Editorial: special issue GROW “plant desiccation stress” (original) (raw)
Related papers
Desiccation Tolerance as The Basis of Long-Term Seed Viability
2020
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...
Integrative and Comparative Biology, 2005
Desiccation-tolerance in vegetative tissues of angiosperms has a polyphyletic origin and could be due to 1) appropriation of the seed-specific program of gene expression that protects orthodox seeds against desiccation, and/or 2) a sustainable version of the abiotic stress response. We tested these hypotheses by comparing molecular and physiological data from the development of orthodox seeds, the response of desiccation-sensitive plants to abiotic stress, and the response of desiccation-tolerant plants to extreme water loss. Analysis of publicly-available gene expression data of 35 LEA proteins and 68 anti-oxidant enzymes in the desiccation-sensitive Arabidopsis thaliana identified 13 LEAs and 4 anti-oxidants exclusively expressed in seeds. Two (a LEA6 and 1-cys-peroxiredoxin) are not expressed in vegetative tissues in A. thaliana, but have orthologues that are specifically activated in desiccating leaves of Xerophyta humilis. A comparison of antioxidant enzyme activity in two desiccation-sensitive species of Eragrostis with the desiccation-tolerant E. nindensis showed equivalent responses upon initial dehydration, but activity was retained at low water content in E. nindensis only. We propose that these antioxidants are housekeeping enzymes and that they are protected from damage in the desiccation-tolerant species. Sucrose is considered an important protectant against desiccation in orthodox seeds, and we show that sucrose accumulates in drying leaves of E. nindensis, but not in the desiccation-sensitive Eragrostis species. The activation of ''seed-specific'' desiccation protection mechanisms (sucrose accumulation and expression of LEA6 and 1-cys-peroxiredoxin genes) in the vegetative tissues of desiccation-tolerant plants points towards acquisition of desiccation tolerance from seeds.
Desiccation-tolerance in vegetative tissues of angiosperms has a polyphyletic origin and could be due to 1) appropriation of the seed-specific program of gene expression that protects orthodox seeds against desiccation, and/or 2) a sustainable version of the abiotic stress response. We tested these hypotheses by comparing molecular and physiological data from the development of orthodox seeds, the response of desiccation-sensitive plants to abiotic stress, and the response of desiccation-tolerant plants to extreme water loss. Analysis of publicly-available gene expression data of 35 LEA proteins and 68 anti-oxidant enzymes in the desiccation-sensitive Arabidopsis thaliana identified 13 LEAs and 4 anti-oxidants exclusively expressed in seeds. Two (a LEA6 and 1-cys-peroxiredoxin) are not expressed in vegetative tissues in A. thaliana, but have orthologues that are specifically activated in desiccating leaves of Xerophyta humilis. A comparison of antioxidant enzyme activity in two desiccation-sensitive species of Eragrostis with the desiccation-tolerant E. nindensis showed equivalent responses upon initial dehydration, but activity was retained at low water content in E. nindensis only. We propose that these antioxidants are housekeeping enzymes and that they are protected from damage in the desiccation-tolerant species. Sucrose is considered an important protectant against desiccation in orthodox seeds, and we show that sucrose accumulates in drying leaves of E. nindensis, but not in the desiccation-sensitive Eragrostis species. The activation of ''seed-specific'' desiccation protection mechanisms (sucrose accumulation and expression of LEA6 and 1-cys-peroxiredoxin genes) in the vegetative tissues of desiccation-tolerant plants points towards acquisition of desiccation tolerance from seeds.
Revista Árvore
Understanding the loss of desiccation tolerance is of great importance in seed technology for its implications in the development of strategies for seed conservation and seedling production. In the present work, the loss of desiccation tolerance was studied in seeds of tree species Bowdichia virgilioides, Libidibia ferrea, Cedrela fissilis, Enterolobium contortisiliquum, Handroanthus impetiginosus, and Piptadenia gonoacantha. The seeds were collected in the region of Lavras, MG, and subjected to desiccation experiments individually for each species. Imbibition curve was created for each species by measuring seed weight at regular intervals under germination conditions. Based on this information, the seeds were allowed to imbibe for a time inferred from the imbibition curve, and then allowed to dry until reaching the initial water content measured before the imbibition begun. Then, the seeds were rehydrated, and those that developed into normal seedlings were considered desiccation-t...
Size is not everything for desiccation-sensitive seeds
Journal of Ecology, 2012
1. Almost 50% of all seed plants produce desiccation-sensitive seeds. For these species, pregermination survival may be equally as important a basis of seed trait selection as seedling establishment. However, few studies have explored correlations among seed traits considered influential in the retention of viability prior to germination. 2. We examine four physiological traits: critical water content (W r50), the mean seed water content when a cohort of seeds reaches 50% mortality, desiccation rate (t 0.368), the time taken for each seed to reach a relative water content of 36.8%, mean time to germination (T G), the time taken for 50% of seeds within a cohort to germinate; and specific relative water content (W M), the proportion of available water to dry seed mass; two morphological traits: seed size (M D), dry seed mass and seed coat ratio (SCR), the proportional mass between the seed coat and dry seed mass; and one phenological variable: mean monthly rainfall at mean time of seed dispersal (R M) in 16 plant species that produce desiccation-sensitive seeds from a seasonal tropical forest in Cairns, Queensland. 3. We first test for relationships among species, and then assess relationships between species in trait space via principal component analysis (PCA). Regression analysis revealed a significant negative relationship between R M and SCR, so that species that had dispersal periods at times of high moisture availability invested proportionally less into seed coats. No other pairwise trait combinations were significantly related. PCA revealed two axes of trait space. The first axis was associated with the traits SCR, T G , t 0.368 , R M and W M , and explained 44.1% of the variation between species. There were strong positive loadings for SCR, T G and t 0.368, and strong negative loadings for R M and W M. Traits with strong loadings on the second axis (total variance 21%) were M D and W r50 and W M. There were strong positive loadings for W r50 and strong negative loadings for M D and W M. 4. Synthesis. Our findings reveal an axis of trait variability among desiccation-sensitive seeds that is orthogonal to size. These traits might be important in surviving pre-germination environmental conditions, independent of the advantages and/or disadvantages that size has been shown to confer on seed survival and seedling establishment. The implication of this finding is that seed size alone may not account for pre-germination viability in desiccation-sensitive seeds and may be inadequate to predict long-term persistence of these species if climate changes occur on the scale predicted.
Towards a systems-based understanding of plant desiccation tolerance
Trends in Plant Science, 2009
Vegetative desiccation tolerance occurs in a unique group of species termed 'resurrection plants'. Here, we review the molecular genetic, physiological, biochemical, ultrastructural and biophysical studies that have been performed on a variety of resurrection plants to discover the mechanisms responsible for their tolerance. Desiccation tolerance in resurrection plants involves a combination of molecular genetic mechanisms, metabolic and antioxidant systems as well as macromolecular and structural stabilizing processes. We propose that a systems-biology approach coupled with multivariate data analysis is best suited to unraveling the mechanisms responsible for plant desiccation tolerance, as well as their integration with one another. This is of particular relevance to molecular biological engineering strategies for improving plant drought tolerance in important crop species, such as maize (Zea mays) and grapevine (Vitis vinifera).
Seed desiccation: a bridge between maturation and germination
Trends in Plant Science, 2010
The development of orthodox seeds concludes by a desiccation phase. The dry seeds then enter a phase of dormancy, also called the after-ripening phase, and become competent for germination. We discuss physiological processes as well as gene expression and metabolic programs occurring during the desiccation phase in respect to their contribution to the desiccation tolerance, dormancy competence and successful germination of the dry seeds. The transition of developing seeds from the phase of reserve accumulation to desiccation is associated with distinct gene expression and metabolic switches. Interestingly, a significant proportion of the gene expression and metabolic signatures of seed desiccation resemble those characterizing seed germination, implying that the preparation of the seeds for germination begins already during seed desiccation.