Plants lack a nervous system yet mount coordinated whole-body defence responses. Discuss the signalling mechanisms involved and their relevance for sustainable crop protection in India.

Plants cannot flee and have no nerves. Yet an insect bite on one leaf warns distant, undamaged leaves within minutes [1]. A 2026 study by NIPGR, New Delhi found a new calcium channel, CNGC13. It shows that this alarm passes through several layers of signals. That knowledge could help India rely less on chemical pesticides.

Signalling mechanisms

• Local response: at the wound, calcium, reactive oxygen species (ROS) and the hormone jasmonic acid switch on defence genes and strengthen cell walls [1].
• Long-distance waves: hydraulic, electrical, calcium and ROS signals carry the alert to other leaves. "Electrical" here means the movement of charged particles (ions), not nerve impulses [1].
• Channel gateways: scientists long credited glutamate receptor-like channels (GLRs) with passing on the alarm. CNGC13 sits mainly in the xylem and phloem. It lets calcium (Ca²⁺) into cells as the signal passes, and it works alongside GLRs, not in place of them [1].
• Systemic outcome: warned leaves raise their levels of glucosinolates, defence chemicals that deter insects, before the insects reach them [1].

Insect bite → Ca²⁺, ROS, jasmonic acid at wound
   ↓  hydraulic + electrical + Ca²⁺/ROS waves through xylem–phloem (GLRs + CNGC13)
Distant leaves → defence genes switched on → more glucosinolates

Fig: The whole-plant alarm relay

Relevance for sustainable crop protection in India

• Scale of need: pests cause avoidable losses of about 10–30% of India's total crop production [2].
• Defence-triggering chemicals: the researchers say the finding may help design chemicals that let plants fight off pests themselves [1]. This could reduce broad-spectrum spraying, pesticide residues and harm to pollinators.
• Fits IPM: fields under Integrated Pest Management (IPM) used 50–100% less pesticide in rice and 30–50% less in cotton. Farmers spray only when pests cross the economic threshold level [3]. Defences triggered inside the plant would add one more tool to IPM.
• Oilseeds: glucosinolates are typical of the mustard family (Brassicas), so mustard is a logical first crop to test.

Caveats

• The work was done on laboratory plants. It still has to be tested in Indian crops in the field.
• Growth–defence trade-off: if the alarm stays switched on, the plant may put energy into defence instead of yield.
• Any new product would need registration under the Insecticides Act, 1968.

Plants therefore coordinate their defence through a combined chemical and electrical network, with GLRs and CNGC13 acting as gateways. ICAR field trials should measure yield as well as pest damage, and any product should be used within IPM. This can turn the science into tools farmers can use, support SDG 2 (Zero Hunger) and SDG 12 (Responsible Consumption and Production), and reduce India's dependence on chemical pesticides.