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Arsenic Stress Response (As journey through the plant (ARSENATE TO ARSNITE…

- - - - AsV uses Pi chanels
        
        Phosophires is chemcially anaologys to asV
        
        DIfferent PHT (P trnasporter protien) make up Pi channels
        
        PHT1 high affinty, low affinty unknown
      - Asiii uses NIPs (nodulin-26-lie intrisic protines
        
        bidirectional trsport and uptake and remove, PI is unidirectional
        
        NIPS are subfamily of the aquaproin family
        
        one of hte 3 type sof NIPs
        
        trnasport is regualted bu asparagine-proline-alanine boxes and but aromatic/argine (ar/R)
      - Asiii also uses silcion trnasporters as has simualrty to silcion
        
        Lsi1 and Lsi2
        
        This si most important in rice
        
        n rice, the Si influx transporter Lsi1 (Low silicon rice 1; OsNIP2;1) is responsible for AsIII uptake while Si efflux transporter Lsi2 (Low silicon rice 2) mediates AsIII efflux (Ma et al., 2006, 2007, 2008).
        
        Silcion trnasporters medate flow of Si and As across endodermis and towards xylem for trnaslocation
        
        Knockout study
        
        Transporters of arsenite in rice and their role in arsenic accumulation in rice grain.Ma JF, Yamaji N, Mitani N, Xu XY, Su YH, McGrath SP, Zhao FJ Proc Natl Acad Sci U S A. 2008 Jul 22; 105(29):9931-5.
        
        lis1 knockout slight decrease in as in straw but not grain
        
        lis2 knockout has large dressrex in straw and grain (51-63% grain. suggesting more important in As trnasport in rice.
        
        but Lis2 knockout stops essetial siclon uptake with is needed for rice growth and can decrease yeild
      - rice NRAMP (Natural Resistance-Associated Macrophage Protein) transporter, OsNRAMP1
        
        Maybe be involved as found to incresae As accuation in aribidopsis roots and shoots when overexpresses
        
        Also found maybe used in root to shoot transolction
        
        Study only in aribidopsis, futher work on rice needed
        
        Tiwari M., Sharma D., Dwivedi S., Singh M., Tripathi R. D., Trivedi P. K. (2014). Expression in Arabidopsis and cellular localization reveal involvement of rice NRAMP, OsNRAMP1, in arsenic transport and tolerance. Plant Cell Environ. 37 140–152. 10.1111/pce.12138
      - Lis1 may take up methasyed As version, but much less effecinetly than AsV or asiii
      - :explode:reveiws used: Chen 2017 and Abbas 2018
      - Orangic uptake via NIPS is much slower than inorgnic uptake
- - - - In rice, OsABCC1 mediates vacuolar AsIII–PC sequestration, thus reducing As accumulation in rice grains (Song et al., 2014)
      - OsABCC1 is expressed in the exodermis and pericycle and si an ABC transporter
      - :star: Song W. Y., Yamaki T., Yamaji N., Ko D., Jung K. H., Fujii-Kashino M., et al. (2014). A rice ABC transporter, OsABCC1, reduces arsenic accumulation in the grain. Proc. Natl. Acad. Sci. U.S.A. 111 15699–15704. 10.1073/pnas.1414968111
        
        Coudl critquie this paper on knock out OsABCC1 from 2014
      - Because complexation of AsIII by thiols is a critical step for As transport into the vacuoles, simultaneously expressing the ABC transporters and PC synthase, the rate-limiting step in PC biosynthesis, may maximize As sequestration. In addition, root-specific promoters may be useful in controlling gene expression for genetically engineering low-As rice
      - Chen 2017 and Katalin :explode:
    - - PC, ser-PC, Des-PC and Glu-PCs are produced
      - Corraltion bettwen about of PC produced and amount fo i-AS in roots
      - PC-As reduces how much As is trnaslocted intot he grain , but this is speicifc to different varities
  - - - Glutathione S-Transferases: Role in Combating Abiotic Stresses Including Arsenic Detoxification in Plants )
    - - superoxide dismutase (SOD)
        
        Different types: Mn-SOD, Cu/Zn-SOD I and Cu/Zn-SOD II
      - peroxidase (POD)
    - - Can expland here
    - - H2O2 conc and lipid peroxidation levels (as shown by MDA conc) increases with accumation of As