Doubled-Haploid Breeding Technology
Great Lakes Hybrids, a division of AgReliant Genetics LLC, has accelerated hybrid development with innovative doubled-haploid breeding technology. This approach produces pure parent lines in one year, compared to three to five years using conventional methods. For corn growers, that means faster access to new purebred lines and accelerated gains in yield and profitability.Doubled-haploid technology enhances “forward breeding” by allowing hybrids to be bred with new traits (GMO and non-GMO) without locking up the germplasm, and by developing stacks without negative side effects. This gives us an earlier look at new lines and greater knowledge about their environmental adaptability before they are fully tested, developed and marketed.
Over the past four years, the doubled-haploid breeding program has grown significantly:
- 2000 First haploids were induced.
- 2001 More than 2,500 doubled-hapoid lines were developed.
- 2002 More than 13,000 doubled-haploid lines were developed.
- 2002 The first doubled-haploid lines were yield-tested.
- 2003 More than 40,000 doubled-haploid lines were developed.
- 2004 More than 56,000 doubled-hapolid lines were developed.
- 2005-06 Our first doubled-haploid hybrids will be entering the marketplace.
- 2009-10 Almost all our product development is done through the doubled-haploid process
Breakdown of Corn Chromosomes
Corn has ten pairs of chromosomes. One chromosome of each pair comes from the female parent and one comes from the male parent. In any chromosome pair, the genes on the left chromosome of the pair may not be the same as the genes on the right chromosome of the pair.
Two Key Objectives of Corn BreedingThe first objective is to develop an inbred parent line that has the same genes on both the left and right chromosome of the pair. This is called a genetically stable or homozygous inbred. The second stage is to select the best of the newly developed inbreds through an intense breeding and testing program.
An inbred parent line must be homozygous or genetically stable so that:
- we can produce the hybrid year after year, and
- we can be certain the hybrid is the same genetically, and has the same agronomic performance potential, each time it is produced.
The Process of Corn Breeding
During corn breeding, the new inbred parent lines are crossed to make research hybrids that are tested for a number of traits, including:
- Test Weight
- Stalk Strength
- Root Strength
- Disease Resistance
- Harvest Appearance
- Plant Height
- Ear Height
- Various Grain Quality Traits
Traditional vs. Doubled-haploid Methods
The traditional method of stabilizing the genes and developing an inbred line was accomplished by self-pollinating the plants for eight or nine generations. Using both summer and winter nursery operations, this took about three to five years to complete.The doubled-haploid method is much faster and can produce a new, genetically stable inbred line in one year. The plants in the genetic population (germplasm pool) are pollinated with a haploid inducer. When the harvested kernels are planted, they produce haploid plants. A haploid plant has only one chromosome from each pair. One can say that a haploid plant has ten single chromosomes. A normal plant has ten pairs of chromosomes.
The haploid plants are subjected to a special treatment compound that causes the single chromosome to double – think of it as making a “photocopy” of the chromosome. The photocopy is genetically identical to the original.The haploid that had ten single chromosomes, now has ten chromosome pairs. The plant that is grown from this seed is referred to as a doubled-haploid. The genes on the left and right chromosome of each pair are identical (one is a copy of the other). This means that the new inbred is a genetically stable parent line (homozygous). A hybrid can be produced year after year with this parent inbred and it will always be the same, identical hybrid.
The doubled-haploid method greatly reduces the time required to develop new parent inbreds. Observation, testing and selection work is conducted on these newly developed lines. The goals of the traditional method and the doubled-haploid method are the same. However, the doubled-haploid method reaches those goals much faster.