Chromosome Doubling in Haploid Maize Embryos
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Solution Overview
Problem
The process of obtaining homozygous plants is inefficient due to the need for multiple generations of self-pollination and segregation analysis, which is labor and time-intensive.
Innovation Solution
The method involves isolating immature haploid embryos from maize ears pollinated with an inducer line, contacting them with a chromosome doubling agent, and culturing them on specific media to produce doubled haploid plants, reducing the time and labor required to achieve homozygous plants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple generations of self-pollination are used to obtain homozygous plants, then homozygosity is achieved, but the process requires excessive time and labor resources
Solution Approach 1:
The patent applies preliminary action by inducing haploid embryos early in development (4-21 days after pollination) and doubling chromosomes before plant maturity. This preliminary chromosomal manipulation eliminates the need for multiple generations of self-pollination, achieving homozygosity in a single generation rather than requiring 5-6 generations of traditional breeding.
Solution Approach 2:
The patent changes the chromosomal parameter from haploid (n) to doubled haploid (2n) through chemical treatment with colchicine or other mitotic inhibitors. This parameter change in chromosome number directly produces homozygous plants without requiring temporal progression through multiple generations, thereby resolving the time-homozygosity contradiction.
2Reliability
If multiple generations of self-pollination are used to obtain homozygous plants, then homozygosity is achieved, but labor resources are excessively consumed
Solution Approach 1:
The patent replaces the mechanical process of repeated hand pollination and phenotypic selection across multiple generations with a biochemical approach. By applying chromosome-doubling agents to haploid embryos, the method substitutes manual breeding operations with chemical treatment, dramatically reducing labor requirements while achieving the same homozygosity outcome.
Solution Approach 2:
The patent introduces chromosome-doubling agents (colchicine, oryzalin, etc.) as intermediaries to achieve homozygosity. These chemical mediators directly induce chromosomal doubling in haploid embryos, serving as an intermediary mechanism that bypasses the need for repeated mechanical pollination and selection processes.
3Ease of manufacture
If chromosome doubling is performed at later stages, then plant regeneration is easier, but the frequency of doubled haploids obtained decreases
Solution Approach 1:
The patent performs chromosome doubling at an early embryonic stage (4-21 days after pollination) rather than at later developmental stages. This preliminary intervention in the embryo allows for higher frequencies of doubled haploid recovery because the treated embryos can be cultured en masse on regeneration media, whereas later-stage treatment would require individual plant manipulation and yield fewer doubled haploids.
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 increases the efficiency and speed of producing doubled haploid plants, resulting in a high frequency of fertile homozygous plants without residual heterozygosity, suitable for various genetic analyses and breeding applications.
Implementation Method 1
contacting said isolated haploid embryo scutellum side up on an embryo culture medium containing a chromosome doubling agent to produce at least one doubled haploid embryo cell
Data Source
AI summary
Methods for producing doubled haploid corn (Zea mays) plants, seeds and plant cells are provided.