HORT227 Final Exam

What are the five major problems with cloning?

lose genetic purity, mutations, monocultures, clone degeneration, costs

Why are monocultures in the urban environment considered bad?

Monocultures are vulnerable to insects and disease.

What are the disease pathogens that can be perpetuated in clonal propagation?

Virus, bacteria, fungi, nematodes, and phytoplasms

Are viruses transmitted thru seed from an infected plant? Why?

No, the seed coat prevents this

What are some of the symptoms of viruses infected plants?

Stunted growth, unproductive plant, chlorosis, albinism mosaic pattern or variegation, witches' brooming

How do you detect if you have a virus?

visual inspection, grafting or budding, inoculating, culture indexing, electron microscopy, ELISA tests

How are pathogens (diseases) spread to clones?

Mechanical, insect vectors, nematodes, natural root grafting, pollen transfer, infected prop material

What is degeneration of a clone?

Plant loses vigor over time due to pathogens

How can you prevent diseases being propagated in clones? (there are 8 solutions, discuss at least 4)

disease/insect free stock, meristem tip tissue culture, clean facility, practice IPM, control pathogen vectors, heat treatment, thermotherapy

What are the advantages of using seed propagation over asexual propagation?

cheapest method, easy to handle, store, ship, genetic variability, germplasm preservation, virus free production

annuals

complete the entire life cycle from seed to flowering to death in one growing season, like tomatoes

Compare time till reproduction in annuals and biennials vs herbaceous and woody perennials

annuals and biennials shortest time, perennials take longest

Can you propagate ferns and mosses by seed?

No, they use spores

gymnosperms

produces a "naked" seed, no true fruit, includes juniper, conifers

Where are the seeds of each gymno v angiosperms?

Gymnosperm seeds form in strobili, angiosperm form in ovary

monocots

produce only one cotyledon at germination, like corn

monoecious

a plant that produces both male and female structures/flowers on one plant

Why do we need to know if a plant is either monoecious or dioecious in terms of pollination and seed propagation?

males smelly female messy

Does double fertilization occur in gymnosperms?

No, only angiosperms

What is a seed?

matured, ripened ovule inside a fruit

How does an embryo develop? What is its ploidy level?

results from union of male and female gametes, develops into the new plant, 2N

What are cotyledons and its ploidy level?

2N seed leaves, fall off, storage reserve

What is the function of the storage reserve tissue in seeds?

energy source before true leaves

What 3 areas in a seed can store material?

Endosperm, perisperm, cotyledons

What are the possible components of the storage reserve material inside a seed? (think tasty here)

oils, carbs, proteins

What is the endosperm ploidy level for monocots and dicots?

3N

What is the perisperm and its ploidy level?

2n ovule nucellus tissue

where does the seed coat come from in angiosperms

from ripened ovary and accessory tissue

What does the outer seed coating consist of?

remains of the nucellus and endosperm and sometimes part of the fruit

three stages of seed development

Embryo differentiation, cell expansion, maturation drying

What major hormone is involved in seed development

Gibberellic acid

orthodox seeds

seeds tolerate maturation drying and survive at less than 10% moisture

quiescent

seeds fail to germinate due to being dry

Do the fruit and accessory tissue surrounding the seeds need to be removed before or after seed stratification or seed scarification? Why does it need to be removed?

Fruit should be removed because the tissue in fruits have inhibitors

Describe apomixis? What tissues are the seed derived from?

form of asexual reproduction, seed forms from the maternal cell without fertilization

What is polyembryony?

A type of Apomixis with development of multiple embryos within one seed, a mix of sexually and asexually produced embryo

What are the advantages of apomixis?

Easy, cheap, virus-free, advantages of asexual propagation without going through breeding

Explain the GA:ABA ratio for seed germination and seed dormancy release

High GA: Low ABA

Application of what hormone can release dormancy in some seeds?

GA

three stages of seed germination

imbibition, lag phase and metabolism activation, organ growth

What four environmental conditions are required for seed germination?

overcome dormancy, removal of inhibitors, proper environmental conditions, live embryo, pathogen free, strat/scar

What are the optimum seed germination temperature ranges for warm season vs. cool season vegetable crops?

Warm season 77-86F Cool season: >59 F

Does alternating day/night temperatures improve germination and seedling growth?

Alternating temperatures of 18ºF results in higher germination and seedling growth

What is thermoinhibition?

inhibition of germination by high or low temperatures

How does water influence seed germination?

Water is critical in initiating germination

seed priming what is

pre-germination treatment to alleviate thermoinhibition and increase germination

What happens to the seed if the soil O2 levels are low?

If O2 levels are too low the seeds won't germinate

How does light influence seed germination?

light is involved in dormancy induction and release

What is phytochrome?

photochemically reactive plant pigment; changes with exposure to red and far-red light

What is damping off?

death of small seedlings due to various fungi

Are warm-temperature or cold-temperature requiring seeds more susceptible to damping off?

Cold temperature seeds are more susceptible, fungi do better in the cold

Seed germination %

Percent of seeds that germinate

non-dormant seeds

germinate in proper conditions

Why is primary dormancy beneficial?

allows seeds to survive unfavorable environmental conditions

What is secondary dormancy?

induced dormancy under unfavorable environmental conditions

What is external primary dormancy caused by?

imposed by factors outside the embryo, including the seed coat and/or parts of the fruit

Can the fleshy pulp or fruit covering inhibit seed germination? Why?

Yes, the compounds inside it can inhibit germination

scarification techniques

mechanical, chemical, heat

What scarification techniques happen in nature?

Freezing and thawing cycles, digestive system, soil microbes, fire

What is internal primary dormancy caused by?

imposed by factors within the embryo

What hormone could potentially replace the stratification requirement in some seeds?

GA

What is after-ripening?

internal physiological dormancy disappears as the seeds remain in dry storage

Do the seeds need to be imbibed with water before or after stratification?

Seeds must be imbibed with water first

Give a range of temperatures for stratification usually required for temperate plants and temps. for tropical plants

Temperate plants (33-45 F)

Tropical plants: >77 F

What happens inside the seed during the stratification process?

Decrease in lipid storage, increase in sugars and amino acids; increased osmotic potential

What is double dormancy? Give a plant example.

combination of physiological and morphological primary dormancy, ex pawpaw

What is combinational dormancy?

seed has external physical and internal physiological dormancy

What is provenance

Geographic origin of seed collected

Discuss the morphological and physiological differences for the above two provenances (north and south)

adaptation to climate, soil and pH, resistance to pests, variation in cold hardiness, heat tolerance, and length of dormancy

What is the Plant Variety Protection Act (PVPA)?

Legal protection for a seed propagated cultivar only, established in 1970, revised in 1994

What qualifies a plant to be protected under the PVPA?

Cultivar must be new and distinctive, and uniform/stable during seed propagation

What is a plant patent? What does it cover? How long before it expires? Can it be renewed?

patents to originators of new plant which can be asexually produced, lasts 20 years, cannot be renewed

What qualifies a plant to be protected by a plant patent?

It is asexually produced

Can seed propagated plants receive a plant patent?

No

Does a plant patent require the addition of a cultivar name?

Yes

What are the advantages of a plant patent?

Can exclude others from using, get royalty income, improved plant diversity, holds up in court

What is a utility patent? What does it cover? How long before it expires? Can it be renewed?

Used to control the use of specific genes. If a plant carries the gene, then entire plant is covered, lasts 20 years, no renewal

What are trademarks? What does it cover? How long before it expires? Can it be renewed?

Only protects the name of the plant (not cultivar name), lasts indefinitely, must be renewed every 10 years

Does trademarking cover propagation rights?

No

What is the difference between ™ and ®?

Unregistered is TM, registered is R

Can you change a cultivar name and apply a new cultivar name along with a new trademark?

Cultivar names cannot be changed

Can you use the same name for both the cultivar and trademark?

No, they have to be different

Do trademarks and cultivars have to be "real" words?

Yes

What are the advantages of trademarks?

collect royalties, doesn’t expire, easier to file for, can sue others

Can you have a plant patent and a trademark on the same plant?

Yes

What do we aim for in % for family, genus and species/cultivars for both trees and shrubs?

20% from a family, 10% from a genus, 5% from a species

disadvantages of seed propagating over asexual

dormancy restrictions, non viable seeds, non uniform plants, longer time for reproductive maturity, longer time for bigger plant

biennials

require two growing seasons to complete their entire life cycle, like carrots

perennials

plants that live for more than two years and repeat the vegetative and reproductive cycle annually, like fruit crops

angiosperms

produces seed enclosed by a fruit, dry or fleshy, includes roses

dicots

produce two cotyledons at germination, roses

dioecous

plant produces only male or only females flowers on one plant

why is provenance important?

plants evolved to specific conditions of their origin site

some ways to prevent damping off

sterile media, reduce moisture stress, IPM, scouting, fungicide

damping off symptoms

constricted hypocotyl, wilting, flopping at collar, small seedlings,

seed priming how

imbibe then dry out, starts stages 1-2 of seed germ, limits spread of germ times

what does oxygen do in seed germ

speed up metabolism

recalcitrant seeds

need moisture 30-50%

What hormone is involved in stage 3 of seed development

ABA

What hormones are involved in stages 1 and 2 of seed development

IAA, GA, Cytokinin, ethelyne