An optodigital system for visualizing the leaf epidermal surface using embedded speckle SIM: A 3D non-destructive approach

Intricate characterisation of the leaf epidermal surface is of utmost importance in agricultural crop management. The epidermal surface serves as a plant's outermost interface with the environment and is responsible for several physiological functions such as, balancing plant metabolism, regulating photosynthesis rate, and controlling plant-pathogen interactions. Existing microscopic techniques for large-scale, high-resolution characterisation of epidermal surfaces are in general destructive and time consuming, allowing only a single time point to be measured per sample. Here, the first time use of embedded speckle structured illumination microscope (ES-SIM) for the non-destructive characterisation of plant epidermal surface is reported. The developed optodigital system and analysis algorithm can enable automated characterisation of epidermal surface at multiple time points. The effectiveness of the proposed method for accurate detection of necrosis through 3D surface profiling of the leaf epidermis of a traditional medicinal plant, Piper sarmentosum, is demonstrated. ES-SIM provided 2.2 times better sensitivity for necrosis detection in comparison to conventional microscopy.