Temporal and spatial distribution of pectin, β (1-4)-galactans, xylan and lignin during differentiation of living fibre in young shoots of Leucaena leucocephala (Lam.) de Wit
Pramod S, K S Rajput and Karumanchi S Rao
Maharaja Sayajirao University of Baroda, India
: J Plant Physiol Pathol
Abstract
The distribution pattern of pectins and lignin differentiation in the cell walls of living fibers in the secondary xylem of Leucaena leucocephala was examined by light and electron microscopy. The expansion of primary walls during early stage of fiber development was characterized by change in the organization of pectic polysaccharides in the middle lamellae region. The intercellular regions became filled with pectic polysaccharides following initiation of SW deposition. Subsequently, lignification started at cell corners with the deposition of guaiacyl units that co-polymerize with syringyl moieties in the final stages of fiber development. The transmission electron microscopic analysis confirmed the disorganization of pectic polysaccharides in the middle lamellae region during cell expansion and it is inhomogenous distribution in the cell corners following secondary wall deposition. Immunofluorescence microscopy revealed that β-1, 4-galactans are mainly incorporated in the middle lamellae region that undergoes disorganization and reorganization during and after cell expansion. In mature fibers, LM 10 labeling indicated that the less substituted xylans are distributed throughout the SW while labeling of highly substituted xylans with LM 11 appeared more intense at corner regions of SW compared to other regions. The KMnO4 staining revealed the relatively higher lignin distribution in xylem fibers in compound middle lamellae and S3 wall layers. The transition zone between S1 and S2 layers showed relatively high lignin distribution in comparison to rest of the S2 wall layer. The ultra-structural studies demonstrated that the inhomogenous distribution of lignin corresponds with that of pectins at the cell corners of fibers. The cell wall delignification resulted in significant reduction of lignin at cell corners, compound middle lamellae and secondary wall layers of fibers.
Biography
E-mail: pramodsiv@gmail.com
