Identification and expression of different dehydrin subclasses involved in the drought response of Trifolium repens

Abstract

Reversely transcribed RNAs coding for YnKn, YnSKn, SKn, and KS dehydrin types in droughtstressed white clover (Trifolium repens) were identified and characterized. The nucleotide analyses revealed the complex nature of dehydrin-coding sequences, often featured with alternative start and stop codons within the open reading frames, which could be a prerequisite for high variability among the transcripts originating from a single gene. For some dehydrin sequences the existence of natural antisense transcripts were predicted. The differential distribution of dehydrin homologues in roots and leaves from a single white clover stolon under normal and drought conditions was evaluated by semi quantitative RT-PCR and immunoblots with antibodies against the conserved K-, Y-and S-segments. Obtained data suggest that different dehydrin classes have distinct roles in drought stress response and vegetative development, demonstrating some specific characteristic features. Substantial levels of YSK-type proteins with different molecular weights were immunodetected in the non-stressed developing leaves. The acidic SK2 and KS dehydrin transcripts exhibited some developmental gradient in leaves. A strong increase of YK transcripts was documented in the fully expanded leaves and roots of drought stressed individuals. The immunodetected drought-induced signals imply that Y-and Ksegment containing dehydrins could be the major inducible Late Embryogenesis Abundant class 2 proteins (LEA 2) which accumulate predominantly under drought. Identification and expression of different dehydrin subclasses involved in

Drought stress and carbon assimilation in a warming climate: Reversible and irreversible impacts

“…The lowered leaf temperature may again cause partial closure of stomata within minutes, decrease cooling efficiency by transpiration and lead to a temperature increase again. These assumptions as well as a trade-off between abscisic acid-induced closure and heat-induced opening of stomata were confirmed by measuring stomatal aperture (Reynolds-Henne et al, 2010;Feller and Vaseva, 2014).…”

“…Ambient temperature, air humidity, photon flux density, stomatal opening and air convection affect the temperature in the mesophyll (Feller, 2006;Reynolds-Henne et al, 2010;Carvalho et al, 2015). Various regions of the same leaf may differ considerably in their actual temperatures (Reynolds-Henne et al, 2010;Gilgen and Feller, 2014;Feller and Vaseva, 2014). Furthermore, stomatal control may indirectly affect xylem embolism and influence as a consequence drought responses in a complex manner (Jones and Sutherland, 1991).…”

“…Photon flux density may change very rapidly during the day as a consequence of altered spatial arrangements (e. g. angle of the sun relative to crop plants, especially when grown in rows as for cereals). Oscillations in leaf temperature were detected in several plant species after transferring leaves from darkness to light (Feller, 2006;Reynolds-Henne et al, 2010;Feller and Vaseva, 2014). These oscillations can be explained by a rapid heating of previously darkened leaves (within seconds) followed by a slow start of cooling by stomatal opening (within minutes).…”

“…Leaf temperature, water status and stomatal opening are interconnected in a complex manner (Valladares and Pearcy, 1997;Feller, 2006;Reynolds-Henne et al, 2010;Feller and Vaseva, 2014;Teskey et al, 2015). Increased abscisic acid levels cause closure of stomates and reduce leaf cooling by transpiration.…”

“…In the latter case, new enzyme molecules may be produced and become active already during the stress phase or during the recovery phase as long as compartmentation and basic cellular functions including gene expression and protein synthesis are maintained (Fu et al, 2008;Cartagena et al, 2015;Chen et al, 2014;Liu et al, 2014;Wang et al, 2015). During the stress phase, protein synthesis is important for the adaptation of the metabolism, especially for the formation of protective proteins such as dehydrins (Close, 1997;Volaire and Lelievre, 2001;Vaseva et al, 2014) or enzymes involved in the detoxification of reactive oxygen species (Ahmed et al, 2015;Jain et al, 2015) and in the production of compatible solutes and secondary metabolites (Jain et al, 2015;Simova-Stoilova et al, 2015).…”