Mini-Review / Perspective / Commentary: The presence of oxygenated lipids in plant defense in response to biotic stress: a metabolomics appraisal

Glutathione and reactive oxygen species (ROS) play important roles, within different cell compartments, in activating plant defense and the development of resistance. In mitochondria, the accumulation of ROS and the change of glutathione towards its oxidized state leads to mitochondrial dysfunction, activates cell death, and triggers resistance. The accumulation of glutathione in chloroplasts and peroxisomes at the early stages of plant pathogen interactions is related to increased tolerance and resistance. The collapse of the antioxidative system in these two cell compartments at the later stages leads to cell death through retrograde signaling. The cytosol can be considered to be the switchboard during biotic stress where glutathione is synthesized, equally distributed to, and collected from different cell compartments. Changes in the redox state of glutathione and the accumulation of ROS in the cytosol during biotic stress can initiate the activation of defense genes in nuclei through pathways that involve salicylic acid, jasmonic acid, auxins, and abscisic acid. This review dissects the roles of glutathione in individual organelles during compatible and incompatible bacterial, fungal, and viral diseases in plants and explores the subcelluar roles of ROS, glutathione, ascorbate, and related enzymes in the development of resistance.

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Insight into melatonin-mediated response and signaling in the regulation of plant defense under biotic stress

Plant Molecular Biology ◽

10.1007/s11103-021-01202-3 ◽

2021 ◽

Author(s):

Rahul Kumar Tiwari ◽

Milan Kumar Lal ◽

Ravinder Kumar ◽

Vikas Mangal ◽

Muhammad Ahsan Altaf ◽

...

Keyword(s):

Plant Defense ◽

Biotic Stress ◽

Insight Into

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Plant Defense Responses to Biotic Stress and Its Interplay With Fluctuating Dark/Light Conditions

Frontiers in Plant Science ◽

10.3389/fpls.2021.631810 ◽

2021 ◽

Vol 12 ◽

Author(s):

Zahra Iqbal ◽

Mohammed Shariq Iqbal ◽

Abeer Hashem ◽

Elsayed Fathi Abd_Allah ◽

Mohammad Israil Ansari

Keyword(s):

Plant Defense ◽

Biotic Stress ◽

Defense Mechanisms ◽

Defense Mechanism ◽

Defense Responses ◽

Light Environment ◽

Microbial Pathogens ◽

Signaling Cascade ◽

Dark Light ◽

The Impact

Plants are subjected to a plethora of environmental cues that cause extreme losses to crop productivity. Due to fluctuating environmental conditions, plants encounter difficulties in attaining full genetic potential for growth and reproduction. One such environmental condition is the recurrent attack on plants by herbivores and microbial pathogens. To surmount such attacks, plants have developed a complex array of defense mechanisms. The defense mechanism can be either preformed, where toxic secondary metabolites are stored; or can be inducible, where defense is activated upon detection of an attack. Plants sense biotic stress conditions, activate the regulatory or transcriptional machinery, and eventually generate an appropriate response. Plant defense against pathogen attack is well understood, but the interplay and impact of different signals to generate defense responses against biotic stress still remain elusive. The impact of light and dark signals on biotic stress response is one such area to comprehend. Light and dark alterations not only regulate defense mechanisms impacting plant development and biochemistry but also bestow resistance against invading pathogens. The interaction between plant defense and dark/light environment activates a signaling cascade. This signaling cascade acts as a connecting link between perception of biotic stress, dark/light environment, and generation of an appropriate physiological or biochemical response. The present review highlights molecular responses arising from dark/light fluctuations vis-à-vis elicitation of defense mechanisms in plants.

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Abscisic Acid-Induced Stomatal Closure: An Important Component of Plant Defense Against Abiotic and Biotic Stress

Frontiers in Plant Science ◽

10.3389/fpls.2021.615114 ◽

2021 ◽

Vol 12 ◽

Author(s):

Pulimamidi Bharath ◽

Shashibhushan Gahir ◽

Agepati S. Raghavendra

Keyword(s):

Abscisic Acid ◽

Plant Defense ◽

Biotic Stress ◽

Stomatal Closure ◽

Compatible Solutes ◽

Guard Cells ◽

Model Systems ◽

Stress Factors ◽

Abiotic And Biotic Stress ◽

Reactive Carbonyl Species

Abscisic acid (ABA) is a stress hormone that accumulates under different abiotic and biotic stresses. A typical effect of ABA on leaves is to reduce transpirational water loss by closing stomata and parallelly defend against microbes by restricting their entry through stomatal pores. ABA can also promote the accumulation of polyamines, sphingolipids, and even proline. Stomatal closure by compounds other than ABA also helps plant defense against both abiotic and biotic stress factors. Further, ABA can interact with other hormones, such as methyl jasmonate (MJ) and salicylic acid (SA). Such cross-talk can be an additional factor in plant adaptations against environmental stresses and microbial pathogens. The present review highlights the recent progress in understanding ABA’s multifaceted role under stress conditions, particularly stomatal closure. We point out the importance of reactive oxygen species (ROS), reactive carbonyl species (RCS), nitric oxide (NO), and Ca2+ in guard cells as key signaling components during the ABA-mediated short-term plant defense reactions. The rise in ROS, RCS, NO, and intracellular Ca2+ triggered by ABA can promote additional events involved in long-term adaptive measures, including gene expression, accumulation of compatible solutes to protect the cell, hypersensitive response (HR), and programmed cell death (PCD). Several pathogens can counteract and try to reopen stomata. Similarly, pathogens attempt to trigger PCD of host tissue to their benefit. Yet, ABA-induced effects independent of stomatal closure can delay the pathogen spread and infection within leaves. Stomatal closure and other ABA influences can be among the early steps of defense and a crucial component of plants’ innate immunity response. Stomatal guard cells are quite sensitive to environmental stress and are considered good model systems for signal transduction studies. Further research on the ABA-induced stomatal closure mechanism can help us design strategies for plant/crop adaptations to stress.

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