GB

12_MycorrhizaF24

Introduction

  • Course: Bio 101 Fall 2024

  • Topic: Mycorrhiza

Learning Objectives

  • Differentiate between fungi and plants.

  • Define symbiosis.

  • Explain mutualism and provide evidence for it.

  • Discuss benefits of mutualism for fungi and plants.

Classification of Life

  • Five Kingdom System (Whittaker's System):

    • Kingdoms: Plantae, Fungi, Animalia, Ciliophora, Monera

    • Eukaryotic kingdoms include multicellular and unicellular organisms.

Kingdom Fungi

  • Description: Eukaryotic microbes that play a vital role as decomposers, recycling carbon and other elements.

  • Types of Fungi: Molds, mildews, yeast, truffles, mushrooms, rusts.

  • Structure:

    • Bodies are mycelial.

    • Cell walls made of chitin or cellulose.

    • Primarily reproduce asexually; sexual reproduction occurs via spores.

Structure of Fungi

  • Key Components:

    • Fruiting Body: the reproductive structure.

    • Hyphae: the filamentous threads that form the mycelium.

    • Mycelium: network of hyphae, functions in nutrient absorption.

Reproduction in Fungi

  • Process:

    • Young fruiting bodies form spores.

    • Spores germinate in proper conditions (moisture, nutrients).

    • Hyphae grow and mate to form new fungal structures.

Symbiosis

  • Definition: Close relationship between two or more species.

  • Types:

    • Mutualism (+/+): both species benefit.

    • Commensalism (+/o): one benefits, the other is unaffected.

    • Parasitism (+/-): one benefits at the other's expense.

Mycorrhizal Types

  • Two Main Guilds of Mycorrhizae:

    • Arbuscular Mycorrhiza (AM): distinct physiological traits.

    • Ectomycorrhiza (EM): distinct functional traits.

Mycorrhizal Distribution

  • Variation by Region:

    • AM trees dominate in some areas, EM in others across the U.S.

Ecological Importance of Mycorrhizae

  • Functions:

    • Facilitate nutrient exchange (Phosphorus or Nitrogen for carbohydrates).

    • Act as pollutant filters.

    • Improve resistance to pathogens.

    • Create connections among resilient plants.

Evidence for Carbon Transfer

  • Study: Examines net transfer of carbon between ectomycorrhizal species.

  • Findings:

    • Significant carbon transfer occurs in trees facilitated by mycorrhizal fungi.

    • Research conducted in British Columbia, Canada.