Kashmir researchers review how maize can retain a biological memory of drought, identifying calcium chloride seed treatment as a promising, field-tested approach to strengthen crop resilience.
SRINAGAR: A review by researchers from the University of Kashmir and SKUAST-K has identified seed treatment as a promising way to help maize withstand recurring drought, with calcium chloride priming emerging as the approach with the strongest field-based evidence. The research explores how plants can retain a biological memory of earlier water shortages and respond more effectively when drought strikes again.
The review, Epigenetic and Metabolic Regulation of Drought Stress Memory in Maize: From Molecular Mechanisms to Field-Applicable Priming Strategies, examines how maize plants may retain a biological record of previous drought exposure, allowing them to react faster and more efficiently when water becomes scarce again.
The paper was published by Frontiers in Plant Physiology on August 7, 2026. The work was authored by Bushra Quyoom and Latif Ahmad Peer, from the Department of Botany, University of Kashmir, and Ajaz Ahmad Lone and Zahoor Ahmad Dar, from the Dryland Agriculture Research Station, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir (SKUAST-K).
A Biological Memory
The researchers explain that plants, like other living organisms, can retain traces of earlier environmental stress. When a maize plant experiences drought, it undergoes changes in its cells that may persist even after water becomes available again. If drought returns, these changes can help the plant respond more quickly.
The paper calls this phenomenon “drought stress memory”. Its main focus is on memory retained within the same plant during successive drought and recovery cycles. It does not establish that drought tolerance is reliably passed from one generation of maize to the next.
The process involves changes in the way plant genes are regulated, without changing the underlying DNA sequence. This is known as epigenetic regulation. In simple terms, it is a biological system that can switch certain genes into a more responsive state, helping the plant prepare for a future challenge.
Seeds Prepared
One of the most practical approaches discussed in the review is seed priming. It involves partially soaking seeds before planting so that early biological processes begin, then drying them under controlled conditions. The treatment is intended to prepare the seeds to germinate and establish themselves more effectively when they encounter difficult growing conditions.
The authors examine several approaches, including hydropriming, in which seeds are soaked in water; osmopriming, which uses solutions such as calcium chloride and polyethylene glycol; and treatments involving melatonin, salicylic acid, chitosan and nanoparticles.
Among these, calcium chloride osmopriming has the strongest field-based evidence in the literature reviewed. Previous field studies cited in the paper reported improvements in root development, grain yield and economic returns under drought conditions.
The authors distinguish this from some other promising approaches. Melatonin, for instance, has shown encouraging results in controlled experiments, but requires further field validation. Simple water soaking can improve germination and early seedling growth, although its benefits for grain yield under severe drought appear more limited.
Cellular Defences
The review also explains how maize plants protect themselves against water shortage through changes in their metabolism.
One important substance is proline, an amino acid that helps plant cells maintain their water balance and limit damage during drought. The review describes how proline accumulation is associated with drought responses, although it cautions that higher proline levels alone do not necessarily prove that a plant is drought-resistant.
Plants also adjust how they use and distribute carbon and nitrogen while attempting to maintain photosynthesis, the process through which leaves use sunlight to convert carbon dioxide and water into sugars.
These adjustments help plants maintain growth and cellular functions when water is limited. The researchers argue that the interaction between these metabolic changes and the regulation of genes is central to the development of drought memory.
Genome Clues
A particularly interesting feature of maize is that approximately 85 per cent of its nuclear DNA consists of transposable elements, stretches of DNA that can move or change their position within the genome.
Once regarded largely as genetic material without a useful function, these elements can influence how nearby genes behave. The review discusses evidence that some of them help regulate genes involved in responses to environmental stress.
The authors also examine DNA methylation and histone modifications. These are chemical changes that influence how tightly DNA is packaged and whether particular genes are more or less active. Such changes may help preserve a plant’s readiness to respond to another drought episode.
In effect, the plant’s previous experience of water shortage may leave behind molecular signals that influence its response when the stress returns.
Research Gaps
Despite the promise of these findings, the authors identify several gaps before drought-memory research can be translated into reliable agricultural practices.
They point out that researchers still lack sufficient direct measurements of key enzymes involved in proline production in primed maize. The role of phosphorylation, a chemical process that can switch enzyme activity on or off, in regulating an important photosynthetic enzyme, phosphoenolpyruvate carboxylase, also remains poorly understood under drought-priming conditions.
The review further stresses that many chemical and hormonal seed treatments have not undergone sufficiently extensive field trials across different environments. More research is also needed to establish whether observed epigenetic changes actually cause drought tolerance, rather than merely occurring alongside it.
The authors recommend combining laboratory analysis with multi-location field trials over several growing seasons before these techniques are adopted more widely.
Practical Promise
In its conclusion, the review identifies seed priming as the most immediately applicable approach for using drought stress memory to improve maize resilience. Calcium chloride treatment, in particular, has the strongest supporting evidence from field studies.
The researchers say that understanding how plants retain and use memories of earlier stress could eventually help breeders develop more resilient maize varieties and enable farmers to adopt better seed-treatment and crop-management practices as climate conditions become increasingly unpredictable.
