Plant Reproduction and Responses

1. Plant Reproduction and Responses By: Diana Boyle, Jordan Capelle, Ross Dairiki, Erika Keer

2. General Info. • Fertilization=Fusion of gametes • 2 reproductive structures: FLOWERS & FRUITS

3. Flowers • Flowers=Reproductive shoots of angiosperm sporophytes - Complete Flowershave 4 basic floral organs (sepals, petals, stamens, carpels) - Incomplete Flowerslack 4 basic organs (Example: Grass Flowers) - Some flowers are sterile--lack stamens and carpels - Others are unisexual--lack either stamens or carpels - Inflorescence=Cluster of flowers

4. Diagram of a flower (left) and fertilization (right)

5. Gametophytes MALE FEMALE

6. Mechanism of Fertilization • Pollination=Transfer of pollen from an anther to a stigma - Made possible by wind (random seed dispersal), water, or animals (insects, birds, bats) • Coevolution=Joint evolution of two interacting species, each in response to selection imposed by the other - Many species of flowering plants have coevolved with specific pollinators

7. Double Fertilization The union of 2 sperm cells with different nuclei of the female gametophyte

8. Seed Structure and Function Endosperm • Usually develops before embryo • Triploid nucleus of ovule’s central cell divides, forming “supercell” with multiple nuclei • Cell eventually splits & new cell walls form • Often stores nutrients that can be used by seedling • Example: coconut milk Embryo • Comes from terminal cell (part of first mitotic division) • Other part (basal cell) keeps dividing  produces thread of cells called suspensor • Transfers nutrients to embryo from parent plant (and sometimes endosperm) • Shoots & roots sustain primary growth after seed germinates

9.  Diagram of Seed

10. Fruit Structure & Function • Fruit=developed from flower ovary • Protect enclosed seeds • Aid in dispersal Animals eat fruit and poop out seeds in new location • Fertilization triggers hormonal changes that begin ovary transformation

11. Developmental Origin of Fruits

12. Asexual Reproduction • Can be sustained by meristems=regions of undifferentiated, dividing cells • Parenchyma cells throughout plant divide and differentiate into more specialized types of cells (regenerate lost parts) • Fragmentation=separation of parent plant into parts that develop into whole plants • Apomixis=asexual production of seeds

13. Benefits of Reproductive Methods ASEXUAL • No need for pollinator • Allows plant to pass exact copy of genes (good if environment is stable) • Offspring generally stronger than sexually produced offspring (though germination is still very precarious SEXUAL • Better against unstable environments (pathogens, other fluctuation) because it generates variation • Dispersal of offspring to more distant locations • Seed dormancy puts growth on hold until environmental conditions become more favorable

14. This music video includes some general information about plant reproduction/responses to provide a break from slides! Enjoy 

15. Mechanisms to Prevent Self-Fertilization • Self-fertilization increases genetic variety by ensuring sperm and egg from different parents • Self-incompatibility= Ability of a plant to reject its own pollen and sometimes the pollen of closely related individuals • Dioecious species=Plants can’t self-fertilize because different individuals have either staminate flowers (no carpels) or carpellate flowers (no stamens); other plants have functional carpel and stamens, but mature at diff. times or have unfavorable orientation

16. Human Manipulation • Clones from cutting: most houseplants, woody ornamentals, and orchard trees • Grafting: makes it possible to combine the best qualities of different species or varieties into 1 plant • “Host” plant=stock, grafted part=scion • Test-tube cloning • Protoplast fusionwith tissue culture methods to invent new plant varieties (hybrids) that can be cloned (protoplast=plant cell with wall removed by enzyme treatment)

17. Plant Responses to Internal and External Signals • Plants receive specific signals and respond to them in ways that enhance survival and reproduction • Etiolation: the morphological adaptation for growing in the dark • De-etiolation: the change that plants undergo when shoot reaches light • Stem elongation slows, leaves expand, roots elongate, & shoot produces chlorophyll

18. Reception • Signals are first detected by receptors, proteins that undergo changes & shape in response to a specific stimulus • Receptor involved in de-etiolation is a type of phytochrome • Located in cytoplasm • Receptors can be sensitive to weak environmental or chemical signals

19. Transduction • Some de-etiolation responses=triggered by extremely low levels of life • Second messengers=small molecules & ions that amplify signal & transfer it from receptor to other proteins that carry out response • Ca2+ & cyclic GMP=second messengers in de-etiolation • Changes in Ca2+ levels=important in photochrome signal transduction • Photochrome activation opening of Ca2+ channels & a transient 100-fold increase in cytosolic Ca2+ levels • Photochrome changes shape, which leads to activation of guanylylcyclase • cGmp induces partial de-etiolation response

20. Response • Involves increased activity of enzymes • 2 mechanisms that can enhance an enzymatic step in a biochemical pathway= • post-translational modification 2) transcriptional regulation • post-translational modification- activates pre-existing enzymes • transcriptional regulation- increases/decreases the synthesis of mRNA encoding a specific enzyme

21. Overview of Reception, Transduction, Response

22. Plant Hormones • Hormone=signaling molecule produced in organism’s body & transported to other parts, where it binds to specific receptor & triggers responses in target cells & tissues • Every aspect of plant growth & development=due to hormonal control • Tropism=any growth response that results in plant organs curving toward/away from stimuli • Triple Response=hormone that enables shoot to avoid obstacles • Senescence=programmed death of certain cells or organs on the entire plant

23. Plant Hormones (continued)

24. Responses to Light • Blue-light receptors: control hypocotyl elongation, stomatal opening, & phototropism • Red and Blue light=most important colors in regulation of plant’s photomorphogenesis (effects of light on plant morphology) • Blue light initiates variety of responses in plants • including phototropism, the light-induced opening of stomata • 3 types of pigments detecting blue light= 1) Cryptochromevs 2) Phototropin 3) Zeaxanthin • Phytochromes: help with information about light, help plants keep track of passage of days and seasons • Action spectrum: graph that depicts relative effectiveness of diff wavelengths of radiation in driving a particular process

25. Responses to light Continued • Circadian rhythms: physiological cycle of ~24 hrs that persists even in absence of external cues • Photoperiodism: physiological response to photoperiod, such as flowering • Short-day plantsrequire light period shorter than critical length to flowers • Long-day plantsflower late in spring or early summer, need longer than a certain number of hours • Day-neutral plants (tomatoes, rice, dandelions)= unaffected by photoperiod & flower when they reach a certain stage of maturity

26. Reponses the light continued • Plants detect direction, intensity, & wavelength (color) • Phytochrome conversion also provides info about relative length of day & night (photoperiod) & hence time of year • Photoperiodism regulates time of flowering in many species • Free-running circadian cycles ~24 hours

27. Florigen: hypothetical signaling molecule for flowering

28. Plant Response to Stimuli • Gravitropism=response to gravity • Occurs as soon as a seed germinates • Statoliths=dense cytoplasmic components that settle under influence of gravity to lower portions of the cell • Action potentialsresemble nerve impulses in animals, but 1000x slower • Abiotic: nonliving stresses that plants encounter • Biotic: living stresses, such as herbivores and pathogens • Heat-shock proteins: help protect other proteins from heat stress

29. Environmental Stresses/Responses

30. Plant Defense pathogen Plants respond to attacks by herbivores and pathogens • Physical defenses--thorns & trichromes • Produce chemicals=distasteful & toxic • 1stline of defense: epidermis and periderm • 2nd line of defense: chemical attack that destroys pathogen and prevents spread of infection • Plant has little specific defense against virulent pathogens • Avirulent pathogens: strains of pathogens that mildly harm but do not kill host plants herbivore

31. Defense responses against an avirulent pathogen

32. Plants Defense (Continued) • Gene-for-gene recognition=form of plant disease resistance in which pathogen-derived molecules (effectors) are recognized by one of the 100s of resistance genes in plant’s genome • Hypersensitive response: defense response that causes cell and tissue death near infection site • Systemic acquired resistance: arises from plant-wide expression of defense genes • Salicylic acid: activates signal transduction pthwy that induces production of pathogenesis-related (PR) proteins & resistance to pathogen attack

33. Bibliography • Textbook Website in general: CHAPTER 38- Parts of flower, fertilization, male/female gametophytes, hummingbird, double fertilization, seed structure, origin of fruits, and preventing self-fertilization CHAPTER 39- Reception and transduction and response, flowering hormone, and avirulent defense responses http://view.ebookplus.pearsoncmg.com/ebook/launcheText.do?values=bookID::4487::platform::1004::invokeType::lms::launchState::goToEBook::scenarioid::scenario3::logoutplatform::1004::platform::1004::scenario::3::globalBookID::CM81419602::userID::1911037::pageid::::hsid::5434934bda1919e8fb46a13ad18940ba • (Chloroplast)-http://www.google.com/imgres?imgurl=http://www.biologycorner.com/resources/chloroplast_labeled.jpg&imgrefurl=http://www.biologycorner.com/APbiology/cellular/notes_cells2.html&usg=__jt46BLhGK2kXtfsnXvEk_pehTOI=&h=273&w=240&sz=19&hl=en&start=1&zoom=1&tbnid=0GPQ6DgB0MPpSM:&tbnh=113&tbnw=99&ei=OeGWT8acB6rAiQfc4ZWgCg&prev=/search%3Fq%3Dlabeled%2Bchloroplast%26um%3D1%26hl%3Den%26sa%3DN%26gbv%3D2%26tbm%3Disch&um=1&itbs=1

34. Bib Cntd. • (Linear electron flow)- http://www.bio.miami.edu/dana/pix/noncyclic.jpg • (Cyclic electron flow)- http://kvhs.nbed.nb.ca/gallant/biology/cyclic_electron_flow.jpg • (C3 and C4 plant)- http://www.google.com/imgres?q=c3+and+c4+plants&hl=en&biw=1203&bih=629&gbv=2&tbm=isch&tbnid=HVXznDU79kIssM:&imgrefurl=http://www.nature.com/scitable/content/each-plant-species-utilizes-one-of-several-13311179&docid=ST2PXVLQNsCjcM&imgurl=http://www.nature.com/scitable/content/ne0000/ne0000/ne0000/ne0000/13311179/taub_figure2_ksm.jpg&w=500&h=384&ei=sHSdT9fpC8nMiQKx8fBE&zoom=1&iact=hc&vpx=828&vpy=178&dur=661&hovh=197&hovw=256&tx=134&ty=110&sig=112547099696337624223&page=1&tbnh=122&tbnw=159&start=0&ndsp=18&ved=1t:429,r:4,s:0,i:91

35. Bib Cntd. • (CAM plant)- http://www.google.com/imgres?q=c3+and+c4+plants&hl=en&biw=1203&bih=629&gbv=2&tbm=isch&tbnid=5Wn-TnII7WaFSM:&imgrefurl=http://ihatecreataccount.blogspot.com/&docid=u6rKD-Gr1qVHqM&imgurl=http://4.bp.blogspot.com/-8mocbeEDyAE/TfzKBj9B4lI/AAAAAAAAABA/-l-B3ghAZ3s/s1600/C4-and-CAM-plants.jpg&w=614&h=602&ei=sHSdT9fpC8nMiQKx8fBE&zoom=1&iact=hc&vpx=937&vpy=73&dur=383&hovh=222&hovw=227&tx=155&ty=169&sig=112547099696337624223&page=1&tbnh=122&tbnw=124&start=0&ndsp=18&ved=1t:429,r:5,s:0,i:93 • (Mitochondria)-http://www.google.com/imgres?q=mitochondria&num=10&hl=en&gbv=2&biw=1203&bih=629&tbm=isch&tbnid=7G9QL6X6c6JrGM:&imgrefurl=http://micro.magnet.fsu.edu/cells/mitochondria/mitochondria.html&docid=Fzfn06X-Mo1mlM&imgurl=http://micro.magnet.fsu.edu/cells/mitochondria/images/mitochondriafigure1.jpg&w=296&h=312&ei=93SdT6maF9PbiALUtPRg&zoom=1&iact=rc&dur=403&sig=112547099696337624223&sqi=2&page=1&tbnh=124&tbnw=118&start=0&ndsp=19&ved=1t:429,r:1,s:0,i:109&tx=45&ty=26

36. Bib Cntd. • (Calvin Cycle)- http://www.emc.maricopa.edu/faculty/farabee/biobk/alcferm.gif • (Fermentation)- http://galvez-808.cghub.com/files/Image/086001-087000/86629/095_stream.jpg • (Sun)-http://www.google.com/imgres?q=the+sun&um=1&hl=en&sa=N&biw=1203&bih=629&tbm=isch&tbnid=eRnRauaHGhZV4M:&imgrefurl=http://www.bobthealien.co.uk/sun.htm&docid=2Zh8xL_2UaBKCM&imgurl=http://www.bobthealien.co.uk/sunmain2.png&w=320&h=320&ei=l4udT72rDqGSiQKrn7x4&zoom=1&iact=rc&dur=205&sig=112547099696337624223&page=1&tbnh=125&tbnw=124&start=0&ndsp=21&ved=1t:429,r:12,s:0,i:160&tx=94&ty=74

37. Bib Cntd. • (Tomato)- http://www.google.com/imgres?q=tomatoes&um=1&hl=en&sa=N&biw=1203&bih=629&tbm=isch&tbnid=-DcjM3eIeLrVNM:&imgrefurl=http://www.bewellbuzz.com/general/what-you-didnt-know-about-tomatoes/&docid=rci-XKvrxbp8xM&imgurl=http://cdn.bewellbuzz.com/wpcontent/uploads/2009/06/tomatoes=293x300.jpg&w=293&h=300&ei=Bo2dT6PfLsjhiAKH3OmkAQ&zoom=1&iact=hc&vpx=672&vpy=168&dur=233&hovh=227&hovw=222&tx=128&ty=73&sig=112547099696337624223&page=1&tbnh=132&tbnw=129&start=0&ndsp=20&ved=1t:429,r:4,s:0,i:143 • (Reception, transduction, response)- http://view.ebookplus.pearsoncmg.com/ebook/launcheText.do?values=bookID::4487::platform::1004::invokeType::lms::launchState::goToEBook::scenarioid::scenario3::logoutplatform::1004::platform::1004::scenario::3::globalBookID::CM81419602::userID::1911037::pageid::::hsid::5434934bda1919e8fb46a13ad18940ba

38. Bib Cntd. • (Gravitropism leaf)-http://www.google.com/imgres?q=gravitropism&hl=en&gbv=2&biw=1203&bih=651&tbm=isch&tbnid=DyjaGkCPk7oHBM:&imgrefurl=http://herbarium.desu.edu/pfk/page8/page9/page9.html&docid=zfQ1M6RevvnjYM&imgurl=http://herbarium.desu.edu/pfk/page8/page9/files/page9_1.jpg&w=301&h=265&ei=QS6eT-4G5JqIAuyF-Hg&zoom=1&iact=rc&dur=488&sig=112547099696337624223&page=1&tbnh=145&tbnw=165&start=0&ndsp=19&ved=1t:429,r:3,s:0,i:76&tx=104&ty=67 • (Herbivore)- http://www.google.com/imgres?q=herbivores&um=1&hl=en&sa=N&biw=1203&bih=629&tbm=isch&tbnid=NcMGzieuixaetM:&imgrefurl=http://www.qrg.northwestern.edu/projects/marssim/simhtml/info/whats-a-herbivore.html&docid=4j8edxN7tTtbCM&imgurl=http://www.qrg.northwestern.edu/projects/marssim/simhtml/pics-for-sim/pronghorn.jpg&w=215&h=198&ei=FC-eT8-DKeSpiALYyeCcAQ&zoom=1&iact=rc&dur=291&sig=112547099696337624223&page=1&tbnh=125&tbnw=123&start=0&ndsp=20&ved=1t:429,r:0,s:0,i:135&tx=86&ty=40

39. Bib Cntd. • (Grafting)-http://www.google.com/imgres?q=grafting+of+plants&num=10&um=1&hl=en&biw=1203&bih=651&tbm=isch&tbnid=oSjdfEPHjhuwiM:&imgrefurl=http://anpsa.org.au/grafting.html&docid=O4TojW7M8_dPMM&imgurl=http://anpsa.org.au/gif/grafta.gif&w=261&h=341&ei=ryKeT4KNJ4-NigLBqMWZAQ&zoom=1&iact=rc&dur=382&sig=112547099696337624223&sqi=2&page=1&tbnh=133&tbnw=102&start=0&ndsp=21&ved=1t:429,r:8,s:0,i:84&tx=63&ty=44 • (Pathogen)- http://www.google.com/imgres?q=pathogen&um=1&hl=en&sa=N&biw=1203&bih=629&tbm=isch&tbnid=v2OabBWgeetIRM:&imgrefurl=http://www.beltina.org/health-dictionary/pathogen-definition-what-is.html&docid=LpmLvh6jzfJ3dM&imgurl=http://www.beltina.org/pics/pathogen.jpg&w=291&h=284&ei=YC-eT7v9D8muiAL9wtCiAQ&zoom=1&iact=hc&vpx=112&vpy=167&dur=740&hovh=222&hovw=227&tx=140&ty=135&sig=112547099696337624223&page=1&tbnh=126&tbnw=130&start=0&ndsp=21&ved=1t:429,r:0,s:0,i:135

40. Bib Cntd. • (Hypersensitive response leaf)-http://www.google.com/imgres?q=hypersensitive+response&um=1&hl=en&sa=N&biw=1002&bih=524&tbm=isch&tbnid=6osVRRAmmlx0tM:&imgrefurl=http://www.sidthomas.net/SenEssence/Development/devexamples.htm&docid=0hSHRJW6boWvbM&imgurl=http://www.sidthomas.net/images/hypersensitive.jpg&w=400&h=300&ei=3DOeT8PmGYSXiALWtKCeAQ&zoom=1&iact=rc&dur=483&sig=112547099696337624223&page=1&tbnh=159&tbnw=218&start=0&ndsp=8&ved=1t:429,r:1,s:0,i:71&tx=126&ty=59