1. C HAPTER 10: I NTRODUCTION TO P LANT B IOTECHNOLOGY Introduction to Biotechnology, BIOL1414 Austin Community College, Biotechnology Dept http://www.forbes.com/2002/03/04/0304japan.html

2. L EARNING O UTCOMES Describe mechanisms of plant pollination and differentiate between haploid and diploid cells and their role in sexual reproduction Identify various natural and artificial ways to propagate plants to increase genetic variety or maintain the genetic composition Discuss the function and composition of different plant structures, tissues, and organelles and give examples of foods that are derived from various plant organs Describe the processes of germination and plant growth Perform the calculations to predict expected plant phenotypes for specific genetic genotypes, using Punnett Square analysis in a plant breeding experiment Describe the role of meristematic tissue in asexual plant propagation Explain the role of plant growth regulators, as well as the advantages and disadvantages of plant tissue culture Note about this PowerPoint – There are several links in this PPT that allow you to explore more into different topics. Some of these links are animations, movies, or exercises. Please note, you must be in the slide show to activate the links. You can press F5 any time to active the slide show and “Esc” to exit.

3. I NTRODUCTION TO P LANT P ROPAGATION There are several methods of modifying or improving plants or plant parts. One of the first advances occurred when farmers discovered they could control pollination and the resulting seed crop. Wheat, corn, rice and oats have been cultivated for thousands of years in this fashion Plant breeding involves both sexual and asexual reproduction.

4. Flower Structure. Most flowers are “complete” with both male (stamen) and female (pistil) sex organs. A seed develops when a pollen sperm nucleus reaches and fertilizes an ovule.

5. New Gene Combinations. Crossing-over and gene shuffling during meiosis (sex cell division) created new combinations of genetic information on chromosomes. The new combination of genes is carried in sex cells to the zygote of the next generation. S EXUAL R EPRODUCTION

6. S ELECTIVE B REEDING New varieties of plants are commonly produced during selective breeding; pollen from plants with desired traits is purposefully crossed with other plants exhibiting desirable traits The majority of agricultural crops on the market today are the result of selective breeding But sometimes you want to produce identical plants! Asexual reproduction, also called cloning, is the production of plants from a single parents The offspring are identical to the parents and each other

7. A SEXUAL R EPRODUCTION T ECHNIQUES The oldest method of asexual propagation is the use of cuttings Pieces of stems, leaves or roots, place in appropriate media and under the right conditions, existing cells in growing tissue will develop into missing roots, stems or leaves Many house plants start from cuttings!

8. A SEXUAL R EPRODUCTION T ECHNIQUES Another kind of asexual reproduction is called tissue culture One or a few cells, under sterile conditions is placed in a medium containing all the nutrients necessary for growth Cells will grow and divide, resulting in a mass of cells called callus The callus is place in media and produces roots, stems and leaves

9. B ASIC P LANT A NATOMY Plants are multicellular organisms composed of organs and tissues Plants have a wide variety of organ structures Plant organs are grown as food or commercial crops Plant Tissue Plant tissues are groups of similar cells with a specific function Interesting to biotechnologists is the meristematic tissue, the only region of plant cells that undergo cell division Plant Cells Plant cells have all the organelles found in other cells, plus special organelles

11. P LANT G ROWTH, S TRUCTURE AND F UNCTION Meristematic tissue – the tissue found in shoot buds, leaf buds, and root tips that is actively dividing and responsible for growth Plants have specific regions where cell division can occur. Meristems are found at each growing tip.

12. During mitosis, cells make exact copies of themselves. The tightly wound mitotic chromosomes are visible using a microscope.

13. O NION R OOT T IP M ITOSIS

14. Dicot See Germination. The diagram shows a germinating bean seed with an enlarged radicle growing down. The epicotyl will grow up into the leaves and stem. The two cotyledons emerge from the seed as a food source, but they wither after a short while. Monocot Seed Germination. Four germinated corn seedlings. The coleoptile protects the emerging leaves. Corn plants are monocots since they have only one section to the seed.

15. I NTRODUCTION TO P LANT B REEDING Plants are diploid organisms represented by the symbol “2N” Diploid refers to the fact that each cell of the organism (except the sex cell) has two sets of homologous (matching) chromosomes Cells that have only one set of chromosomes are referred to as haploid or “1N” These cells are the sex cells – the sperm carries one set of chromosomes and the egg carries one set of chromosomes When the sperm fertilizes the egg it reestablishes the diploid 2N chromosomes for that organism

16. I NTRODUCTION TO P LANT B REEDING Alternation of generations. Each sex cell gets one copy (1N) of each chromosome and, therefore, one copy of each gene. Most genes exist in one of two or more forms (alleles). When the zygote (2N) forms, it receives both sets of chromosomes (and genes) for the two sex cells. Depending on what was carried in the sex cells, the zygote could receive two matching alleles or two different alleles for a particular trait. The alleles of an organism are its genotype and, ultimately, determine the traits expressed (phenotype).

17. I MPORTANT P LANT B REEDING T ERMINOLOGY o Diploid – having two sets (2N) of homologous (matching) chromosomes o Haploid – having only one set (1N) of chromosomes o Alleles – alternative forms of a gene o Dominant – referring to how an allele for a gene is more strongly expressed than an alternate form (allele) of the gene o Recessive – referring to how an allele for a gene is less strongly expressed than an alternate form (allele) of the gene; a gene must be homozygous recessive (ie, hh or rr) for an organism to demonstrate a recessive phenotype o Homozygous – having two identical forms or alleles of a particular gene o Homozygous dominant – having two of the same alleles for the dominant version of the gene (ie, HH or RR) o Heterozygous recessive – have two different forms or alleles of a particular gene (ie, Hh or Rr) o Polygenic – traits that result from expression of several different genes o Punnett Square Analysis – a chart that shows the possible gene combinations that could result when crossing specific genotypes

18. G ENOTYPE AND P HENOTYPE Allele – Alternate forms of a gene is called an allele Genotype – what the organism looks like genetically (alleles an organism possesses) Phenotype – what the organism looks like physically (the plants physical characteristics) Plant breeders try to study, predict, and manipulate crosses between flowers in an attempt to produce plants of desired phenotypes.

19. G ENOTYPE AND P HENOTYPE When one allele is dominant over the other, this means it is preferentially expressed and that cell exhibits the trait by that allele. This is represented by upper case letter The other allele is said to be recessive and is represented by a lower case letter When both alleles are the same they are said to be homozygous When two different alleles are present, they are said to be heterozygous. Scientists use a Punnett Square Analysis to show the possible gene combinations that could result when crossing specific genotypes.

20. G ENETIC A LLELES AND H OMOLOGOUS C HROMOSOMES Homologous chromosomes Have genes at specific loci. Have alleles of a gene at the same locus.

21. M ONOHYBRID C ROSSES A monohybrid cross is a cross between parent plants that differ in only one characteristic.

22. Figure 9.6b

23. I N -C LASS E XERCISE : M ONOHYBRID C ROSS A pea plant that is true breeding for yellow seeds (a Dominant trait) was crossed with a pea plant that is true breeding for green seeds which is a recessive trait. Using a Punnett square, show the genotype and phenotype for the cross

24. In-Class Exercise: Monohybrid Cross A pea plant that is true breeding for yellow seeds (a Dominant trait) was crossed with a pea plant that is true breeding for green seeds which is a recessive trait. Using a Punnett square, show the genotype and phenotype for the F1 and F2 progeny. Genotypes: YY x yy Phenotypes: (yellow) (green) Y Y y y Yy F1 Outcome: 100% = Yy (genotype) = Yellow (phenotype)

25. D IHYBRID C ROSS – T WO T RAITS

26. Using Numerical Data to Ensure Accuracy Instead of using words to describe data, scientists try to make all observations of experiments in numerical form. Using Multiple Replications to Determine Averages Experiments must be repeated enough to ensure that results reflect what really happens. S TATISTICAL A NALYSIS OF D ATA

27. E VALUATING V ALIDITY OF D ATA – T HE 10% R ULE S TANDARD D EVIATION 10% Error Rule. A quick calculation of 10% of the expected value gives you an idea if the data make sense or not For example if you measure 10mL of juice, the 10% error rule is +/- 1mL Values of juice measurement between 9 and 11 mL would be valid and acceptable Another way of determining validity of data is by determining the standard deviation (SD) The SD is a value that describes the range on either side of the mean (average) where data are considered valid.

28. E VALUATING V ALIDITY OF D ATA – T HE 10% R ULE S TANDARD D EVIATION Standard Deviation. If the SD is twice as large (right graph) as another (left graph), then we know that the data for the right graph are very dissimilar, and we would have less confidence in the data collection.

29. How To Calculate the Chi Square Value (  2 )  2 =  [(O-E) 2 /E] The terms represent the following: O = observed number for a phenotype group E = expected number for a phenotype group  = the Greek letter Sigma, which represents “sum of” U SING G OODNESS OF F IT (C HI S QUARE A NALYSIS ) TO T EST THE H YPOTHESIS Chi Square analysis is commonly used in genetics and breeding experiments Provides a numerical value that determines whether the actual data are close enough to the expected data to support he experimental hypothesis

30. A SEXUAL P LANT P ROPAGATION Using breeding techniques, a plant biotechnologist can produce variety in the offspring of selected parental plants. In asexual plant propagation, identical offspring are produced by a single parent.

31. Q UESTIONS AND C OMMENTS ?

32. R EVIEW Q UESTIONS Your Turn! Put your name at the top of a sheet of paper, answer these questions and hand in: 1. How many parents are necessary for an offspring to be produced by sexual reproduction? How many parents are necessary for an offspring to be produced by asexual reproduction? 2. What is the smallest number of cells required to clone a plant through tissue culture? 3. Which plant tissue type is the source of cells for tissue culture? 4. Give an example of a plant that has been modified by genetic engineering. 5. Name the parts of the plants that contain actively dividing cells. 6. When a seed germinates, what is the first plant part to emerge from the sprouting seed? 7. A plant has purple flowers and hairy stems. Is this description its genotype or its phenotype? 8. Consider a cross between two Brassica rapa parent plants known to be heterozygous tall. Using the same allelic symbols as in the text, show the entire cross (problem), including the chances of this breeding resulting in short plants. 9. A set of plant DNA extractions is measured on the UV Spec. There are 13 samples, and the average concentration is 18.7 μg/mL. One sample has a value of 17.2 μg/mL. Using the 10% rule, is the sample’s value valid and acceptable? 10. An experiment is conducted to determine the number of kindergarten children with attention deficit disorder (ADD) in the United States. The result shows that 80 out of 1000 students, on average, with a standard deviation of 5, exhibit ADD. A town near a nuclear plant has an average of 84 students per 1000 with ADD. Should the citizens be concerned? Why or why not? 11. A family had 22 children: 14 boys and 8 girls. Calculate the Chi Square value for such a cross and determine whether the results are due to a random mating or an environmental or genetic disorder.