Thanks
A fair question. Well breeding can generally be summed up as "cross the best with the best and hope for the best".
I'm not a geneticist so I won't be overly technical.
In the case of crops, there are generally two types of breeding - conventional and hybrid.
This is used for most cereals and grasses. These plants are self pollinating (each plant has a male and female part on the plant). The male part (Anther) produces pollen (like sperm) and this falls into the female part and fertilises it and hey presto you have a seed.
In the case of lets say wheat, a breeder will look at existing varieties and maybe even wild wheats and pick out those that he likes the look of. He might pick them because the produce large seeds or are resistant to a disease etc.
One plant will be chosen as the male and the other will be chosen as the female. To make one of the plants "female only" he will cut off the anthers, therefore it cannot fertilise itself. He then scatters the pollen from the other plant into it and he knows that the "female" plant can only have been fertilised by the other plant - in other words he has crossed one with the other.
The new seeds formed on the female plant are again planted and the breeder watches to see what grows. What grows will be a mix of new varieties - most useless but some may look promising. He chooses those promising ones and plants their seeds again. The seeds produced by these should then be relatively pure. He then puts them into trials to see how they compare with new varieties. Then he might give some to the likes of Goldcrop who will see if they grow ok in the Irish climate. If we chose one, we then put into Dept of Ag trials for another 3 years and at the end it may or may not become commercial.
As you can see, it takes many years to produce the new variety and the vast majority of new varieties are stopped during the process.
If a variety looks promising, the breeder will have to make sure to keep a maintenance crop of the variety each year to make sure the variety stays pure and also doesn't run out.
Similar principal as in two parents are used. However the parents are crossed each year - the seed is not remultiplied.
The reason that a fresh cross is done each year is because of "hybrid vigour" or Heterosis as it is also known. When two varieties are crossed for the first time, the progeny (children) of the cross exhibit higher vigour than their parents (this could be more power to survive tough conditions or more yield etc).
Unfortunately, when if the children are multiplied up this vigour does not re-occur. Therefore a fresh cross needs to be done each time - this is expensive.
Hybrids are used in cereals to a limited degree but they are very popular in other crops such as vegetables, oilseed rape etc.
You asked about the TuYV virus in the oilseed rape video. This resistance was first identified in another brassica plant and such a plant would have been crossed with oilseed rape to transfer the resistance into oilseed rape. When this transfer occurs for the first time, other traits will be transferred to the oilseed rape. Most of these traits are negative or useless. So, once you have an oilseed rape with the desired virus resistance, you will need to keep crossing the oilseed rape plant with good varieties to come up with better oilseed rape plants that also have the desired resistance.
Sometimes, in order to speed up the process, a breeder might harvest the crop in the northern hemispehere (eg. the UK or Ireland) and then send the seeds to the southern hemisphere (eg. New Zealand) in order to get two harvests in the one year and thus speed up the multiplication of the seeds.
They will also use special glasshouses with special lighting and temperature to speed up the growth of the plants.
We hear mention of Gene editing in the press. The EU is currently re-examining Gene editing to see if it can be made legal in the EU (I think it should be made legal).
Gene editing is much more precise than the traditional methods described above. It involves adding removing genes to improve a plant.
The difference between gene editing and GM is that gene editing only involves genes from the same plant - for example wheat genes put into a wheat plant whereas with GM, tomato genes can be put into a wheat plant.
As you can see, there's a lot to it and a lot of cost also. As chemicals come under more pressure across the world, more focus has been put on genetics to provide solutions and improve yields. This has resulted in some of the traditional "chemical companies" buying or setting up new breeding programmes to move their business more towards that.
However, many breeding companies remain privately owned by families or in many cases farmer cooperatives.
Breeding is a long term game and not a game for shareholders who want a quick return on capital.
I have only grazed the surface of crop breeding here but I hope it gives some explanation.
I have always loved plants, ever since I was a child. When I was 5 or 6, I used to plant plots of crops in my mothers garden using seeds from whatever my father was planting. I used to grow them and harvest them and clean the grain using a lettuce spinner. I used to even make up "potions" with whatever chemicals I could find in the house and make my own "sprays".
I'm not sure if I ever really grew up.
You can have plants without humans or animals but you can't have humans or animals without plants.