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Jasmonic acid and plant growth: How does it influence root development?
Jasmonic acid and its derivatives, as important hormones for plants, are essential to their growth and development. These lipid-based phytohormones play key roles in regulating multiple physiological processes in plants, including growth, photosynthesis, and reproductive development. Among these processes, jasmonic acid is particularly critical for resistance to herbivores and plant responses to adverse environments. Recent studies have also shown that certain jasmonic acids can be released in the form of volatile organic compounds, promoting communication between plants to indicate impending common dangers.
History and biosynthesis of jasmonic acid
The discovery of jasmonic acid dates back to 1962, when scientists isolated methyl jasmonic acid (MeJA) from jasmine oil. Jasmonic acid itself was isolated from Lasiodiplodia theobromae by Alderidge et al. in 1971. The biosynthetic pathway of jasmonic acid is very complex. It is mainly converted from linoleic acid, first forming 12-oxo-phytodienoic acid (OPDA) in the chloroplast membrane, and then undergoing reduction and oxidation processes to finally form jasmonic acid. In this process, only the conversion to OPDA occurs in the chloroplasts, while subsequent reactions are completed in the peroxisomes.
The synthesis of jasmonic acid not only affects plant growth, but also plays an indispensable role in the plant's immune response.
Function of jasmonic acid and plant defense mechanism
Although jasmonic acid plays multiple roles in many processes in plants, it is best known for its role in the wound response. When plants are mechanically damaged or attacked by herbivores, jasmonic acid biosynthesis is rapidly initiated, followed by the expression of related response genes. In tomatoes, damage promotes the production of defense molecules that inhibit insect leaf feeding.
When a plant is damaged, the signal from jasmonic acid prompts the surrounding plants to prepare for defense, forming a symbiotic defense mechanism.
In addition, jasmonic acid-labeled volatile compounds can be transmitted through the air to nearby plants, further increasing their levels of gene transcription for damage responses. This transfer of energy not only strengthens its own defenses, but also prompts neighboring plants to initiate defense measures to cope with potential herbivory pressure.
The role of jasmonic acid in plant growth
Many studies have shown that jasmonic acid has a significant effect on the root development of plants. Early findings indicated that when JA is overexpressed, root growth is inhibited. Although the exact mechanism of this phenomenon remains unclear, it is known that COI1-dependent signaling pathways are essential in inhibiting root growth.
Interactions and synergistic defense of jasmonic acid
It is noteworthy that there are cross-talks between JA signaling and other defense pathways, such as the fructose (SA) and ethylene (ET) pathways. In many cases, cooperation between these pathways helps plants optimize their defense mechanisms in response to different abiotic and biotic challenges. SA mainly promotes immunity by inducing the expression of pathogen-related genes, but when plants are invaded by insects, the defense response of jasmonic acid is more active.
Studies have shown that the interactions between JA and SA are complex and have a significant impact on plant defense capabilities and resource allocation.
When a plant's JA signal is enhanced, its resistance to pathogens may be improved, while its response to insect herbivory may be relatively weakened. This balance ensures that plants can allocate resources appropriately across different challenges to improve their chances of survival.
Diversity of jasmonic acid in plant development and growth
In addition to its role in defense responses, jasmonic acid is also involved in plant development. For example, in some species, jasmonic acid secretion is linked to key steps such as flower opening, seed germination, and root development. JA can also promote plant symbiosis, especially in the signaling process between legumes and rhizobia.
These research results emphasize the diversity and importance of jasmonic acid in plant physiological processes, reminding us to pay attention to the surrounding ecology while understanding the growth mechanism of plants.
With the advancement of science, our understanding of jasmonic acid is deepening. Not only does it play an important role within the plant, but it also forms a complex network of interrelationships between plants. This raises a question worth pondering: In future agricultural practices, how can we better utilize the properties of jasmonic acid to promote the healthy growth and development of plants?
