Re: How do crop breeders transfer genes from one plant to another

I assume that your question relates to the transfer of foreign genes, 
rather than conventional plant breeding methods. First of all, the 
scientists have to decide which gene to transfer, then find and isolate 
the gene of choice from the plant of choice (e.g. soybean) and make many 
more copies. That can be done in the test tube by a protein enzyme- 
catalyzed reaction that is also known as polymerase chain reaction (PCR). 
One has to have some knowledge of the information (nucleotide sequence) 
contained in the gene. Alternatively, one can connect the gene to a piece 
of bacterial DNA, transfer this vector/plant gene chimera into a suitable 
host bacterium by a process commonly referred to as cloning, and let the 
bacteria make more copies of the plant gene as they divide.

To introduce the plant gene into another plant (e.g. tobacco), one has two 
possibilities:

	1. There are “gene guns” that literally shoot genes into plant 
tissue. Tiny metal bullets (projectiles) that are coated with the gene to 
be transferred are accelerated to bombard a piece of plant tissue (e.g. 
part of a tobacco leaf). Many of the bombarded cells will die, but a few 
will live and incorporate the foreign gene into their own DNA. The 
following site describes how this technology can be used by the orchid 
breeding industry:   http://www.accessexcellence.org/AB/BA/Gene_Gun_Orchid_Color.html

	2. The soil bacterium called Agrobacterium tumefaciens contains a 
DNA molecule (the Ti plasmid) which, connected to a gene of choice, is a 
very good delivery vehicle (a vector) of foreign genes into cells of many 
different plant species. The following site gives you more in-depth 
information on Agrobacterium Ti plasmid-mediated plant transformation:   http://www.accessexcellence.org/AB/BA/Transforming_Plants.html

	If you are interested in many different aspects of agricultural 
biotechnology, this site contains a wealth of information:   http://www.accessexcellence.org/AB/BA/Gene_Gun_Orchid_Color.html