Tomato 7-DR2 Enzyme Editing for Provitamin D3 Accumulation
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Solution Overview
Problem
Vitamin D insufficiency is a widespread public health issue due to inadequate dietary availability and reduced UV-B penetrance in skin, particularly in elderly individuals and vegans, leading to increased risks of various health problems, including cancer and immune function deficiencies.
Innovation Solution
Genome editing techniques, such as CRISPR, are used to reduce the activity of 7-dehydrocholesterol reductase (7-DR) in tomato plants, increasing the accumulation of provitamin D3, which can then be converted to vitamin D3 through UV-B exposure, enhancing the biofortification of food sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If 7-DR enzyme activity is reduced to accumulate provitamin D3, then vitamin D3 levels in plants increase, but cholesterol biosynthesis may be affected
Solution Approach 1:
The patent applies segmentation by targeting a specific isoform of 7-DR (7-DR2) that is responsible for converting provitamin D3 to cholesterol, while leaving other 7-DR isoforms (7-DR1, 7-DR3) intact. This selective approach allows accumulation of provitamin D3 without completely disrupting cholesterol biosynthesis, as alternative pathways remain functional. The segmentation of enzyme specificity enables differential control of metabolic flux through the sterol pathway.
Solution Approach 2:
The patent employs local quality by using tissue-specific or stage-specific expression patterns of 7-DR2 to achieve provitamin D3 accumulation in specific plant organs (such as leaves or fruits) while maintaining normal cholesterol metabolism in other tissues. This spatial differentiation allows localized biofortification without systemic disruption of essential sterol biosynthesis.
2Quantity of substance
If genome editing is used to reduce 7-DR activity, then vitamin D3 production increases, but plant growth and development may be impacted
Solution Approach 1:
The patent applies partial action by using moderate reduction of 7-DR2 activity (rather than complete knockout) to achieve sufficient provitamin D3 accumulation while avoiding complete blockage of the pathway. This partial inhibition allows enough cholesterol biosynthesis to maintain normal plant growth and development, while still achieving biofortification goals. The balanced approach prevents physiological stress that would result from complete pathway disruption.
3Quantity of substance
If UV-B exposure is applied to convert provitamin D3 to vitamin D3, then vitamin D3 levels increase, but skin cancer risk increases in humans
Solution Approach 1:
The patent applies preliminary action by accumulating high levels of provitamin D3 (7-dehydrocholesterol) in the plant tissue before harvest, so that when consumers ingest the plant material, the provitamin D3 is already present in biofortified amounts. The conversion to vitamin D3 can then occur through mild UV exposure during processing or storage, or through endogenous conversion in the human body, avoiding the need for intense UV-B exposure that would increase skin cancer risk.
Solution Approach 2:
The patent uses the plant matrix as an intermediary vehicle to deliver provitamin D3 to humans. Instead of directly exposing human skin to UV-B radiation for vitamin D synthesis, the provitamin D3 is embedded in edible plant tissue that serves as a safe delivery system. The conversion to active vitamin D3 occurs through controlled, low-dose UV exposure during food processing or through metabolic conversion in the human body, eliminating the harmful effects of high-dose UV exposure.
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 significantly increases the levels of vitamin D3 in tomato plants, potentially addressing vitamin D deficiencies and providing a sustainable, vegan-friendly source for dietary supplementation, while also reducing cholesterol levels.
Implementation Method 1
the 7-DR2 enzyme converts provitamin D3/7-DHC to cholesterol for the synthesis of tomatine
Implementation Method 2
UV-B exposure of leaves of tomato produces vitamin D3
Data Source
AI summary
Methods for increasing levels of provitamin D3 and/or vitamin D3 in plants are described. Tomato plants were genetical modified resulting in decreased activity of 7-dehydrocholesterol reductase.