Receptor kinases (RKs) are of paramount importance in transmembrane signaling that governs plant reproduction, growth, development, and adaptation to diverse environmental conditions. Receptor-like ...cytoplasmic kinases (RLCKs), which lack extracellular ligand-binding domains, have emerged as a major class of signaling proteins that regulate plant cellular activities in response to biotic abiotic stresses and endogenous extracellular signaling molecules. By associating with immune RKs, RLCKs regulate multiple downstream signaling nodes to orchestrate a complex array of defense responses against microbial pathogens. RLCKs also associate with RKs that perceive brassinosteroids and signaling peptides to coordinate growth, pollen tube guidance, embryonic and stomatal patterning, floral organ abscission, and abiotic stress responses. The activity and stability of RLCKs are dynamically regulated not only by RKs but also by other RLCK-associated proteins. Analyses of RLCK-associated components and substrates have suggested phosphorylation relays as a major mechanism underlying RK-mediated signaling.
It is well established that oxidative stress is an important cause of cellular damage. During stress conditions, plants have evolved regulatory mechanisms to adapt to various environmental stresses. ...One of the consequences of stress is an increase in the cellular concentration of reactive oxygen species, which is subsequently converted to H2O2. H2O2 is continuously produced as the byproduct of oxidative plant aerobic metabolism. Organelles with a high oxidizing metabolic activity or with an intense rate of electron flow, such as chloroplasts, mitochondria, or peroxisomes are major sources of H2O2 production. H2O2 acts as a versatile molecule because of its dual role in cells. Under normal conditions, H2O2 immerges as an important factor during many biological processes. It has been established that it acts as a secondary messenger in signal transduction networks. In this review, we discuss potential roles of H2O2 and other signaling molecules during various stress responses.
Present and future food security is a critical issue compounded by the consequences of climate change on agriculture. Stress perception and signal transduction in plants causes changes in gene or ...protein expression which lead to metabolic and physiological responses. Phytohormones play a central role in the integration of different upstream signals into different adaptive outputs such as changes in the activity of ion-channels, protein modifications, protein degradation, and gene expression. Phytohormone biosynthesis and signaling, and recently also phytohormone crosstalk have been investigated intensively, but the function of jasmonates under abiotic stress is still only partially understood. Although most aspects of jasmonate biosynthesis, crosstalk and signal transduction appear to be similar for biotic and abiotic stress, novel aspects have emerged that seem to be unique for the abiotic stress response. Here, we review the knowledge on the role of jasmonates under drought and salinity. The crosstalk of jasmonate biosynthesis and signal transduction pathways with those of abscisic acid (ABA) is particularly taken into account due to the well-established, central role of ABA under abiotic stress. Likewise, the accumulating evidence of crosstalk of jasmonate signaling with other phytohormones is considered as important element of an integrated phytohormonal response. Finally, protein post-translational modification, which can also occur without de novo transcription, is treated with respect to its implications for phytohormone biosynthesis, signaling and crosstalk. To breed climate-resilient crop varieties, integrated understanding of the molecular processes is required to modulate and tailor particular nodes of the network to positively affect stress tolerance.
Various environmental stresses singly or in combination generate excess amounts of reactive oxygen species (ROS), leading to oxidative stress and impaired redox homeostasis. Generation of ROS is the ...obvious outcome of abiotic stresses and is gaining importance not only for their ubiquitous generation and subsequent damaging effects in plants but also for their diversified roles in signaling cascade, affecting other biomolecules, hormones concerning growth, development, or regulation of stress tolerance. Therefore, a good balance between ROS generation and the antioxidant defense system protects photosynthetic machinery, maintains membrane integrity, and prevents damage to nucleic acids and proteins. Notably, the antioxidant defense system not only scavenges ROS but also regulates the ROS titer for signaling. A glut of studies have been executed over the last few decades to discover the pattern of ROS generation and ROS scavenging. Reports suggested a sharp threshold level of ROS for being beneficial or toxic, depending on the plant species, their growth stages, types of abiotic stresses, stress intensity, and duration. Approaches towards enhancing the antioxidant defense in plants is one of the vital areas of research for plant biologists. Therefore, in this review, we accumulated and discussed the physicochemical basis of ROS production, cellular compartment-specific ROS generation pathways, and their possible distressing effects. Moreover, the function of the antioxidant defense system for detoxification and homeostasis of ROS for maximizing defense is also discussed in light of the latest research endeavors and experimental evidence.
Salt stress reduces land and water productivity and contributes to poverty and food insecurity. Increased salinization caused by human practices and climate change is progressively reducing ...agriculture productivity despite escalating calls for more food. Plant responses to salt stress are well understood, involving numerous critical processes that are each controlled by multiple genes. Knowledge of the critical mechanisms controlling salt uptake and exclusion from functioning tissues, signaling of salt stress, and the arsenal of protective metabolites is advancing. However, little progress has been made in developing salt-tolerant varieties of crop species using standard (but slow) breeding approaches. The genetic diversity available within cultivated crops and their wild relatives provides rich sources for trait and gene discovery that has yet to be sufficiently utilized. Transforming this knowledge into modern approaches using genomics and molecular tools for precision breeding will accelerate the development of tolerant cultivars and help sustain food production.
Abiotic stress, a serious threat to plants, occurs for extended periods in nature. Abscisic acid (ABA) plays a critical role in abiotic stress responses in plants. Therefore, stress responses ...mediated by ABA have been studied extensively, especially in short‐term responses. However, long‐term stress responses mediated by ABA remain largely unknown. To elucidate the mechanism by which plants respond to prolonged abiotic stress, we used long‐term ABA treatment that activates the signalling against abiotic stress such as dehydration and investigated mechanisms underlying the responses. Long‐term ABA treatment activates constitutive photomorphogenic 1 (COP1). Active COP1 mediates the ubiquitination of golden2‐like1 (GLK1) for degradation, contributing to lowering expression of photosynthesis‐associated genes such as glutamyl‐tRNA reductase (HEMA1) and protochlorophyllide oxidoreductase A (PORA), resulting in the suppression of chloroplast development. Moreover, COP1 activation and GLK1 degradation upon long‐term ABA treatment depend on light intensity. Additionally, plants with COP1 mutation or exposed to higher light intensity were more sensitive to salt stress. Collectively, our results demonstrate that long‐term treatment of ABA leads to activation of COP1 in a light intensity‐dependent manner for GLK1 degradation to suppress chloroplast development, which we propose to constitute a mechanism of balancing normal growth and stress responses upon the long‐term abiotic stress.
Here, we show that long‐term ABA promotes GLK1 degradation through COP1 to suppress chloroplast development dependent on light intensity, revealing that balancing normal growth and stress response in long‐term stress.
PDF
