Water Stress - Types, Causes And Response Of Plants To Water Stress
It has been discovered that water stress is the most significant limiting factor that plays a role in controlling primary production in terrestrial environments. The rate of transpiration in plants will slow down when there is less water available to the roots of the plant, which is what we mean when we talk about water stress. It is most commonly brought on by a lack of water, which may be due to conditions of drought or the salinity of the soil.
Katya RyderAug 03, 20233370 Shares146513 Views
It has been discovered that water stressis the most significant limiting factor that plays a role in controlling primary production in terrestrial environments.
The rate of transpiration in plants will slow down when there is less water available to the roots of the plant, which is what we mean when we talk about water stress.
It is most commonly brought on by a lack of water, which may be due to conditions of drought or the salinity of the soil.
The disruption of agricultural production that results from water stress ultimately leads to a decrease in the amount of food that is produced globally, which in turn causes starvation.
One of the most common environmental factors that affect plant growth is stress caused by an insufficient supply of water.
Through catalytic processes like phosphorylation, membrane-localized receptor and sensor proteins communicate information to cytoplasmic target proteins.
The first step in determining the water status of the environment outside may involve signaling at the plasma membrane.
Osmotic-stress signaling in prokaryotes is mediated by AHK1, an Arabidopsis plasma membrane HK.
AHK1 also functions as an osmosensor.
Arabidopsis developed drought resistance due to AHK1 overexpression.
AHK1 is an osmosensor and a positive regulator of osmotic-stress signaling, as shown by the decreased abscisic acid (ABA) sensitivity and downregulation of ABA and/or stress-responsive genes in AHK1 mutants.
As a multiple His-Asp phosphorelay, it appears that AHPs and ARRs regulate the downstream AHK1 cascades.
It is unclear which components make up signaling cascades or which factors are affected by AHK1 signals.
According to research on Arabidopsis, the ABA and drought signaling are negatively regulated by the cytokinin (CK) receptor HKs, AHK2, AHK3, and AHK4.
Numerous ahk2, ahk3, and ahk4 mutants are ABA-sensitive and drought-resistant.
These findings imply that there is cross-talk between the ABA, CK, and stress signaling pathways.
In Arabidopsis, there are more than 600 members of the receptor-like kinase (RLK) family, with LRR-RLKs constituting the largest subgroup.
The plasma membrane-localized RLKs are the first step in the osmotic-stress signaling pathway in many plant species.
It is possible that environmental stimuli can activate RLK-mediated signaling pathways and transmit external osmotic conditions because these stress-related RLKs have a variety of extracellular domains (such as an LRR domain, an extensin-like domain, or a cysteine-rich domain).
Recent studies suggest that RLKs that bind to cell walls, such as CrRLKs (Catharanthus roseus RLK1-like family), proline-rich extensin-like receptor kinases (PERKs), and WAKs, may play a role in the perception of turgor pressure.
An association between RLKs and cell-wall binding, ABA biosynthesis, and the water stress response may be discovered by examining the roles of RLKs in signaling systems linked to mechanosensing pathways activated by water stress.
This finding may contribute to our understanding of the early signaling mechanism that regulates growth and tolerance to water stress.
Plant photosynthesis is impacted by the reduced carbon dioxide (CO2) availability caused by stomatal closure and/or photosynthetic metabolism.
Excess light (EL) reduces photosynthesis when water stress lowers rates of photosynthesis.
An estimated 70% of the genes activated by EL are also activated by drought. EL promotes the production of reactive oxygen species (ROS), such as H2O2, superoxide (O2-), and singlet oxygen (1O2), which also inhibits photosynthesis, through photochemical and biochemical processes.
Several genes are up-regulated by H2O2, some of which overlap with genes that are also up-regulated in response to methyl viologen, extremely cold or hot temperatures, or protracted drought.
Cytosolic ascorbate peroxidase (APX)-encoding genes (cytosolic APXs) transcription is induced by light stress and the plastoquinone redox state. These genes help remove hydrogen peroxide from cytosol.
Degraded chloroplast proteins accumulated in APX loss-of-function mutants, indicating that APXs shield chloroplast proteins from ROS under EL conditions.
It is possible that APX mediates ROS scavenging in response to oxidative stress and nutrient limitation because AtAPX2 was also induced by drought stress and ABA.
Gain-of-function mutant altered apx2 expression 8 (alx8) with increased APX2 expression enhanced Water use efficiency (WUE) and drought resistance.
In Arabidopsis, plants exposed to EL or ROS treatment induce the zinc-finger TFs ZAT10 and ZAT12. APXs and other stress-related genes were induced by ZAT10 and ZAT12 overexpression.
Increased drought stress tolerance was seen in several transgenic lines that overexpressed ZAT10.
The regulation of ROS-mediated responses to EL and drought by ZAT10 and ZAT12 may safeguard photosynthesis under water stress.