Abscisic Acid Inhibits Cortical Microtubules Reorganization and Enhances Ultraviolet-B Tolerance in Arabidopsis thaliana.

Ultraviolet-B (UV-B) radiation is one of the important environmental factors limiting plant growth. Both abscisic acid (ABA) and microtubules have been previously reported to be involved in plant response to UV-B. However, whether there is a potential link between ABA and microtubules and the consequent signal transduction mechanism underlying plant response to UV-B radiation remains largely unclear. Here, by using sad2-2 mutant plants (sensitive to ABA and drought) and exogenous application of ABA, we saw that ABA strengthens the adaptive response to UV-B stress in Arabidopsis thaliana (A. thaliana). The abnormal swelling root tips of ABA-deficient aba3 mutants demonstrated that ABA deficiency aggravated the growth retardation imposed by UV-B radiation. In addition, the cortical microtubule arrays of the transition zones of the roots were examined in the aba3 and sad2-2 mutants with or without UV-B radiation. The observation revealed that UV-B remodels cortical microtubules, and high endogenous ABA can stabilize the microtubules and reduce their UV-B-induced reorganization. To further confirm the role of ABA on microtubule arrays, root growth and cortical microtubules were evaluated after exogenous ABA, taxol, and oryzalin feeding. The results suggested that ABA can promote root elongation by stabilizing the transverse cortical microtubules under UV-B stress conditions. We thus uncovered an important role of ABA, which bridges UV-B and plants' adaptive response by remodeling the rearrangement of the cortical microtubules.

Recent Advancements and Biotechnological Implications of Carotenoid Metabolism of Brassica.

Carotenoids were synthesized in the plant cells involved in photosynthesis and photo-protection. In humans, carotenoids are essential as dietary antioxidants and vitamin A precursors. Brassica crops are the major sources of nutritionally important dietary carotenoids. Recent studies have unraveled the major genetic components in the carotenoid metabolic pathway in Brassica, including the identification of key factors that directly participate or regulate carotenoid biosynthesis. However, recent genetic advances and the complexity of the mechanism and regulation of Brassica carotenoid accumulation have not been reviewed. Herein, we reviewed the recent progress regarding Brassica carotenoids from the perspective of forward genetics, discussed biotechnological implications and provided new perspectives on how to transfer the knowledge of carotenoid research in Brassica to the crop breeding process.

Upconversion core/shell nanoparticles with lowered surface quenching for fluorescence detection of Hg2+ ions.

In this study, we reported a fluorescent nanoprobe assembled with upconversion core/shell nanoparticles and a chromophore ruthenium complex (N719@UCNPs). Functional groups (NCS) of the ruthenium complex N719 could react with Hg2+, which made N719 lose the efficacy in quenching the fluorescence of upconversion nanoparticles (UCNPs) and resulted in the recovery of the fluorescence intensity of UCNPs eventually. This fluorescent nanoprobe could provide a rapid and efficient detection of Hg2+ ions in vivo based on the fluorescence resonance energy transfer (FRET) between UCNPs and N719, and a detection limit of 0.1 µg mL-1 can be achieved based on this nanoprobe. It's worth mentioning that, compared with bare core upconversion nanoparticles, the core/shell UCNPs could greatly reduce the surface quenching of the fluorescence induced by solvents instead of N719, thus leading to the enhancement of signal-to-noise ratios. Moreover, the excitation of core/shell UCNPs requires a much lower power (0.06 W cm-2) than that of bare cores, which is beneficial for reducing the decomposition of N719 to stabilize the FRET processes.

Elegant Shadow Making Tiny Force Visible for Water-Walking Arthropods and Updated Archimedes' Principle.

Forces acted on legs of water-walking arthropods with weights in dynes are of great interest for entomologist, physicists, and engineers. While their floating mechanism has been recognized, the in vivo leg forces stationary have not yet been simultaneously achieved. In this study, their elegant bright-edged leg shadows are used to make the tiny forces visible and measurable based on the updated Archimedes' principle. The force was approximately proportional to the shadow area with a resolution from nanonewton to piconewton/pixel. The sum of leg forces agreed well with the body weight measured with an accurate electronic balance, which verified updated Archimedes' principle at the arthropod level. The slight changes of vertical body weight focus position and the body pitch angle have also been revealed for the first time. The visualization of tiny force by shadow is cost-effective and very sensitive and could be used in many other applications.