Ultraviolet‐B radiation effects on plants: induction of morphogenic responses

Abstract

Plants raised under field conditions are acclimated to ambient levels of solar UV‐B radiation. Morphogenic responses are part of the UV‐B acclimation process and have been hypothesized to contribute to UV avoidance. UV‐B induced morphogenic responses include inhibition of hypocotyl and stem elongation, leaf curling, leaf thickening and increased axillary branching. So far, neither the photosensory nor the signal transduction mechanism involved in UV‐B mediated morphogenesis has been identified. The combination of classical photobiological techniques and Arabidopsis genetic resources comprises a powerful tool for the analysis of morphogenic responses. However, no morphogenic mutants, specifically altered in their response to UV‐B, have yet been identified. In this paper we discuss the possibility that some UV‐B driven morphogenic responses do not involve a dedicated photosensory system, but rather are a consequence of UV‐B induced changes in secondary metabolism. UV‐B induced flavonoid aglycones and phenol‐oxidizing peroxidases can affect, respectively, polar auxin transport and auxin catabolism, and hence plant architecture. Integration of genetic, photobiological, biochemical and physiological approaches is necessary to fully appraise the ecophysiological role of UV‐B radiation in controlling plant architecture.

Effects of Hexaconazole on Growth and Antioxidant Potential of Cucumber Seedlings under UV-B Radiation

“…High levels of UV-B may constitute a significant environmental stress for terrestrial plants limiting plant yield and distribution in many regions of the world. UV-B radiation induces a multitude of rapid and longterm morphogenic responses which are mediated by an unknown number of unidentified photosensory systems (Jansen, 2002).…”

Ultraviolet-B-Induced Stomatal Closure in Arabidopsis Is Regulated by the UV RESISTANCE LOCUS8 Photoreceptor in a Nitric Oxide-Dependent Mechanism

“…High doses of UV-B may damage macromolecules, including DNA, and induce the production of reactive oxygen species (ROS), affecting cell integrity and viability (Jordan, 1996;Brosché and Strid, 2003;Frohnmeyer and Staiger, 2003). However, UV-B is also a signaling stimulus that regulates various metabolic and developmental processes and modifies plant architecture (Jansen, 2002;Frohnmeyer and Staiger, 2003;Jenkins, 2009;Heijde and Ulm, 2012;Jansen and Bornman, 2012). Research undertaken in recent years has facilitated understanding of the initial mechanisms of UV-B perception and signaling in plants.…”

Developmental stage is an important factor that determines the antioxidant responses of young and old grapevine leaves under UV irradiation in a green-house

“…On the other hand, many effects of UV-B radiation concern morphogenetic changes in plants rather than damage, especially in response to lower UV doses [8][9]. In addition, UV-B affects the secondary metabolism of plants indicating that solar UV-B is to be regarded as an environmental challenge rather than a damage-inducing source of stress [10][11]. Plants protect themselves from this potentially harmful radiation by altering metabolic functions and a number of studies confirmed the role of UV-B in regulation of gene expression [9,[12][13][14].…”