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Paramvir Singh Ahuja - One of the best experts on this subject based on the ideXlab platform.
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tea camellia sinensis clones with shorter periods of winter Dormancy exhibit lower accumulation of reactive oxygen species
Tree Physiology, 2007Co-Authors: Dhiraj Vyas, Sanjay Kumar, Paramvir Singh AhujaAbstract:Tea (Camellia sinensis (L.) O. Kuntze) is a perennial crop grown throughout the world. During winter, tea undergoes a Dormancy period when growth of apical buds almost ceases, severely reducing the commercial yield of tea. Low temperatures prevail during the period of winter Dormancy, which alone or in combination with high solar irradiance have the potential to induce oxidative stress in plants. We studied six tea clones under field conditions to test whether a relationship exists between oxidative stress and winter Dormancy. Data on the behavior of the enzymatic antioxidative system was collected for all clones during different phases of winter Dormancy. There was a strong positive correlation among clones between accumulation of reactive oxygen species (ROS) and the length of the Dormancy period. Clones having shorter Dormancy periods exhibited higher induction of antioxidative enzymes. Results suggest that efficient scavenging of ROS is a desirable feature in tea because it leads to lower accumulations of ROS during winter months and is associated with reduced winter Dormancy.
Dhiraj Vyas - One of the best experts on this subject based on the ideXlab platform.
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tea camellia sinensis clones with shorter periods of winter Dormancy exhibit lower accumulation of reactive oxygen species
Tree Physiology, 2007Co-Authors: Dhiraj Vyas, Sanjay Kumar, Paramvir Singh AhujaAbstract:Tea (Camellia sinensis (L.) O. Kuntze) is a perennial crop grown throughout the world. During winter, tea undergoes a Dormancy period when growth of apical buds almost ceases, severely reducing the commercial yield of tea. Low temperatures prevail during the period of winter Dormancy, which alone or in combination with high solar irradiance have the potential to induce oxidative stress in plants. We studied six tea clones under field conditions to test whether a relationship exists between oxidative stress and winter Dormancy. Data on the behavior of the enzymatic antioxidative system was collected for all clones during different phases of winter Dormancy. There was a strong positive correlation among clones between accumulation of reactive oxygen species (ROS) and the length of the Dormancy period. Clones having shorter Dormancy periods exhibited higher induction of antioxidative enzymes. Results suggest that efficient scavenging of ROS is a desirable feature in tea because it leads to lower accumulations of ROS during winter months and is associated with reduced winter Dormancy.
Mark Norton - One of the best experts on this subject based on the ideXlab platform.
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Summer Dormancy in perennial temperate grasses
Annals of Botany, 2006Co-Authors: Florence Volaire, Mark NortonAbstract:• Background and Aims Dormancy has been extensively studied in plants which experience severe winter conditions but much less so in perennial herbaceous plants that must survive summer drought. This paper reviews the current knowledge on summer Dormancy in both native and cultivated perennial temperate grasses originating from the Mediterranean Basin, and presents a unified terminology to describe this trait. • Scope Under severe drought, it is difficult to separate the responses by which plants avoid and tolerate dehydration from those associated with the expression of summer Dormancy. Consequently, this type of endogenous (endo-) Dormancy can be tested only in plants that are not subjected to moisture deficit. Summer Dormancy can be defined by four criteria, one of which is considered optional: (1) reduction or cessation of leaf production and expansion; (2) senescence of mature foliage; (3) dehydration of surviving organs; and (4, optional) formation of resting organs. The proposed terminology recognizes two levels of summer Dormancy: (a) complete Dormancy, when cessation of growth is associated with full senescence of foliage and induced dehydration of leaf bases; and (b) incomplete Dormancy, when leaf growth is partially inhibited and is associated with moderate levels of foliage senescence. Summer Dormancy is expressed under increasing photoperiod and temperature. It is under hormonal control and usually associated with flowering and a reduction in metabolic activity in meristematic tissues. Dehydration tolerance and Dormancy are independent phenomena and differ from the adaptations of resurrection plants. • Conclusions Summer Dormancy has been correlated with superior survival after severe and repeated summer drought in a large range of perennial grasses. In the face of increasing aridity, this trait could be used in the development of cultivars that are able to meet agronomic and environmental goals. It is therefore important to have a better understanding of the genetic and environmental control of summer Dormancy
Florence Volaire - One of the best experts on this subject based on the ideXlab platform.
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Summer Dormancy in ochardgrass: evaluation and characterization through physiological and genetic studies
Crop Science, 2009Co-Authors: Naima Shaimi, Rajae Kallida, Florence Volaire, Chaouki Al FaizAbstract:Climatic change manifested by increasing summer drought necessitates the development of drought-tolerant forage grass cultivars. Summer Dormancy is a major trait conferring drought survival and autumn recovery of perennial grasses in Mediterranean areas. Moroccan ecotypes of orchardgrass (Dactylis glomerata L.) expressed 67% greater degree of summer Dormancy than tested cultivars except the highly dormant ‘Kasbah.’ Furthermore, summer Dormancy was highly correlated with perenniality (r = 0.63, P < 0.01). However, summer Dormancy was associated with low productivity. A breeding program was started to develop productive orchardgrass cultivars with high summer Dormancy. Hybrids between high- and low-Dormancy cultivars produced offspring with combinations of enhanced Dormancy and biomass production indicating potential for breaking the negative Dormancyyield association. For example, Kasbah (dormant) × ‘Medly’ (summer-active) hybrids were 57% more dormant than Medly and 32% higher yielding than Kasbah. Genetic analysis of heritability and molecular markers will provide more information on the genetic control of summer Dormancy. Results of crosses between contrasting populations of orchardgrass indicate potential for combining the desirable traits of summer Dormancy and high annual herbage yield into an eventual cultivar
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Summer drought survival strategies and sustainability of perennial temperate forage grasses in mediterranean aereas
Crop Science, 2009Co-Authors: Florence Volaire, M.r. Norton, François LelièvreAbstract:Perennial grasslands provide numerous agroenvironmental benefits due to continuous soil cover. In Mediterranean areas, chronic summer drought is expected to increase as a result of climate changes. Plant adaptations that protect meristematic tissues include dehydration delay, dehydration tolerance, and summer Dormancy. Summer Dormancy can only be reliably tested in plants not subjected to water deficit. Under summer irrigation, complete Dormancy is manifested by cessation of growth in association with full senescence of foliage and induced dehydration of leaf bases. Incomplete Dormancy occurs when leaf growth is partially constrained and associated with moderate levels of foliage senescence. Summer Dormancy is under hormonal control and is induced under increasing photoperiod and temperature. Recent results show that drought cannot induce summer Dormancy under early-spring short days, although a water deficit under late-spring long days reinforces it and could enhance drought survival. Dehydration tolerance and Dormancy are independent phenomena. Summer Dormancy has been correlated with superior survival after severe summer droughts in many perennial grass species. This trait has potential for improving cultivars able to meet agronomic and environmental goals.
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Summer Dormancy in perennial temperate grasses
Annals of Botany, 2006Co-Authors: Florence Volaire, Mark NortonAbstract:• Background and Aims Dormancy has been extensively studied in plants which experience severe winter conditions but much less so in perennial herbaceous plants that must survive summer drought. This paper reviews the current knowledge on summer Dormancy in both native and cultivated perennial temperate grasses originating from the Mediterranean Basin, and presents a unified terminology to describe this trait. • Scope Under severe drought, it is difficult to separate the responses by which plants avoid and tolerate dehydration from those associated with the expression of summer Dormancy. Consequently, this type of endogenous (endo-) Dormancy can be tested only in plants that are not subjected to moisture deficit. Summer Dormancy can be defined by four criteria, one of which is considered optional: (1) reduction or cessation of leaf production and expansion; (2) senescence of mature foliage; (3) dehydration of surviving organs; and (4, optional) formation of resting organs. The proposed terminology recognizes two levels of summer Dormancy: (a) complete Dormancy, when cessation of growth is associated with full senescence of foliage and induced dehydration of leaf bases; and (b) incomplete Dormancy, when leaf growth is partially inhibited and is associated with moderate levels of foliage senescence. Summer Dormancy is expressed under increasing photoperiod and temperature. It is under hormonal control and usually associated with flowering and a reduction in metabolic activity in meristematic tissues. Dehydration tolerance and Dormancy are independent phenomena and differ from the adaptations of resurrection plants. • Conclusions Summer Dormancy has been correlated with superior survival after severe and repeated summer drought in a large range of perennial grasses. In the face of increasing aridity, this trait could be used in the development of cultivars that are able to meet agronomic and environmental goals. It is therefore important to have a better understanding of the genetic and environmental control of summer Dormancy
Yong Xiang - One of the best experts on this subject based on the ideXlab platform.
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reversal of rdo5 1 a homolog of rice seed Dormancy4 interacts with bhlh57 and controls aba biosynthesis and seed Dormancy in arabidopsis
The Plant Cell, 2020Co-Authors: Hui Zhang, Ling Ding, W J Soppe, Yong XiangAbstract:The control of seed Dormancy by abscisic acid (ABA) has been extensively studied, but the underlying mechanism is not fully understood. Here, we report the characterization of two ABA-related seed Dormancy regulators in Arabidopsis (Arabidopsis thaliana): ODR1 (for reversal of rdo5), an ortholog of the rice (Oryza sativa) Seed Dormancy4 (Sdr4), and the basic helix-loop-helix transcription factor bHLH57. ODR1, whose transcript levels are directly suppressed by the transcription factor ABA INSENSITIVE3 (ABI3), negatively regulates seed Dormancy by affecting ABA biosynthesis and ABA signaling. By contrast, bHLH57 positively regulates seed Dormancy by inducing the expression of the genes 9-CIS-EPOXYCAROTENOID DIOXYGENASE6 (NCED6) and NCED9, which encode ABA biosynthetic enzymes, and thus leads to higher ABA levels. ODR1 interacts with bHLH57 and inhibits bHLH57-modulated NCED6 and NCED9 expression in the nucleus. bhlh57 loss-of-function alleles can partially counteract the enhanced NCED6 and NCED9 expression seen in odr1 mutants and can therefore rescue their associated hyper-Dormancy phenotype. Thus, we identified a novel ABI3-ODR1-bHLH57-NCED6/9 network that provides insights into the regulation of seed Dormancy by ABA biosynthesis and signaling.
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reduced Dormancy5 encodes a protein phosphatase 2c that is required for seed Dormancy in arabidopsis
The Plant Cell, 2014Co-Authors: Yong Xiang, Leónie Bentsink, Kazumi Nakabayashi, Jia Ding, Fei He, W J SoppeAbstract:Seed Dormancy determines germination timing and contributes to crop production and the adaptation of natural populations to their environment. Our knowledge about its regulation is limited. In a mutagenesis screen of a highly dormant Arabidopsis thaliana line, the reduced Dormancy5 (rdo5) mutant was isolated based on its strongly reduced seed Dormancy. Cloning of RDO5 showed that it encodes a PP2C phosphatase. Several PP2C phosphatases belonging to clade A are involved in abscisic acid signaling and control seed Dormancy. However, RDO5 does not cluster with clade A phosphatases, and abscisic acid levels and sensitivity are unaltered in the rdo5 mutant. RDO5 transcript could only be detected in seeds and was most abundant in dry seeds. RDO5 was found in cells throughout the embryo and is located in the nucleus. A transcriptome analysis revealed that several genes belonging to the conserved PUF family of RNA binding proteins, in particular Arabidopsis PUMILIO9 (APUM9) and APUM11, showed strongly enhanced transcript levels in rdo5 during seed imbibition. Further transgenic analyses indicated that APUM9 reduces seed Dormancy. Interestingly, reduction of APUM transcripts by RNA interference complemented the reduced Dormancy phenotype of rdo5, indicating that RDO5 functions by suppressing APUM transcript levels.
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the time required for Dormancy release in arabidopsis is determined by delay of germination1 protein levels in freshly harvested seeds
The Plant Cell, 2012Co-Authors: Kazumi Nakabayashi, Emma Miatton, Yong Xiang, Melanie Bartsch, Silke Pellengahr, Ryoichi Yano, Mitsunori Seo, W J SoppeAbstract:Seed Dormancy controls the start of a plant’s life cycle by preventing germination of a viable seed in an unfavorable season. Freshly harvested seeds usually show a high level of Dormancy, which is gradually released during dry storage (afterripening). Abscisic acid (ABA) has been identified as an essential factor for the induction of Dormancy, whereas gibberellins (GAs) are required for germination. The molecular mechanisms controlling seed Dormancy are not well understood. DELAY OF GERMINATION1 (DOG1) was recently identified as a major regulator of Dormancy in Arabidopsis thaliana. Here, we show that the DOG1 protein accumulates during seed maturation and remains stable throughout seed storage and imbibition. The levels of DOG1 protein in freshly harvested seeds highly correlate with Dormancy. The DOG1 protein becomes modified during after-ripening, and its levels in stored seeds do not correlate with germination potential. Although ABA levels in dog1 mutants are reduced and GA levels enhanced, we show that DOG1 does not regulate Dormancy primarily via changes in hormone levels. We propose that DOG1 protein abundance in freshly harvested seeds acts as a timer for seed Dormancy release, which functions largely independent from ABA.