Systemic responses to environmental stimuli are essential for the survival of multicellular organisms. In plants, they are initiated in response to many different signals including pathogens, ...wounding, and abiotic stresses. Recent studies highlighted the importance of systemic acquired acclimation to abiotic stresses in plants and identified several different signals involved in this response. These included reactive oxygen species (ROS) and calcium waves, hydraulic waves, electric signals, and abscisic acid (ABA). Here, we address the interactions between ROS and ABA at the local and systemic tissues of plants subjected to abiotic stress and attempt to propose a model for the involvement of ROS, ABA, and stomata in systemic signaling leading to systemic acquired acclimation.
► Hormones play central roles in plant adaptation to changing environments. ► Hormonal cross-talk regulates plant responses. ► Large changes in hormone content can have negative effects on plant ...growth and development. ► The use of inducible promoters will facilitate the generation of stress tolerance crops.
Plant hormones play central roles in the ability of plants to adapt to changing environments, by mediating growth, development, nutrient allocation, and source/sink transitions. Although ABA is the most studied stress-responsive hormone, the role of cytokinins, brassinosteroids, and auxins during environmental stress is emerging. Recent evidence indicated that plant hormones are involved in multiple processes. Cross-talk between the different plant hormones results in synergetic or antagonic interactions that play crucial roles in response of plants to abiotic stress. The characterization of the molecular mechanisms regulating hormone synthesis, signaling, and action are facilitating the modification of hormone biosynthetic pathways for the generation of transgenic crop plants with enhanced abiotic stress tolerance.
•Ion and pH homeostasis are critical for plant growth and stress responses.•NHX-type Na+/H+ antiporters (NHXs) are H+-coupled cation exchangers.•NHXs control cellular pH, K+ and Na+ ...homeostasis.•Emerging cellular and physiological functions of intracellular NHXs are highlighted.•Novel NHX roles include vesicle trafficking and the generation of vacuolar turgor.
The biochemical characterization of cation/H+ exchange has been known since 1985 1, yet only recently have we begun to understand the contribution of individual exchangers to ion homeostasis in plants. One particularly important class of exchangers is the NHX-type that is associated with Na+ transport and therefore salinity tolerance. New evidence suggests that under normal growth conditions NHXs are critical regulators of K+ and pH homeostasis and have important roles, depending on their cellular localization, in the generation of turgor as well as in vesicular trafficking. Recent advances highlight novel and exciting functions of intracellular NHXs in growth and development, stress adaptation and osmotic adjustment. Here, we elaborate on new and emerging cellular and physiological functions of this group of H+-coupled cation exchangers.
Two well-known pathways for the degradation of chloroplast proteins are via autophagy and senescence-associated vacuoles. Here, we describe a third pathway that was activated by senescence-and ...abiotic stress-induced expression of Arabidopsis thaliana CV (for chloroplast vesiculation). After targeting to the chloroplast, CV destabilized the chloroplast, inducing the formation of vesicles. CV-containing vesicles carrying stronfiai proteins, envelope membrane proteins, and thylakoid membrane proteins were released from the chloroplasts and mobilized to the vacuole for proteolysis. Overexpression of CV caused chloroplast degradation and premature leaf senescence, whereas silencing CV delayed chloroplast turnover and senescence induced by abiotic stress. Transgenic CIA-silenced plants displayed enhanced tolerance to drought, salinity, and oxidative stress. Immunoprecipitation and bimolecular fluorescence complementation assays demonstrated that CV interacted with photosystem II subunit PsbO1 in vivo through a C-terminal domain that is highly conserved in the plant kingdom. Collectively, our work indicated that CV plays a crucial role in stress-induced chloroplast disruption and mediates a third pathway for chloroplast degradation. From a biotechnological perspective, silencing of CV offers a suitable strategy for the generation of transgenic crops with increased tolerance to abiotic stress.
Summary
Reactive oxygen species (ROS) play a key role in the acclimation process of plants to abiotic stress. They primarily function as signal transduction molecules that regulate different pathways ...during plant acclimation to stress, but are also toxic byproducts of stress metabolism. Because each subcellular compartment in plants contains its own set of ROS‐producing and ROS‐scavenging pathways, the steady‐state level of ROS, as well as the redox state of each compartment, is different at any given time giving rise to a distinct signature of ROS levels at the different compartments of the cell. Here we review recent studies on the role of ROS in abiotic stress in plants, and propose that different abiotic stresses, such as drought, heat, salinity and high light, result in different ROS signatures that determine the specificity of the acclimation response and help tailor it to the exact stress the plant encounters. We further address the role of ROS in the acclimation of plants to stress combination as well as the role of ROS in mediating rapid systemic signaling during abiotic stress. We conclude that as long as cells maintain high enough energy reserves to detoxify ROS, ROS is beneficial to plants during abiotic stress enabling them to adjust their metabolism and mount a proper acclimation response.
Significance Statement
Reactive oxygen species (ROS) primarily function as signal transduction molecules that regulate different pathways during acclimation to stress, but are also toxic byproducts of stress metabolism. Different subcellular compartments contain different sets of ROS‐producing and ROS‐scavenging pathways, and thus ROS levels can have different signatures in different cellular compartments. Here we review recent work on ROS and abiotic stress, and propose that different stresses, such as drought, heat, salinity and high light, result in different ROS signatures that determine the specificity of the acclimation response to a particular stress.
SUMMARY
Global warming and climate change are driving an alarming increase in the frequency and intensity of different abiotic stresses, such as droughts, heat waves, cold snaps, and flooding, ...negatively affecting crop yields and causing food shortages. Climate change is also altering the composition and behavior of different insect and pathogen populations adding to yield losses worldwide. Additional constraints to agriculture are caused by the increasing amounts of human‐generated pollutants, as well as the negative impact of climate change on soil microbiomes. Although in the laboratory, we are trained to study the impact of individual stress conditions on plants, in the field many stresses, pollutants, and pests could simultaneously or sequentially affect plants, causing conditions of stress combination. Because climate change is expected to increase the frequency and intensity of such stress combination events (e.g., heat waves combined with drought, flooding, or other abiotic stresses, pollutants, and/or pathogens), a concentrated effort is needed to study how stress combination is affecting crops. This need is particularly critical, as many studies have shown that the response of plants to stress combination is unique and cannot be predicted from simply studying each of the different stresses that are part of the stress combination. Strategies to enhance crop tolerance to a particular stress may therefore fail to enhance tolerance to this specific stress, when combined with other factors. Here we review recent studies of stress combinations in different plants and propose new approaches and avenues for the development of stress combination‐ and climate change‐resilient crops.
Significance Statement
Climate change and global warming increase the likelihood that trees and crop plants will be subjected to a combination of different abiotic and biotic stresses, compromising global food production and security. This paper reviews recent advances in the study of plant responses to stress combinations and proposes potential strategies to develop crops with high resilience to a wide range of stress factors and their combination.
Abiotic stress conditions such as drought, heat, or salinity cause extensive losses to agricultural production worldwide. Progress in generating transgenic crops with enhanced tolerance to abiotic ...stresses has nevertheless been slow. The complex field environment with its heterogenic conditions, abiotic stress combinations, and global climatic changes are but a few of the challenges facing modern agriculture. A combination of approaches will likely be needed to significantly improve the abiotic stress tolerance of crops in the field. These will include mechanistic understanding and subsequent utilization of stress response and stress acclimation networks, with careful attention to field growth conditions, extensive testing in the laboratory, greenhouse, and the field; the use of innovative approaches that take into consideration the genetic background and physiology of different crops; the use of enzymes and proteins from other organisms; and the integration of QTL mapping and other genetic and breeding tools.
Abiotic and biotic stress combinations Suzuki, Nobuhiro; Rivero, Rosa M.; Shulaev, Vladimir ...
The New phytologist,
July 2014, Letnik:
203, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Environmental stress conditions such as drought, heat, salinity, cold, or pathogen infection can have a devastating impact on plant growth and yield under field conditions. Nevertheless, the effects ...of these stresses on plants are typically being studied under controlled growth conditions in the laboratory. The field environment is very different from the controlled conditions used in laboratory studies, and often involves the simultaneous exposure of plants to more than one abiotic and/or biotic stress condition, such as a combination of drought and heat, drought and cold, salinity and heat, or any of the major abiotic stresses combined with pathogen infection. Recent studies have revealed that the response of plants to combinations of two or more stress conditions is unique and cannot be directly extrapolated from the response of plants to each of the different stresses applied individually. Moreover, the simultaneous occurrence of different stresses results in a high degree of complexity in plant responses, as the responses to the combined stresses are largely controlled by different, and sometimes opposing, signaling pathways that may interact and inhibit each other. In this review, we will provide an update on recent studies focusing on the response of plants to a combination of different stresses. In particular, we will address how different stress responses are integrated and how they impact plant growth and physiological traits.
Cation/H
(NHX-type) antiporters are important regulators of intracellular ion homeostasis and are critical for cell expansion and plant stress acclimation. In Arabidopsis (
), four distinct NHX ...isoforms, named AtNHX1 to AtNHX4, locate to the tonoplast. To determine the concerted roles of all tonoplast NHXs on vacuolar ion and pH homeostasis, we examined multiple knockout mutants lacking all but one of the four vacuolar isoforms and quadruple knockout plants lacking any vacuolar NHX activity. The
triple and quadruple knockouts displayed reduced growth phenotypes. Exposure to sodium chloride improved growth while potassium chloride was deleterious to some knockouts. Kinetic analysis of K
and Na
transport indicated that AtNHX1 and AtNHX2 are the main contributors to both vacuolar pH and K
and Na
uptake, while AtNHX3 and AtNHX4 differ in Na
/K
selectivity. The lack of any vacuolar NHX activity resulted in no K
uptake, highly acidic vacuoles, and reduced but not abolished vacuolar Na
uptake. Additional K
/H
and Na
/H
exchange activity assays in the quadruple knockout indicated Na
uptake that was not H
coupled, suggesting the existence of an alternative, cation/H
-independent, Na
conductive pathway in vacuoles. These results highlight the importance of NHX-type cation/H
antiporters in the maintenance of cellular cation homeostasis and in growth and development.
Citrus is one of the world’s most important fruit crops, contributing essential nutrients, such as vitamin C and minerals, to the human diet. It is characterized by two important traits: first, its ...major edible part is composed of juice sacs, a unique structure among fruit, and second, relatively high levels of citric acid are accumulated in the vacuole of the juice sac cell. Although the major routes of primary metabolism are generally the same in citrus fruit and other plant systems, the fruit’s unique structural features challenge our understanding of carbon flow into the fruit and its movement through all of its parts. In fact, acid metabolism and accumulation have only been summarized in a few reviews. Here we present a comprehensive view of sugar, acid and amino acid metabolism and their connections within the fruit, all in relation to the fruit’s unique structure.
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