Related Experiment Video

Updated: Jul 21, 2026

Bacterial Leaf Infiltration Assay for Fine Characterization of Plant Defense Responses using the Arabidopsis thaliana-Pseudomonas syringae Pathosystem
11:50

Bacterial Leaf Infiltration Assay for Fine Characterization of Plant Defense Responses using the Arabidopsis thaliana-Pseudomonas syringae Pathosystem

Published on: October 1, 2015

Roles for mannitol and mannitol dehydrogenase in active oxygen-mediated plant defense

D B Jennings1, M Ehrenshaft, D M Pharr

  • 1Department of Horticultural Science, North Carolina State University, Raleigh, NC 27695-7609, USA.

Proceedings of the National Academy of Sciences of the United States of America
|December 9, 1998
PubMed

Insights

Phytopathogenic fungi like Alternaria alternata use mannitol to suppress plant defenses. However, plants can counteract this by degrading fungal mannitol using mannitol dehydrogenase, a key defense mechanism.

Area of Science:

  • Plant-pathogen interactions
  • Plant immunity
  • Fungal metabolism

Background:

  • Reactive oxygen species (ROS) are crucial for plant defense signaling and pathogen resistance.
  • Many fungi produce mannitol, a ROS scavenger, which can suppress ROS-mediated plant defenses.
  • The interaction between fungal mannitol production and plant defense mechanisms is not fully understood.

Purpose of the Study:

  • To investigate the role of mannitol in the interaction between the phytopathogenic fungus Alternaria alternata and host plants.
  • To elucidate the plant's mechanism for counteracting fungal mannitol-mediated suppression of defense responses.

Main Methods:

  • Induction of mannitol production and secretion in Alternaria alternata was analyzed in the presence of host-plant extracts.
  • Expression of mannitol dehydrogenase, a mannitol-catabolizing enzyme, was studied in a non-mannitol-producing plant.
  • Plant responses to fungal infection and defense inducers were assessed in relation to mannitol dehydrogenase activity.

Main Results:

  • Alternaria alternata demonstrated induced mannitol production and secretion when exposed to host-plant extracts.
  • A non-mannitol-producing plant showed induced mannitol dehydrogenase in response to fungal infection and plant defense elicitors.
  • This suggests a plant-based counter-defense mechanism against fungal mannitol.

Conclusions:

  • Plants can induce mannitol dehydrogenase to catabolize fungal-derived mannitol, thereby overcoming fungal suppression of ROS-mediated defenses.
  • This study reveals a novel plant defense strategy involving the degradation of a fungal metabolite.
  • Understanding this interaction is crucial for developing strategies to enhance plant resistance to fungal pathogens.

More Related Videos

A Strategy to Validate the Role of Callose-mediated Plasmodesmal Gating in the Tropic Response12:18

A Strategy to Validate the Role of Callose-mediated Plasmodesmal Gating in the Tropic Response

Published on: April 17, 2016

Pattern-Triggered Oxidative Burst and Seedling Growth Inhibition Assays in Arabidopsis thaliana04:11

Pattern-Triggered Oxidative Burst and Seedling Growth Inhibition Assays in Arabidopsis thaliana

Published on: May 21, 2019

Related Concept Videos

C4 Pathway and CAM01:27

C4 Pathway and CAM

Most plants use the C3 pathway for carbon fixation. However, some plants, such as sugar cane, corn, and cacti that grow in hot conditions, use alternative pathways to fix carbon and conserve energy loss due to photorespiration. Photorespiration is the process that occurs when the oxygen concentration is high. Under such conditions, the rubisco enzyme in the Calvin cycle binds O2 instead of CO2, which halts photosynthesis and consumes energy.
C4 Pathway
The C4 pathway is used by plants such as...
Regulation of Transpiration by Stomata02:04

Regulation of Transpiration by Stomata

During photosynthesis, plants acquire the necessary carbon dioxide and release the produced oxygen back into the atmosphere. Openings in the epidermis of plant leaves is the site of this exchange of gasses. A single opening is called a stoma—derived from the Greek word for “mouth.” Stomata open and close in response to a variety of environmental cues.
Responses to Heat and Cold Stress02:45

Responses to Heat and Cold Stress

Every organism has an optimum temperature range within which healthy growth and physiological functioning can occur. At the ends of this range, there will be a minimum and maximum temperature that interrupt biological processes.
Responses to Salt Stress02:02

Responses to Salt Stress

Salt stress—which can be triggered by high salt concentrations in a plant’s environment—can significantly affect plant growth and crop production by influencing photosynthesis and the absorption of water and nutrients.
The Calvin Benson Cycle01:46

The Calvin Benson Cycle

Ribulose 1,5- bisphosphate carboxylase/oxygenase (RuBisCo) is a critical enzyme that catalyzes carbon dioxide assimilation during photosynthesis. However, it is an inefficient enzyme, having an extremely slow catalytic rate. A typical enzyme can process about a thousand molecules per second; however, RuBisCo fixes only around three-carbon dioxides per second. Photosynthetic cells compensate for this slow rate by synthesizing very high amounts of RuBisCo, making it the most abundant single...
Oxygen Requirements and Growth Patterns01:29

Oxygen Requirements and Growth Patterns

Microorganisms exhibit diverse oxygen requirements and growth patterns driven by their metabolic strategies and environmental adaptations. Oxygen, while essential for many organisms, can also be toxic under certain conditions, shaping how microorganisms grow and survive.Oxygen Requirements of MicroorganismsMicroorganisms are classified based on their ability to use or tolerate oxygen:● Obligate aerobes like Mycobacterium tuberculosis need oxygen for energy production, as it serves as the...