• Preparation of a DNA sample in the laboratory
    Line breeding

Line breeding

Overview

In short

Here researchers crossbreed two parent lines that complement each in desired properties as much as possible. From the offspring, homozygotic plant lines are developed, which are called line-bred varieties.

Advantages

Line-bred varieties are very homogeneous and the offspring of the plants are genetically stable.

Disadvantages

Time-consuming: Several cycles/generations must be cross-bred and bred through self-fertilization before the desired result is achieved.

Development

Self-pollinated varieties in traditional agriculture, called landraces, consist of a variety of line mixtures. Line-bred varieties have, somewhat, developed from them.

Application at KWS

Barley and wheat breeding

Line breeding is used for plant varieties that usually breed through self-pollination (e.g. barley, wheat, oats and peas). Such plants are fertilized by their own pollen, even before they leave the flowering stage. However, this does not lead to the increase in genetic diversity that the breeders are looking for, as the genetics are not mixed. To make this possible, breeders use targeted cross-breeding of two parental lines, which complement each other in terms of the desired properties.

Next, breeders select those plants that correspond to the desired performance specifications with regard to plant health, yield and quality (selection). After several of these selection cycles, a new variety is built from the best plant, and because this plant is bred through self-fertilization, the plants of this variety are very uniform (homogeneous). This procedure is called line breeding. It eventually results in largely homozygotic and homogenous line-bred varieties with the new, desireable characteristics. These can be identically reproduced through self-pollination for cultivation in agricultural practice.

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This often tedious process can be accelerated: The doubled haploid technique involves the isolation of haploid plant cells, e.g. pollen. These only carry male genetic material, i.e. half of the chromosome set. If the chromosome set is subsequently reduplicated, all characteristic attributes are present in homozygotic form.

To do this, breeders create pollen cell cultures, from which tissue and, then eventually, a plant grows. Until then, it only has half of a chromosome set. The so-called homozygotic doubled haploid plants result from a reduplication of the chromosome set. This saves time compared to traditional line breeding with repeated self-fertilization. This allows farmers to quickly see breeding progress.

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Thilo Resenhoeft
Thilo Resenhoeft
Corporate Communications
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