SUMMARY

The accumulation of cell wall hydroxyproline-rich glycoproteins (HRGPs) involved in plant defence re-sponse was studied, in terms of hydroxyproline accu-mulation on purified cell walls of leaves of tobacco cvs Havana 425, Xanthi-nc (wild type), and NahG-trans-formed Xanthi (carrying the gene for salicylate hydroxy-lase). The leaves (7th and 8th leaves) were analysed after treatment with salicylic acid (SA) and the SA analogue acibenzolar-S-methyl (ASM). Upper untreated leaves (9th leaf) were also analysed. Infiltration of 1 mM SA so-lution into leaves 8 and 9 of Havana 425 and Xanthi-nc, induced significant HRGP accumulation, which also oc-curred in the upper untreated leaves, more evident at 4 and 5 days after treatment, whereas in NahG plants no accumulation was observed, both in treated and upper leaves. Spraying 1 mM ASM solutions induced insignifi-cant or modest and transitory HRGP accumulation in sprayed leaves of Havana and Xanthi respectively and a clear accumulation in the upper leaves, at 4, 5 and, gen-erally, at 6 days. In NahG plants, modest accumulation was observed only in the upper leaves at 5 or 5 and 6 days. The pattern of HRGP accumulation induced by SA and ASM in Havana and Xanthi-nc appears consis-tent with the involvement of HRGPs in SAR. In SA-in-sensitive NahG plants, the lack (SA treatment) or poor (ASM treatment) HRGP accumulations also hint at their involvement in SAR