Haploid Inducers via Nucleic Acids for Maize Breeding
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Solution Overview
Problem
Current methods for producing haploid and double-haploid plants in crops like maize, sorghum, rye, and sunflower lack efficient and economically viable systems, and the molecular and developmental mechanisms of existing haploid induction in maize lines derived from 'Stock 6' are not fully understood, limiting the improvement or transfer of induction suitability to non-inducer genotypes.
Innovation Solution
Development of nucleic acids and vectors that can impart or enhance the property of haploid induction in plants by influencing pollen tube growth, energy metabolism, and centromere activity, either through transgenic or non-transgenic approaches, including the use of specific genes and regulatory elements such as phospholipases and RNA methyltransferases to promote haploid development.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional inbred line production through multiple selfing steps is used, then genetic purity is maintained, but the process is extremely time-consuming and requires several generations
Solution Approach 1:
The invention segments the traditional multi-generational selfing process into a single-step haploid induction event followed by chromosome doubling. Instead of progressively purifying lines through repeated selfing over generations, the method isolates the gametophytic stage (pollen or egg cell) to generate haploids, which are then doubled to achieve complete homozygosity in one generation rather than requiring multiple generations of selfing.
Solution Approach 2:
The invention performs preliminary action by inducing haploid formation at the gametophytic stage before fertilization occurs. By manipulating the pollen or egg cell to become haploid and then doubling the chromosomes, the complete inbred line is generated in advance of what would traditionally require multiple generations of selfing, effectively shortcutting the time-consuming generational process.
2Productivity
If existing haploid inducer systems from Stock 6 are used, then some induction capability is achieved, but the molecular mechanisms are largely unknown and efficiency is limited
Solution Approach 1:
The invention implements feedback by using next-generation sequencing technology to comprehensively analyze the transcriptome of haploid-induced plants and compare them with conventionally bred plants. This generates detailed molecular data about gene expression differences, which then feeds back into understanding the mechanisms of haploid induction. The sequencing data provides information about which genes are differentially expressed during induction, enabling targeted improvement of induction systems based on actual molecular evidence rather than trial-and-error.
Solution Approach 2:
The invention replaces the mechanical/phenotypic selection approach with molecular analysis. Instead of relying on phenotypic markers or traditional genetic mapping to understand induction mechanisms, the method uses transcriptome sequencing to directly observe gene expression patterns. This substitution of mechanical phenotypic analysis with molecular transcriptomic analysis provides deep mechanistic insights that were previously unavailable.
3Productivity
If transgenic approaches are used to introduce nucleic acids for haploid induction, then induction capacity can be enhanced, but the complexity of the system increases
Solution Approach 1:
The invention applies universality by identifying and manipulating genes that have multiple functions in plant development but can be specifically exploited for haploid induction. The genes involved in pollen tube growth, energy metabolism, and centromere activity are not solely dedicated to induction but perform broader developmental roles. By targeting these universal genes, the system achieves haploid induction capability while utilizing existing cellular machinery and pathways, thereby reducing the need for entirely new complex systems.
Solution Approach 2:
The invention uses intermediaries in the form of specific genes and regulatory elements that mediate between the introduced nucleic acids and the haploid induction outcome. Rather than directly forcing haploid formation, the transgenic approach introduces genes that encode proteins acting as intermediaries—such as those influencing pollen tube growth, energy metabolism, or centromere function—which then naturally lead to haploid induction through their physiological effects. This intermediary approach simplifies the system compared to direct manipulation methods.
Data Source
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AI summary
The present invention relates to the provision of technical means such as nucleic acids, which after transcription or expression in a plant are suitable for imparting the property of a haploid inducer or increasing the inducing power of a haploid inducer. The invention also relates to methods and uses for producing and identifying non-transgenic and transgenic plant haploid inducers as well as to the improvement of existing plant haploid inducers.