Plant Improvement

Question 1

Trash heap method

Answer 1

have a pile of organic ‘trash’ near the village, like a compost pile
as the fruits and vegetables rotted, seeds matured and sprouted when conditions were favorable

Question 2

What traits have improved throughout time

Answer 2

yield
flavor
seed retention 
upright growth habit
ease of harvest 
resistance to pathogens
tolerance of environmental conditions 
efficient utilization of nutrients

Question 3

Important horticultural traits

quality traits

Answer 3

taste
color
storage quality
size and shape

Question 4

Important horticultural traits

important for mechanical harvesting

Answer 4

uniform ripening
thicker shinned
resistant to bruising

Question 5

Important horticultural traits

additional traits

Answer 5

flower shape, size, color, longevity
plant form, size, shape
folair characteristics, variegation, fall color, leaf retention

Question 6

Variation

Answer 6

variation between individuals is the ‘raw ingredient’ for plant improvement
the basis for crop improvement is genetic variation
there is no basis for selection if all individuals are

Question 7

Two factors of variation

Answer 7

environmental variation

genetic variation

Question 8

Variation produces

Answer 8

new genetic combinations

desirable characteristics

Question 9

Sources of new variation for plant improvement

Answer 9

recombination (meiosis)
spontaneous mutation
related species in plant families
germplasm collections

Question 10

center of origin

Answer 10

where they evolved prior to domestication by man

Question 11

gene

Answer 11

unit of inheritance

Question 12

genes are encoded

Answer 12

by the sequences of bases

Question 13

DNA is packaged in

Answer 13

chromosomes

Question 14

chromosomes are contained in the

Answer 14

nucleus

Question 15

information in genes is converted into / most genes encode

Answer 15

protein

Question 16

proteins are responsible for carrying out

Answer 16

most of the essential functions in all organisms

Question 17

different forms of the same gene are called

Answer 17

alleles

Question 18

when both copies of a gene are the same in an individual are described as

Answer 18

homozygous

Question 19

when two alleles of a gene are different in an individual are described as

Answer 19

heterozygous

Question 20

differences between individuals in the sequences of bases in genes can be the source of

Answer 20

genetic variation

Question 21

some alleles are deleterious and have negative effects

Answer 21

in humans cystic fibrosis, sickle cell anemia which are caused by genetic defects

most alleles of genes in plants do not have such drastic effects, red/pink/white flowers

Question 22

genotype

Answer 22

genetic information

Question 23

phenotype

Answer 23

appearance and performance

Question 24

phenotype is determined by

Answer 24

genes and by the environment

Question 25

some traits are controlled by

Answer 25

only one or two genes

Question 26

qualitative inheritance

Answer 26

simply inherited traits

Question 27

quantitative traits

Answer 27

traits are affected by the actions of many genes

Question 28

Strategies for plant improvement

Answer 28

``` selection random mutations polyploidy plant breeding biotechnology ```

Question 29

Selection

Answer 29

identification of desirable varieties in natural population

Question 30

Two important points about selection of horticultural crops

Answer 30

selection is based on the utility of plants to the grower | selection is performed on a wider range of traits in horticultural crops

Question 31

natural selection

Answer 31

evolution

Question 32

in most cases, plants selected for agricultural purposes would not...

Answer 32

survive or be successful under conditions of natural selection

Question 33

Sports (aka mutants)

Answer 33

sports are the result of rare spontaneous mutations in cultivated plants that result in new plants with desirable horticultural characteristics

Question 34

examples of sports include

Answer 34

pink-fleshed grapefruit seedless navel oranges color variants of many apples

Question 35

chimera

Answer 35

only one layer of tissue is altered

Question 36

polyploidy

Answer 36

an organism has more than the normal diploid (2n) number of chromosomes

Question 37

Why are polyploids useful?

Answer 37

polyploids tend to have larger cells, resulting in larger fruits, flowers, leaves can be sterile "seedless" watermelon

Question 38

plant breeding

Answer 38

deliberate hybridization of plants with complementary traits and selection of elite lines that combine these traits

Question 39

Fundamental steps in plant breeding

Answer 39

1. identify plants with complementary characteristics that can hybridize 2. cross these 2 plants - emasculate the female parent - collect pollen from the male parent - pollinate the female parent by hand 3. collect seed and grow progeny 4. evaluate performance of the progeny in subsequent generations 5. select the best progeny after evaluating their performance - evaluation is carried out over several years and at many sites 6. propagation of improved variety - production of seed or through asexual propagation 7. file for a 'plant variety patent'

Question 40

Hybrid vigor

Answer 40

cross, two different parents | plants are more vigorous, have a higher yield than inbred lines

Question 41

F1 hybrids

Answer 41

Parent A (male) + Parent B (female) = F1 hybrid

Question 42

Self-pollination

Answer 42

many crops are self-pollinated because they are not self-incompatible grown as inbred lines essentially all genes are homozygous traits are stably inherited from generation to generation breeding or new varieties requires the development and evaluation of new inbred lines

Question 43

outcrossers

Answer 43

do not self pollinate many horticultural crops are natural outcrossers -some have biological barriers to self-fertilization (incompatibility)

Question 44

gene introgression

Answer 44

new methods of biotechnology allow genes to be transferred from any species for plant improvement

Question 45

Challenges of breeding

Answer 45

only 1 out of 16 of the progeny will contain the combination of those two genes necessary to express both traits