Definition: A symbiotic relationship involves different organisms living closely together, often to mutual benefit.
Plants and Fungi: Over 90% of plants engage in a symbiotic relationship with fungi, particularly through structures called mycorrhizae, where plant roots and fungal hyphae intertwine.
Historical Significance: This relationship is believed to have begun over 500 million years ago when plants began to occupy terrestrial environments.
Ancestry: The aquatic ancestors of land plants are from over 500 million years ago.
Habitat: Early plants occupied nearshore habitats.
Adaptation to Drought: The experience of periodic drying led these plants to develop drought tolerance, which was crucial for survival on land.
Moisture Retention: Mechanisms to maintain moisture in plant bodies.
Structural Support: Development of strong structures to support plants against gravity.
Seed Dispersal: Adaptations for effective seed dispersal mechanisms to ensure propagation.
Transition from algal ancestors to land plants around 470 mya.
Vascular Plants: Emerged around 425 mya.
Seed Plants: First appeared approximately 360 mya.
Nonvascular Plants: Examples include mosses and liverworts.
Vascular Plants: Include lycophytes (e.g., club mosses) and monilophytes (e.g., ferns).
Gymnosperms: Naked seed plants such as conifers.
Angiosperms: Flowering plants that include grasses, shrubs, and trees.
Era: 359-299 million years ago (Coal Forests).
Characteristics: Dominated by mosses and ferns; significant levels of photosynthesis altered atmospheric CO2 levels leading to climate cooling.
Fossil Fuels: Remains of these plants form current fossil fuels.
Current Diversity: Seed plants account for over 90% of modern plant species.
Gymnosperms: Include conifers known for producing naked seeds.
Angiosperms: Known as flowering plants, produce seeds enclosed within fruits, crucial for various ecosystems.
Flower Production: Is energy-intensive but results in significant reproductive advantages.
Pollinator Attraction: Adaptation of flowers to attract pollinators is common; 90% of angiosperms rely on animals for pollen transfer.
Fruit: Represents a ripened ovary of a flower aiding in seed dispersal (e.g., dandelions, edible fruits).
Role: Mycorrhizae are critical in assisting plants with nutrient absorption from the soil, enhancing water and mineral uptake significantly.
Types: Various types of fungi form these beneficial relationships with plants, important for soil health and ecosystem stability.
Hyphae: The basic structural units of fungi that make up the mycelium.
Reproductive Structures: Fungi produce spores via specialized fruiting bodies.
Life Cycle: Involves alternation of generations, with both haploid (n) and diploid (2n) phases, and includes heterokaryotic stages with unfused nuclei.
Chytrids: Primitive fungi known for their flagellated spores.
Zygomycetes: Known for producing zygospores.
Ascomycetes: Sac fungi, responsible for producing spores in sac-like structures.
Basidiomycetes: Club fungi, include mushrooms and shelf fungi.
Leaves: Where photosynthesis occurs; important adaptations such as the cuticle to minimize water loss.
STOMATA: Structures allowing gas exchange; critical for respiration and photosynthesis.
Support Systems: Stems and vascular tissues provide necessary physical support and nutrient transportation.
Mycorrhizal Associations: Enhance nutrient and water uptake through roots' interaction with fungal networks, leading to improved plant health and growth.