Regulation of growth and development in phytochrome mutants of Arabidopsis thaliana by solar UV

Abstract

Phytochrome mutants (phyA, phyB and phyAB) of Arabidopsis thaliana were grown under ambient and UV-excluded sunlight to understand their influence on growth and development by mutual exclusion. Phytochrome A and B played a complementary role in the regulation of germination. Suppression of hypocotyl length was predominantly under the control of phytochrome B; UV photoreceptors were active in suppression of hypocotyl growth only in phyB and phyAB mutants. Exclusion of UV promoted the number and the area of rosette leaves only in presence of phytochrome A and B. Phytochrome mutation reduced petiole length, whereas UV exclusion led to an increase. Requirement of long-day period for flowering was removed in the mutants. Under short-day conditions, flowering was predominantly under the control of phytochrome B, since phyB mutants flowered earlier than phyA mutants. Solar UV regulates the number of boltings and number of siliques per plant. Overall biomass of the plants is enhanced by the exclusion of UV only in the wild type. The interaction of phytochromes with UV photoreceptors is discussed in the paper.

Phytochromes are key regulators of abiotic stress responses in tomato

“…Similar to the tolerance of phyB mutants to stress, as already discussed, UV-B radiation caused less deleterious effects on the growth of these genotypes as compared with WT. Mani and Guruprasad (2015) observed that when excluding the UV-B and UV-A spectra of sunlight using filters, WT had a greater biomass than Arabidopsis phyB and phyAB mutants, indicating the relationship between the UV receiver and the phytochrome B during growth under UV-B radiation. Moreover, the influence of negative control of phytochromes B1 and B2 in response to UV-B radiation in both length and root biomass ( Fig.…”

“…The knowledge of how phytochromes work at the molecular level, the identification of transcription factor families whose action is regulated by phytochromes (Castilon, 2007;Zheng et al, 2014) and the increased availability of phytochrome mutants in different plant species provide ideal tools for studying the participation of these photoreceptors in biotic and abiotic stress responses. With respect to the multitude of abiotic and biotic stresses modulated by phytochromes, they have been shown to be important components of plant signaling pathways involved in responses to insect herbivory (Ballaré, 2009;Howe and Jander, 2008), temperature fluctuations (Auge et al, 2012;Donohue et al, 2008;Foreman et al, 2011), harmful light radiation (e.g., ultraviolet B (UV-B)) (Boccalandro et al, 2001;Kreslavski et al, 2013Kreslavski et al, , 2015Mani and Guruprasad, 2015), salt stress (Balestrasse et al, 2008a;Datta et al, 2008), water stress (D'amico-Damião et al, 2015;Kidokoro et al, 2009) and even heavy metal intoxication . Because those environmental conditions can greatly affect plant productivity, the studies on phytochrome regulation of stress responses have become a hot spot of research.…”

Histidine Kinases: Diverse Functions in Plant Development and Responses to Environmental Conditions

“…In addition to red and far-red lights, the phytochromes are also able to absorb ultraviolet (UV) radiation. Exploring the functions of Arabidopsis PhyA and PhyB in plant response to UV-B light (280-315 nm) showed their regulatory roles in a broad range of biological processes, including hypocotyl elongation (negatively regulated by PhyB), germination, rosette growth (regulated by synergistic action of PhyA and PhyB), and biomass accumulation (regulated by PhyA, PhyB, and other phytochrome members) (104). Furthermore, the importance of these two phytochromes in controlling light-mediated photosynthesis and programmed cell death in response to UV-C light (200-280 nm) has also been demonstrated (130).…”

The high red/far-red ratio supports the acclimation of fernPlatycerium bifurcatumto high light

“…The value of R/FR ratio directly modifies the phytochrome properties, activating or inhibiting the shadow avoidance reaction (Franklin & Quail, 2010). Phytochrome also plays an important role in modulating signaling pathways during plant reactions to various abiotic stresses, including light stress (Mani & Guruprasad, 2015). Phytochrome-dependent photoprotective mechanisms are associated with the change in the structure and size of the LHCII pool.…”