This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: An international study investigating why wild tomatoes are more resistant to the tomato leafminer (Phthorimaea absoluta) than cultivated varieties revealed that the secret lies in the spatial structure of a plant defense molecule. The researchers mapped the biochemical origin of this difference and demonstrated that altering four amino acids in a single enzyme is sufficient to alter the structure of the substance and increase its toxicity against the pest.
This finding paves the way for creating resistant tomatoes through gene editing. The research, published in the journal Nature Communications, was coordinated by Jiancai Li, a professor at the Shanghai Institute of Plant Physiology and Ecology and at the University of the Chinese Academy of Sciences in Beijing. José Maurício Simões Bento, a professor at the Luiz de Queiroz College of Agriculture at the University of São Paulo (ESALQ-USP), also participated in the research.
Li's team works on genetics, biochemistry and the biosynthesis of specialized plant metabolites, while Bento's group focuses on chemical ecology and plant-insect interactions. "Integrating these fields was crucial. Once the genetic and biochemical mechanisms responsible for the different molecular forms were identified, it became crucial to grasp the biological ramifications of those differences and evaluate whether a slight alteration in the three-dimensional structure of a molecule could impact a plant's capacity to defend itself against a pest," says Bento.
The study analyzed steroidal glycoalkaloids (SGAs), natural substances produced by certain plants, such as tomatoes, potatoes and eggplants, of the genus Solanum. These substances play a role in the plants' chemical defense against herbivorous insects and pathogens. One of the main SGAs present in the leaves of cultivated tomatoes (Solanum lycopersicum) is α-tomatine.
However, in the leaves of wild tomatoes (Solanum pennellii), filotomatine predominates. Both substances have the same sugar content, but the three-dimensional structure of their molecular cores is different. This is where chirality comes into play.
A molecule is called chiral when its structure cannot be perfectly superimposed onto its mirror image. The classic example is the right and left hands: they have the same parts arranged in a mirror-image fashion, yet no translation or rotation allows one to fit perfectly over the other. Similarly, a chiral molecule can exist in two forms, such as "right" and "left" versions of the same structure.
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