Atlas 66: Improving Cultivated Wheat Through Donor Selections

[gracy]

1. Atlas 66 has been used as a donor for improving cultivated wheat.what does this mean?MY attempt-Atlas 66 is a cultivar i.e a plant variety that has been produced in cultivation by selective breeding.so it contains desired characters such as more than one Al tolerance gene .so plant breeders can use seeds of Atlas 66 and then cross breed it with another plant having another desired characters,in this way there would be improvement in cultivated wheat.right?if not what is correct explanation of the above sentence?how can Atlas 66 be used as a donor?what is meaning of donor in this context?

 

[jim mcnamara]

donor == contributor of genes. A father and mother each donate genes to their offspring. This sounds funny in English, because we use the word donor in the context of plant genetics more than elsewhere.

Your understanding is correct. One point - what you are learning is plant breeding. I am going to use non-technical terms so I do not have to define every one I use.

Humans have two sets of chromosomes (23 in a set) that look alike. Humans have 46 total, 2 x 23 = 46.

Interbreed means to create viable offspring from two unrelated species - in this context.

Modern wheat has six sets of chromosomes. There are other wheat species - emmer for example. All species are used for food and animal feed. These last one, emmer, has 4 sets of chromosomes. So emmer plants have trouble breeding with modern wheat. Plants evolve into new species because there exists a barrier to interbreeding with close relatives. Having a different chromosome number does a good job of blocking interbreeding. It is only one of lots of known ways of preventing interspecies (between species ) interbreeding in plants.

Example: einkorn (another wheat species) has two sets. Einkorn(2) -> emmer(4) -> modern wheat(6). Farmers did this in 12000 years of cultivation and selective plant breeding. Geneticists are pretty sure the "ancestral" einkorn wheat had 2 sets. Ancestral means the one species some guy 9600 years ago decided to try growing and it changed under domestication. And the world. Someday you should read 'Guns Germs, and Steel' by Jared Diamond.

What happens when your discover that emmer has a wonderful trait, and you want to make that trait available in modern wheat? You have a problem. Plant breeding is the subject of how to get that new wonderful genetic goodie into modern wheat. Or even worse, into tomatoes. Animal husbandry (breeding and care) has similar issues, but they are usually not as difficult as some plant genetic problems. Usually because biologists are not trying to move manatee genes into sheep.

Modern strawberries have 8 sets of chromosomes, the ancestral species from which strawberries were bred has two sets. You see the problem.