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The infection process during nodule organogenesis ─ occur simultaneously

The infection process during nodule organogenesis ─ occur simultaneously. Plant: attractants Rhizobia: Nod factors. Fuse with the membrane of root cell. Cell wall degradation Infection thread formation. Penetrate and new infection thread formation.

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The infection process during nodule organogenesis ─ occur simultaneously

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  1. Theinfectionprocess duringnodule organogenesis ─ occur simultaneously Plant: attractants Rhizobia: Nod factors Fuse with the membrane of root cell Cell wall degradation Infection thread formation Penetrate and new infection thread formation Branching and extending bacteria released into the cytosol Bacteroids: a nitrogen-fixing endosymbiotic organelles (p. 301R)

  2. The energetic of nutrient assimilation ¤nitrate  ammonium consumes ca. 25% of the total energy less than 2% of the total dry weight produce ¤occur in the stroma of the chloroplast ¤Photoassimilation: coupling nutrient assimilation to photosynthetic e- transport use the surplus reductants of Calvin cycle  high light, low [CO2], photoassimilation proceed [CO2]  inhibit photoassimilation inhibitphotorespiration C/N assimilation

  3. C4 plants:photoassimilation occur in mesophyll cells, [CO2] low High [CO2] in bundle sheath cells  Inhibit photoassimilation

  4. Assimilatory quotient(AQ)  CO2 assimilated / O2 evolved as a function of light level Wheat seedling no photoassimilation Photoassimilation  (no photoinhibition)

  5. Photoassimilation: CO2 fixation may interfere with nitrate photoassimilation (3) (1) (2) stroma (1)NADH is supported by chloroplast via malate shuttle (2)The level of reduced ferredoxin (3)The acidification of stroma dissipate the pH gradient CO2 itself and ATP regeneration

  6. WebEssay 12.1 The plants receiving NH4+ were more responsive to CO2 enrichment than those receiving NO3 -

  7. WebEssay 12.1 Doubling CO2 (enrichment): short-term: accelerate carbon fixation in C3 plants by about 30% long-term (days to weeks): carbon fixation declines until it stabilizes at a rate that averages 12% above ambient controls CO2 acclimation shoot N and proteins contents diminish

  8. Sulfur assimilation § Sources: The weathering of parent rock material Industrial contamination, the burning of fossil fuels releases sulfur dioxide and hydrogen sulfide § Absportion pathways: sulfate: H+– SO42- symporter of the roots from the soil sulfur dioxide take up from stomata ＞0.3 ppm, 8 h  extensive tissue damage § Location mostly in leaveswhich cansupply reduced ferredoxin and serine (p. 305R) § The transported form in the phloem glutathione (Gly-Cys--Glu), also acts as a signal that coordinates the absorption of sulfate by the roots and the assimilation of sulfate by the shoot

  9. gallic acid glucoside, glucosinolates, polysaccharides In cytosol 2 In plastids Activated form (photorespiration)

  10. Cysteine  Methionine(Web topic 12.3) S-adenosylmethionine

  11. Sulfur assimilation § Functions: The structural and regulatory roles in proteins, disulfide bridges Electron transfer through iron-sulfur clusters Catalytic sites for several enzymes and coenzymes Secondary metabolites such as Nod factors, antiseptic alliin in garlic, and anticarcinogen sulforaphane in broccoli

  12. Oxygen assimilation ¤Respiration (major) Photorespiration: rubisco oxygenase activity (major) oxygen fixation (minor): oxygen assimilated into organic compounds ¤ the types of oxygenases dioxygenase: monooxygenase: mixed-function oxidase

  13. In ER cell wall protein extensin, posttranslation hydroxylation demethylation A + O2 + BH2 AO + H2O + B

  14. Cation assimilation ¤K, Mg, Ca, Cu, Fe, Mn, Co, Na, Zn ¤coordination bonds and electrostatic bonds p. 306L neutralization oxalate

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