Approaches to elucidate the basis of desiccation-tolerance in seeds

1997 ◽  
Vol 7 (2) ◽  
pp. 75-95 ◽  
Author(s):  
Allison R. Kermode
Keyword(s):  
Water Deficit ◽  
Desiccation Tolerance ◽  
Protein Function ◽  
High Water ◽  
Late Embryogenesis Abundant ◽  
Plant Responses ◽  
Late Embryogenesis ◽  
Essential Components ◽  
Orthodox Seeds ◽  
Adverse Environmental Conditions

AbstractPlants undergo a series of physiological, biochemical and molecular changes in response to adverse environmental conditions or stresses such as drought, low temperature or high salt. Several genes and their corresponding proteins have been described that may play a role in withstanding water-deficit-related stresses or full desiccation. In particular, sugars and late-embryogenesis-abundant (LEA) proteins have received the most attention. Plant responses to water-deficit and desiccation have been well-characterized at the molecular level; however, pinpointing the precise roles of the gene products in protecting cells under conditions of water deficit remains a challenging task. While few plants are capable of withstanding full desiccation, most seeds undergo this event as a pre-programmed and final stage in their development. These are the so-called ‘orthodox’ seeds. In contrast to seeds of orthodox species, those of recalcitrant species do not acquire desiccation tolerance during their development and are shed from the parent plant at relatively high water contents. The essential components of desiccation tolerance of seeds are likely to involve the ability to effect repair upon subsequent rehydration as well as the ability to accumulate protective substances that limit the amount of damage which otherwise would be caused by water loss. Studies have begun to examine whether the desiccation sensitivity of recalcitrant seeds is at least partially the result of an insufficient accumulation of LEA-type proteins, or whether other factors (including a lack of protective sugars) are more important. This review assesses some of these studies as well as recent research to understand gene and protein function using transgenic host plant systems.

scholarly journals Desiccation Tolerance as the Basis of Long-Term Seed Viability

2020 ◽  
Vol 22 (1) ◽  
pp. 101
Author(s):  
Galina Smolikova ◽  
Tatiana Leonova ◽  
Natalia Vashurina ◽  
Andrej Frolov ◽  
Sergei Medvedev
Keyword(s):  
Desiccation Tolerance ◽  
Vascular Plants ◽  
Molecular Mechanisms ◽  
Regulation Of Gene Expression ◽  
Seed Viability ◽  
Late Embryogenesis Abundant ◽  
Maturation Stage ◽  
Terrestrial Plants ◽  
Complex Anatomy ◽  
Orthodox Seeds

Desiccation tolerance appeared as the key adaptation feature of photoautotrophic organisms for survival in terrestrial habitats. During the further evolution, vascular plants developed complex anatomy structures and molecular mechanisms to maintain the hydrated state of cell environment and sustain dehydration. However, the role of the genes encoding the mechanisms behind this adaptive feature of terrestrial plants changed with their evolution. Thus, in higher vascular plants it is restricted to protection of spores, seeds and pollen from dehydration, whereas the mature vegetative stages became sensitive to desiccation. During maturation, orthodox seeds lose up to 95% of water and successfully enter dormancy. This feature allows seeds maintaining their viability even under strongly fluctuating environmental conditions. The mechanisms behind the desiccation tolerance are activated at the late seed maturation stage and are associated with the accumulation of late embryogenesis abundant (LEA) proteins, small heat shock proteins (sHSP), non-reducing oligosaccharides, and antioxidants of different chemical nature. The main regulators of maturation and desiccation tolerance are abscisic acid and protein DOG1, which control the network of transcription factors, represented by LEC1, LEC2, FUS3, ABI3, ABI5, AGL67, PLATZ1, PLATZ2. This network is complemented by epigenetic regulation of gene expression via methylation of DNA, post-translational modifications of histones and chromatin remodeling. These fine regulatory mechanisms allow orthodox seeds maintaining desiccation tolerance during the whole period of germination up to the stage of radicle protrusion. This time point, in which seeds lose desiccation tolerance, is critical for the whole process of seed development.

scholarly journals Desiccation tolerance in streptophyte algae and the algae to land plant transition: evolution of LEA and MIP protein families within the Viridiplantae

2020 ◽  
Vol 71 (11) ◽  
pp. 3270-3278 ◽  
Author(s):  
Burkhard Becker ◽  
Xuehuan Feng ◽  
Yanbin Yin ◽  
Andreas Holzinger
Keyword(s):  
Desiccation Tolerance ◽  
Experimental Studies ◽  
Sister Group ◽  
Land Plant ◽  
Late Embryogenesis Abundant ◽  
Land Plants ◽  
Desiccation Stress ◽  
Protein Families ◽  
Intrinsic Protein ◽  
Late Embryogenesis

Abstract The present review summarizes the effects of desiccation in streptophyte green algae, as numerous experimental studies have been performed over the past decade particularly in the early branching streptophyte Klebsormidium sp. and the late branching Zygnema circumcarinatum. The latter genus gives its name to the Zygenmatophyceae, the sister group to land plants. For both organisms, transcriptomic investigations of desiccation stress are available, and illustrate a high variability in the stress response depending on the conditions and the strains used. However, overall, the responses of both organisms to desiccation stress are very similar to that of land plants. We highlight the evolution of two highly regulated protein families, the late embryogenesis abundant (LEA) proteins and the major intrinsic protein (MIP) family. Chlorophytes and streptophytes encode LEA4 and LEA5, while LEA2 have so far only been found in streptophyte algae, indicating an evolutionary origin in this group. Within the MIP family, a high transcriptomic regulation of a tonoplast intrinsic protein (TIP) has been found for the first time outside the embryophytes in Z. circumcarinatum. The MIP family became more complex on the way to terrestrialization but simplified afterwards. These observations suggest a key role for water transport proteins in desiccation tolerance of streptophytes.

scholarly journals Desiccation Tolerance as The Basis of Long-Term Seed Viability

2020 ◽  
Author(s):  
Galina Smolikova ◽  
Tatiana Leonova ◽  
Natalia Vashurina ◽  
Andrej Frolov ◽  
Sergei Medvedev
Keyword(s):  
Desiccation Tolerance ◽  
Vascular Plants ◽  
Molecular Mechanisms ◽  
Regulation Of Gene Expression ◽  
Seed Viability ◽  
Late Embryogenesis Abundant ◽  
Maturation Stage ◽  
Methylation Of Dna ◽  
Complex Anatomy ◽  
Orthodox Seeds

Desiccation tolerance appeared as the key adaptation feature of photoautotrophic organisms for survival in terrestrial habitats. During the further evolution, vascular plants developed complex anatomy structures and molecular mechanisms to maintain the hydrated state of cell environment, which essentially increased their ability to sustain water deficit and dehydration. However, the role of the genes encoding the mechanisms behind this adaptive feature in the higher vascular plants is restricted to the dehydration protection of spores, seeds and pollen, whereas the mature vegetative stages became sensitive to desiccation. During maturation, orthodox seeds lose up to 95% of their water and successfully enter dormancy. This feature allows seeds maintaining their viability even under strongly fluctuating environmental conditions. The mechanisms behind the desiccation tolerance are activated at the late seed maturation stage and are associated with the accumulation of late embryogenesis abundant proteins (LEA proteins), small heat shock proteins (sHSP), non-reducing oligosaccharides, and antioxidants of different chemical nature. The main regulators of maturation and desiccation tolerance onset are abscisic acid and protein DOG1, which control the network of transcription factors, among which are LEC1, LEC2, FUS3, ABI3, ABI5, AGL67, PLATZ1, PLATZ2. This network is complemented by epigenetic regulation of gene expression by methylation of DNA, post-translational modifications of histones and chromatin remodeling impact on seed desiccation tolerance and longevity. Moreover, orthodox seeds are able to maintain desiccation tolerance during germination up to the stage of radicle protrusion. This time point is critical in the process of seed development, as the seeds lose desiccation tolerance at this moment.

‘Dehydrin-like’ proteins and desiccation tolerance in seeds

1994 ◽  
Vol 4 (2) ◽  
pp. 135-141 ◽  
Author(s):  
O. H. Gee ◽  
R. J. Probert ◽  
S. A. Coomber
Keyword(s):  
Desiccation Tolerance ◽  
Consensus Sequence ◽  
Causal Link ◽  
Late Embryogenesis Abundant ◽  
Acer Pseudoplatanus ◽  
Lea Proteins ◽  
Late Embryogenesis ◽  
Group 2 ◽  
Plant Families ◽  
The Relationship

AbstractThe relationship between tolerance of seeds to extreme desiccation and the presence of ‘dehydrinlike’ proteins was investigated in groups of related taxa from the unrelated plant families Aceraceae and Gramineae. Dehydrin-like proteins were identified by Western blot analysis using an antibody raised against a synthetic oligopeptide representing the 23-amino acid consensus sequence common to all group 2 late-embryogenesis-abundant (LEA) proteins.Evidence is presented that seeds of Acer pseudoplatanus and A. saccharinum are desiccation intolerant (recalcitrant) whereas seeds of A. platanoides and A. rubrum are desiccation tolerant (orthodox). Despite these differences, dehydrinlike proteins at 60 and 20 kDa were detected in all four species.Dehydrins at 20 kDa were also detected in seed samples of two aquatic grasses, Porteresia coarctata and Oryza sativa from the tribe Oryzeae, despite seeds of the former rapidly losing viability on drying, whereas O. sativa is one of the best-known examples of desiccation-tolerant seeds. In O. sativa, there was a correlation between contents of dehydrins detected and the proportion of individuals capable of withstanding extreme drying. However, the possibility of a causal link between these parameters is equivocal. Dehydrin-like proteins were also detected in desiccation-sensitive seeds of Zizania palustris, Z. latifolia and Z. texana and desiccation-intolerant seeds of Spartina anglica, all from the Gramineae.The presence of group 2 LEAs is clearly not diagnostic of desiccation tolerance in seeds. However, a more direct correlation with the expression of other groups of LEAs cannot be discounted.

scholarly journals The Orthodox Dry Seeds Are Alive: A Clear Example of Desiccation Tolerance

Plants ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 20
Author(s):  
Angel J. Matilla
Keyword(s):  
Desiccation Tolerance ◽  
Molecular Mechanisms ◽  
Higher Plants ◽  
Soluble Sugars ◽  
Late Embryogenesis Abundant ◽  
Seed Maturation ◽  
Glassy Matrix ◽  
Cellular Protection ◽  
Living Entity ◽  
Orthodox Seeds

To survive in the dry state, orthodox seeds acquire desiccation tolerance. As maturation progresses, the seeds gradually acquire longevity, which is the total timespan during which the dry seeds remain viable. The desiccation-tolerance mechanism(s) allow seeds to remain dry without losing their ability to germinate. This adaptive trait has played a key role in the evolution of land plants. Understanding the mechanisms for seed survival after desiccation is one of the central goals still unsolved. That is, the cellular protection during dry state and cell repair during rewatering involves a not entirely known molecular network(s). Although desiccation tolerance is retained in seeds of higher plants, resurrection plants belonging to different plant lineages keep the ability to survive desiccation in vegetative tissue. Abscisic acid (ABA) is involved in desiccation tolerance through tight control of the synthesis of unstructured late embryogenesis abundant (LEA) proteins, heat shock thermostable proteins (sHSPs), and non-reducing oligosaccharides. During seed maturation, the progressive loss of water induces the formation of a so-called cellular “glass state”. This glassy matrix consists of soluble sugars, which immobilize macromolecules offering protection to membranes and proteins. In this way, the secondary structure of proteins in dry viable seeds is very stable and remains preserved. ABA insensitive-3 (ABI3), highly conserved from bryophytes to Angiosperms, is essential for seed maturation and is the only transcription factor (TF) required for the acquisition of desiccation tolerance and its re-induction in germinated seeds. It is noteworthy that chlorophyll breakdown during the last step of seed maturation is controlled by ABI3. This update contains some current results directly related to the physiological, genetic, and molecular mechanisms involved in survival to desiccation in orthodox seeds. In other words, the mechanisms that facilitate that an orthodox dry seed is a living entity.

Responses of late embryogenesis-abundant genes in Leymus chinensis to water deficit

2020 ◽  
Vol 43 (3) ◽  
pp. 469-479
Author(s):  
Dongli Wan ◽  
Xiu Feng ◽  
Yongqing Wan ◽  
Yong Ding ◽  
Heping Li
Keyword(s):  
Water Deficit ◽  
Late Embryogenesis Abundant ◽  
Leymus Chinensis ◽  
Late Embryogenesis

scholarly journals Transcriptomic Effects of Acute Ultraviolet Radiation Exposure on Two Syntrichia Mosses

2021 ◽  
Vol 12 ◽  
Author(s):  
Jenna T. B. Ekwealor ◽  
Brent D. Mishler
Keyword(s):  
Ultraviolet Radiation ◽  
Desiccation Tolerance ◽  
Late Embryogenesis Abundant ◽  
Terrestrial Plants ◽  
Transcriptomic Response ◽  
Syntrichia Caninervis ◽  
Late Embryogenesis ◽  
Ultraviolet Radiation Exposure ◽  
Inducible Protein ◽  
Genetic Responses

Ultraviolet radiation (UVR) is a major environmental stressor for terrestrial plants. Here we investigated genetic responses to acute broadband UVR exposure in the highly desiccation-tolerant mosses Syntrichia caninervis and Syntrichia ruralis, using a comparative transcriptomics approach. We explored whether UVR protection is physiologically plastic and induced by UVR exposure, addressing the following questions: (1) What is the timeline of changes in the transcriptome with acute UVR exposure in these two species? (2) What genes are involved in the UVR response? and (3) How do the two species differ in their transcriptomic response to UVR? There were remarkable differences between the two species after 10 and 30 min of UVR exposure, including no overlap in significantly differentially abundant transcripts (DATs) after 10 min of UVR exposure and more than twice as many DATs for S. caninervis as there were for S. ruralis. Photosynthesis-related transcripts were involved in the response of S. ruralis to UVR, while membrane-related transcripts were indicated in the response of S. caninervis. In both species, transcripts involved in oxidative stress and those important for desiccation tolerance (such as late embryogenesis abundant genes and early light-inducible protein genes) were involved in response to UVR, suggesting possible roles in UVR tolerance and cross-talk with desiccation tolerance in these species. The results of this study suggest potential UVR-induced responses that may have roles outside of UVR tolerance, and that the response to URV is different in these two species, perhaps a reflection of adaptation to different environmental conditions.

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