Plant cuticle is an important interface on the outmost region of plant and will make the response to environmental changes. However, research about how the variable nutritional status affect plant cuticle is limited. This was the first report about the manners of rice leaf cuticle in answer to different nutritional circumstances of nitrogen detected by the Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS) which with a main superiority for in situ and depth-profiling in mid-infrared range. Rice leaves from the seedlings treated with three nitrogen levels designed as low (22N1), medium (N2) and high (N3) concentration were scanned by three moving mirror velocities (0.32 cm s-1, 0.47 cm s-1, and 0.63 cm s-1) at 900-4000 cm-1 to acquire the spectra of leaf surfaces. Well-resolved peaks had been detected at 3400, 2800, 1650, 1520 and 1050 cm-1. Combining with the structures and compositions of cuticle, the spectra recorded with 0.63 cm s-1 were identified to be from cuticle, and were used to analyze the responses of cuticle. Through curve-fitting, the absorption ratio of the peaks at (cm-1) 1050/3400, 1050/2800 and 1650/2800 shown regular changes，which were suggested to corresponded with ν(CO)/ν(OH), ν(CO)/ν(CH) and ν(C=C)/ν(CH) mainly. These ratios were supported to reflect the amount or variation of cuticle components, such as cutin, fatty alcohols, acids and unsaturated compounds. It provided insights about how nitrogen affected cuticles and showed great potentials to utilized FTIR-PAS for detecting cuticle variations.
Keywords: Depth-profiling; FTIR-PAS; In situ detection; Nitrogen supply; Plant cuticle.
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