Related Experiment Video
Updated: Jul 4, 2026
08:16
Inoculation Strategies to Infect Plant Roots with Soil-Borne Microorganisms
Published on: March 1, 2022
Mannitol biosynthesis is required for plant pathogenicity by Alternaria alternata
Heriberto Vélëz1, Norman J Glassbrook, Margaret E Daub
1Department of Plant Pathology, NC State University, Raleigh, NC 27695, USA.
FEMS Microbiology Letters
|June 14, 2008
Summary
Mannitol biosynthesis is crucial for the fungus Alternaria alternata to cause disease in tobacco. While not essential for initial infection, it is required for full pathogenicity.
Area of Science:
- Mycology
- Plant Pathology
- Biochemistry
Background:
- Mannitol is a sugar alcohol with a hypothesized role in antioxidant defense.
- The enzymes mannitol dehydrogenase (MtDH) and mannitol 1-phosphate 5-dehydrogenase (MPDH) are involved in mannitol biosynthesis.
- Alternaria alternata is a fungal pathogen that affects tobacco plants.
Purpose of the Study:
- To investigate the role of mannitol biosynthesis in the pathogenicity of Alternaria alternata on tobacco.
- To determine if trehalose can substitute for mannitol in fungal germination and storage.
- To assess the necessity of mannitol for spore germination, appressoria formation, and host penetration.
Main Methods:
- Generation of disruption mutants for MtDH and MPDH enzymes in Alternaria alternata.
- Gas chromatography-mass spectrometry (GC-MS) for analyzing carbohydrate composition.
- In planta pathogenicity assays on tobacco and microscopy for infection structure analysis.
Main Results:
- Mutants exhibited normal conidia viability and germination.
- Elevated trehalose levels were observed in mutants, suggesting it as a potential substitute storage compound.
- The MPDH mutant and the double mutant showed significantly reduced disease severity on tobacco compared to wild type.
- The double mutant successfully germinated, formed appressoria, and initiated infection, but caused less disease.
Conclusions:
- Mannitol biosynthesis is essential for the full pathogenesis of Alternaria alternata on tobacco.
- Mannitol is not required for spore germination (in vitro or in planta) or initial host infection.
- Trehalose may play a compensatory role in mannitol-deficient mutants for germination and storage.
More Related Videos
Related Concept Videos
01:09Microbe-Plant Interactions
Microbe-plant interactions represent a dynamic spectrum of associations shaped by intricate chemical signaling. These interactions can be neutral, beneficial, or detrimental, and profoundly influence plant physiology, growth, and ecosystem function. The plant microbiome, comprising bacteria, fungi, archaea, protists, and viruses, plays a pivotal role in mediating these effects through surface colonization, internal colonization, or systemic symbiosis.Mutualistic associations, particularly with...
02:22Introduction to Plant Diversity
From Water to Land
01:29Fungal Group Zygomycota
Zygomycota, previously classified as a distinct fungal group, are primarily terrestrial, saprophytic molds that play a crucial role as decomposers. Recent phylogenetic studies have revealed that these fungi are now divided into two major clades — Mucoromycota, which includes many symbiotic species, and Zoopagomycota, which primarily consists of parasitic and pathogenic fungi. These groups exhibit distinct ecological roles and reproductive strategies while sharing key structural and...
01:27C4 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...
C4 Pathway
The C4 pathway is used by plants such as...
02:26Defenses Against Pathogens and Herbivores
Plants present a rich source of nutrients for many organisms, making it a target for herbivores and infectious agents. Plants, though lacking a proper immune system, have developed an array of constitutive and inducible defenses to fend off these attacks.
01:02Role of Microtubules in Cell Wall Deposition
Microtubules are small hollow tubes in eukaryotic cells. The cell wall microtubules are polymerized dimers of two globular proteins, α-tubulin and β-tubulin, two globular proteins. With a diameter of about 25 nm, microtubules are the widest components of the cytoskeleton. They help the cell resist compression and provide a track along which vesicles move through the cell or pull replicated chromosomes to opposite ends of a dividing cell. Microtubules go through quick cycles of disassembly and...