A Depth-Controlled Longitudinal Cutting Strategy Enhances MALDI-MSI of Entire Leaves

Matrix-assisted laser desorption/ionization mass spectrometry
imaging
(MALDI-MSI) enables spatial analysis of endogenous metabolites in
plant leaves, contributing to insights into the complex chemical,
spatial, and temporal variations in plant metabolism. Longitudinal
sectioning can offer rich information about tissue heterogeneity and
molecular distribution within flat leaf tissues but is much more challenging.
In this study, we developed a depth-controlled longitudinal cutting
(DCLC) strategy for leaf processing. An in-house device was used to
achieve longitudinal cutting of various leaves, which has an adjustable
cutting range of up to 3 cm. Longitudinal sections as thin as 5 μm
can be prepared, and a thickness of 30 μm was chosen in this
work to balance the tissue integrity and MALDI-MSI performance. For
leaves with a pronounced cuticle, DCLC facilitates exposure of internal
tissues and reduces cuticle-related ion suppression in MALDI-MSI.
By changing the blade-base gap and repeating the cutting procedure,
multiple longitudinal sections can be obtained from a single leaf,
allowing the “middle” part to be further resolved into
multiple consecutive planes in future applications.