Engineering topics

Zhang, Kewei

Publications and source records attributed to Zhang, Kewei.

7 records

DOE OSTI2022

Arabidopsis ABCG14 forms a homodimeric transporter for multiple cytokinins and mediates long-distance transport of isopentenyladenine-type cytokinins

Phytohormone cytokinins (CKs), primarily including trans-zeatin (tZ) and isopentenyladenine (iP) types, play critical roles in plant growth, development, and stress response. Long-distance transport of trans-zeatin (tZ)-type CKs has been well elucidated. However, long-distance transport of isopentenyladenine (iP)-type CKs remains unknown. Here, we demonstrated that the physiologically characterized ABC transporter AtABCG14 is also involved in long-distance transport of iP-type CKs. Biochemical characterization of AtABCG14 revealed that it forms homodimers and exhibits transporter properties towards multiple CKs, including iP and tZ types. AtABCG14 expression was induced by iP-type CKs in wild type and cyp735a1/a2 (cypDM) double mutant. The triple mutant atabcg14 cypDM exhibited more severe developmental phenotypes than atabcg14 and cypDM. CK quantification and 2 H 6 -iP isotope tracer experiment showed that the root-to-shoot transport of iP-type CKs was suppressed in atabcg14 cypDM. The reciprocal grafting of atabcg14 cypDM and cypDM revealed that AtABCG14 is responsible for the root xylem-loading and shoot phloem-distribution in the shootward transport of iP-type cytokinoins. Additionally, 2 H 6 -iP tracer experiment showed that the rootward transport of iP-type CKs was dependent on AtABCG14 expression in the roots. Collectively, our results demonstrate the long-distance circular transport of iP-type CKs mediated by AtABCG14 and provide new insights into the transport of CKs and other phytohormones.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2021

Monolignol acyltransferase for lignin p-hydroxybenzoylation in Populus

Plant lignification exhibits significant plasticity. Lignin in many species including Populus spp. has long been known decorated with p-hydroxybenzoates. However, the molecular basis for such structural modification remains undetermined. Here we report the identification and characterization of a Populus BAHD family acyltransferase that catalyzes monolignol p-hydroxybenzoylation, thus controlling the formation of p-hydroxybenzoylated lignin structures. We reveal that Populus acyltransferase PHBMT1 kinetically preferentially utilizes p-hydroxybenzoyl-CoA to acylate syringyl lignin monomer sinapyl alcohol in vitro. Consistently, disrupting PHBMT1 in Populus via CRISPR/Cas9 gene editing nearly completely depletes p-hydroxybenzoates of stem lignin; conversely, overexpression of PHBMT1 enhances stem lignin p-hydroxybenzoylation, suggesting PHBMT1 functions as a prime monolignol p-hydroxybenzoyltransferase in planta. Altering lignin p-hydroxybenzoylation significantly changes lignin solvent dissolution rate, indictive of its structural significance on lignin physiochemical properties. Identification of monolignol p-hydroxybenzoyltransferase offers a valuable tool for tailoring lignin structure and physiochemical properties and for engineering the industrially important platform chemical in woody biomass.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2021

Phloem unloading via the apoplastic pathway is essential for shoot distribution of root-synthesized cytokinins

Abstract Root-synthesized cytokinins are transported to the shoot and regulate the growth, development, and stress responses of aerial tissues. Previous studies have demonstrated that Arabidopsis (Arabidopsis thaliana) ATP binding cassette (ABC) transporter G family member 14 (AtABCG14) participates in xylem loading of root-synthesized cytokinins. However, the mechanism by which these root-derived cytokinins are distributed in the shoot remains unclear. Here, we revealed that AtABCG14-mediated phloem unloading through the apoplastic pathway is required for the appropriate shoot distribution of root-synthesized cytokinins in Arabidopsis. Wild-type rootstocks grafted to atabcg14 scions successfully restored trans-zeatin xylem loading. However, only low levels of root-synthesized cytokinins and induced shoot signaling were rescued. Reciprocal grafting and tissue-specific genetic complementation demonstrated that AtABCG14 disruption in the shoot considerably increased the retention of root-synthesized cytokinins in the phloem and substantially impaired their distribution in the leaf apoplast. The translocation of root-synthesized cytokinins from the xylem to the phloem and the subsequent unloading from the phloem is required for the shoot distribution and long-distance shootward transport of root-synthesized cytokinins. This study revealed a mechanism by which the phloem regulates systemic signaling of xylem-mediated transport of root-synthesized cytokinins from the root to the shoot.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2019

Anomalous Hall Effect in Epitaxial Ni–Mn–Ga Thin Films Grown on MgO(001) Substrate during the Martensitic Transformation

Epitaxial Ni–Mn–Ga thin films had been grown on MgO (001) by DC magnetron sputtering. And the anomalous Hall effect (AHE), microstructures, magnetism, and magnetoresistance (MR) were investigated. The AHE was measured in the film of Ni{sub 47.8}Mn{sub 30.8}Ga{sub 21.4} during the martensitic transformation. Meanwhile, the mechanism of the AHE was explained which indicates that the hall resistivity measured in our sample is primarily determined by AHE. The microstructures of the austenite phase and 7M martensite plates at room temperature had been observed on the film of Ni{sub 46.7}Mn{sub 31.7}Ga{sub 21.6} and Ni{sub 47.8}Mn{sub 30.8}Ga{sub 21.4}, respectively. Magnetic measurements reveal that all films possessed the martensitic transformation during the heating and cooling processes. In addition, the MR showed a negative value during the martensitic transformation which is mainly due to the reduction of spin-dependent scattering.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2019

Martensitic Transformation and Magnetocaloric Effect in High-Pressure Synthesized Ni{sub 53}Mn{sub 23.5}Ga{sub 23.5} Alloys

The polycrystalline Ni{sub 53}Mn{sub 23.5}Ga{sub 23.5} ferromagnetic alloy was synthesized by high-pressure method. The Ni{sub 53}Mn{sub 23.5}Ga{sub 23.5} ribbons were prepared by melt-spinning; then, the ribbons were pressed to the bulk samples under the 6-GPa high-pressure and heated to 1173 K for 30 min. The surface morphology, phase transition, and magnetocaloric effect (MCE) were investigated in the Ni{sub 53}Mn{sub 23.5}Ga{sub 23.5} bulk sample. Structural analysis and magnetic measurements studies of the bulk samples revealed the martensitic transformation at room temperature with a low thermal hysteresis of magnetization, and the nanocrystalline was observed by atomic force microscope measurements. The Ni{sub 53}Mn{sub 23.5}Ga{sub 23.5} bulk sample exhibits the directionality, and the magnetic properties have the large magnetization and low coercivity when the sample direction of the applied pressure was perpendicular to the direction of the applied magnetic field. The maximum entropy changes (∆S{sub M}) of − 4.8 J/kg K have been obtained at 330 K under the field of 30 kOe in the Ni{sub 53}Mn{sub 23.5}Ga{sub 23.5} bulk sample.

36 MATERIALS SCIENCE↗

DOE OSTI2019

Cytokinin Transporters: Multisite Players in Cytokinin Homeostasis and Signal Distribution

Here, cytokinins are a group of mobile adenine derivatives that act as chemical signals regulating a variety of biological processes implicated in plant development and stress responses. Their synthesis, homeostasis, and signaling perception evoke complicated intracellular traffic, intercellular movement, and in short- and long-distance translocation. Over nearly two decades, subsets of membrane transporters have been recognized and implicated in the transport of cytokinins as well as the related adenylates. In this review, we aim to recapitulate the key progresses in the exploration of the transporter proteins involved in cytokinin traffic and translocation, discuss their functional implications in the cytokinin-mediated paracrine and long-distance communication, and highlight some knowledge gaps and open issues toward comprehensively understanding the molecular mechanism of membrane transporters in controlling spatiotemporal distribution of cytokinin species.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2019

Structural and Magnetic Properties of FePt/SiO{sub 2} Core/Shell Nanoparticles

The disorder-order phase transition of FePt/SiO{sub 2} core/shell nanoparticles (NPs) induced by rapid thermal annealing was investigated. The FePt/SiO{sub 2} NPs were synthesized using FePt cores as seeds. For as-prepared FePt/SiO{sub 2} NPs, the average size of the FePt core and the thickness of the SiO{sub 2} shell are about 4.8 and 1.2 nm respectively, and the FePt NPs exhibit a disordered fcc structure. The FePt core NPs show obvious phase transformation from a disordered to an ordered structure after they were annealed at 600 °C for 2 min. Moreover, increasing annealing time can promote effectively the formation of the ordered fct-FePt phase. The relatively large coercivity H{sub c} is obtained for FePt NPs with a thicker SiO{sub 2} shell. The H{sub c} decreases firstly with decreasing temperature from 300 to 100 K and then increases from 100 to 10 K, which is ascribed to the coexistence of magnetically hard fct-FePt and magnetically soft fcc-FePt in the sample, and the incomplete exchange coupling between the hard and soft magnetic phases.

77 NANOSCIENCE AND NANOTECHNOLOGY↗