CHEMICAL SCIENCE

Researchers take pictures of a variety of plant leaf metabolites


Professor Pan Yang’s team at the National Synchrotron Radiation Laboratory of the University of Science and Technology of China used the self-developed desorption electrospray ionization/secondary ionization (DESI/PI) mass spectrometry imaging platform combined with porous PTFE blot technology to “shoot” the spatial imaging of metabolites in a variety of plant leaves. The research results were published as a cover paper in the journal Analytical Chemistry.

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The research results were published as a cover paper in the journal Analytical Chemistry Courtesy of the University of Science and Technology of China

In known plant populations, the chemical structure of about 200,000 plant metabolites has been identified. Compositional analysis and spatial imaging of plant metabolites are of great significance to explore the biosynthesis, transport, physiological mechanisms, self-regulation mechanisms, and interaction between plants and ecology.

Mass spectrometry imaging is a molecular imaging technique that has emerged in recent years, which has the advantages of fluorescence-free labeling and does not require complex sample preparation. However, due to the presence of plant cuticle and epidermal wax, conventional soft ionization techniques are difficult to penetrate the stratum corneum and act on mesophyll tissue, making it impossible to directly image metabolites in plant leaves.

The research group transferred the plant metabolites in the leaves to the porous PTFE material by the blot method, and imaged the imprinted material, realizing the indirect imaging of the plant metabolites in the leaves. Due to the use of desorption electrospray ionization/secondary photoionization technology, up to 100 new secondary metabolites such as terpenes, flavonoids, amino acids and glycosides can be detected in positive ion mode. In negative ion mode, the overall metabolite signal intensity can be increased by an order of magnitude, which is conducive to obtaining more plant metabolite spatial imaging.

The research group further used this technology to study tea leaves, and found that caffeine was enriched in the leaf midvein, and theanine was enriched in the petiole and extended to the midrib and leaf tail, which provided strong evidence for the synthesis of caffeine mainly in the middle vein of tea and the synthesis of theanine in the root of tea and then transported to the biosynthetic sites and transport pathways of leaves. The experiments also detected important flavonoid metabolites in the biosynthesis network of tea and showed the spatial distribution in the form of mass spectrometry imaging, indicating that blot desorption electrospray ionization/secondary photoionization imaging technology has great potential in exploring plant metabolic transformation sites and pathways.

Dr. Liu Tian Wu of the National Synchrotron Radiation Laboratory is the first author of the paper, and Liu Chengyuan is a special associate researcher and Professor Pan Yang is the co-corresponding author. (Source: Wang Min, China Science Daily)

Related Paper Information:https://doi.org/10.1021/acs.analchem.2c03329



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