CTV-Based Transient Expression Vector for Citrus Trees
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Solution Overview
Problem
Current virus-based transient-expression vectors are not suitable for tree crops due to their instability and slow systemic infection, which limits their effectiveness in expressing genes in woody plants like citrus trees, where breeding and improvement processes are lengthy and require more stable and efficient gene expression tools.
Innovation Solution
Development of a Citrus tristeza virus (CTV)-based transient-expression vector system that includes specific sgRNA control elements and gene positioning strategies to achieve stable expression of foreign genes in citrus trees, enabling systemic infection and prolonged expression of beneficial proteins, with some constructs remaining stable for up to five years.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If existing virus-based vectors are used to infect trees, then gene expression can be achieved, but the time required for systemic infection and analysis exceeds the stability of known virus-based vectors
Solution Approach 1:
The patent modifies the viral vector parameters by using Citrus tristeza virus (CTV) instead of traditional herbaceous plant viruses, and by optimizing the ratio of viral to total RNA to at least 1:4, thereby changing the fundamental parameters of the vector system to achieve both rapid infection and long-term stability in tree crops
Solution Approach 2:
The patent creates a dynamic balance between viral replication speed and vector stability by controlling the viral RNA proportion and using CTV's natural properties, allowing the system to adapt to the slow growth characteristics of trees while maintaining vector integrity for extended periods
2Reliability
If virus-based vectors are designed for rapid gene expression, then expression levels are sufficient, but the vectors are not stable long enough to be useful in tree crops
Solution Approach 1:
The patent changes the expression parameter by controlling the viral RNA to total RNA ratio to be at least 1:4, ensuring sufficient gene expression while extending vector stability. This parameter optimization allows the vector to maintain both high expression levels and long-term stability in tree crops
Solution Approach 2:
The patent achieves continuous useful action by designing the CTV-based vector to maintain stable gene expression over extended periods (at least 2 months) in tree crops, allowing continuous analysis and study without vector degradation or loss of functionality
3Duration of action of stationary object
If traditional virus vectors are used in herbaceous plants, then vector stability is maintained, but the system cannot be effectively applied to tree crops with lengthy breeding processes
Solution Approach 1:
The patent achieves universality by developing a CTV-based vector system that can be applied to multiple tree crop species (citrus, mango, avocado, etc.), extending the utility beyond herbaceous plants. The vector maintains stability and functionality across different tree species, making it a versatile tool for tree crop research and breeding
Solution Approach 2:
The patent modifies the vector system parameters by selecting CTV as the viral basis and optimizing RNA ratios, thereby adapting the vector for use in tree crops with different biological characteristics from herbaceous plants, enabling effective application across diverse tree species
Data Source
AI summary
Disclosed herein are viral vectors suitable for transfection into woody trees for purposes of delivering and expressing beneficial genes with increased stability. Specifically exemplified herein are vectors for transfecting citrus trees. The vectors allow for the expression of useful proteins, such as those that can protect the tree from disease.