Physiology And Molecular Biology Of Stress Tolerance In Plants Pdf
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- Biotechnological Approaches to Study Plant Responses to Stress
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- Physiological, Biochemical, and Molecular Mechanisms of Heat Stress Tolerance in Plants
- Physiology and Molecular Biology of Stress Tolerance in Plants
Drought stress is an increasingly common and worrying phenomenon because it causes a loss of production in both agriculture and forestry. Teak is a tropical tree which needs alternating rainy and dry seasons to produce high-quality wood. However, a robust understanding about the physiological characteristics and genes related to drought stress in this species is lacking. Consequently, after applying moderate and severe drought stress to teak seedlings, an infrared gas analyzer IRGA was used to measure different parameters in the leaves.
Biotechnological Approaches to Study Plant Responses to Stress
Plant responses to abiotic stresses during vegetative growth have been extensively studied for many years. Daily environmental fluctuations can have dramatic effects on plant vegetative growth at multiple levels, resulting in molecular, cellular, physiological, and morphological changes.
Plants are even more sensitive to environmental changes during reproductive stages. However, much less is known about how plants respond to abiotic stresses during reproduction.
Fortunately, recent advances in this field have begun to provide clues about these important processes, which promise further understanding and a potential contribution to maximize crop yield under adverse environments. Here we summarize information from several plants, focusing on the possible mechanisms that plants use to cope with different types of abiotic stresses during reproductive development, and present a tentative molecular portrait of plant acclimation during reproductive stages.
Additionally, we discuss strategies that plants use to balance between survival and productivity, with some comparison among different plants that have adapted to distinct environments.
Plants are sessile and cannot move to avoid unfavorable environmental conditions; therefore, they must cope with adverse environmental conditions by cellular changes. The environmental factors that can limit plant growth and reproduction include water, temperature, light, and nutrients Zhu, Fluctuations in these abiotic conditions may lead to minute initial cellular changes and subsequently result in a series of dramatic biochemical, physiological, and morphological changes in plants Osakabe et al.
These impacts have been extensively studied and discussed for plant responses during vegetative development Cramer et al. Adverse abiotic factors also negatively impact plant reproduction and yield; such negative effects are responsible for substantial losses in agriculture and economy Hasanuzzaman et al. Despite the importance, there have been a relatively small number of studies on plant reproductive development under abiotic stresses.
This is partly because studies involving reproductive development require longer plant growth periods with more space and greater efforts to obtain the relevant materials. For example, Arabidopsis thaliana floral buds are small, requiring meticulous handling of tiny floral organs such as the stamen and pistil Wellmer et al. Moreover, the high degree of sensitivity of reproducing plants to environmental changes means that small changes of the growth condition could cause phenotypical differences, making it difficult to recognize phenotypic changes due to gene functional manipulations.
More importantly, with the rapid advances of reverse genetics, the lack of obvious phenotypic differences is often considered as no effect due to a mutation, whereas potentially measurable quantitative traits are not investigated, with missed opportunities for uncovering gene functions.
Nevertheless, recent advances in technologies such as large-scale data analysis Su et al. Here, we summarize studies Table 1 that explored plant reproductive development under abiotic stresses, and discuss strategies that plants employ in response to different types of abiotic stresses at reproductive stages. Water availability is one of the most important abiotic factors that affect plant growth and development. Both drought and salt stresses can lead to water scarcity, especially given that both stresses change osmotic homeostasis, accumulate similar metabolites, and can activate overlapping signaling pathways Zhu, , Drought is known to cause flowering time change, flower abortion, reduction of pollen fertility and seed number, as well as immature or aborted seeds in plants Su et al.
Salt stress also has similar negative effects on reproductive development in rice, wheat, and grape Khan and Abdullah, ; Zheng et al.
Below, we discuss molecular genetic analyses of gene functions and genes identified using large-scale experiments Fig. Transcriptional regulation, epigenetic regulation, and protein modification are labeled in yellow, purple, and green boxes, respectively. Key regulators discussed in this review are listed with the same color codes.
Guo et al. In general, changes in floral morphology, seed production, and related gene expression patterns together support the importance of the gene function in reproductive development under stress. In an Arabidopsis study in which plants were treated with drought starting at the onset of flowering to the end of their life cycle Su et al. Floral defects were observed at different flower stages in drought-treated plants, including abnormal anther development, lower pollen viability, reduced filament elongation, ovule abortion, and failure of the flower to open.
These genes can mitigate anther defects and improve pollen fertility and seed production under drought stress. Specifically, ANAC functions as an early drought response regulator, which can be induced in flowers soon 3 d after drought treatment Su et al.
The mRNA level of ANAC is much higher in the inflorescence than in the leaf when plants are grown with insufficient water, especially when plants recover after a period 7—14 d of acclimation to severe drought Sukiran et al. The anac mutant showed significant shortening of the stamen and pistil, and delayed recovery of flowering under drought stress as compared with the wild-type WT plant. In addition, several important drought-responsive and floral genes were expressed differentially in the anac mutant compared with the WT, consistent with mutant phenotypes.
These observations support a critical role for ANAC in promoting not only reproductive development but also drought tolerance Fig. Another Arabidopsis gene, AtMYB37 , also plays an important role in drought response and regulation of seed production, as overexpression lines displayed both increased seed production and drought tolerance; moreover, the expression levels of several key ABA-responsive genes were altered in these lines Yu et al.
Flower development under drought stress: morphological and transcriptomic analyses reveal acute responses and long-term acclimation in Arabidopsis. The Plant Cell 25, —, www. Ovals represent genes with known functions in either stress response or developmental process; boxes show different proposed functions.
Dashed lines with arrows represent positive regulatory relationships, whereas hammer-ended dashed lines represent inhibitions. Red symbols indicate stress-related interactions, whereas cyan symbols indicate developmental regulation.
Another rice gene, OsERF , is also preferentially expressed in flowers, and transgenic lines with overexpression of OsERF displayed elevated peroxidase activity and proline content, which in turn contributed to increased drought tolerance and improved pollen fertility.
Together, these Arabidopsis and rice results strongly support the roles of TFs in drought response during reproductive development. However, the functions of some regulators in drought response and development are not similarly conserved.
It was demonstrated that the Atbhlh mutant exhibits reduced salt tolerance, whereas the overexpression of OsbHLH in Arabidopsis decreases levels of the reactive oxygen species ROS H 2 O 2 and enhances salt tolerance. However, the Atbhlh mutant and OsbHLH overexpression lines both exhibit late-flowering phenotypes. It is possible that the function of these two bHLH genes in stress response was ancestral, but the Arabidopsis and rice genes have diverged functionally in control of flowering time.
Although the molecular mechanisms are still unclear for regulation of downstream genes by the above-mentioned TFs, some studies have begun to address this question. It is known that salt stresses can delay flowering in Arabidopsis Riboni et al. The expression of a key regulator of flower development, AP1 , is reduced in salt-stressed plants, but the repression of AP1 expression is less severe in the atbft mutant than that in the WT Ryu et al.
Therefore, AtBFT functions as a floral repressor under high salinity. Delayed flowering is usually caused by the repression of flowering time genes.
This strategy allows plant to conserve energy and resources to survive the unfavorable environment. Future studies may yet reveal other mechanisms for transcriptional regulation. Another level of the regulation of gene expression is epigenetic regulation, which can impact seed germination, phase transition, flowering time control, vegetative and reproductive development, as well as defense and stress response Chinnusamy and Zhu, ; Pikaard and Mittelsten Scheid, One important and widely investigated aspect of epigenetic regulation is histone modification, which is involved in flowering and salt stress response Zhang et al.
One type of histone modification is methylation on an arginine R3 residue of the subunit histone 4 H4 and is carried out by arginine methyltranserases Wang et al. Furthermore, the atskb1 mutant is also hypersensitive to salt stress. It was also found that salt stress caused an increased methylation of the small nuclear ribonucleoprotein Sm-like4 AtLSM4, related to mRNA splicing and the atlsm4 mutant is sensitive to salt, suggesting that regulation of mRNA splicing might be important in tolerance to salt.
The authors therefore proposed that, under salt stress, plants exhibit decreased H4R3sme2 and altered splicing, inducing stress-responsive and floral repressor genes, and thus achieving salt tolerance and delayed flowering. In general, Polycomb group proteins act in an opposite fashion to the Trithorax group factors in regulating gene expression de la Paz Sanchez et al. Pu et al. Protein modifications, particularly protein phosphorylation, are important for multiple cellular processes, such as cell cycle progression controlled by cyclin-dependent kinases CDKs , and intracellular signaling regulated by the mitogen-activated protein kinase MAPK cascade Rodriguez et al.
Similarly, a study on rose Rosa hybrida flowers Meng et al. Other protein modifications likely to be involved in regulation of flower development under stress include protein palmitoylation. An analysis of AtPAT10, a member of the protein S -acyl transferase PAT family implicated in palmitoylation, showed that it is crucial for reproduction and salt stress response Zhou et al.
The two close paralogs in Arabidopsis, CBL2 and CBL3, function in both vegetative and reproductive development, with the double mutant showing impaired siliques and seeds and weak stress tolerance R. Tang et al.
Plant cells under osmotic stresses, such as drought and salt, are known to accumulate metabolites osmolytes such as glycine betaine GB and proline to reduce dehydration Yancey, For example, GB was found to play a role in salt tolerance during seed germination and vegetative growth Sakamoto and Murata, Specifically, enhanced GB synthesis in transgenic Arabidopsis plants help to protect plant reproductive organs against structural defects found in the WT under salt stress and promote salt tolerance in these transgenic plants Sulpice et al.
The differential expression in different organs of the two AtP5CS genes might lead to differential accumulation of proline and different degrees of stress tolerance. In addition, the loss of AtP5CS1 and AtP5CS2 function causes defective male gametophytes and reduced fertility, indicating that proline is required for pollen development Mattioli et al.
A rice nucleolin gene OsNUC1 is differentially expressed between salt-sensitive and salt-resistant rice lines under salt stress Sripinyowanich et al. Nucleolin is involved in the synthesis and maturation of ribosomes in the nucleolus.
However, the OsNUC1-S -expressing atnuc1-l lines displayed a higher growth rate with longer roots and lower H 2 O 2 levels under high salt conditions. In the Arabidopsis ferritin triple mutant fer , the elongation of stamen filaments was reduced, with a failure to position the anthers above the stigma, and stigmatic papillae rarely develop well, leading to sterility. Ravet et al. Also the expression of a rose ferritin gene RhFer1 is induced by dehydration and ABA during flower senescence.
Additionally, a putative rice lipid transfer protein gene OsDIL is expressed in the anther, primarily in response to drought, salt, cold, and ABA Guo et al. Overexpression of OsDIL in drought-treated rice plants led to elevated tolerance to drought stress during vegetative development and reduced anther defects at reproductive stages Guo et al.
In addition to the studies focusing on individual gene functions, transcriptomic studies have detected global gene expression changes during reproductive development under drought stresses in Arabidopsis and rice Jin et al.
In Arabidopsis plants treated with drought starting at the onset of flowering to the end of their life cycle Su et al. Different subsets of genes displayed different temporal expression patterns during the period of drought stress.
Genes responsive to water deprivation and the ABA signaling pathway were enriched among those up-regulated after 5 d of drought treatment, indicating enhanced stress response; whereas genes for cell cycle, DNA unwinding, and nucleosome assembly were repressed 5 d after drought treatment, suggesting that the growth rate was lowered.
As the severity of drought can be important, further studies were performed on the effects of various extents of drought Ma et al. As expected, the majority of genes showed similar levels of expression under MD as compared with SD. During four stages of flower development as monitored by size, most of these genes were affected in only one or two stages, suggesting that the developmental stage is a key determinant of drought response in flowers.
Genes involved in anther development, cell wall formation or expansion, and various signaling pathway were uncovered, indicating interactions between reproductive development and phytohormone signaling in drought-stressed plants. Taken together, under moderate drought conditions, plants induce the genes that function in protecting it against the stresses and in ensuring reproductive success. Under severe drought, however, plants attenuate the expression of genes for reproductive development, and devote greater amounts of energy and resources to ensure survival and, when possible, facilitate modest seed production after acclimation.
Temperature is another major factor affecting the distribution and seasonal behavior of plants. Plants under cold stresses exhibit plasma membrane disintegration, cold-induced dehydration, and metabolic dysfunction Yadav, In addition, cold-activated signaling pathways are also known to crosstalk with drought and salt stress signaling pathways Jonak et al. As global warming is approaching, plant species that are unable to alter flowering time in response to temperature are disappearing from their previous natural habitats, with a tendency to shift to higher altitudes and latitudes Quint et al.
In Arabidopsis, heat stress induces photosynthetic acclimation, respiration, and changes in carbon balance Quint et al. Both cold and heat stresses affect plant reproductive development. Here, we review the available information and discuss how plants respond to low or high temperature stress Fig.
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Plant responses to abiotic stresses during vegetative growth have been extensively studied for many years. Daily environmental fluctuations can have dramatic effects on plant vegetative growth at multiple levels, resulting in molecular, cellular, physiological, and morphological changes. Plants are even more sensitive to environmental changes during reproductive stages. However, much less is known about how plants respond to abiotic stresses during reproduction. Fortunately, recent advances in this field have begun to provide clues about these important processes, which promise further understanding and a potential contribution to maximize crop yield under adverse environments.
Multiple biotic and abiotic environmental stress factors affect negatively various aspects of plant growth, development, and crop productivity. Plants, as sessile organisms, have developed, in the course of their evolution, efficient strategies of response to avoid, tolerate, or adapt to different types of stress situations. The diverse stress factors that plants have to face often activate similar cell signaling pathways and cellular responses, such as the production of stress proteins, upregulation of the antioxidant machinery, and accumulation of compatible solutes. Over the last few decades advances in plant physiology, genetics, and molecular biology have greatly improved our understanding of plant responses to abiotic stress conditions. In this paper, recent progresses on systematic analyses of plant responses to stress including genomics, proteomics, metabolomics, and transgenic-based approaches are summarized. Plants and animals share some response mechanisms to unfavorable environmental conditions; however, plants, being sessile organisms, have developed, in the course of their evolution, highly sophisticated and efficient strategies of response to cope with and adapt to different types of abiotic and biotic stress imposed by the frequently adverse environment.
Physiological, Biochemical, and Molecular Mechanisms of Heat Stress Tolerance in Plants
Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. Sairam and A. Sairam , A.
Salinity is a major abiotic stress limiting growth and productivity of plants in many areas of the world due to increasing use of poor quality of water for irrigation and soil salinization. Plant adaptation or tolerance to salinity stress involves complex physiological traits, metabolic pathways, and molecular or gene networks. A comprehensive understanding on how plants respond to salinity stress at different levels and an integrated approach of combining molecular tools with physiological and biochemical techniques are imperative for the development of salt-tolerant varieties of plants in salt-affected areas. Recent research has identified various adaptive responses to salinity stress at molecular, cellular, metabolic, and physiological levels, although mechanisms underlying salinity tolerance are far from being completely understood.
Physiology and Molecular Biology of Stress Tolerance in Plants
Priming-Mediated Stress and Cross-Stress Tolerance in Crop Plants provides the latest, in-depth understanding of the molecular mechanisms associated with the development of stress and cross-stress tolerance in plants. Plants growing under field conditions are constantly exposed, either sequentially or simultaneously, to many abiotic or biotic stress factors. As a result, many plants have developed unique strategies to respond to ever-changing environmental conditions, enabling them to monitor their surroundings and adjust their metabolic systems to maintain homeostasis. Recently, priming mediated stress and cross-stress tolerance i. Priming-Mediated Stress and Cross-Stress Tolerance in Crop Plants comprehensively reviews the physiological, biochemical, and molecular basis of cross-tolerance phenomena, allowing researchers to develop strategies to enhance crop productivity under stressful conditions and to utilize natural resources more efficiently.
High temperature HT stress is a major environmental stress that limits plant growth, metabolism, and productivity worldwide. Plant growth and development involve numerous biochemical reactions that are sensitive to temperature. Plant responses to HT vary with the degree and duration of HT and the plant type. HT is now a major concern for crop production and approaches for sustaining high yields of crop plants under HT stress are important agricultural goals. Plants possess a number of adaptive, avoidance, or acclimation mechanisms to cope with HT situations. In addition, major tolerance mechanisms that employ ion transporters, proteins, osmoprotectants, antioxidants, and other factors involved in signaling cascades and transcriptional control are activated to offset stress-induced biochemical and physiological alterations.
The physiological and molecular mechanism of brassinosteroid in response to stress: a review. The negative effects of environmental stresses, such as low temperature, high temperature, salinity, drought, heavy metal stress, and biotic stress significantly decrease crop productivity. Plant hormones are currently being used to induce stress tolerance in a variety of plants. Brassinosteroids commonly known as BR are a group of phytohormones that regulate a wide range of biological processes that lead to tolerance of various stresses in plants. BR regulate antioxidant enzyme activities, chlorophyll contents, photosynthetic capacity, and carbohydrate metabolism to increase plant growth under stress.
Physiology and Molecular Biology of Stress Tolerance in Plants. Editors: Madhava Rao, K.V., Raghavendra, A.S., Janardhan Reddy, K. (Eds.) Free Preview.