Homozygous Onion Downy Mildew Resistance via Lethal Factor Separation

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Solution Overview

Problem

Current methods fail to produce homozygously resistant Allium cepa and Allium fistulosum plants against downy mildew caused by Peronospora destructor, as the introgressed resistance locus from Allium roylei is linked with a lethal factor, preventing the creation of plants that can self-pollinate and produce 100% resistant progeny.

Innovation Solution

The separation of the resistance locus from the lethal factor through recombination events allows for the development of plants that are homozygously resistant to downy mildew, ensuring that any progeny from self-pollination also inherits the resistance, by physically disjoining the sequences conferring resistance from those causing lethality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the introgressed resistance locus from Allium roylei is used to provide resistance to downy mildew, then resistance is achieved, but the resistance cannot be made homozygous due to linkage with a lethal factor

Engineering Contradiction:

Improveresistance to downy mildewVSAvoidability to produce homozygous resistant plants

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies the extraction principle by isolating and transferring only the specific resistance locus (Pd gene) from Allium roylei to Allium cepa, separating it from the lethal factor through precise molecular breeding techniques. This allows the resistance trait to be obtained without the harmful linked gene, enabling homozygous resistant plant production.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent utilizes parameter changes by modifying the genetic composition at the molecular level - specifically changing the linkage relationship between the resistance locus and lethal factor through recombination events. By selecting for plants where recombination has separated these two genetic elements, the patent transforms the inherited resistance from heterozygous to homozygous state without the lethal effect.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If heterozygous resistant plants are used for breeding, then resistance is present, but segregation occurs in progeny preventing 100% resistant offspring

Engineering Contradiction:

Improveresistance to downy mildewVSAvoidsegregation of resistance trait

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent applies preliminary action by performing molecular marker-assisted selection during the breeding process to identify and select plants that have already achieved homozygosity for the resistance locus before they are used for further breeding. This preliminary identification and selection of homozygous individuals ensures that subsequent progeny will inherit the resistance trait without segregation, achieving 100% resistant offspring.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the introgression fragment containing the resistance locus is maintained, then resistance is conferred, but the fragment also contains a lethal factor that prevents homozygosity

Engineering Contradiction:

Improveresistance to downy mildewVSAvoidlethal factor in introgression fragment

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies the extraction principle by removing the lethal factor from the introgression fragment through molecular breeding and recombination. The resistance locus is isolated and transferred to a clean genetic background in Allium cepa, separating it from the harmful lethal gene that was originally linked in the A. roylei introgression fragment.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the harmful linkage between resistance and lethal factor into a benefit by using the lethal factor's presence as a selectable marker. Plants that survive and show resistance are selected, and through continued breeding and recombination, the resistance locus is eventually separated from the lethal factor, transforming the originally harmful linkage into a useful selection tool.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS8119856B2Resistance to downy mildew of onion caused by the fungus <i>peronospora destructor</i>

Publication Date: 2012.02.21 HAZERA SEEDS BV

AI summary

The present invention relates to plants of the Allium cepa species, which are resistant to the downy mildew of onion caused by the fungus Peronospora destructor, due to a Pd resistance locus, wherein any fragment of a chromosome, comprising the Pd resistance locus, can be present homozygously in progeny without causing lethality. The present invention also encompasses plants of the Allium cepa species which are resistant to downy mildew of onion caused by the fungus Personospora destructor (Pd) due to Pd resistance locus present homozygously in the genome of the plants. The present invention also provides processes for obtaining plants resistant to downy mildew of onion, which are suitable for obtaining cultivated onions and shallots.