Plastid Transformation Efficiency via ACC2 Gene Mutations
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Plastid transformation in recalcitrant plant species, such as Arabidopsis, is inefficient due to low sensitivity to spectinomycin, which hinders the recovery of transplastomic clones.
Innovation Solution
Introducing a method that involves creating ACC2 nuclear gene mutants or using CRISPR/Cas to inactivate the ACC2 gene, thereby increasing sensitivity to spectinomycin and other plastid translation inhibitors, allowing for the selection and regeneration of transplastomic plants by using spectinomycin-resistant markers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plastid transformation is performed in recalcitrant plant species like Arabidopsis using conventional methods, then transformation can be attempted, but transformation efficiency is extremely low due to low sensitivity to spectinomycin
Solution Approach 1:
The invention changes the genetic parameter of the plant by introducing mutations in the ACC2 nuclear gene, which encodes a plastid-targeted homomeric acetyl-CoA carboxylase. This parameter change increases the sensitivity of plastids to spectinomycin, thereby enabling efficient selection of transplastomic clones. The mutation alters the biochemical state of the plastid metabolism, making it susceptible to spectinomycin inhibition while maintaining plant viability through compensation by the nuclear ACC2 enzyme.
2Reliability
If spectinomycin is used for selection in conventional plastid transformation, then selection of transplastomic clones should occur, but recovery of transplastomic clones is hindered due to low sensitivity to spectinomycin in recalcitrant species
Solution Approach 1:
The invention modifies the genetic parameter of the plant system by introducing mutations in the ACC2 nuclear gene, which alters the metabolic state of plastids to increase their sensitivity to spectinomycin. This parameter change enables reliable selection of transplastomic clones, as the mutated plants show enhanced response to spectinomycin treatment, allowing clear differentiation between transformed and non-transformed cells during the selection process.
3Productivity
If ACC2 nuclear gene is inactivated to increase spectinomycin sensitivity, then plastid transformation efficiency improves, but plant metabolism may be affected due to ACC2's role in fatty acid biosynthesis
Solution Approach 1:
The invention uses the nuclear ACC2 enzyme as an intermediary to compensate for the loss of plastid-encoded ACCase activity. The nuclear ACC2 gene produces a homomeric acetyl-CoA carboxylase that is imported into plastids and can partially substitute for the inhibited heteromeric ACCase complex. This intermediary mechanism allows the plant to maintain fatty acid biosynthesis capacity even when plastids are sensitive to spectinomycin, thereby ensuring plant viability while enabling efficient transformation selection.
Solution Approach 2:
The invention introduces specific mutations in the ACC2 nuclear gene that fine-tune the enzyme's properties. These parameter changes in the nuclear gene sequence result in altered enzyme characteristics that enable the nuclear-encoded ACC2 to compensate for spectinomycin inhibition of plastid-encoded ACCase, balancing transformation efficiency with plant metabolic requirements.
Data Source
AI summary
Compositions and methods for improving plastid transformation in difficult to transform plants are disclosed.