Plant Transformation Without Callus Using WUS/WOX Regeneration
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Solution Overview
Problem
Current methods for plant transformation, particularly in monocots like maize, are time-consuming and inefficient, often requiring weeks to produce transgenic plants due to the need for callus formation and the use of high auxin or cytokinin levels, which limits the speed and efficiency of transgenic plant production.
Innovation Solution
A method involving transformation of plant cells with an expression construct encoding WUS/WOX homeobox polypeptides or AP2-DNA binding domains, allowing regenerable plant structure formation in the absence of exogenous cytokinin, and germinating this structure to produce transgenic plants within days to weeks without callus formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard transformation and regeneration protocols are used involving callus formation and high auxin or cytokinin levels, then transformed resistant callus tissue can be selected, but the process takes 10-12 weeks or more to produce plants
Solution Approach 1:
The invention extracts and eliminates the callus formation step from the traditional transformation protocol. By using Agrobacterium-mediated transformation directly on immature embryos without requiring dedifferentiation into callus, the method removes the time-consuming phase while maintaining transformation efficiency through direct regeneration of whole plants from transformed embryos
Solution Approach 2:
The invention performs preliminary selection of transformed embryos at the embryo stage rather than after callus formation. By selecting transformed resistant embryos directly after Agrobacterium co-culture and before any callus development, the method accelerates the process while ensuring reliable selection of transformed events
2Reliability
If multiple manual transfers and different media types are used throughout the transformation process, then callus can be cultured and regenerated, but the procedure becomes complex and time-consuming
Solution Approach 1:
The invention uses a single type of media for the entire transformation and regeneration process. The same Agrobacterium co-culture medium serves multiple functions: supporting embryo development, enabling Agrobacterium transformation, and facilitating direct regeneration of whole plants without requiring switches to different callus induction or regeneration media
Solution Approach 2:
The invention merges the transformation and regeneration steps into a unified process. By combining Agrobacterium-mediated transformation with direct embryo-to-plant regeneration in a single continuous protocol without intermediate callus formation steps, the method reduces procedural complexity while maintaining regeneration capability
Data Source
AI summary
The disclosure pertains to methods and compositions for the rapid and efficient transformation of plants. The disclosure further provides methods for producing a transgenic plant, comprising (a) transforming a cell of an explant with an expression construct comprising (i) a nucleotide sequence encoding a WUS/WOX homeobox polypeptide; (ii) a nucleotide sequence encoding a polypeptide comprising two AP2-DNA binding domains; or (iii) a combination of (i) and (ii); and (b) allowing expression of the polypeptide of (a) in each transformed cell to form a regenerable plant structure in the absence of exogenous cytokinin, wherein no callus is formed; and (c) germinating the regenerable plant structure to form the transgenic plant. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present disclosure.