When you go to the supermarket these days, you find yourself selecting foods that have been genetically modified to look greener, taste better and last longer. These are GMO foods, and in my opinion is something we need as a society. Imagine one year for some reason, there is a slight decrease in rain water, and there is less rice grown because of these issue; Would not you want a line of rice that was able to grow under these reduced water condition? To grow these modified crops genome editing is being used, such as CRISPR. However, there are different ways to obtain a specific mutation in the genome without using genome editing and creating GMO foods. How you may ask? EMS.
EMS (ethyl methanesulfonate) is a mutagen capable of inducing random mutations in a genome. It generates T/A and C/G transitions, generating either loss or partial loss of function of a specific gene. The beauty of EMS is that with less than 5000 individual plants you will find your desired mutation in the gene. You will find these mutations either by sequencing or map based cloning. However, random mutations may appear somewhere else in the genome combined with your desired mutated gene mutation. Here is where back crossing comes into play.
In a back cross, you have one plant that will have the mutation in the desired genes (plus some other undesired random mutations), and you will cross that plant with an elite line, to which you will want to add that mutated gene. The plant resulting from this crosses may have to be back crossed again to the elite line; until you are able to have an elite line plant with the mutation in your desired gene, and only that mutation.
This method is definitely more expensive, time consuming and tedious than performing genome editing nowadays. However, many countries do not allow GMOs, therefore this is a way to obtain modified crops without gene editing.