Unit II â€¢ Biotechnology and Plants Classical Plant Breeding 5

Unit II • Biotechnology and Plants

138 Lesson 5 Classical Plant Breeding

5Classical

Plant Breeding

Biotechnology gives plant breeders the capacityto streamline breeding programs by precisely ma-nipulating individual genes. However, classicalplant breeding remains the primary means forproducing commercial varieties of plants, andeven when genetic engineering is applied to de-veloping a new variety, it is usually in the con-text of a traditional breeding program. Further-more, many of the basic concepts of biotechnol-ogy, such as those for finding genes, cannot beunderstood without a grasp of the basic processesof heredity and sexual reproduction. This lessonreviews these processes and some of their appli-cations.

Classical Genetics

The facts of life for plants

In 1865, a monk named Gregor Mendel published"Experiments with Plant Hybrids," the first articleto explain how traits are inherited. Although thiswork went unnoticed for more than 30 years, wenow base modern plant and animal breeding onMendel’s principles.

Mendel did most of his early work with peaplants. Like all plants with flowers, peas repro-duce using male and female germ cells, calledgametes. The male gametes in flowering plantsare pollen, and the female gametes are ovules. Thepollen and ovules combine to form a cell, called azygote, that develops into an embryo inside a

seed. Like all plant breeders, Mendel controlledthe combination of gametes by applying pollenfrom the anthers of one selected plant to the ovule-bearing pistil of another selected plant. This con-trolled combination, called a cross, was Mendel’schief tool in his study. Mendel knew nothing ofchromosomes or genes. He knew only that some“factors” inside the gametes were combining toshape characteristics of offspring, or progeny. Toobserve this, Mendel produced many seeds fromeach cross, and planted them. The result was alarge and variable population of plants. The varia-tion in the characteristics of offspring turns out tobe an important innate feature of sexual repro-duction, and it was Mendel who made sense of itfor the first time.

Sexual reproduction and variation

Variation in offspring results from thereassortment or shuffling of hereditary informa-tion during sexual reproduction. Part of the shuf-fling occurs because plants and animals receivetwo sets of chromosomes, one from each parent.Both sets carry the same traits, but may carry dif-ferent versions of these traits. For example, oneparent plant might contribute a white flowercolor, and the other blue. Each version (e.g. whiteor blue) of the same trait (e.g. flower color) iscalled an allele. It is the alleles that are shuffledas each generation inherits traits from the last.

Only one of the two alleles appears as a visiblecharacteristic, or is expressed. However, both the


Lesson 5 Classical Plant Breeding 139

expressed and unexpressed alleles are passed onto succeeding generations. Alleles that are ex-pressed even if received from only one parent arecalled dominant. Alleles expressed only when in-herited from both parents are called recessive.

The diagram below illustrates inheritance ofdominant and recessive alleles. This diagram,used to determine the outcome of a cross, is calleda Punnet Square. The letters across the top are al-leles carried in pollen. Down the left are all pos-sible combinations of the same alleles carried inovules. Each box in the square contains the com-bined alleles for that row and column. Any allelelabeled with a capital letter is dominant.

The example on the left below illustrates a crossof peas, one carrying Round (R), and one carry-ing wrinkly (r) alleles for seed shape. Round isdominant. When a plant carrying only wrinkly(r) alleles pollinates one carrying only Round (R)alleles, the whole population of first generation

offspring carries an Rr combination. BecauseRound (R) is dominant, the whole population ofoffspring has Round seeds. The visible trait, in thiscase Roundness, is known as the phenotype, andthe genetic characteristic, in this case the Rr allelecombination, is called the genotype.

Segregation

On the right below, the all-round Rr offspringfrom the first generation cross are crossed again,just as Mendel did in his studies. This time, thealleles shuffle, and every box is different, produc-ing variation in the population. This diagram il-lustrates Mendel’s principle of segregation. Thisprinciple states that when germ cells form, allelesfor each trait separate and are distributed (segre-gate) among the different individual germ cells.In the diagram below, the letters above the squareare alleles carried in pollen. Letters on the left arealleles carried in ovules. In the second genera-tion (at the right below), peas with an Rr geno-

Segregation and Variation in Punnet Square Diagrams

First Generation Second Generation

GENOTYPE PHENOTYPE GENOTYPE PHENOTYPE

rr

RR

R

R

r r

Rr Rr

RrRr

Ovule alleles

Rr

Rr

Rr

Rr

Cross Rr x Rr fromthe 1st generation

Pollen alleles

R

r

R r

RR Rr

rrRr

Ovule alleles

Pollen alleles RR

Rr

Rr

rr

Rr

all round 3 round:1 wrinkly 1RR:2Rr :1r r

Rr

Rr

RR

Rr

Ratio



type produce equal numbers of R and r germ cells.Each plant makes many germ cells. The diagramshows that the combination of those cells pro-duces a population containing three genotypes:RR, Rr, and rr. In that population, the three geno-types occur in the ratio of 1RR:2Rr:1rr. Both phe-notypes (Round and wrinkly) result from thesecombinations, but just one in four inherits two ralleles to produce wrinkly peas. To express a re-cessive trait, the plant must inherit a recessive al-lele from bothparents.

Independent assortment and variation

Variation also results from another fundamentalprinciple of sexual reproduction, called indepen-dent assortment. Independent assortment is likethe principle of segregation, but it describes thedistribution of alleles for multiple traits. Indepen-dent Assortment states that alleles for differenttraits are distributed among the gametes indepen-dently of each other. As a result, alleles for differ-ent traits are inherited independently. Taking seedcolor (one trait) and seed shape (another trait) forexample, color has two versions, pale (d) and dark(D), and shape has two versions, round (R) andwrinkly (r). Independent assortment states that awrinkly seed could be either pale or dark; a roundseed could be either pale or dark; a dark seedcould be either wrinkly or round; and a pale seedcould be either wrinkly or round. This “indepen-dent” inheritance of traits allows the maximumamount of variation in any given cross.

It’s important to note here that independent as-sortment does not apply when traits happen tobe located near each other on the same chromo-some. Alleles near each other on a chromosomeare often inherited together, and are said to belinked. Later, we will see that this fact forms thebasis of one of the important techniques for find-ing a gene.

Distribution of Multiple Alleles Among Germ Cells

Parent Cellshape & color

alleles inheritedfrom female parent

shape & color alleles inherited from male parent

R D r d R d r D

R r D d

Gametes or Germ Cells

MEIOSIS

Heredity, chromosomes, and variation

An important cellular process lies at the heart ofthe allele shuffling described above, and is one ofthe primary causes of the variation producedthrough sexual reproduction. This process is bestunderstood with a short review of the action ofchromosomes during reproduction.

The diagram, “Haploid Gametes from DiploidCells” on the next page shows that chromosomesin non-germ cells exist in pairs, one member ofthe pair coming from the mother and one fromthe father. Cells with two of each chromosomeare called diploid. All normal plant and animalcells, except germ cells, are diploid. Germ cellsare haploid, having just half the number of chro-mosomes as the parent plant cells. Diploid cellsgive rise to haploid germ cells through a specialkind of cell division called meiosis.

Each member of a diploid cell’s chromosome paircontains the same traits but different alleles. Mem-bers of a pair of chromosomes which are similarin this way are said to be homologous to each



other. During meiosis, homologous chromosomesdo not simply split up and become incorporated,one at a time, in newly forming germ cells. In-stead, before germ cells form, meiosis shuffles thealleles among the homologous chromosomes andcreates new chromosomes with a unique assort-ment of alleles. The germ cells incorporate theseunique chromosomes, giving each germ cell aunique assortment of alleles, different from par-ent cells and other germ cells. Therefore, whengerm cells unite to form zygotes, each zygote con-tains a unique assortment of alleles from all fourgrandparents.

Genetics and plant breeding programs

The shuffling of genetic information is both ablessing and a curse for breeders. It creates thevariation that is essential for developing newplants. Unfortunately for breeders, as thoroughas the shuffling is, it still occurs in large blocks. Itis as if you shuffled a deck of cards and acciden-tally let large chunks of cards interleave. The re-sulting mix of traits may include desirable char-acteristics, but other traits are also included, good,bad, and indifferent. Most breeding programs aremethodical attempts to manage the randomnessthat is an inherent and necessary feature of sexual

reproduction. Adding only desired traits is a longand costly process. It usually requires large popu-lations and many generations of plants to begrown.

Plant breeding methods

Traditional plant breeding uses sexual reproduc-tion to recombine genetic material and producevariation in the population of offspring. From thevariants produced, breeders select plants withdesirable traits, and breed again. They continueuntil the trait is stably incorporated into the plantor until the seed will reliably produce plants withthe desired trait. The aim is to produce cultivars,distinct groups of genetically similar plants whichcan be named and distributed as agricultural va-rieties. In the process, breeders must assemble avariety of breeding stock which contains desiredtraits, carefully control pollination, select progeny,and repeat the cycle many times, using varioustechniques of hybridization or backcrossing.

Assembly of germplasm or breeding stock. Theraw material for a breeding program is a widerange of interbreeding lines with desired traits.For example, germplasm may include wild types

Diploid Parent Cells (full set of chromosomes)

Haploid Gametes from Diploid Parent Cells

MEIOSIS

OvulesHaploid Gametes

(half set of chromosomes)

PollenHaploid Gametes

(half set of chromosomes)

Diploid Offspring

Fertilization

MEIOSIS



with resistance to an insect and advanced breed-ing lines with proven productivity. The goal is toeventually stabilize the desired trait along withexisting traits in a population, making all of thetraits reliably inherited from generation to gen-eration. Many countries maintain vast germplasmcollections for use by breeders. China, for ex-ample, has more than 16,000 different soybeans.Variation in the starting germplasm enablesbreeders to produce genetically variable popula-tions in the early stages. Variation in the popula-tion increases the likelihood of producing plantswith the desired combination of traits. Breedersselect these, cross them, and plant their seed inthe next generation. The goal is for the desiredtraits to become more and more common in suc-cessive breeding populations.

Pollination: self-pollination and cross-pollina-

tion. Breeders must assure that pollen with de-sired alleles fertilizes ovules with desired alleles.To do so, they must place specific pollen on spe-cific ovules. In some plants, such as peas, pollenand ovules from the same plant produce fertileseed. Such plants are called self-pollinating. Toproduce a cross in self-pollinating plants, breed-ers may remove the anthers (the male parts) orproduce male-sterile plants, so that they can fer-tilize with pollen from another selected plant. If aplant accepts pollen only from other plants, breed-ers must shield the flower from pollen other thanthe pollen carrying the desired allele.

Selection. Selection is the process of choosing de-sirable plants for further breeding, based eitheron their visible characteristics or their genetic heri-tage. Selection of desirable plants continually re-fines and improves the variety’s heritable traits

Hybridization

X Parents are selected for desirable traits(big flowers and big leaves)

In succeeding generations, plants are selectedfor the presence of desired traits, and crossed.

After multiple generations the desired traits are reliably present in the offspring.



in successive generations. Breeders may use amethod called mass selection, in which they se-lect plants based solely on observable character-istics, or phenotype. Alternatively, breeders mayuse a method called pure line selection, whichfocuses on the plant’s genetic heritage. This tech-nique involves creating a single self-pollinatedplant which has identical alleles on the homolo-gous chromosomes. Such plants are called ho-mozygous. If a single self-pollinated homozygousplant has the desired traits, all of its progeny reli-ably inherit these traits.

Hybridization. Hybridization takes advantage ofgene recombination by cross-pollinating geneti-cally different but carefully selected parent plants.After the cross, multiple generations of the plantare grown, and in each generation, individualswith desirable traits combined from both parentsare selected. After many generations of selection

and inbreeding, the desired traits are stabilizedin the population.

F1 Hybrid cultivars. F1 hybrid cultivars resultfrom parent lines which are multiplied and main-tained separately by continued self-fertilizationand inbreeding until both the maternal and pa-ternal lines are extremely uniform genetically. Toproduce the hybrid seed or cultivar, the maternalline is pollinated only by the paternal line(crossed), and the seed of the first generation af-ter the cross (F1) is the hybrid cultivar. F1 hybridcultivars are extremely uniform and reliable.However, in the second (F2) generation, recessivetraits are expressed and uniformity is lost.

Backcrossing. Backcrossing is a form of inbreed-ing used when breeders have developed a culti-var with mostly desirable traits, but which stilllacks a certain desirable trait. The developed cul-

F1 Hybrid Cultivars

Each parental line is inbred until it is genetically uniform

Parents F1 generation



tivar lacking the trait is crossed only once to abreeding line that contains the trait. Afterward,progeny are selected for the desirable trait. How-ever, progeny lack some of the positive traits ofthe original parent, and they contain negativetraits from the cross. To regain the positive traitsand keep the new trait, progeny are repeatedlycrossed back to the original cultivar parent. Aftermany generations of backcrosses, most of the posi-tive features are recovered from the parent line.Through selection, the new trait has been main-tained. This works best if the trait being added issimply inherited, dominant, and easily recog-nized.

Terms

allele – one of the alternative versions of a traitwhich occupies a specific location on a chro-mosome.

backcrossing – a plant breeding technique usedto add a trait to an existing cultivar. The culti-var is crossed to a plant which contains thedesired trait, and progeny with the desiredtrait are selected. These now lack importantcultivar traits and contain new undesired

Backcrossing

X

X

X

Suitable cultivar is crossed with a plant with a desirable trait

Offspring with the desired trait is crossed back with the original parent stock

After many backcrosses, the offspring reliably exhibit the desired trait, along with the characteristics of the parent

traits. To regain the qualities of the cultivarand retain the trait, progeny are repeatedlyselected for the desired trait and crossed backto the cultivar.

cross – to interbreed two genetically distinct or-ganisms.

cross-pollination – the process of producing fer-tile seed from pollen and ovules from differ-ent plants.

cultivars – distinct groups of genetically similarplants that can be named and distributed asagricultural varieties.

diploid – cells with the full complement of chro-mosomes. The full complement of chromo-somes exists in pairs, one each inherited fromthe maternal and paternal sides. Each mem-ber of the pair contains the same traits.

dominant – a version of a trait which will be ex-pressed regardless of which allele is passedfrom the other parent.

expressed trait – a trait which appears as a vis-ible characteristic rather than a latent one inthe genetic makeup.



F1 hybrid cultivars – the result of a plant breed-ing technique in which parent lines are inbredto produce genetic uniformity. The geneticallyuniform parent lines are then crossed to pro-duce seed, and the first generation (F1) seed issold. F1 hybrid seed is very uniform and reli-able, but seed saved from it is not.

gametes – germ cells or sex cells such as pollen,sperm, ovules, or ova, containing half thenumber of chromosomes as other cells.

genotype – an individual organism’s specific ge-netic makeup.

germ cells – the same as gametes, reproductivecells such as pollen or ovules.

germplasm – the raw material for breeding pro-grams, usually several interbreeding lines ofplant stock with a broad range of traits.

haploid – a cell containing half the number ofchromosomes as other cells in the organism.

homologous – the chromosomes which comefrom separate parents and which contain thesame traits.

homozygous – an organism which has identicalalleles from both parents on both homologouschromosomes. In plant breeding, usually theprogeny of a single self-pollinated plant.

hybridization – the crossing, through sexual re-production, of genetically different interbreed-ing parent organisms.

independent assortment – multiple alleles locatedon different chromosomes segregate indepen-dently of each other during gamete formation.The population of offspring therefore carriesa random mix of dominant and recessive al-leles for different traits.

mass selection – a plant breeding technique whichselects plants purely on the basis of observ-able characteristics, without regard to geneticheritage.

meiosis – the special process of cell division whichcreates haploid sex cells (gametes or germcells) and shuffles the parent’s genetic mate-rial.

phenotype – the observable characteristics of anorganism (in contrast to invisible genetic char-acteristics which are only expressed in latergenerations).

progeny – offspring.

pure line selection – a plant breeding techniquewhich selects plants on the basis of geneticheritage, usually the progeny of a single self-pollinated homozygous plant.

recessive – a version of a trait which will be ex-pressed only if inherited from both parents.

segregation – the separation and distribution ofalleles which occurs in the formation of germcells. Segregation results in germ cells whichmay pass on either allele to offspring.

self-pollination – the process of producing fer-tile seed from pollen and ova which comefrom the same plant.

zygote – the fertilized egg which develops intoan embryo.



Sources and Resources

Plant breeding educational resourceson the Internet

Access Excellence – a collection of science acti-vities,www.accessexcellence.org/AE. Anactivity that simulates Mendel’s pea experi-ment (www.accessexcellence.org/AE/AEC/AEF/1996/nolin_pea.html).

Methods in Plant Breeding: a Cornell Universityon-line course - http://nightshade. cit.cornell.edu/coursepak/poe9.html

Books on plant breeding

Borojevic, S. 1990. Principles and Methods of PlantBreeding. Amsterdam: Elsevier.

Carson, M.L. 1997. Plant Breeding. Newark, DE:E.I. DuPont de Nemours Co., Inc.

Iltis, H. 1932. The Life of Mendel. New York: Norton.

Newsletters

GENErations – A science education newsletterfrom the Genetics Society of America. Dr. GailSimmons, [email protected].

http://www.accessexcellence.org/AE

http://www.accessexcellence.org/AE/AEC/AEF/1996/nolin_pea.html


TeacherWorksheet

Unit II • Activity 5-1 Teacher Worksheet

About this ActivityThe following paper activity is a “Punnet Squares”exercise to help students understand the principleof independent assortment. Students should befamiliar with the Punnet square from the discus-sion of segregation in the text. Depending on stu-dents’ familiarity with the subject, you may wantto make overheads of both the segregation andindependent assortment graphics.

Objectives

• explain the basic concepts of Mendelian genet-ics, including segregation and independentassortment

• discuss the relationship between independentassortment, plant breeding techniques, andmeiosis.

• analyze a Punnet Square.

Related Skill Standards

• explain the genetic basis of diversity

• identify the basic unit of inheritance as the gene

• describe/explain genetics in general, includ-ing chromosomes, diversity, dominant/reces-sive traits, genotype/phenotype, inheritance,mitosis/meiosis, etc.

• describe the factors important to plant andanimal breeding and production

• explain the term hybrid.

Time requiredThis activity should take about 30 minutes.

Background ReadingThe class should have read and discussed Lesson5, Classical Plant Breeding, especially the sectionson segregation and independent assortment.

Materials

Photocopies and overheads of the Segregation andIndependent Assortment student worksheets.

Teacher Preparation

Photocopy worksheets for each group of students(or for individual students) and prepare overheadtransparencies of the Punnet squares.

Answer Key for Student Questions1. On the line below, list the pea genotypes that

would result. For example, RRdd is the geno-type in the upper left hand box.

ANSWER: RRdd, RRDd, RRDD, Rrdd, RrDd,RrDD, rrdd, rrDd, rrDD.

2. What will be the ratio among the genotypes?

ANSWER: 1 RRdd : 2 RRDd : 1 RRDD : 2 Rrdd:4 RrDd : 2 RrDD : 1 rrdd : 2 rrDd : 1rrDD.

3. Draw a picture of each type of pea in the ap-propriate box in the diagram. On the line be-low, list the pea phenotypes that result. Forexample, you would draw a Round and palepea in the upper left hand corner and list thegenotype on the line below as Round and pale.

Answer: Round and Dark, Round and pale, wrin-kly and Dark, wrinkly and pale.

Segregation andIndependent Assortment

Activity 5 -1


Teacher Worksheet Unit II • Activity 5-1

4. In the blanks below, write the number of oc-currences of the 4 phenotypes that would ap-pear in the 16 genotypes.

ANSWER: 9 Round and Dark, 3 Round andpale, 3 wrinkly and Dark, 1 wrinkly and pale.

5. A pea breeder crossed two RrDd plants whichproduced seed, and the breeder grew 1600plants from that seed. How many of the 1600plants would carry pure recessive (rrdd) alle-les? How could you find them?

ANSWER: 1/16 of the plants, or 100 plants(1600/16 = 100) would be rrdd. These wouldbe identifiable as those plants bearing wrin-kly and pale peas. Only rrdd genotypes pro-duce wrinkly and pale phenotypes.


StudentWorksheet

Activit

Unit II • Activity 5-1 Student Worksheet

About this ActivityThe law of independent assortment states that inthe process of inheritance, the two alleles for dif-ferent traits distribute among gametes and assortindependently into all possible combinations.When a pea with dominant alleles for two traitsis crossed with a pea with recessive alleles for thesame two traits, the first generation populationappears as dominant versions of both traits. Whenthese are crossed to create a second generation,four different pea phenotypes result.

The Punnet square diagram on the following pageis a grid which geneticists use to determine theoutcome of a cross. All possible combinations ofalleles in male gametes are arrayed across the top,and all possible combinations of alleles in femalegametes are arrayed down the left side. Each boxin the square contains the combination of allelesand traits that would result from fusion of the ga-metes in that row and column. In this problem,roundness or wrinkliness are two versions of one

trait (shape), and paleness or Darkness are twoversions of another (color). Round (R) and Dark(D) are dominant. The recessive traits are pale (d)and wrinkly (r). Independent assortment predictsthat RrDd plants would produce pollen andovules with four different combinations, Roundpale (Rd), Round Dark, (RD) wrinkly pale (rd),and wrinkly Dark (rD). The squares of the gridon the right of the diagram on the next pageshould contain all possible combinations of alle-les produced by these germ cells. The second rowthird column of the Punnet Square on the righthas been filled in to show that RD and rD com-bine to produce RrDD.

Directions

Two locations have been filled to get you startedfilling in the grid. Fill in the empty squares withthe correct combinations of alleles, and answerthe five questions.

Segregation andIndependent Assortment

Activity 5 -1


Student Worksheet Unit II • Activity 5-1

Questions

1. On the line below, list the pea genotypes that would result. For example, RRdd is the genotype inthe upper left hand box.

______________________________________________________________________________________

2. What will be the ratio among the genotypes? Place the number of occurrences before the genotype,a colon, then the next number and genotype. For example: 1 RRdd: etc.

1 RRdd : __________ : __________ : __________ : __________ : __________ : _________

3. Draw a picture of each type of pea in the appropriate box in the diagram. On the line below, list thepea phenotypes that result. For example, you would draw a Round and pale pea in the upper lefthand corner and list the genotype on the line below as Round and pale.

Round and pale, ___________________ , ____________________ , ______________________ .

4. In the blanks below, write the number of occurrences of the 4 phenotypes that would appear in the16 genotypes.

_____Round and dark _____Round and pale ______wrinkly and Dark ______wrinkly and pale

5. A pea breeder crossed two RrDd plants which produced seed, and the breeder grew 1600 plantsfrom that seed. How many of the 1600 plants would carry pure recessive (rrdd) alleles? How couldyou find them? Answer below:

Independent AssortmentRound (R) and Dark (D) are dominant, wrinkly (r) and pale (d) are recessive

First Generation Second Generation

RD

RD

RD

RDovule alleles

all Round DarkRrDd

pollen alleles

All possible allelecombinations in pollen

and ovules

xx

Round Dark (RD) wrinkly pale (rd)

RrDd

RrDd

RrDd

RrDd

RrDd

RrDd

RrDd

RrDd

RrDd

RrDd

RrDd

RrDd

RrDd

RrDd

RrDd

RrDd

rd rd rd rd

Rd

RD

rD

rd

RRdd

RrDD

Rd RD rD rd

RrDd RrDd


TeacherWorksheet

Unit II • Activity 5-2 Teacher Worksheet

Wisconsin Fast Plants ™Mendelian Genetics

Activity 5 -2

About this Activity

This activity gives students a chance to see Men-delian genetics in action. It is important that theyreflect on what they observe to connect their ob-servations with plant breeding methods, meiosis,independent assortment, and segregation.

Wisconsin Fast Plants™ are a fast-growing formof brassica produced through traditional breeding.The plants are ideal for hands-on classroom ac-tivities because they produce so quickly. The Wis-consin Fast Plants™ Monohybrid Genetics Kit(Carolina Biological 15-8770), and Dihybrid Ge-netics Kit (Carolina Biological 15-8774) are goodactivities to help students understand how tradi-tional breeding programs work.

• The Monohybrid Genetics Kit contains a 55-daydemonstration which illustrates dominanceand segregation. It contains everything nec-essary for 30 students to grow and pollinateF1 hybrid plants to produce F2 seed in the class-room. The class analyzes inheritance based onthe segregation of one gene in the F2 genera-tion.

• The Dihybrid Genetics Kit contains a 55-daydemonstration which illustrates independentassortment and other Mendelian principles..The activity follows the inheritance of twogenes that segregate in the F2 generation.

Objectives

• demonstrate fundamentals of crossing plants

• distinguish between genotype and phenotypeand explain their relationships

• demonstrate principles of dominant and reces-sive traits

• demonstrate principles of segregation and in-dependent assortment.

Related Skill Standards

• gather pollen and hand pollinate

• pot and repot plants

• perform small-scale field tests according to aprotocol

• manage plants for optimal growth

• maintain organized and neat work place

• recognize unexpected results

• communicate well with others.

Time Required

Three class periods over 55 days.

Background Reading

Lesson 5, Classical Plant Breeding.


Teacher Worksheet Unit II • Activity 5-2

Materials/Equipment

The contents of a Wisconsin Fast Plants™ Mono-hybrid or Dihybrid Genetics kit and a place withlight source for growing plants in small flats.

Sources

• Wisconsin Fast Plants, 1-800-462-7417 (www.fastplants.cals.wisc.edu)

• Carolina Biological Supply, 1-800-334-5551,(www.carolina.com) for the Monohybrid Ge-netics Kit 15-8770, Dihybrid Genetics Kit 15-8774, or Wisconsin Fast Plants™ booklet, Inves-tigating Mendelian Genetics 15-8955 (containsgood exercises).

Procedure

Set up teams of students who will be responsiblefor their group of plants for the whole 55 days ofthe activity.

http://www.carolina.com

Documents

Unit II â€¢ Biotechnology and Plants Classical Plant Breeding 5