Which GM variety of rice has enhanced beta-carotene and iron?

January 11, 2026 •

4 min read

Over two billion people worldwide suffer from micronutrient deficiencies, a condition known as 'hidden hunger'. Addressing this global health challenge, researchers have developed specific GM varieties of rice, such as Golden Rice, that have been enhanced with critical nutrients like beta-carotene and, in some variants, iron.

Quick Summary

Golden Rice is a biofortified GM rice variety genetically engineered to produce beta-carotene. Later advancements combined enhanced beta-carotene with improved iron storage using specific genes.

Key Points

Golden Rice 2 is the most recognized GM variety: This version utilizes genes from maize and bacteria to produce high levels of beta-carotene in its endosperm, serving as a provitamin A source.
Enhanced iron is a separate biofortification effort: Researchers have developed GM rice varieties with increased iron content by inserting the soybean ferritin gene for improved storage and bioavailability.
Multi-nutrient varieties combine traits: Advanced research has successfully combined both the beta-carotene pathway and iron-enhancing genes into a single rice variety to address multiple micronutrient deficiencies simultaneously.
Bioavailability improvements are key: To ensure the body can absorb the enhanced nutrients, additional genetic modifications, such as adding phytase genes, are sometimes included to reduce nutrient-blocking compounds.
Regulatory challenges delay distribution: Despite promising results, commercialization and widespread distribution of these biofortified crops, including Golden Rice, have been significantly delayed by regulatory hurdles and public debate.

The Development of Golden Rice for Beta-Carotene

Golden Rice is the most recognized GM variety of rice developed for enhanced nutrient content. Its story began as a humanitarian project to address Vitamin A Deficiency (VAD) in developing nations where rice is a dietary staple. Ordinary white rice does not contain beta-carotene, the precursor to Vitamin A. The rice plant has the metabolic pathway for beta-carotene synthesis but it is inactive in the endosperm, the edible part of the grain.

To activate this pathway, genetic engineers inserted foreign genes into the rice genome. The initial version, Golden Rice 1, was developed by Ingo Potrykus and Peter Beyer and published in 2000. This variety contained two transgenes: a phytoene synthase (psy) gene from the daffodil plant and a carotene desaturase (crtI) gene from the bacterium Erwinia uredovora. However, the beta-carotene levels in the first generation were relatively low.

Subsequent research by a team at Syngenta led to the development of Golden Rice 2 in 2005. This improved version replaced the daffodil psy gene with one from maize (Zea mays), which resulted in a significant boost in beta-carotene production—up to 23 times higher than the original Golden Rice. This deep golden-yellow color signals the presence of high beta-carotene levels in the grain's endosperm.

How Enhanced Iron is Added to GM Rice

Alongside the development of Golden Rice, parallel research has focused on biofortifying rice with enhanced iron content to combat Iron Deficiency Anemia (IDA), another widespread nutritional problem. Researchers have employed several strategies to increase iron levels and improve its bioavailability within the rice grain:

Increasing Iron Storage with Ferritin: The primary method involves introducing and overexpressing a ferritin gene, typically from a legume like soybean (Phaseolus vulgaris). Ferritin is a protein that can store thousands of iron atoms in a non-toxic form. Placing this gene under the control of an endosperm-specific promoter ensures the ferritin is produced where it is needed most—in the edible grain. This approach has been shown to increase iron content several-fold compared to conventional rice.
Enhancing Iron Uptake and Transport: Other methods involve manipulating genes related to iron uptake from the soil and transport within the plant. Overexpression of nicotianamine synthase (NAS) genes, for example, can lead to increased iron chelation and translocation to the grain.
Improving Bioavailability: A major challenge with plant-based iron is its poor absorption by the human body due to inhibiting compounds like phytic acid. To counteract this, researchers have engineered rice to produce phytase, an enzyme that breaks down phytic acid, thereby releasing the chelated minerals and increasing their bioavailability. Combining the ferritin gene with phytase and other proteins rich in cysteine (an enhancer of iron absorption) has yielded highly effective results.

Creating a Single Rice Variety with Both Enhanced Nutrients

While Golden Rice was initially developed for beta-carotene and other GM rice variants for iron, research has successfully combined multiple nutritional improvements into a single rice variety. Scientists at institutions like ETH Zurich, in collaboration with the International Rice Research Institute (IRRI) and other partners, have developed multi-nutrient rice variants. This was achieved by inserting a gene cassette containing genes for beta-carotene, iron (ferritin), and zinc into a single genetic locus. This allows for the simultaneous enhancement of multiple essential micronutrients within the same plant, a strategy that is particularly effective for addressing 'hidden hunger' in regions where diets are often lacking in multiple nutrients.

The Science Behind Nutrient Enhancement

The genetic engineering process for these biofortified crops relies on a thorough understanding of plant metabolic pathways. For beta-carotene, the two new genes complete the biochemical pathway within the rice endosperm. For iron, researchers must consider not only storage but also the transport of iron from the roots to the grains and its ultimate bioavailability in humans. This often means introducing multiple genes to manage different stages of the nutrient's journey through the plant and digestion. Combining these complex pathways into a single, stable genetic insertion is a significant scientific achievement.

Comparative Analysis: Biofortified vs. Conventional Rice


Feature	Conventional White Rice	Golden Rice 2	Multi-Nutrient GM Rice	Notes
Appearance	White	Golden-yellow	Golden-yellow	The color indicates beta-carotene content.
Beta-Carotene	Absent	Up to 37 μg/g	Present (variable, also contains zinc)	Beta-carotene provides provitamin A.
Iron Content	Low (around 4 ppm)	Not typically enhanced for iron	Significantly increased	Multi-nutrient variants specifically target iron.
Iron Bioavailability	Low (due to phytate)	Not typically enhanced	Improved (e.g., via added phytase)	Additional genes improve absorption in the gut.
Development Goal	Standard yield	Combat VAD	Combat VAD and IDA/zinc deficiency	Addresses multiple deficiencies for better health outcomes.
Regulatory Status	Widespread	Limited approvals, humanitarian focus	Research or limited trials	Faces significant public debate and regulatory hurdles.

Regulatory Status and Future Outlook

The development of GM biofortified rice has been a long and complex journey, with approvals moving slowly due to regulatory hurdles and public opposition, particularly from anti-GMO groups. However, significant progress has been made. The Philippines was the first country to approve the commercial propagation of Golden Rice (variety GR2E) for food, feed, and processing in 2021. Despite facing setbacks, such as a temporary cease-and-desist order in the Philippines, the development and regulatory evaluation of these nutritious crops continues. Research and development efforts are supported by organizations like the Golden Rice Humanitarian Board and the IRRI, focusing on adapting these varieties to local rice strains and climates to better serve vulnerable populations.

Conclusion

Addressing the question, Which GM variety of rice has enhanced beta-carotene and iron?, the answer is more complex than a single variety name. While Golden Rice 2 is the most prominent GM variety enhanced with beta-carotene, research has progressed to develop multi-nutrient varieties that combine enhanced beta-carotene with significant increases in iron content. These advancements in biofortification technology represent a promising, sustainable strategy for tackling 'hidden hunger' and improving the health of millions who rely on rice as a primary food source.

Learn more about the project at the official Golden Rice Project website.

Frequently Asked Questions

Golden Rice is a genetically modified rice variety that has been engineered to produce beta-carotene, which the human body converts into Vitamin A. It gets its name from the distinctive golden-yellow color of its grains.

Iron is enhanced in GM rice varieties primarily by incorporating a gene that produces ferritin, a protein that effectively stores large amounts of iron. The gene most often used for this purpose is sourced from the soybean plant.

Yes, research has demonstrated the feasibility of developing a single GM rice variety with both enhanced beta-carotene and increased iron content. This is achieved by combining the necessary genes into a single genetic modification.

Yes, clinical trials have confirmed that beta-carotene from Golden Rice is effectively converted into Vitamin A in the human body. Studies have shown it to be as effective as pure beta-carotene in oil.

Simply increasing iron content isn't enough because rice contains phytates that can block the mineral's absorption. Increasing bioavailability ensures the added iron is effectively absorbed by the human body during digestion.

The regulatory status varies by country and is subject to complex processes and ongoing debate. The Philippines has approved Golden Rice for commercial propagation, while other nations have faced delays and opposition.

Golden Rice is considered a sustainable, food-based approach to address malnutrition, especially for populations dependent on rice. It complements other interventions like supplementation programs and diversification of diet.