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Glenbard East High School ESRP 2019

The Characterization of Phytochelatins Mediating Zinc Transport in Arabidopsis thaliana

Authors:

  • Students:
    • Hayden Dudek
    • Lauren Elias
    • Preaksha Garg
    • Sahil Mehta
    • Samir Mehta
    • Eha Srivastava
    • Katie Tonielli
    • Grace Tu
  • Teachers:
    • Karen Beardsley
  • Mentors:
    • Antonio Lanzirotti (Argonne National Laboratory, SE CARS Beamline 13IDE)
    • Matt Newville (Argonne National Laboratory, SE CARS Beamline 13IDE)

Advanced Photon Source Sector 13: GSECARS

Zinc is an essential microelement involved in multiple higher plant processes that require enzymatical cofactors for function. Both excess and deficient levels of zinc are problematic for higher plants. The homeostasis of zinc in higher plants involves a complex interaction of responses to environmental stimuli and regulation by multiple genes resulting in efflux, sequestration and chelation of zinc. It is desirable to more fully understand the complex nature of zinc homeostasis due to current increase in anthropogenic activities that contribute to toxicity or deficiency in soils which leads to food insecurity. Ionomics as a means to characterize phenotypes of mutant plants has led to a greater understanding of complex nature of gene functions that code for the regulation of microelements. Synchrotron xrf allows for increased resolution and detection of these microelements without seed preparation that can potentially affect tissue integrity. One mechanism of Zn homeostasis that is of interest involves the production of phytochelatins (PC) as a feedback response to environmental zinc levels. It has been hypothesized that Zn-PC chelated complexes may be involved with the translocation of Zn. This study used Synchrotron X-ray fluorescence (SXRF) and microtomography to evaluate microelement speciation, placement and relative concentration in A. thaliana wild type Col-0 versus PC-deficient mutant cad 1-3 seed. Differences in whole seed Zn concentration as measured by sxrf (counts per pixel) suggest that the translocation of Zn-PC complexes to seed is affected. Whole wild type Col-0 seed concentrations were twice that of cad 1-3 seed. Unanticipated increased embryonic vascular tissue Fe deposition were detected. Microtomography results do not suggest variation in wild type versus mutant seed microelement deposition patterns.

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