Plant Gene Expression Cassettes for Controlled Transgene Excision

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Solution Overview

Problem

Current plant transformation methods rely on introducing polynucleotides into rapidly proliferating embryonic tissues, which is time-consuming and costly, and recombinase systems for transgene excision often result in premature excision.

Innovation Solution

The use of promoter constructs comprising a modified maize rab17 promoter and an attB site for regulated expression of coding sequences, along with the introduction of babyboom (BBM) polynucleotides and polypeptides, allows for the transformation of more mature tissues and minimizes premature excision of transgenes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If transformation methods use rapidly proliferating embryonic tissues, then transformation efficiency is improved, but time and cost increase

Engineering Contradiction:

Improvetransformation efficiencyVSAvoidtransformation time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent changes the target tissue parameter from embryonic to mature tissues, and modifies the promoter parameter to rab17 which is specifically active in mature tissues. This allows transformation of mature tissues while maintaining efficiency, eliminating the need to use embryonic tissues and thereby reducing time and cost.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses the rab17 promoter which is naturally active in mature tissues without requiring prior developmental stages. This preliminary positioning of the promoter system allows direct transformation of mature tissues, avoiding the time-consuming process of generating embryonic tissues first.

Inventive Principle:

Principle #10Preliminary action

2Ease of manufacture

If recombination systems are used for transgene excision, then transgene removal is achieved, but premature excision occurs

Engineering Contradiction:

Improvetransgene excision capabilityVSAvoidpremature excision

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent employs an inducible promoter system (rab17) that dynamically controls recombinase expression. The promoter remains inactive during normal plant development and is only activated when specifically induced, thereby preventing premature excision while maintaining the capability for controlled transgene removal when needed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The inducible promoter system provides feedback control where recombinase expression is tightly regulated and only occurs in response to specific induction signals. This feedback mechanism ensures that transgene excision happens only when intended, eliminating premature excision events that occur with constitutive promoter systems.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS12497628B2Methods and compositions for the introduction and regulated expression of genes in plants

Publication Date: 2025.12.16 CORTEVA AGRISCIENCE LLC

AI summary

Compositions and methods are provided for the introduction and the regulated expression of genes in plants. Compositions include promoter constructs that provide a level of activity useful for the regulated expression of site-specific recombinases, while avoiding premature excision. Further provided are isolated polynucleotides encoding novel babyboom polypeptides, expression cassettes, and plants comprising the same. Methods for the introduction of genes into plants are provided, including methods for plastid transformation and methods for the transformation of tissues from mature seeds and leaves.