Researchers at the Max Planck Institute for Chemical Ecology have identified GAME15 as a key protein that regulates the biosynthesis of steroidal glycoalkaloids and steroidal saponins in plants of the genus Solanum. The protein is essential for the formation of these natural products from a cholesterol precursor. Black nightshade plants that were no longer able to produce the protein and thus the steroidal saponins were more susceptible to insects. This discovery could lead to the production of high-quality steroidal molecules for medical applications and support targeted strategies for controlling agricultural pests. The study published in Science sheds light on the biosynthetic pathway of specific steroidal compounds in nightshade plants and the enzymes involved in their production.
The research group led by Prashant Sonawane investigated the missing component in the biosynthetic pathway of steroidal compounds in Solanum plants. Through a series of experiments, they identified the gene responsible for a protein called GAME15, which interacts with enzymes responsible for the hydroxylation of cholesterol, leading to the formation of steroidal glycoalkaloids and saponins. Knocking out the GAME15 gene in Solanum nigrum plants resulted in the plants no longer being able to produce these important compounds. This discovery has potential implications for the production of high-value steroidal molecules with medical applications.
Steroidal saponins and steroidal glycoalkaloids have shown promising medicinal properties, such as anti-cancer, antimicrobial, and anti-inflammatory activities. By identifying GAME15, the researchers were able to reconstitute the biosynthetic pathway for steroidal compounds in other plants, such as Nicotiana benthamiana. This process, referred to as pharming, involves the production of drugs cost-effectively and on a large scale using genetically modified plants. The study opens up possibilities for improved production of important steroid-based compounds with potential medical applications.
The ecological role of saponins in plant defense against herbivores was explored in the study. Steroidal glycoalkaloids are already known as important plant defense substances, but the role of steroidal saponins in Solanum nigrum leaves was previously unknown. Ecological experiments showed that plants lacking the ability to produce saponins were more susceptible to insect herbivores compared to wild-type plants. This finding provides evidence for the role of steroidal saponins in plant defense and highlights the importance of these compounds in protecting different plant tissues from herbivores and pathogens.
The discovery of GAME15 as a crucial player in the biosynthesis of steroidal molecules in Solanum plants opens up new opportunities for engineering crops with enhanced resistance to pests and pathogens. By understanding the role of this protein in the production of important steroidal compounds, researchers can develop targeted strategies for pest control and improve the production of medicinal compounds. The study sheds light on the complex biosynthetic pathways involved in the production of steroidal glycoalkaloids and saponins and provides insights into the ecological role of these compounds in plant defense mechanisms against herbivores.