Anatomical and Chemical Characteristics of a Rolling Leaf Mutant of Rice and Its Ecophysiological Properties

The anatomical and chemical characteristics of a rolling leaf mutant (rlm) of rice (Oryza sativa L.) and its ecophysiological properties in photosynthesis and apoplastic transport were investigated. Compared with the wild type (WT), the areas of whole vascular bundles and xylem as well as the ratios of xylem area/whole vascular bundles area and xylem area/phloem area were higher in rlm, whereas the area and the width of foliar bulliform cell were lower. The Fourier transform infrared (FTIR) microspectroscopy spectra of foliar cell walls differed greatly between rlm and WT. The rlm exhibited lower protein and polysaccharide contents of foliar cell walls. An obvious reduction of pectin content was also found in rlm by biochemical measurements. Moreover, the rate of photosynthesis was depressed while the conductance of stoma and the intercellular CO2 concentration were enhanced in rlm. The PTS fluorescence, which represents the ability of apoplastic transport, was 11% higher in rlm than in WT. These results suggest that the changes in anatomical and chemical characteristics of foliar vascular bundles, such as the reduction of proteins, pectins, and other polysaccharides of foliar cell walls, participate in the leaf rolling mutation, and consequently lead to the reduced photosynthetic dynamics and apoplastic transport ability in the mutant.