The history and science of lucerne breeding (part 2)

Date posted: 17 June 2016

In part one of our plant breeding blog we touched on the history and importance of plant breeding. Essentially it’s all about breeding new plant varieties that are better suited to local conditions, the consumer (both humans and animals) and farmer needs.

Not all plants are created equal. Some tolerate frosts or heat well, others are resistant to disease and others have different quality or yield characteristics. A plant breeder’s role is to find plants with the best traits, then develop new varieties that perform well from the paddock to the plate.

So how is this done? Here are the basic steps used in a conventional lucerne breeding program:

1) Scientists search the world for two parent plants, each with desirable traits (i.e. parent one is resistant to disease while parent two is high quality).

2) The scientist crosses, or mates, the two parents. This is based on the work bees usually do, but since the scientist can’t buzz from flower to flower, they use tweezers and pluck the male anthers (which contain pollen) from parent one and dab them on the female sexual column of parent two. The pollen then moves down into the ovule resulting in fertilisation… Interesting fact: The process of removing the male parts from a flower is known as “emasculation”.

3) Each of the fertilised flowers is labelled and has a small bag placed over them. This ensures they are not contaminated with other wind born pollen, and can be identified later.

4) Following fertilisation, a tiny seed begins to grow. Once they reach maturity, the seeds are collected and sown in experimental plots. This first round of crossing is known as the F₁generation.

5) Scientists monitor the plants’ performance throughout the growing season, looking for those that outperform the others. This “phenotypic assessment” helps eliminate those that have not inherited the good characteristics and keep those that thrive.

6) Sometimes, plant breeders might choose to cross the F₁ offspring back with one of the parent plants. “Backcrossing” is a common procedure used to introduce more of the desirable parent plant’s DNA into the offspring. Some plant breeding lines can end up having more than 90 per cent of their DNA from one parent! Again, the next generation is tested in the field, with the winners selected for further review.

7) Along with the phenotypic assessment, many plant breeders now also assess the plant’s genes. Using a conventional breeding technology known as “DNA fingerprinting” or “marker assisted selection”, varieties can be screened to determine which ones have the characteristics of interest. This saves time monitoring their performance in the field as they can be screened to see if they have inherited the genes of interest from their parents.

8) The grains and hay products are tested for nutrition and quality.

9) After many seasons of crossing, back crossing, gene assessment, and nutrient assessment a new variety is released to the farmer. It can then be grown for humans and animals to eat.(

Plant breeders have been instrumental in feeding animals and humans alike. In fact, if farmers were using the same varieties and technology today as they were 50 years ago, they would only produce half as much grain as we do today!

It’s all part of the paddock to plate process.