The responses of trichome mutants to enhanced ultraviolet-B radiation in Arabidopsis thaliana.

To gain a better understanding of the protective function of the trichome in Arabidopsis against UV-B radiation, we performed a study using several Arabidopsis trichome mutants (gl1, gis, gis2, zfp8, try82, and gl3), overexpressing trichome positive regulator lines (35S:GIS and 35S:GIS2), and wild-types (WT) under simulated enhanced UV-B radiation conditions. The flowering time, height, diameter of rosette, leaf size, trichome density, and expression levels of GL3 gene were measured. Significant decreases in height, diameter of rosette, leaf size, and a notable delay in flowering time were observed in all mutants and wild-types after exposure to UV-B. Moreover, the trichome density showed a significant increase, suggesting a clear induction of trichome formation by UV-B. Comparing the mutants and WT, we found that the mutants that had more trichomes showed a lower sensitivity to UV-B than the WT, whereas the mutants that had fewer trichomes were more sensitive to UV-B. These results indicated that the trichome plays a key shielding role against UV-B radiation. qRT-PCR analysis indicated that UV-B radiation induced expression of GL3 and an increase in GL3 transcript level correlated with the increase in trichome density and, suggesting a possible role of GL3 by integrating the environmental signal to control trichome initiation.