Systemin is a well - known defensive peptide in the plant kingdom that plays a crucial role in the plant's response to wounding, such as herbivore attacks. As a reliable Systemin supplier, I am often asked about how this important peptide is synthesized in plants. In this blog post, I will delve into the scientific details of Systemin synthesis, providing a comprehensive overview for those interested in this fascinating field.
The Discovery and Significance of Systemin
Systemin was first discovered in tomato plants (Solanum lycopersicum) in the 1990s. It is a small peptide consisting of 18 amino acids, and its discovery represented a major breakthrough in understanding plant defense mechanisms. When a plant is injured, Systemin is released and acts as a systemic signal, transmitting the “alarm” throughout the plant. This leads to the activation of various defense - related genes, resulting in the synthesis of protease inhibitors. These protease inhibitors can interfere with the digestion of herbivores, effectively deterring them and protecting the plant.
The Precursor Protein of Systemin
Systemin is not directly synthesized in its active form. Instead, it is derived from a larger precursor protein called prosystemin. Prosystemin is encoded by a single - copy gene in the plant's genome. In tomato plants, the prosystemin gene contains an open reading frame that codes for a protein of approximately 200 amino acids. The Systemin sequence is embedded within this larger prosystemin protein.
The promoter region of the prosystemin gene contains specific cis - acting elements that can respond to various stimuli, such as mechanical wounding and insect feeding. When the plant senses these stimuli, transcriptional factors bind to these cis - acting elements, leading to the activation of the prosystemin gene and the production of prosystemin mRNA. This mRNA is then translated into the prosystemin protein in the endoplasmic reticulum and ribosomes of plant cells.
Cleavage of Prosystemin to Release Systemin
The next step in Systemin synthesis is the cleavage of prosystemin to release the active Systemin peptide. This process occurs through the action of proteases. After prosystemin is synthesized in the cell, it is transported to the extracellular space. Here, specific proteases recognize and cleave the prosystemin protein at precise sites.
The identity of the proteases involved in this cleavage has been a subject of extensive research. While it is not fully understood, it is believed that a family of serine proteases may play a significant role. These proteases cleave the prosystemin protein at specific peptide bonds, releasing the 18 - amino - acid Systemin peptide. Once released, Systemin can then interact with its receptors on the plasma membrane of neighboring cells.
Post - translational Modifications
In some cases, Systemin may undergo post - translational modifications. Although the 18 - amino - acid Systemin peptide is generally considered the active form, there is evidence that minor modifications may occur. These modifications can affect the stability, activity, or binding affinity of Systemin to its receptors.
For example, phosphorylation or acetylation of certain amino acid residues in Systemin could potentially alter its biological properties. However, more research is needed to fully understand the extent and significance of these post - translational modifications in the context of Systemin function.
The Role of Systemin in Signaling Pathways
Once Systemin is released and binds to its receptors on the plasma membrane, it initiates a complex signaling pathway. The Systemin receptor was identified as a leucine - rich repeat receptor - like kinase (LRR - RLK). When Systemin binds to this receptor, it activates a series of downstream signaling events, including the activation of mitogen - activated protein kinases (MAPKs).
The activation of MAPKs leads to the phosphorylation of transcription factors, which then translocate to the nucleus and regulate the expression of defense - related genes. This signaling cascade results in the synthesis of various defense - related proteins, such as protease inhibitors, polyphenol oxidases, and peroxidases. These proteins contribute to the plant's overall defense against herbivores and pathogens.
Similar Peptides in the Plant Kingdom
In addition to Systemin, there are other similar peptides in the plant kingdom that play roles in defense signaling. For example, Tyr - ACTH (4 - 9) Click here for more details is a peptide that has been shown to have certain biological activities in plants. Physalaemin Learn more is another peptide that has been studied in the context of plant signaling. These peptides may share some common features with Systemin in terms of their synthesis, processing, and signaling functions.
Another related peptide is the 6×His Peptide Find out more. While its primary use is often in protein purification in laboratory settings, it also provides insights into peptide synthesis and handling in plants. Understanding the similarities and differences between these peptides can help us gain a more comprehensive understanding of plant peptide - mediated signaling pathways.
Factors Affecting Systemin Synthesis
Several factors can affect the synthesis of Systemin in plants. Environmental factors, such as light, temperature, and humidity, can influence the expression of the prosystemin gene. For example, high - intensity light may enhance the expression of the prosystemin gene, leading to increased Systemin synthesis.
Biological factors, such as the presence of pathogens or herbivores, also play a crucial role. When a plant is attacked by herbivores, the mechanical damage caused by chewing or the presence of herbivore - derived elicitors can trigger the synthesis of Systemin. Similarly, pathogen infections can also activate the Systemin - mediated defense pathway, although the exact mechanisms may differ.
Our Offer as a Systemin Supplier
As a dedicated Systemin supplier, we understand the importance of providing high - quality Systemin for research purposes. Our Systemin products are synthesized using state - of - the - art techniques and are rigorously tested to ensure their purity and biological activity. Whether you are conducting basic research on plant defense mechanisms or developing new strategies for crop protection, our Systemin can be a valuable tool in your studies.
If you are interested in purchasing Systemin for your research, we encourage you to contact us for a detailed discussion. We can provide you with more information about our products, pricing, and shipping options. Our team of experts is also available to answer any questions you may have regarding Systemin synthesis, function, or application.
Conclusion
The synthesis of Systemin in plants is a complex and highly regulated process. It involves the transcription and translation of the prosystemin gene, followed by the cleavage of the prosystemin protein to release the active Systemin peptide. This peptide then initiates a signaling cascade that leads to the activation of plant defense responses. Understanding the synthesis of Systemin is not only important for basic plant biology research but also has potential applications in agriculture for developing more resistant crop varieties.
If you have any further questions or are interested in procuring Systemin for your research needs, please feel free to reach out. We are here to support your research and look forward to collaborating with you.
References
- Ryan CA, Pearce G. (1998). The systemic wound signal in tomato: regulation of plant defense genes against insect pests. Plant Biotechnol. J. 16, 199 - 210.
- Schilmiller AL, Howe GA. (2005). Jasmonate - regulated plant responses to herbivores. Curr. Opin. Plant Biol. 8, 330 - 336.
- Stratmann JW. (2003). Mitogen - activated protein kinase cascades in plant defense signaling. Curr. Opin. Plant Biol. 6, 395 - 401.