Zeatin is a naturally occurring plant hormone, belonging to a class of compounds known as cytokinins. It was first identified in immature corn kernels, from the genus Zea, which is how it received its name. Zeatin is a derivative of adenine, a building block of DNA, and is a potent growth regulator for plants.
Zeatin’s Role in Plant Development
Zeatin influences plant growth by promoting cell division and differentiation. It stimulates cyclin-dependent kinases (CDKs), which regulate the cell cycle, driving cellular proliferation and new tissue development.
It also balances root and shoot growth. Zeatin promotes lateral bud growth and stimulates cell division in the shoot apical meristem, leading to bushier plants. While promoting root growth through cell division, it can inhibit root elongation by reducing cell elongation.
Zeatin delays senescence. By maintaining cellular activity, it prolongs the lifespan of leaves and overall plant vigor. Plants primarily synthesize zeatin in their roots, and it is then transported to other parts of the plant, often through the xylem.
Agricultural Uses of Zeatin
Zeatin is used in agriculture to improve crop productivity and quality. Its ability to promote cell division and delay aging increases crop yields. For instance, trials in India have shown a 12–18% yield increase in zeatin-treated rice varieties under drought conditions.
Zeatin is also applied in plant tissue culture to promote adventitious shoot growth and prevent excessive root formation. It is often used in combination with other growth regulators, such as auxins, to initiate callus formation and promote fruit set. For example, a combination of zeatin, gibberellic acid (GA3), and naphthaleneacetic acid (NAA) sprayed on fruit can improve fruit development.
It also enhances the shelf life of produce by retarding yellowing in vegetables, such as with a 20 ppm spray. It can also improve plant resistance to stressors like heatwaves; studies show treated soybean crops maintained 85% productivity during heatwaves, compared to 62% in untreated fields. Its natural origin aligns with the growing demand for organic farming practices.
Potential Human Applications
Beyond its established roles in plants, zeatin has been investigated for potential human health applications, particularly its anti-aging properties in skin. Research suggests zeatin can exhibit gerontomodulatory effects on human adult skin fibroblasts, cells responsible for producing collagen and elastin. Studies have shown that zeatin can help prevent cell enlargement and reduce intracellular debris, markers of cellular aging.
Zeatin’s potential anti-aging mechanism involves acting as an antioxidant, neutralizing free radicals that contribute to skin aging. It has been shown to be more effective than vitamin C in scavenging reactive oxygen species. Some studies indicate zeatin can stimulate fibroblast activity, potentially reducing wrinkles, improving skin texture, and increasing hyaluronic acid production for skin hydration. However, these are areas of ongoing research, and its primary established uses remain within plant biology and agriculture.