Al-induced root cell wall chemical components differences of wheat (Triticum aestivum L.) differing in Al tolerance
Root growth is different in plants with different levels of Al-tolerance under Al stress. Cell wall chemical components of root tip cell are related to root growth. The aim of this study was to explore the relationship between root growth difference and cell wall chemical components. For this purpose, the cell wall chemical components of root tip cell in two near-isogenic lines (NIL) wheat (Triticum aestivum L.), ET8 (Al-tolerant) and ES8 (Al-sensitive) were investigated. In ET8 and ES8, after treatments with Al (50 μM), relative root elongation (RRE) and relative cell length (RCL) decreased with time increase (6, 12 and 24 h), but was more significant in ES8. There was a good correlation between RRE and RCL (R2= 0.866). Activities of the metabolism enzyme of cell wall chemical components varied, for example, phenylalanine ammonia-lyase (PAL, EC 126.96.36.199), cinnamyl alcohol dehydrogenase (CAD, EC 188.8.131.52) and peroxidase (POD, EC 1.11.1) increased; and activities of callase (EC 184.108.40.206), cellulase (EC 220.127.116.11) decreased. Cell wall chemical contents of lignin, H2O2 and callose increased and contents of cellulose decreased. Changes of enzyme activities and cell wall chemical components were significant in both lines, but were more prominent in the ES8 line. The analysis indicated that under Al stress, differences in cell wall chemical components of root tip cell between wheat lines with different Al tolerances induce the root tip elongation differences, thereby causing different root growth.
Key words: Aluminum toxicity, callose, cellulose, hydrogen peroxide, lignin, wheat.