Abstract
There are several evidences that trichome plays roles in the defense mechanism against biotic and abiotic stresses. The randomly selected clones were used to construct EST libraries of tobacco (Nicotiana tabacum L. cv. Xanthi) glandular leaf trichomes. Genes for defense and stress responses, including the genes for diterpene biosynthesis, antipathogenic T-phylloplanin-like proteins, pathogenesis-related (PR) proteins such as metallocarboxypeptidase inhibitors, Bet v 1 homologous proteins, and lipid transfer proteins were scored highly. LC-ESI-MS analysis of the leaf exudates and the extract of trichome cells identified anti-herbivorous cembrene-type diterpenes. Trichome specific expression of Cys-rich PR proteins were demonstrated by RT-PCR analysis, indicating that they were candidates for heavy metal cheaters. Glutathione is a potential redox-regulator for Cys-rich proteins. The confocal laser-scanning microscopy visualized the glutathione accumulation in tip cells of the trichomes. Our results showed the tobacco trichome is a biologically active and stress-responsive tissue.
