In this investigation, we applied previously proposed simple algorithms to analyze the attenuated total reflection Fourier transform infrared (ATR FT-IR) spectra of cotton fibers during secondary cell wall (SCW) biosynthesis. The infrared crystallinity ( CIIR) and maturity ( MIR) indices were compared from developmental fibers representing two pairs of upland cotton near isogenic lines (NILs). One pair of NILs consisted of Texas Marker-1 (TM-1) and an immature fiber ( im) mutant that differ in fiber maturity. The other pair of NILs included MD52ne and MD90ne that show variations in fiber strength. The observations revealed significant difference in the MIR values between developmental TM-1 and im NILs grown at a field in crop year 2015, and also a significant difference in the CIIR values between these NILs grown at the same field in crop year 2011. These different patterns of CIIR and MIR values during fiber development for the two different crop years indicated the impact of genetics and crop year on the development of fiber maturity and crystallinity of the TM-1 and im fibers. Furthermore, the tendency of linking CIIR with MIR values suggested that the im fibers have more CIIR development than the TM-1 fibers when the fibers have the similar MIR values. In contrast, the NIL pair having variations in fiber strength showed insignificant differences in the patterns of CIIR and MIR as well as the relationship between CIIR and MIR values. The results suggested that CIIR and MIR indices from ATR FT-IR measurement could be used to facilitate the understanding of how fiber genetics and crop year affect fiber maturity and crystallinity during SCW biosynthesis.
Keywords: mutant; ATR; FT-IR; Fourier transform infrared spectroscopy; algorithm analysis; attenuated total reflection; cotton near isogenic lines; fiber secondary cell wall biosynthesis; immature fiber.