Comprehensive Plant Biology & Evolution: Structures, Reproduction, Symbiosis

Reasons plants are amazing

1) Plants can't move (deal with local conditions), 2) Plants make their own food from sunlight, 3) Plants can regenerate/clone themselves, 4) Plants do all this quietly and modestly

Red dots on plant evolution charts

Important mutation events that enabled plants to live on land instead of in water

Blue highlighting on plant evolution charts

Plants with vascular systems (tubes to move water and nutrients)

Early flowering plants appearance

During the mid-Cretaceous era

Else Marie Friis discovery about early flowers

That they were actually tiny, not huge as people assumed in the 1960s

Main functions of plant cell walls

Store CO2, connect cells, act as exoskeleton, determine shape, provide barriers, anchor sensory proteins, protect from pathogens, provide xylem strength

Main cell wall components

1) Cellulose (strong fiber), 2) Hemicellulose (holds cellulose together), 3) Pectin (gel-like, affects water/ion transport), 4) Lignin (glue/cement that makes wood stiff)

Recalcitrance

The intrinsic resistance of cell walls to decomposition of their component polymers to sugars and aromatics

Meristems

Special spots in plants where cells keep dividing so the plant can grow

Types of meristems

1) Shoot apical meristem (makes new stems/leaves), 2) Root apical meristem (makes roots grow longer)

Primary vs Secondary growth

Primary growth = makes plants taller/creates basic form; Secondary growth = makes plants thicker (like tree trunks)

Phytomer

A repeating unit that builds plant stems/branches; contains internode, node, leaf, and axillary bud

Types of plant tissues

1) Dermal tissue (outer protection), 2) Ground tissue (fills most of plant, stores food), 3) Vascular tissue (plumbing system)

Parts of vascular tissue

1) Xylem (transports water/minerals up from roots), 2) Phloem (moves sugars from leaves to other parts)

Apical dominance

The top bud prevents side buds from growing (makes plant grow up, not out); removing top bud allows side branches

Abscission

Plant hormones (auxin and ethylene) slow production and tell stem to drop old leaves

Location of plant DNA

In the nucleus (and other places), surrounded by nuclear envelope with nuclear pores

Main flower parts for reproduction

Stamen (male part - anther produces pollen), Carpel/pistil (female part - contains ovary/ovule)

Pollination

Moving pollen grains from anther (male) to stigma

Self-pollination

Within same flower (easy but causes inbreeding)

Cross-pollination

Between different plants (healthier, more variety)

Double fertilization

Two sperm in pollen tube: 1) One joins egg → makes embryo, 2) Other joins polar nuclei → makes endosperm (seed food)

Embryogenesis

Process where fertilized egg grows into tiny baby plant (embryo) and builds up food for after seed sprouts

Mutualism

A symbiotic relationship where both organisms benefit

Commensalism

A symbiotic relationship where one organism benefits without negatively affecting the other

Coevolution

Linked adaptations of two or more organisms that evolve together

Lichens

A composite of fungus + photosynthetic partner (usually algae), NOT plants; about 14,000 species worldwide

Lichens and air quality

They 'eat' the air and are like 'canaries in the coal mine' - sensitive species need clean air, tough species can handle pollution

Lichen deserts

Areas with so much pollution that even tough lichens can't survive (like downtown areas)

Arbuscular mycorrhizal fungi

80% of plants, agricultural importance

Ectomycorrhizal fungi

Mainly trees like pines/oaks

Over-achievers with mycorrhizal partnerships

Willows, poplars, aspens, eucalyptus (use both types)

Under-achievers with mycorrhizal partnerships

Cabbage, spinach, macadamia nuts (use neither)

Nitrogen-fixing bacteria (rhizobia)

Convert nitrogen gas from air into forms plants can use, living in special nodules on plant roots

Plant growth-promoting rhizobacteria (PGPR)

Live around roots and help plants fight diseases, get nutrients, and handle stress

Plant-fungal partnerships

About 400+ million years - almost as long as land plants have existed

Forgotten apple varieties

Each was unique (grown from seeds, not cloned), had different flavors/uses, and told stories about local history and people

Types of apples

Transparent (early, delicate), Dessert (eating raw), Cooking (baking, firm), Cider (bitter, for hard cider)

Lichens in Edmonton

River valley = diverse lichens (clean, humid air filtered by trees); Downtown = lichen desert (polluted air); Hilltops = fewer lichens (drier conditions)