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Interactions between a blue‐green reversible photoreceptor and a separate UV‐B receptor in stomatal guard cells
Author(s) -
Eisinger William R.,
Bogomolni Roberto A.,
Taiz Lincoln
Publication year - 2003
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.3732/ajb.90.11.1560
Subject(s) - phototropin , guard cell , phototropism , biology , arabidopsis , mutant , biophysics , botany , photosynthesis , hypocotyl , commelinaceae , microbiology and biotechnology , blue light , biochemistry , gene , physics , optics
Stomatal opening exhibits two main peaks of activity in the visible range—a red peak, mediated by photosynthesis, and a blue peak, mediated by one or more blue light (BL) photoreceptors. In addition, a pronounced peak in the UV‐B region has been characterized, as has a smaller UV‐A peak. The BL‐induced stomatal opening can be reversed by green light (GL). Here we report that UV‐B‐induced opening is also antagonized by GL. To determine whether UV‐B is being absorbed by the BL photoreceptor or by a separate UV‐B receptor, the UV‐B responses of two different Arabidopsis mutants, npq1 and phot1/phot2, were tested. Both putative BL‐photoreceptor mutants exhibited normal stomatal opening in response to UV‐B, consistent with the existence of a separate UV‐B photoreceptor. Moreover, GL failed to antagonize UV‐B‐induced stomatal opening in the phot1/phot2 double mutant and only partially antagonized UV‐B opening in npq1. Thus, both phot1 and phot 2, as well as zeaxanthin, are required for the normal GL inhibition of UV‐B. A model for a photoreceptor network that regulates stomatal opening is presented. Unlike the situation in guard cells, the UV‐B bending response of Arabidopsis hypocotyls during phototropism appears to be mediated by phototropins.