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.