by plant scientists. This work is somewhat dated (2004), but since people have been using X-rays since 1927 to create gene variants in plants, I would be surprised if the story has changed in the last 12 years. These investigators also note that some 2250 plant varieties now on the market were derived via these unnatural for [...]

Answered By Dr. L. Curtis Hannah - Aug 21, 2015

A: Thanks for the question. I had to do some digging on this one. In terms of which person-directed mutagenesis method is more common among commercial varieties, Ahloowalia et al (Euphytica 135: 187-204, 2004) state that radiation is the most frequently employed method used by plant scientists. This work is somewhat dated (2004), but since people have been using X-rays since 1927 to create gene variants in plants, I would be surprised if the story has changed in the last 12 years. These investigators also note that some 2250 plant varieties now on the market were derived via these unnatural for [...]

GMO Basics How GMOs Are Made

Question

Q: Which is the more common method of mutagenesis chemical or radiation?

Answered By Dr. L. Curtis Hannah - Aug 21, 2015

A: Thanks for the question. I had to do some digging on this one. In terms of which person-directed mutagenesis method is more common among commercial varieties, Ahloowalia et al (Euphytica 135: 187-204, 2004) state that radiation is the most frequently employed method used by plant scientists. This work is somewhat dated (2004), but since people have been using X-rays since 1927 to create gene variants in plants, I would be surprised if the story has changed in the last 12 years. These investigators also note that some 2250 plant varieties now on the market were derived via these unnatural for [...]

Answered By Dr. L. Curtis Hannah - Aug 21, 2015

A: Thanks for the question. I had to do some digging on this one. In terms of which person-directed mutagenesis method is more common among commercial varieties, Ahloowalia et al (Euphytica 135: 187-204, 2004) state that radiation is the most frequently employed method used by plant scientists. This work is somewhat dated (2004), but since people have been using X-rays since 1927 to create gene variants in plants, I would be surprised if the story has changed in the last 12 years. These investigators also note that some 2250 plant varieties now on the market were derived via these unnatural for [...]

GMO Basics How GMOs Are Made

Question

Q: What is roundup ready seed? What vegetables are gene spliced with roundup?

Answered By Dr. L. Curtis Hannah - Dec 11, 2015

A: Thank you for your question. Roundup Ready refers to plants genetically engineered to be resistant to the herbicide Roundup. The active ingredient in this herbicide is a chemical called glyphosate. This chemical blocks the production of an essential component needed for plant life and consequently the plant dies after treatment with this herbicide.     More specifically glyphosate inhibits an enzyme called 5-enolpyruvylshikimate 3-phosphate synthase, sometimes abbreviated EPSPS. This enzyme is needed for the synthesis of a particular class of amino acids. Scien [...]

Answered By Dr. L. Curtis Hannah - Dec 11, 2015

A: Thank you for your question. Roundup Ready refers to plants genetically engineered to be resistant to the herbicide Roundup. The active ingredient in this herbicide is a chemical called glyphosate. This chemical blocks the production of an essential component needed for plant life and consequently the plant dies after treatment with this herbicide.     More specifically glyphosate inhibits an enzyme called 5-enolpyruvylshikimate 3-phosphate synthase, sometimes abbreviated EPSPS. This enzyme is needed for the synthesis of a particular class of amino acids. Scien [...]


Question

Q: What is roundup ready seed? What vegetables are gene spliced with roundup?

Answered By Dr. L. Curtis Hannah - Dec 11, 2015

A: Thank you for your question. Roundup Ready refers to plants genetically engineered to be resistant to the herbicide Roundup. The active ingredient in this herbicide is a chemical called glyphosate. This chemical blocks the production of an essential component needed for plant life and consequently the plant dies after treatment with this herbicide.     More specifically glyphosate inhibits an enzyme called 5-enolpyruvylshikimate 3-phosphate synthase, sometimes abbreviated EPSPS. This enzyme is needed for the synthesis of a particular class of amino acids. Scien [...]

Answered By Dr. L. Curtis Hannah - Dec 11, 2015

A: Thank you for your question. Roundup Ready refers to plants genetically engineered to be resistant to the herbicide Roundup. The active ingredient in this herbicide is a chemical called glyphosate. This chemical blocks the production of an essential component needed for plant life and consequently the plant dies after treatment with this herbicide.     More specifically glyphosate inhibits an enzyme called 5-enolpyruvylshikimate 3-phosphate synthase, sometimes abbreviated EPSPS. This enzyme is needed for the synthesis of a particular class of amino acids. Scien [...]


Question

Q: Whats the difference between Transgenic and Genetically Modified?

Answered By Dr. L. Curtis Hannah - Apr 19, 2016

A: Thanks for a great question!! Your question addresses much of the confusion in the popular press. To a geneticist, genetic modification means exactly what the words say: there is modification in the genetic material. This heritable form of variation of course is caused by mutation. Mutation can be natural or induced. Classic agents that induce mutation are some chemicals and some forms of radiation. For years, plant breeders have used induced mutation breeding to create favorable traits in plants as well as other organisms. These investigators treat seed with a powerful mutagenic agent and th [...]

Health & Safety

Question

Q: Im aware of a few examples of naturally occurring GMOS such as the sweet potato, butterflies and some plants, but where can I find a more extensive list and how often does this occur?

Answered By Community Manager - Apr 19, 2016

A: Currently, there are nine crops from GM seeds commercially available in the United States. These crops are corn (field and sweet), soybeans, cotton, canola, alfalfa, sugar beets, papaya, potatoes and squash. Apple is approved and coming to market soon.   To learn more about the commercially available crops, check out the Explore section here. [...]

Answered By Dr. L. Curtis Hannah - Apr 19, 2016

A: Thanks for such an interesting question. I like this because it allows me to discuss the vast area of gene movement and gene variability that occurs in living organisms. Initially, one can go back to “the beginning” of higher life forms such as the plants we grow, the animals in our lives and yes even “us” and note that some of the organelles we have in our cells originally came from bacteria. All higher life forms have mitochondria and plants have chloroplasts as well. Both of these organelles were originally bacteria that were taken up by cells of higher organisms. T [...]

GMO Basics How GMOs Are Made

Question

Q: Do GMOs cause allergies?

Answered By Dr. L. Curtis Hannah - Mar 29, 2017

A: Thank you for your question regarding the allergies and GMOs. Our experts have answered similar questions in the past – please see below for a comprehensive overview on this topic which should help address your question. DO GMOS CAUSE ALLERGRIES? Lisa Katic, RD, answered this question by explaining that “No commercially available crops contain allergens that have been created by genetically engineering a seed/plant. And the rigorous testing process ensures that will never happen.” In another post, Lisa goes on to say, “food allergies are mainly caused by eight major foods (milk, eggs, p [...]

GMO Basics Health & Safety

Question

Q: Are GMOs harmful to the environment?

Answered By Dr. L. Curtis Hannah - Mar 30, 2017

A: In addressing this question, one should realize that there are three federal agencies involved in regulating the commercial growth of GMO crops: the US Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS), the Food and Drug Administration (FDA) and the Environmental Protection Agency (EPA). Hence potential environmental concerns of a new GMO crop are addressed by the EPA long before commercial growth is allowed.   The major GMO crops currently on the market contain genes conditioning resistance to the herbicide Round-Up and/or resistance to attack by certain in [...]

Environment

Question

Q: If an unmodified, wild Agrobacterium Rhizogenes is used to produce hairy root, is it catheterized as GMO? where i can find regulations for this?

Answered By Community Manager - Jun 25, 2018

A: In addition to the below, the USDA Animal and Plant Health Inspection Service (APHIS) regulates the use and release of plant pathogens, either genetically engineered or not. The Biotechnology Regulatory Services (BRS), which is within APHIS, has recently replied to a request for guidance on the use of naturally occurring isolate of Agrobacterium rhizogenes  - to induce a reduction in height in ornamental kalanchoe plants. You can find the BRS response regarding the regulatory status of the resulting plants here.  [...]

Answered By Dr. L. Curtis Hannah - May 18, 2018

A: Thank you for your question. There are various aspects of your question. I assume your question refers to the use of Agrobacterium rhizogenes by scientists to intentionally transfer genes from the bacterium to plants. Infection and DNA transfer from this bacterium occurs in nature all the time to cause disease. Such transformed plants are not classified as GMOs since transfer occurred naturally. If this is done by scientists then it would be classified as a GMO. Rules and regulations about GMOs are covered by the USDA, FDA and EPA. An overview can be found here. Each [...]

GMO Basics