Use of Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy in Direct, Nondestructive, and Rapid Assessment of Developmental Cotton Fibers Grown In Planta and in Culture.

Cotton fibers are routinely harvested from cotton plants (in planta), and their end-use qualities depend on their development stages. Cotton fibers are also cultured in controlled laboratory environments, so that cotton researchers can investigate many aspects of experimental protocols in cotton breeding programs at reduced expenses. In this work, attenuated total reflection Fourier transform infrared (ATR FT-IR) spectra of cotton fibers grown in planta and in culture were collected to explore the potential of FT-IR technique as a simple, rapid, and direct method for characterizing the fiber development. Complementary to visual inspection of spectral variations, principal component analysis (PCA) of ATR FT-IR spectra revealed the occurrence of phase transition from primary to secondary cell wall synthesis and also the difference of starting the phase transition between two types of fibers. Like PCA observation, three simple algorithms were capable of monitoring the secondary cell wall formation effectively. Interestingly and uniquely, simple algorithms were able to detect the subtle discrepancies in fibers older than 25 days post-anthesis, which was not apparent from PCA results. The observation indicated the feasibility of FT-IR technique in rapid, routine, nondestructive, and direct assessment of fiber development for cotton physiology and breeding applications.