Quartet Breeding via Maternal Chromosome Elimination
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Solution Overview
Problem
Current plant breeding methods face challenges in preserving the genetic constitution of heterozygous plants with high agronomic or ornamental value, as sexual reproduction introduces genetic variation and meiotic recombination can lead to reduced gamete viability and inappropriate chromosome segregation, limiting the efficiency of technologies like reverse breeding and Near Reverse Breeding.
Innovation Solution
A method involving the production of seeds genetically identical to male gametes by inducing the loss of maternal chromosomes using a haploid inducer line with a transgenic expression cassette encoding altered CENH3, CENPC, MIS12, NDC80, or NUF2 polypeptides, which results in seeds lacking maternal chromosomes and maintaining paternal genetic composition, allowing for the reconstruction of hybrid plants with near-identical genetic constitution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If sexual reproduction is used to multiply plants, then genetic variation is increased, but uniformity of offspring is reduced
Solution Approach 1:
The invention segments the reproductive process into two distinct phases: first, sexual reproduction to generate genetic variation through meiosis and fertilization; second, somatic doubling to restore uniformity by creating genetically identical clones from the sexually reproduced plant. This segmentation allows both genetic variation and uniformity to be achieved at different stages of the breeding process.
Solution Approach 2:
The invention applies preliminary action by performing somatic chromosome doubling immediately after sexual reproduction to prevent the loss of uniformity in subsequent generations. By doubling the chromosomes of the sexually reproduced plant before further propagation, the method ensures that the genetic composition is fixed and uniformly transmitted to all offspring, while still benefiting from the genetic variation introduced by the sexual reproduction step.
2Adaptability or versatility
If meiotic recombination is allowed during sexual reproduction, then genetic diversity is enhanced, but gamete viability and chromosome segregation are reduced
Solution Approach 1:
The invention segments the genetic processes by allowing meiotic recombination to occur during the sexual reproduction phase to generate genetic diversity, then separates this from the propagation phase by applying somatic chromosome doubling. This segmentation ensures that recombination benefits are captured while its harmful effects on gamete viability are confined to the controlled sexual reproduction step and do not propagate to subsequent generations.
Solution Approach 2:
The invention converts the harmful effect of meiotic recombination (reduced gamete viability) into a benefit by allowing recombination to occur in controlled sexual crosses to generate diverse genotypes, then using somatic doubling to fix the desired genotype. The temporary reduction in gamete viability during recombination is offset by the ability to select and propagate only the most viable and desirable genotypes through the subsequent somatic doubling step.
3Productivity
If traditional breeding methods with multiple rounds of empirical selection are used, then genetic improvement is achieved, but time and resource consumption increase
Solution Approach 1:
The invention applies preliminary action by performing somatic chromosome doubling early in the breeding process, immediately after identifying a plant with desirable traits through sexual reproduction. This preliminary doubling fixes the genotype in advance, eliminating the need for multiple subsequent rounds of inbreeding and selection that would otherwise be required to stabilize the genetic composition. This dramatically reduces the breeding cycle time while maintaining genetic improvement.
Solution Approach 2:
The invention skips the traditional multi-generational inbreeding process by directly applying somatic chromosome doubling to a sexually reproduced plant with desirable traits. Instead of rushing through multiple generations of empirical selection and inbreeding, the method jumps directly to the point where uniformity is achieved through somatic doubling, thereby reducing both time and resource consumption while maintaining the ability to achieve genetic improvement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method significantly increases the efficiency of identifying and reconstructing plants with complementary genetic compositions, enabling the preservation of desirable traits and allowing for further genetic improvement while minimizing genetic variation.
Implementation Method 1
inducing the loss of maternal chromosomes from the zygotes to obtain a number of seeds that constitute a seed set in which seeds the maternal chromosomes are absent
Implementation Method 2
the female is a transgenic plant that comprises a heterologous transgene expression cassette, the expression cassette comprising a promoter operably linked to a polynucleotide encoding a recombinantly altered CENH3, CENPC, MIS12, NDC80 or NUF2 polypeptide
Data Source
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AI summary
The invention relates to a method for the production of a set of seeds which are genetically identical to the male gametes from which they arise, comprising placing a limited number of paternal gametes that have the form of tetrads or dyads on the stigma of a flower to fertilize maternal egg cells to obtain a number of zygotes; and inducing the loss of maternal chromosomes from the zygotes to obtain a seed set containing a limited number of seeds in which the maternal chromosomes are absent. In a preferred embodiment the father plant exhibits suppression of chromosome recombination or second division restitution (SDR) during meiosis.