Using infrared spectroscopy and Raman spectroscopy to evaluate the conformation of biomolecules in maize (Zea mays L.) lines

Currently, there are few non-invasive methods that allow you to control the content and conformation of molecules in plant cells and tissues, not only in the laboratory, but also in the field. Infrared microscopy and Raman spectroscopy (IR and Raman spectroscopy) are actively used to analyze the role of molecules of certain substances in crop breeding. Using methods of vibronic spectroscopy, we investigated changes in the content and conformation of chloroplast molecules of various maize lines. Using infrared (IR) spectroscopy (3500-3000 cm-1) it was found that in the chloroplasts, the proportion of vibrations of OH-groups and intramolecular and intermolecular H bonds is maximum for the maize line ZPPL 186, and vibrations of NH-groups of amides (proteins) is minimal for ZPPL 225. It has been proven that ZPPL 186 chloroplasts are characterized by the maximum proportion of stretching vibrations from alkane molecules, carboxylic acids (region 2920-2860 cm-1) and deformation vibrations of aromatic structures (band at 1000 cm-1), and for the line M1-3-3-sdms, the fraction of stretching vibrations of O=C=O bonds (band at 2300 cm-1) is characteristic. Using Raman spectroscopy (range of 1250-500 cm-1 and 1535-1400 cm-1), it was found that differences in the chloroplasts of different maize lines are associated with changes in the conformation of chloroplast carotenoid molecules (rather than cellulose molecules). It was found that in two samples (except ZPPL 225), carotenoid molecules are in the 15-trans form with different conformation of the polyene chain. We note that the conformation of carotenoids of the ZPPL 186 line is characterized by a minimum amount of rotation outside the plane of the polyene chain and has more pronounced vibrations of the lateral CH3-group. It was assumed that carotenoids of leaf chloroplasts of various maize lines lack interactions with aromatic amino acids of proteins. According to the authors, the combined use of IR and Raman spectroscopy of the leaf chloroplast fraction can be recommended for monitoring the content and conformation of biomolecules in maize breeding.