2/1/15%1%%Plants%%Human%use%of%Plants%Aesthe4cally%pleasing%%2/1/15%2%Human%use%of%Plants%Agriculture%–%ar4ficial%selec4on%Human%use%of%Plants%Fuel%sources%–%wood,%coal%!%2/1/15%3%Human%use%of%Plants%Forestry%%Human%use%of%Plants%BioCprospec4ng%!%medicinal%uses%Taxol%–%Pacific%Yew%tree%bark% Asprin%–%Willow%Bark%2/1/15%4%Ecological%Roles%of%Plants%• Produce%oxygen%• Contribute%to%soil%(via%decomposers)%• Protect%against%erosion%–%hold%soil%together%• Retain%moisture%in%soil%• Buffer%local%climate%Photosynthesis Respiration Photoautotrophs%produce%their%own%carbon%energy%source%(food)%using%sunlight%They%“fix”%carbon:%Inorganic%C%!%Organic%C%CO2%C2H12O2%provide habitat; provide foodC6H12O62/1/15%5%Chloroplasts Spinach%cells%with%chloroplasts%Photosynthesis%C6H12O6%%+%%O2%CO2%%+%%H2O%%sunlight%chlorophyll%2/1/15%6%Red%Algae%&%Brown%Algae%• Have%addi4onal%pigments%%• Absorb%different%wavelengths%of%light%• Allows%for%use%of%different%niches%%!%red%algae%can%grow%in%deeper%water%%Porphyra%sp.%!%nori%Phylogeny%of%Plants%2/1/15%7%Evolu4on%of%Terrestrial%Plants%Charophytes:%Coleochaete% %& % %%Chara%Green%Algae%Land-Plants:-Water-to-Land-Transi4on--• First%terrestrial%colonizer%%– Animals%transi4oned%to%land%a_er%plants%• Able%to%grow%with%4ssues%exposed%to%air%• Dominant%primary%producers%in%terrestrial%food%chains%%%%%2/1/15%8%Moving%from%Water%to%Land%%Challenges:%– Gas%Exchange%&%Water%loss%– Transport%&%Support%– Reproduc4on%Evolu4onary%trends:%%3%major%divisions%%of%terrestrial%plants%2/1/15%9%Typical features of a plant cell Plasma membrane Mitochondria Nucleus The%plant%cell-wall%is%a%rigid%barrier%composed%of%polysaccharides.%Chloroplasts-enable%plant%cells%to%harness%the%energy%of%sunlight%to%synthesize%sugars.%Vacuoles-are%waterCfilled%organelles%that%contribute%to%the%structural%rigidity%of%plants%by%maintaining%turgor%pressure%against%cell%walls.%Vacuoles Cell wall Plant cell Dehydrated plant cell H2O Vacuoles%exert%hydrosta4c%pressure%on%the%cell%walls%and%provide%rigidity%to%the%plant%cell.%Dehydra4on%collapses%vacuoles,%relieves%the%hydrosta4c%pressure,%and%results%in%wil4ng.%er; plasma desmata?2/1/15%10%Waxy%Cu4cle%&%Stomata%Adapta4ons%to%avoid%desicca4on%CO2%Uptake%in%Leaves%• Light%s4mulates%stomata%to%open%%• High%levels%of%CO2%inside%the%leaf%cause%stomata%to%close%%2/1/15%11%Stomata%&%Guard%Cells%Low%water%supply%!%%Guard%cells%dehydrate%&%shrink%!%%Stomata%close%Adapta4ons%to%avoid%desicca4on%Adapta4ons%to%avoid%desicca4on%CAM%photosynthesis:%– Open%stomata%at%night%&%store%CO2%– Photosynthesize%during%day%with%stomata%closed%– Adapta4on%to%arid%condi4ons%2/1/15%12%Transport%&%Support%Evolu4onary%Trend%=%Increase%in%vascular%4ssue%Plant%Stems%2/1/15%13%Forces%that%Pull%Water%from%the%Soil%Phloem%Transport%from%Source%to%Sink%-Most%photosynthesis%%occurs%in%the%leaves%-Leaves-=-Source-of-fixed-C--%2/1/15%14%Rhizosphere: the soil layer that surrounds actively growing roots The rhizosphere is rich in microbial populations that aid in decomposition Phloem%Feeds%Plant%&%Rhizosphere%Plant Growth & Development2/1/15%15%Primary%Growth%–%%%Shoot%Apical%Meristem%&%Elonga4on%Zone%Secondary%Growth%–%%%Lateral%Meristems%increase%plant%diameter%2/1/15%16%Growth%Rings%• Record%of%annual%growth%(age)%• Record%of%past%clima4c%condi4ons%(temp.,%moisture,%fire)%Roots%2/1/15%17%Phototropism: – Growth toward light (shoots) – Growth away from light (roots) Gravitropism: – Growth against gravity (shoots) – Growth toward gravity (roots) Growth%Orienta4on%Symbioses:%Plants%&%Fungi%both increase size of root2/1/15%18%Symbioses:%Plants%&%Bacteria%Uptake%of%Nitrogen%Parasi4c%Plants%Dodder% Rafflesia1Mistletoe%2/1/15%19%Evolu4onary%Trends%across%3%major%divisions%%of%terrestrial%plants%Mosses% Ferns%Gymnosperms%Angiosperms%Generalized%Plant%Life%Cycle%Alterna4on%of%Genera4ons%mitosis2/1/15%20%Major%trends%in%plant%evolu4on:%• Increase%in%vascular%4ssue%• Gametophyte%to%sporophyte%dominant%life%cycles%– Trend%from%sporophyte%dependent%on%the%gametophyte%%% %to%gametophyte%dependent%on%the%sporophyte%• Evolu4on%of%pollen%!%H2O%dependent%to%H2O%independent%fer4liza4on%%• Evolu4on%of%the%seed%Evolu4onary%trend:%Gametophyte%dominant%to%Sporophyte%dominant%2/1/15%21%Water%to%Land%Transi4on%Evolu4onary%Trend:%Increased%H2O%independence%Bryophyte%Diversity%Moss- Liverwort- Hornwort-2/1/15%22%Sperm%release%is%s4mulated%by%raindrops.%The%diploid%zygote%is%retained,%and%the%sporophyte%develops%in%place,%supported%mechanically%and%nutri4onally%by%the%gametophyte.%The%mul4cellular%sporophyte%produces%thousands%of%haploid%pores%by%meiosis.%Haploid%spores%are%released%into%the%air.%Those%that%land%in%a%suitable%site%will%germinate%to%form%a%new%gametophyte%genera4on.%Fer4liza4on%The%egg%is%retained.%Dispersal%Meiosis%HAPLOID (1n) Haploid spores DIPLOID (2n) Sporopollenin wall Sporophyte Gametophytes Male Female Mosses%Gametophyte%(1n)%Sporophyte%(2n)%• Gametophyte%dominant%• H2O%dependent%for%fer4liza4on%• Disperse%via%spores%(1n)%prevents drying out2/1/15%23%Adapta4on:%Sporopollenin--– UV protection – Desiccation protection Coloured%scanning%electron%micrograph%of%spores%from%a%stag'sChorn%clubmoss%EYE1OF1SCIENCE1/1SCIENCE1PHOTO1LIBRARY%Sequen4al%s4ll%frames%from%a%video%filmed%at%10,000fps.%Each%frame%is%1/10,000%of%a%second.%Photo%series%by%Clara%Hard,%Joan%Edwards%and%Dwight%Whitaker.%Capsules%from%Sphagnum1henryeuse.%Two%round%are%unexploded.%Photo%by%Joan%Edwards.%Spore%dispersal%Sphagnum%Moss%• Major%component%of%peat%bogs%• Changes%pH%of%water%• Slow%decomposi4on%%%Peat%bogs%store%large%%%amounts%of%organic%C%%%%!%Coal%forma4on%2/1/15%24%Lycophytes,%Ferns%and%Horsetails%Lycophytes%~%1200%extant%species%%%%%Ex4nct%treeCsized%lycophytes%320%mya%Change%in%climate%dried%out%swamp%habitats%!%Coal%deposits%2/1/15%25%Ferns%&%Horsetails%Tree%%Fern%Azolla%sp.%%%Aqua4c%fern%w/%symbio4c%%NCfixing%cyanobacteria%40%%of%ferns%are%epiphyDc1!Epiphyte:%plant%growing%on%another%plant%Example:%Staghorn%Fern%Where%are%the%roots?%How%does%it%get%water?%like living on other thingsfrom the trees2/1/15%26%Diploid sporophyte Haploid gametophyte Sporopollenin%wall%Underground stem Roots Sporophyte Leaf Haploid spores Gametophytes Sporophyte Fer4liza4on%Dispersal%Meiosis%HAPLOID (1n) DIPLOID