Biology of Plants
Biology of Plants PLB 203
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This 29 page Class Notes was uploaded by Mercedes Stokes on Saturday September 19, 2015. The Class Notes belongs to PLB 203 at Michigan State University taught by Staff in Fall. Since its upload, it has received 58 views. For similar materials see /class/207456/plb-203-michigan-state-university in Plant Biology at Michigan State University.
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Date Created: 09/19/15
Fair trade underground Nutrient exchange in mycorrhizal symbioses Yair ShacharHill The importance of mycorrhizal symbioses For The Plant m the soil WWMMS r ved water elations 19 tamhgmammal Horticultural uses Low input agriculture Arbuscular mycorrhizae versus Ectomycorrhizae EcM both occur in the fine root system difference in penetration of cortex cells AM fungal hyphae penetrate the cortex cells forming vesicles and arbuscules endomycorrhizae EcM do not penetrate cell walls of cortex cell ectomycorrhizae Arbuscules highly branched structures that are the site of nutrient transfer they do not penetrate cell membrane shortlived structures Vesicles ovalshaped darkly staining structures that are thought to function as nutrient reservoir EcM do not penetrate cell walls of cortex cells EcM form a puzzledshape covering of hyphae over the cortex cells called a Hartig net site of nutrient transfer relatively longlived structures Alteration of root morphology VAM do not significantly alter root morphology ofine roots possess root hairs Occurance estimated that 300000 plant species to have VAM only 150 spp fungi participate est 2000 plant species have EcM 5000 fungi participate taxonomic distribution VAM restricted to Glomerales ectomycorrhiza in gt70 genera in 9 orders Basidiomycota Ascomycota host distribution ectomycorrhiza mostly trees Gymnosperms eg Pinaceae Angiosperms eg Fagaceae Betulaceae Salicaceae Dipterocarpoideae Myrtaceae VAM woody amp herbaceous plants 90 of vascular plants normally assocw VAM fungi AM and EcM mycorrhizal symbioses are mutualismS Fungal benefits carbohydrates photosynthates monosaccharides that are converted to trehalose mannitol glycogen necessary cofactors for spore germination Plant benefits greater absorptive area uptake of P N Ca K Cu Mb Mg Zn water protection against soil borne pathogens Ecosystem Distributions VAM VAM are common in most habitats Dominant mycorrhizae in grasslands and tropical ecosystems EcM dominant in coniferous forests especially boreal or alpine regions common in many broadleaved forests in temperate and mediterranean regions also occur in some tropical or subtropical savanna or rain forests habitats Nonmycorrhizal NM Plants most common in disturbed habitats or sites with extreme environmental high latitude or elevation or soil conditions appear to be more common in Australia than on other continents Mycorrhizal fungi strongly influence plant communities gas v E 7 v a n w a E a v v E z E A 3 92 a a g g m I 2453mm 245310 214 Am bv v A 2 Etzo m 15 mun L Eton a g m u 99 90 v m 3 so a g 5 r 70 393 o y 2 A a 3 m 2 M w s E to 2 m 0 gm fqzsm 1 E Emu mam 1 m E 5 Y Em YT lt Em 2 9 E Ema Ewan 25910 2 24531012 Number otmyoovvmzal mugs spams Numhel Mmymrmlzai tungal species Root colonization by Glomerales hyphae enter the root through root hairs or by forming appressoria between epidermal cells cortical cells causing invagination of the plasma membrane Ammmm 7 at m Imam Epidemtie labmailmanquot l hyphaa Valle Hm adwwism lntarmlluiar implm in all W M Arbumlgs form arbuscules and if produced by a species vesicles Arbuscules highly branched haustoriumlike structures extend through the host cell wall but not cell plasma membrane increased surface area between the fungus and the host cell plasma membrane bidirectional transfer of metabolites and nutrients between the two mycorrhizal partners shortlived remains alive only for a few days before disintegrating and being digested by the cells of the plant in a healthy VAM mycorrhizal relationship there is a continuous sequence of development and disintegration of arbuscules Arbuscule Germinating spore Branched hyphae A phylum of their own Glomeromycota Amhaeaspam es 0rd mm i rrhaemlmmcmc r H Ar Irappei I J 7 L r T 1 Emil Ab 1 1 Ar emeticm amp QM r v Ar gardwnumfi quot XX 39 cosi mammalac Gimeraies Ga Wquot 1 x Mr Punulcu mlww V w P brastmmm Emup A8 KN ff amp P occultme V 7 71 HI I If Wigwam 39 7 i V 7 g Humeraccsle I I 139 393 1 w mam Efgllp H I fff H m m w 7 F R 35 fix Q E hmmhing mi msalwdl M1 5 I 1 5 v Acuulmpu G g i39anuc Acauloqu as a amp I Enlruphasgym 3 autgmup s m wa f Iicnimrnccac i Glumus GrufugrQa r imrsisp rai s arm aw Nutrient exchange is the basis for one of the world s most important relationships ecause of mycorrhizal symbioses billions of tons of carbon move annually from shoots to roots and hundreds of millions of tons of mineral nutrients move in the other direction Extraradical mycelium ERM Studying VI VO 5 Monoxenic culture Labeling with stable isotopes metabolism in AM NMR amp MS spectra MS NMR amp Radiolabeling Iquot regulation 1t Gene expression regulation 739 Gene identification validation Axenic culture Interpretation Trehalose H Exogenous hexose Hexose CH33N39R Lipids Triose C02 l Xyoxylate My CoA Carbon movement in the AM symbiosis Hexose Trehalose sher leyegyrllate rr gon H cycle 7 v Triose Hexose Trehalose Carbon Transfer between plants via the mycorrhizal network Carbon supplied as 140 glucose to one root system is transferred to a second root system via a common mycorrhizal network dpm X 103 mg391 dwt a CL 000 OO 25 2O 88 l O ofinitially added 14 O time in d 140 in donor and recipient mycorrhizal roots 714212835424956 14C in extraradical hyphae of donor and recipient root compartments 7 1 4 28 42 56 time in d 140 in the medium of donor and recipient root compartments But mass spectra of fungal and host metabolites after supplying the donor roots with 1301 glucose show that the carbon transferred remains in fungal compounds a 80 so 8 so 396 Trehalose Sucrose 395 Fatty aCId 1621 E 60 60 g 50 N m 390 390 C C 3 40 4O 3 40 N m 9 2 E 20 20 E 20 03 a n O n 0 0 442 443 444 445 446 442 443 444 445 446 268 39 269 39 270 quot271 39 272 Atomic mass units Atomic mass units Atomic mass units Unlabeled standard natural abundance 13C level I Extracted from donor roots I Extracted from recipient roots Simulated assuming 125 labeling in alternate positions Carbon transferred between root systems usually stays in the fungus A guess about the movement of Nitrogen Hexose 39 13 39 39 39 39 39 39 quotquotquotI Intraradlcal carbon pool Extraradlcal carbon pool Labeling in free amino acids after exposure to 15NH4 in the fungal compartment as measured by GC mass spectrometry 15Nenrichment 100 90 80 70 60 50 4O 30 20 10 O Amino Acids Free amino acids of mycorrhizal roots Free amino acids of extraradical hyphae Labeling in free amino acids after exposure to 15NH4 in the fungal compartment for 1 week 15N enrichment A c 00 O o o o O l O L Amino Acids UIE 51V Mil UJO Free amino acids of mycorrhizal roots Free amino acids of extraradical hyphae But carbon doesn t accompany the nitrogen Average 15N Enrichment in Root Protein Amino Acids following 15N andor 130 labeling ofthe ERM for 8 Weeks Label Supplied label in Protein Amino Acids 13012 acetate 15N03 ala gly 451 val 498 leu 487 ser 475 thr 479 phe 472 51 791 asp 518 cys 341 glu 682 asn 586 lys 584 gln 683 arg 610 tyr 421 13c 2 acetate 2015 ala l 0 gly 02 val l 8 leu 01 met 25 ser 54 thr 30 Phe 32 Asp 26 Cys 03 Glu 066 Asn 2 9 His 1 8 Arginine is translocated from ERM to IRM Mass isomer abundance Mass spectrometry data of 13C Arg labeling expt 70 20 VsYsEYEsY Y Y Y gtY Y Y Y Y Y Y I Unlabeled stan ard Arg in unlabele roots Arg in ERM aft r labeling Arg from roots fter labeling Arg from root protein Arg from root proteinArg D DD V V 31 442 Ww e t rm 447 444 445 446 Mass isomers of arginine mz l l iiimvm 449 450 451 Comparing the expression of genes involved in primary nitrogen metabolism in the intraradical and extraradical fungal tissues Expression ratio 00007 30 27 24 21 18 15 12 Nitrate Ammonium I Glutamine Synthetase I Glutamate dehydrogenase I Ornithine aminotransferase Urease associated protein Current status of testing the model Hexose 31 Intraradical carbon pool
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