Role Of Dehydrins Research Articles

Dehydrin Content in Fresh and Desiccated Pistachio (Pistacia vera L.) Seeds

Seeds may desiccate after independence from parent plant and remain in a dry inactive state until the conditions for germination are conducive. Dehydrin proteins pattern and expression in mature pistachio seeds were surveyed at fresh and 48-h desiccated states by western blot method, using an antibody against conserved K-segment. Mature seeds lost 92.4% moisture after desiccation without any loss in complete germinability. Five dehydrin bands were detected in both cotyledon and embryonic axis. At fresh state, 23, 25, and 48 kDa bands had a lower content in cotyledon than in axis, but increased to an equal level by desiccation. The 32 and 39 kDa bands were detected only in fresh stage, preferentially in cotyledons, and disappeared after desiccation; therefore, they have other roles rather than dehydration protection. Some bands of 17, 19, 20, 28, 67, 77 and 98 kDa were detected only in axes at both states. Among them, the 28 kDa band was only used for densitometry and was not stimulated by dehydration. Further studies are required to establish the exact role of dehydrins which do not have a role in dehydration tolerance.

The role of dehydrins in plant response to cold

Dehydrins present a distinct biochemical group of late embryogenesis abundant (LEA) proteins characterised by the presence of a lysine-rich amino acid motif, the K-segment. They are highly hydrophilic, soluble upon boiling, and rich in glycine and polar amino acids. It is proposed that they can act as emulsifiers or chaperones in the cells, i.e., they protect proteins and membranes against unfavourable structural changes caused by dehydration. Cold usually precedes freezing in nature and induces many physiological and biochemical changes in the cells of freezing-tolerant plant species (cold-acclimation) that enable them to survive unfavourable conditions. It is demonstrated that the induction of dehydrin expression and their accumulation is an important part of this process in many dicotyledons (both herbaceous and woody species), and also in winter cultivars of cereals, especially wheat and barley. Some mechanisms which are proposed to be involved in regulation of dehydrin expression are discussed, i.e., endogenous content of abscisic acid, homologues of Arabidopsis C-repeat binding factor (CBF) transcriptional activators, the activity of vernalization genes and photoperiodic signals. Finally, we outline some new approaches emerging for the solution of the complex mechanisms involved in plant cold-acclimation, especially the methods of functional genomics that enable to observe simultaneously changes in the activity of many genes and proteins in a single sample.

Differential expression of dehydrin in flower buds of two Japanese apricot cultivars requiring different chilling requirements for bud break

In this study, we investigated seasonal changes in protein profiles in dormant flower buds of Japanese apricot (Prunus mume Siebold Zucc.) cultivars 'Ellching', from subtropical Taiwan, and 'Nanko', from temperate Japan. One protein, isolated by two-dimensional polyacrylamide gel electrophoresis of flower bud extracts, was shown by peptide sequencing to be a dehydrin (the group of D-11 LEA (late embryogenesis-abundant) proteins). Patterns of dehydrin protein and transcript accumulation differed between the cultivars, with greater accumulations and longer persistence in 'Nanko' than in 'Ellching'. These differences correspond with the greater requirement for chilling to break flower bud dormancy in 'Nanko' than in 'Ellching'. Our study supports the findings of earlier work comparing dehydrin expression in the bark tissue of the evergreen and deciduous peach (Prunus persica (L.) Batsch) genotypes, and suggests that the role of dehydrin during the dormant season is common to all Prunus species.

Nucleus and nucleolus in pea root meristems are affected by variations in moisture content

ABSTRACT This paper examines the morphological and biochemical variations occurring in the nucleus when considerable changes in moisture content take place in the tissue. The tissue used for this investigation was the root meristem of Pisum sativum L. at three different developmental stages: during seed maturation, during seed germination and during a vegetative stage. These different developmental stages were representative of three different degrees of moisture content. Seed maturation represented the case of tissue undergoing desiccation whereas seed germination represented the case of tissue undergoing hydration. PEG-treated seedlings represented the case of a vegetative tissue subjected to water stress. The data demonstrated that when moisture content in root meristems was low, the nucleus underwent a reduction in diameter and a change in chromatin arrangement. The nucleolus shrank considerably in diameter and became less visible. These events were simultaneous to qualitative and quantitative variations in the nuclear protein pattern. The relationship between morphological and biochemical events is unknown. However, when the moisture content in the tissue was low, the cell cycle in meristematic cells was arrested in G1 and G2 phases in the case of seed maturation. In water-stressed seedlings the cell cycle was arrested in late S or early Gl phase. The differences observed between natural desiccation and artificially induced water stress could be due to the different rate of water loss from tissues. This paper reports for the first time the presence of Dehydrins in nuclei of higher plants. These proteins undergo quantitative variations related to changes in the moisture content of the tissue. The hypothesis of a possible role of Dehydrins in protecting DNA is discussed.