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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: What are the breeding obstacles to releasing GMO traits in hybrid seed? What are the performance liability issues related to same, and what are the regulatory issues related to such a release into the environment?

Answered By Dr. L. Curtis Hannah - Sep 04, 2013

A: First, thank you very much for your series of questions.  In terms of regulatory issues for releasing transgenic cultivars that are hybrid (such as corn or maize), versus, I assume, ones that are not (such as soybeans), there are no formal differences in the regulatory process. Questions concerning the nature of the gene, its function, its insertion site in the host genome, effect on plant growth and composition, allergenic properties of the added protein, etc., must be satisfied before the transgene can be “deregulated” and used commercially. Your question may be getting at the fac [...]

GMO Basics How GMOs Are Made

Question

Q: How can Monsanto assure that artificial GMO genes do not propagate into natural ecosystems or non-GMO crops?

Answered By Cathleen Enright - Mar 07, 2014

A: The short answer can be found in the last paragraph of this response, but I thought in responding to your question, I might first correct a misconception and then spend just a minute talking about gene flow to ensure we are starting from the same place. GMO genes are not artificial. They are already found in nature. Bt genes, for example, are genes found in the soil bacteria Bacillus thuringiensis, which are ubiquitous around the world. (Smart organic farmers have been applying these bacteria to crops for almost 100 years, to combat pests that Bt crops also target.) With GM technology, w [...]

Answered By Dr. L. Curtis Hannah - Mar 07, 2014

A: Thank you for your question. In order for Monsanto to be in a position to make such assurances, it would have to have total control of plant agriculture, from planting to consumption. This is not the way modern agriculture and the food chain function. And I have not heard of any suggestion that Monsanto (or any other seed company that sells GMO crops) should control these activities. It should be mentioned that seed producers have the right to protect their invention from subsequent unlicensed propagation, through the Plant Variety Protection Act or conventional utility patents. The [...]

Environment Crop protectants

Question

Q: I am an agricultural economist writing a book chapter on GMOs. I tried to explain how genetic modification takes place with the statement, "A GMO is an organism where the genes from another organism (usually a bacteria) are deliberately inserted into the

Answered By Dr. L. Curtis Hannah - Oct 09, 2013

A: Thank you for your important question. The definition of a “GMO” or a transgenic organism refers to an organism containing a gene inserted by man. This is quite evident when one reviews the criteria for release of these organisms as defined by the Joint Food Standards Program of the Food and Agriculture Organization of the United Nations and the World Health Organization, as well as Codex Alimentarius Commission (reviewed in Steiner, H-Y, Halpin C., Jez J., Kough J., Parrott W and , Hannah, LC. 2013 Evaluating the Potential for Adverse Interactions within Genetically Engineered Breeding Stack [...]

GMO Basics How GMOs Are Made

Question

Q: Some of the answers I've read on your website make it seem like the science of genetic modification is completely precise: 1) that a foreign gene is inserted exactly where it needs to go without any disruption of the genes on either side of it and 2) that

Answered By Dr. L. Curtis Hannah - Dec 09, 2013

A: I love your questions because it allows me to address some of the confusion out there concerning GMOs. The ability to precisely insert a gene at a particular site in the genome is an area of active research. The day likely will come when all new gene inserts are done at precise locations.  However to the best of my knowledge all commercially used gene inserts in today’s market arose from methodologies that did not use precise insertion techniques.  However, following insertion the location of the inserts in commerce was precisely determined by DNA sequencing. Knowing this infor [...]

GMO Basics How GMOs Are Made

Question

Q: In transgenetic Bt cultivars, do all the cells of the plant contain DNA which includes the transgene? And in those cells which do contain the gene, when and under what conditions is the insecticide protein expressed?

Answered By Dr. L. Curtis Hannah - Jun 19, 2014

A: Thank you for two excellent questions.  First, “Do all cells in a Bt-containing transgenic plant contain the Bt transgene?  The general answer is yes.  Barring rare mutation or rare chromosomal abnormalities, all somatic cells in a plant contain the same DNA.  The large part of a cereal seed (corn, wheat, oats, rye, rice, etc) is called an endosperm and it has three doses of each gene whereas other cells and tissues contain only two copies.  However it is the same complement of genes in all tissues. Germ cells (pollen and ovaries) contain only one copy of each gene an [...]

Answered By Dr. L. Curtis Hannah - Jun 19, 2014

A: Thank you for two excellent questions.  First, “Do all cells in a Bt-containing transgenic plant contain the Bt transgene?  The general answer is yes.  Barring rare mutation or rare chromosomal abnormalities, all somatic cells in a plant contain the same DNA.  The large part of a cereal seed (corn, wheat, oats, rye, rice, etc) is called an endosperm and it has three doses of each gene whereas other cells and tissues contain only two copies.  However it is the same complement of genes in all tissues. Germ cells (pollen and ovaries) contain only one copy of each gene an [...]

Health & Safety

Question

Q: In transgenetic Bt cultivars, do all the cells of the plant contain DNA which includes the transgene? And in those cells which do contain the gene, when and under what conditions is the insecticide protein expressed?

Answered By Dr. L. Curtis Hannah - Jun 19, 2014

A: Thank you for two excellent questions.  First, “Do all cells in a Bt-containing transgenic plant contain the Bt transgene?  The general answer is yes.  Barring rare mutation or rare chromosomal abnormalities, all somatic cells in a plant contain the same DNA.  The large part of a cereal seed (corn, wheat, oats, rye, rice, etc) is called an endosperm and it has three doses of each gene whereas other cells and tissues contain only two copies.  However it is the same complement of genes in all tissues. Germ cells (pollen and ovaries) contain only one copy of each gene an [...]

Answered By Dr. L. Curtis Hannah - Jun 19, 2014

A: Thank you for two excellent questions.  First, “Do all cells in a Bt-containing transgenic plant contain the Bt transgene?  The general answer is yes.  Barring rare mutation or rare chromosomal abnormalities, all somatic cells in a plant contain the same DNA.  The large part of a cereal seed (corn, wheat, oats, rye, rice, etc) is called an endosperm and it has three doses of each gene whereas other cells and tissues contain only two copies.  However it is the same complement of genes in all tissues. Germ cells (pollen and ovaries) contain only one copy of each gene an [...]

Health & Safety

Question

Q: Why cant GMO be used by organic farmers outside of science denial? GMOs are supposed to be better for the environment than conventional crops. If organic farming methodologies are better for the environment, why dont organic farmers use GMOs? Wouldnt that

Answered By Dr. L. Curtis Hannah - Nov 06, 2014

A: You raise a very valid point. There is no scientific reason why organic growers cannot use genetically engineered plants. In fact, when GM plants first came on the market, I thought the organic growers would be the first to use them. The fact that plants could be engineered to avoid any spraying with insecticides would be ideal for the organic growers. Clearly I was wrong. Perhaps the arbitrary ban placed on GE technology by the organic community is because the use of genetic engineering will eventually minimize the difference between commercial and organic agriculture. Perhaps it is simply a [...]


Question

Q: Do you think it would be possible to grow GM crops in a large scale contained environment?. This way, it would prevent GM crops from unintentionally spreading out of GM cultures and thus lower the risk of causing important modification to the environment.

Answered By Dr. L. Curtis Hannah - Dec 18, 2014

A: First, thank you for an interesting question. The simple answer to your question is yes. Let me amplify though on some of the points to which I think you are alluding. First, growth of any experimental transgenic plant material in an outside environment is not a decision investigators can make by themselves. Outside growth requires that a permit be issued by the U.S. Department of Agriculture. This agency examines the gene inserted and its probable function and then makes a decision of whether the material can be grown outside of the laboratory or greenhouse. If so, t [...]


Question

Q: Pretreating seeds via electromagnetism, since many ages ago, was the key to increasing yields, sustaining soil quality, enhancing crops resistance to floodsearly frosts... Is this magnetism still a key GMO?

Answered By Dr. L. Curtis Hannah - May 08, 2015

A: Thank you for your interesting question. As far as I know and as far as I can determine, electromagnetic treatment of seed is not used at any appreciable level in the seed industry, either conventional or GMO. If you have any reference to its use in the commercial seed industry, I would appreciate receiving word of it. [...]

Health & Safety Other

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 [...]

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