Identification of characteristic organic molecules in kernels of maize (Zea mays L.) hybrid grain using infrared spectroscopy

Abstract

Modern biophysical methods have provided a breakthrough in investigations of the status and functions of the intact plants at the molecular level. The infrared (IR) spectroscopy allows us to analyze the molecular composition and structure by recording the absorption of infrared radiation as a function of frequency of valent and deformation vibrations (wavenumber, cm-1) for chemical bonds. We used the IR Fourier spectroscopy method (IR spectra with Fourier Transformation,) to investigated the grain composition in maize hybrids - ZP 341, ZP 434 and ZP 505 created at Maize Research Institute (Zemun Polje, Belgrade, Serbia). The resulted spectra differed in peak number and intensity, and in oscillation frequency. Particularly, there are 20 to 23 peaks and characteristic spectral bands within the wavenumber range of 400 to 4000 cm-1. Characteristic spectral bands were analyzed for each hybrid with regard to absorption intensity in %, experimentally determined wavenumber in cm-1, and published wavenumber range. A comparison of these peaks to reference IR spectra from databases revealed biogenic organic molecules: alcohols, amines, esters, alkanes, carboxylic acids, alkenes, aldehydes, ketones and esters in the studied grain hybrids. In a typical IR spectrum of maize hybrid ZP 341 there were three most distinct bands with wavenumbers of 3400, 2900 and 1000 cm-1. Four peaks (3400, 2950, 1700 and 1000 cm-1) were characteristic of the ZP 434 hybrid, and eight major peaks of 3400, 2900, 2850, 1750, 1700, 1450, 1150 and 1000 cm-1 were observed in ZP 505. That is, the grain charterisics in ZP 505 slightly differ from those in ZP 341 and ZP 434, whereas in ZP 341 and ZP 434 the grain structure is more similar. In general, Serbian hybrids are characterized by high quality, productivity and technological suitability. The developed methodology for IR spectra recording and analysis in grain allows to reveal the composition and structure of biogenic compounds. It is important not only for diagnosis and breeding, but also for the development of biotechnological screening methods, or the estimation of grain storage time.