Botany240 Exam 1

Solanaceae

nightshade family

Cultivated nightshades

potatoes, tomatoes, peppers, eggplant, tomato, tobacco, petunia

Characteristics of the flowers of nightshades

• superior ovary

• fruit is a berry

• 5 sepals, 5 petals, 5 stamens, often 2 carpels in wild species

• actinomorphic flowers (radially symmetrical)

• fusion of parts (corolla tube, stamens to corolla)

• close touching of parts (anthers) in some

• Some edible, some toxic (from alkaloids)

Nightshade family edibility

Some edible, some toxic (from alkaloids)

Why was the scientific name for tomatoes changed to genus Solanum?

DNA-based phylogenies show tomatoes are “nested within” genus Solanum, so the scientific name was changed to reflect current understanding of relationships.

true or false: potatoes are edible tubers

true

Why is soil hilled up around plants to prevent exposure to sunshine?

helps prevent tubers from being exposed to sunlight which can cause greening and the production of a toxic alkaloid called Solanine

What in green potato tubers makes them toxic?

Solanine alkaloid in green potato tubers makes them toxic

Where did potatoes originate from?

Andean Mountains of South America

Thousands of varieties

Capsicum species

hot chili peppers and sweet peppers

how is the Capsicum species measured

scoville units

Tobacco = Nicotiana tabacum—Characteristics

• note fused corolla tube

• nicotine alkaloid can be used as an insecticide

  • use of some kinds of tobacco as ornamentals

Petunias as ornamentals

Fused corollas bred to be large, with varied showy colors

Underground storage organs

• Distinguish among root, tuber, tuberous root, bulb, corm, rhizome

• Note that tubers and corms are hard to distinguish, and botanists don’t agree on the definitions

• Likewise for distinguishing rhizomes and stolons, so I will not ask you questions to distinguish among them

True tap roots may have developed from tissues of…

hypocotyl as well as root.

true tap roots are often found in…

biennial crops that we grow as annuals (carrots, parsnips, turnips, etc.)

Tuberous roots

root tubers form from lateral roots

Examples of bulbs, corms, tubers, rhizomes, tuberous roots that we eat (or grow as ornamentals)?

• bulbs: onion, garlic, tulips

• corms: taro

• tubers: potatoes

• rhizomes: ginger

• tuberous roots: sweet potatoes

Allioideae subfamily

Allium

onion/garlic family

onion, garlic, chives, shallots, ramps, garlic chives

Allioideae subfamily Characteristics

• flower parts in multiples of 3

• strap-like leaves, may be flattened or cylindrical and hollow with parallel veins

• bulbs usually at base

• scape (flowerstalk with no leaves) leading up to an umbel (inflorescence in which all the flowers come out at one point—umbrella)

• Odor is like garlic/onions (sulfur compounds)

• Fruit is capsule with three carpels

• most are edible to humans (but not for dogs and cats)

Poaceae

grass/cereal grain family

Poaceae Characteristics

• fruits are grains (or achenes)

  • grains are seeds with fruit fused to seed wall

  • achenes are seeds free in the cavity (sunflower)

• non-shattering rachis and increased number of seeds in domesticated grains

• 3 stamens

• parallel leaf veins

• specialized wind pollinated flowers

• rhizome: horizontal, underground stem

• stolon: horizontal stem that grows along the surface of the ground

• spikelets

• specialized, wind-pollinated flowers (florets) surrounded by bracts called lemma, palea, and

  glumes.

Poaceae Fruits

• grains: single seeded, seed fused to fruit wall

• achene: single seeded, seed free from fruit wall (sunflower)

grain structure

• endosperm—starch, protein

• Bran—fiber

  • seed coat

  • pericarp

• germ (embryo)—protein, fats

What are the 3 crops that provide most of calories to humanity?

1. rice

2. wheat

3. maize

Traits of domesticated grains:

1. non-shattering: plant keeps seeds instead of dispersing when mature

2. free-threshing: plant has ability to drop its seed when threshed (manual beaten to drop seeds)

grains are polyploidy

• role of polyploidy in evolution of wheat

  • having more than 2 sets of chromosomes; 

• Ploidy levels (number of chromosome sets) of

  • einkorn: 2—non-shattering mutation

  • emmer: 4—hybridization event, higher protein

  • durum: 4—free-threshing mutation

  • bread wheat: 6—even higher protein

gluten contains:

1. glutenin: protein in gluten that aids in stickiness and viscosity

2. gliadin: protein in gluten that aids in elasticity

Zea mays subsp. mays

• Researchers of maize domestication

  • Hugh Iltis

  • John Doebley

• compare domesticated maize to wild teosinte

  • same biological species

  • maize has many ranks (columns)

• traits of teosinte ear and grains

  • 2 ranks (columns) of grain

  • grains imprisoned in a woody shell

• Iltis’s alternative hypothesis of why Zea was domesticated if grain was not originally edible

  • could maize have been domesticated for its sweet stems and not the grain?

• What is the relevance to central Balsas River valley in Mexico to origin of maize?

  • this is where the original teosinte grew

Fabaceae

legume/bean/pea/pulse family

Fabaceae Characteristics

• fruit is legume—dry dehiscent

• habits of trees. shrubs, herbs

• zygomorphic flower (bilateral symmetry)

  • specialized petals called standard, wings, and keel

• compound leaves often trifoliate, pinnate, sometimes palmate

• leaves with stipules

• harbor Rhizobia in root nodules (symbiosis) which fix nitrogen

  • role in nitrogen cycle

Fabaceae fruit

Legume: one carpel but opens/splits  into two sides

domesticated legumes:

• have fruits that do not split open

• larger seeds than wild ones

• if wild ones have toxins, the domesticated ones usually do not have toxins

Monocot Species of the week

1. Allioideae

2. Poaceae

adaptive syndrome of domestication

1. deliberate selection

OR

2. not deliberate ("unconscious selection")

where and when does domestication take place?

• domestication centers around the world

• timing of domestication: oldest known archaeological evidence is 10,000 to 12,000 years old

typical traits of the domestication syndrome

1. loss of seed dispersal mechanism

2. shattering and non-shattering rachis

   1. evidence from archaeology of rice

   2. wheat comparing wild ancestor, emmer, durum, bread wheat

3. divert biomass to parts used by humans

   1. examples from eastern North America domestication center: compare sizes of achenes of marsh elder and sunflower, squash seeds

4. reduction of seed dormancy

   1. goosefoot Chenopodium berlandieri seed coat (testa) thickness as example

5. loss of toxic or unpalatable compounds under domestication.

   1. Cucurbita pepo (squash/pumpkin/gourd) as example

6. Divergent selection from one wild species to several different crops for different purposes.

   1. Beta vulgaris L. selection into separate crops: beetroot, Swiss chard, sugar beet

   2. Cannabis sativa L. selection for fiber, oil, or THC (and now CBD)

Conservation of crop genetic diversity—examples of need for conservation:

• Irish potato famine

• Southern corn leaf blight

• International Rice Research Institute (IRRI) in the Philippines is breeding "climate ready rice"

  • selecting for: tolerance to drought, heat, salinity, and submergence

in-situ conservation

takes place on the farm

ex-situ conservation

takes place in gene banks

Nitrogen fixing

process of converting atmospheric nitrogen gas into a biologically useful form such as amonia

rhizobia

• Rhizobium and other related bacteria form a symbiotic mutualistic relationship with legumes

  • legumes provide bacteria with a home (root nodules) and nutrients

  • bacteria fix atmospheric nitrogen into usable form for plant

Symbiosis

close interaction between two species

Mutualistic

to the benefit of both

Nitrogen-fixing Rhizobia in legume root nodules

• role of nitrogen fixing bacteria in nitrogen cycle.

• Most nitrogen in living things came from this process in the past, but now:

  • Haber-Bosch industrial nitrogen fixation, introduced in 1913, is responsible for about half of the nitrogen in our bodies today (or half of humans being alive today). It is one of the biggest uses of energy in agriculture today.