| UPSC Relevance GS-3 (Agriculture, Science & Technology, Environment) |
Why in News
Researchers at Zhejiang University (China), in collaboration with scientists from the Netherlands and Switzerland, have discovered a natural plant-to-plant communication system that helps maize crops resist insect attacks. Their study, published in Science (August 2025), highlights how the volatile compound linalool strengthens crop resilience, offering a sustainable alternative to chemical pesticides.
Background
- Maize (Zea mays) is the world’s most widely cultivated grain, central to food security, livestock feed, biofuel, and industrial products.
- Originating from teosinte (a wild grass in Mesoamerica), maize was domesticated over 9,000 years ago and improved by Indigenous farmers.
- Today, maize is grown in large-scale monocultures, making it highly vulnerable to pests, pathogens, and climate change stressors.
- Projections suggest maize productivity could decline by up to 24% by the late 21st century under the high-emissions SSP585 scenario.
The Research Findings
Plant Warning Signals
When maize (corn) plants are attacked by insects, they give out a kind of “warning perfume.” This perfume is actually a chemical called linalool, which has a floral smell.
● Think of linalool like an alarm signal.
● Nearby maize plants “smell” this signal.
● Once they detect it, they prepare their own defence system in advance—almost like neighbours locking their doors after hearing a theft alarm.
The Mechanism (How it Works)
The process works step by step:
1. Insect attack begins → The attacked maize plant releases linalool into the air.
2. Neighbouring plants sense linalool → Their roots activate something called the jasmonate pathway, a defence-related chemical signal.
3. Defensive chemical production → The roots start making HDMBOA-Glc, a substance that fights off attackers. This is released into the soil.
4. Soil microbes join in → These microbes sense the chemical and help trigger another defence signal: salicylic acid in nearby plants.
5. Final outcome → Together, these signals make neighbouring plants stronger and more resistant to many different pests and diseases.
Experimental Proof
Scientists tested this in different ways:
● Fall armyworm (insect) → Larvae grew poorly on maize that had received the “warning signal.”
● Root-knot nematodes (worms that attack roots) → Fewer galls (swellings on roots) were formed.
● Fungal disease (Exserohilum turcicum, causes leaf blight) → Plants showed stronger resistance.
● Viral disease (Rice black-streaked dwarf virus) → The spread of infection was reduced.
👉 This means the “plant warning system” protects against insects, worms, fungi, and viruses — a broad-spectrum defence.
Growth–Defence Trade-Off
But there is a catch.
● In denser maize fields (where plants are close together), the defence signal becomes stronger.
● While this makes the plants safer from pests, it also means they grow slower and produce less biomass (smaller size, lower yield).
So, plants face a choice:
● Spend more energy on defence → safer but smaller crops.
● Spend more energy on growth → bigger yield but weaker defence.
In simple words: Maize plants can “talk” to each other using smell signals. They warn each other of danger, which boosts their immunity. But this teamwork comes at a cost—plants grow less when they spend too much energy defending themselves.
Future Applications of the Research
Breeding Approaches
- Scientists can use reporter genes (like Bx1 and Bx6) as markers to find out which maize varieties respond best to the linalool alarm signal.
- With this knowledge, breeders can select and develop maize strains that are naturally better at “listening” to warning signals.
- Advanced tools such as genomic prediction models can further speed up this breeding process, making it possible to quickly create pest-resistant, climate-smart crops.
Farm Management Strategies
Depending on the environment, farmers can apply this knowledge in two different ways:
1.Low-Pest Zones (safe areas)
- Here, pests are not a big problem.
- Farmers can engineer maize plants to ignore linalool signals so that they don’t waste energy on unnecessary defence.
- Result: higher yields and growth.
2.High-Pest Zones (vulnerable areas)
- In regions where pests are frequent and harmful, farmers can use synthetic linalool sprays.
- This would “warn” all the plants in advance and activate their defence system before the attack begins.
- Result: stronger protection and reduced crop losses.
Implications for Agriculture
- Reduced pesticide use → Farmers will depend less on chemical pesticides, which are costly, harmful to soil health, and dangerous for biodiversity.
- Sustainable and eco-friendly defence → This method uses the plant’s own natural signalling system, making it a self-reliant, biological solution.
- Climate resilience → With unpredictable pest outbreaks due to climate change, this approach provides farmers with an adaptable and reliable tool.
- Balanced productivity and protection → Farmers in dense cropping systems can balance between growth (yield) and resilience (defence) depending on local needs.
In simple terms: This research opens doors to a future where crops can be bred and managed in smarter ways — either to grow faster in safe zones or to defend strongly in risky zones — all while reducing pesticide dependence and adapting to climate challenges.
Challenges Ahead
● Scalability: Need testing across diverse maize varieties and geographies.
● Economic Feasibility: Farmers may hesitate to adopt new systems without cost-benefit clarity.
● Knowledge Gap: Requires farmer awareness and training in eco-friendly pest control.
● Policy Integration: Must align with schemes like National Food Security Mission and National Mission on Sustainable Agriculture (NMSA).
Way Forward
1. Research & Scaling: Test across diverse maize varieties and regions.
2. Policy Push: Integrate plant communication insights into National Food Security Mission and pest management schemes.
3. Farmer Awareness: Promote eco-friendly pest control methods alongside IPM (Integrated Pest Management).
4. Global Cooperation: Share research findings with other maize-producing nations in Africa and Latin America.
Conclusion
The discovery of linalool-driven signalling in maize represents a breakthrough in sustainable agriculture. By tapping into natural plant communication, farmers can reduce chemical dependence, strengthen resilience against climate change, and balance productivity with ecological health. However, its success will depend on scalable research, policy integration, and farmer participation.
In essence, plant-to-plant communication could become a cornerstone of climate-smart, pest-resilient agriculture in the 21st century.
UPSC Prelims practice question
Q1. With reference to linalool, recently in news, consider the following statements:
- It is a naturally occurring volatile compound released by maize plants under insect attack.
- It activates jasmonate signalling in roots, which further enhances defence response.
- It is primarily a synthetic pesticide used in integrated pest management.
Which of the above statements is/are correct?
- (A) 1 only
- (B) 1 and 2 only
- (C) 2 and 3 only
- (D) 1, 2 and 3