New study sheds more light on plant growth-regulating compounds

Scientists at ICBA and their partners at Korea’s Yeungnam University have recently shed some light on how certain organic compounds can govern plant growth and a plant’s tolerance to different stresses. A paper recently published in Journal of Plant Growth Regulation presents a comprehensive review of polyamines, which are poorly understood organic compounds that can regulate plant growth and contribute to a plant’s defenses.

Scientists have known about polyamines (PAs) since the Dutch microbiologist Antonie van Leeuwenhoek first documented them in 1667. But four centuries later, they still do not know exactly their role in plant growth. “There are very few studies on the role of polyamines in plants,” said Dr. Henda Mahmoudi, a plant physiologist at ICBA and co-author of the paper. “We know that the formation of polyamines in plants is highly regulated, but we’re still unclear about the biological function of polyamines.”

The study provides a comprehensive review of the distribution, biosynthesis, and function of PAs in plants. It emphasizes their involvement in improving growth and abiotic stress tolerance.

Plants experience continuously changing environmental conditions and various stresses throughout their life cycle. These environmental stresses reduce crop growth and development, which translates to lower yields.

Plants have various genes that can synthesize biological molecules which can help them combat these environmental stresses. One type of biological molecule, the polyamines, is a kind of growth regulator in plants.

Polyamines play various roles in the physiological processes of plants including their growth and development, abiotic stress response, defense response, and aging.

Take, for example, salinity. Salt stress is the second most significant abiotic factor affecting agricultural productivity globally. Salt stress affects the integrity of membranes in the plant and reduces the efficiency of photosynthesis and enzymes. “PAs play a key role in mitigating salinity stress by activating biochemical, physiological, and molecular defense systems,” said Dr. Henda Mahmoudi. “Researchers have shown that applying a PA known as putrescine can improve the plant’s defenses against salinity.”

In some cases, PAs may be too effective at combatting stresses. Greater tolerance to stress doesn’t always equate to higher yields. “PAs can respond to stress by altering various features to allow the plant to survive,” said Dr. Henda Mahmoudi. “For example, PAs may trigger the plant to close its pores for prolonged periods to reduce drought stress but this in turn can limit the crop’s ability to photosynthesize and that leads to lower yields.”

It's been four centuries since Antonie van Leeuwenhoek first wrote about the role of polyamines and it will take more time for scientists to fully understand how they can use PAs to increase crop yields and ensure food security while our climate is changing.