Maize ZmPT7 regulates Pi uptake and redistribution which is modulated by phosphorylation.

Phosphorus, an essential mineral macronutrient, is a major constituent of fertilizers for maize (Zea mays L.) production. However, the molecular mechanisms of phosphate (Pi) acquisition in maize plants and its redistribution remain unclear. This study presents the functional characterization of ZmPT7 in Pi uptake and redistribution in maize. The ZmPT7 was expressed in roots and leaves, and induced during Pi starvation. The ZmPT7 complemented the Pi-uptake deficiency of yeast mutant phoΔnull and Arabidopsis mutant pht1;1Δ4Δ, indicating that ZmPT7 functioned as a Pi transporter. We generated zmpt7 mutants by CRISPR/Cas9 and ZmPT7-overexpressing lines. The zmpt7 mutants showed reduced, whereas the ZmPT7-overexpressing lines displayed increased Pi-uptake capacity and Pi redistribution from old to young leaves, demonstrating that ZmPT7 played central roles in Pi acquisition and Pi redistribution from old to young leaves. The ZmCK2 kinases phosphorylated ZmPT7 at Ser-521 in old maize leaves, which enhanced transport activity of ZmPT7. The Ser-520 of Arabidopsis AtPHT1;1, a conserved residue of ZmPT7 Ser-521, was also phosphorylated by AtCK2 kinase, and the mutation of Ser-520 to Glu (phosphorylation mimic) yielded enhanced transport activity of AtPHT1;1. Taken together, these results indicate that ZmPT7 plays important roles in Pi acquisition and redistribution, and its transport activity is modulated by phosphorylation.

Study on self-assembly of gold nanoparticles directed by glutathione with resonance light scattering technique and its analytical applications.

In this paper, it has been demonstrated that gold nanoparticles can self-assemble to form network structure in the presence of glutathione, which results in great enhancement of resonance light scattering (RLS). Results from this RLS experiments confirm that RLS is a sensitive and convenient technique for studying the self-assembly of nanoparticles. The principles of the enhanced RLS of nanoparticle assemblies are discussed, and the mechanism of the interaction between gold nanoparticles and glutathione is investigated. The enhanced RLS of gold nanoparticle assemblies directed by glutathione is also successfully applied to sensitive determination of glutathione. Under the optimal conditions, the calibration curve for glutathione determination is linear in concentration range of 0.01-0.1 microg/ml, and the corresponding detection limit is 4.7 ng/ml (3sigma, 15.3 nM).