Abstract
Background: Xyloglucan endotransglycosylase/hydrolases (XTH) can disrupt and reconnect the xyloglucan chains, modify the cellulose-xyloglucan complex structure in the cell wall to reconstruct the cell wall. Previous studies have reported that XTH plays a key role in the aluminum (Al) tolerance of tea plants (Camellia sinensis), which is a typical plant that accumulates Al and fluoride (F), but its role in F resistance has not been reported. Results: Here, 14 CsXTH genes were identified from C. sinensis and named as CsXTH1-14. The phylogenetic analysis revealed that CsXTH members were divided into 3 subclasses, and conserved motif analysis showed that all these members included catalytic active region. Furthermore, the expressions of all CsXTH genes showed tissue-specific and were regulated by Al3+ and F- treatments. CsXTH1, CsXTH4, CsXTH6-8 and CsXTH11-14 were up-regulated under Al3+ treatments; CsXTH1-10 and CsXTH12-14 responded to different concentrations of F- treatments. The content of xyloglucan oligosaccharide determined by immunofluorescence labeling increased to the highest level at low concentrations of Al3+ or F- treatments (0.4 mM Al3+ or 8 mg/L F-), accompanying by the activity of XET (Xyloglucan endotransglucosylase) peaked. Conclusion: In conclusion, CsXTH activities were regulated by Al or F via controlling the expressions of CsXTH genes and the content of xyloglucan oligosaccharide in C. sinensis roots was affected by Al or F, which might finally influence the elongation of roots and the growth of plants.