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Summary: Abiotic stresses affect plant growth and development by causing cellular damage and/or restricting resources. Plants often respond to stresses through abscisic acid (ABA) signaling. Exogenous ABA application can therefore be used to mimic stress responses, which can be overridden by glucose (Glc) addition during seed germination. It remains unclear whether ABA‐mediated germination inhibition is due to regional or global suppression of Glc availability in germinating Arabidopsis seeds.We used a genetically engineered Förster resonance energy transfer (FRET) sensor to ascertain whether ABA affects the spatiotemporal distribution of Glc, 14C‐Glc uptake assays to track potential effects of ABA on sugar import, and transcriptome and mutant analyses to identify genes associated with Glc availability that are involved in ABA‐inhibited seed germination.Abscisic acid limits Glc in the hypocotyl largely by suppressing sugar allocation as well as altering sugar metabolism. Mutant plants carrying loss‐of‐function ABA‐inducible sucrose‐phosphate synthase (SPS) genes accumulated more Glc, leading to ABA‐insensitive germination. We reveal that Glc antagonizes ABA by globally counteracting the ABA influence at the transcript level, including expansin (EXP) family genes suppressed by ABA.This study presents a new perspective on how ABA affects Glc distribution, which likely reflects what occurs when seeds are subjected to abiotic stresses such as drought and salt stress. [ABSTRACT FROM AUTHOR]

Ultrasonic atomization is employed to generate size-controllable droplets for a variety of applications. Here, we minimize the number of parameters dictating the process by studying the atomization of a single drop pending from an ultrasonic horn. Spatiotemporally resolved X-ray phase-contrast imaging measurements show that the number-median sizes of the ejected droplets can be predicted by the linear Navier–Stokes equations, signifying that the size distribution is controlled by the fluid properties and the driving frequency. Experiments with larger pendant water drops indicate that the fluid–structure interaction plays a pivotal role in determining the ejection onset of the pendant drop. The atomization of viscoelastic drops is dictated by extended ligament formation, entrainment of air, and ejection of drop-encapsulated bubbles. Existing scaling laws are used to explain the required higher input amplitudes for the complete atomization of viscoelastic drops as compared to inviscid drops. Finally, we elucidate the differences between capillary wave-based and cavitation-based atomization and show that inducing cavitation and strong bubble oscillations quickens the onset of daughter drop ejection but impedes their size control. [Display omitted] • Time-resolved X-ray phase-contrast imaging of ultrasonic drop atomization. • Drop atomization is driven by surface capillary waves and not by cavitation. • Onset of daughter drop ejection is dictated by the fluid–structure interaction. • Viscoelastic drops require higher input amplitudes for complete atomization. • Cavitation-related mechanisms quicken ejection onset but impede production control. [ABSTRACT FROM AUTHOR]

Plant roots secrete a significant portion of their assimilated carbon into the rhizosphere. The putative sugar transporter SWEET2 is highly expressed in Arabidopsis roots. Expression patterns of SWEET2-β-glucuronidase fusions confirmed that SWEET2 accumulates highly in root cells and thus may contribute to sugar secretion, specifically from epidermal cells of the root apex. SWEET2-green fluorescent protein fusions localized to the tonoplast, which engulfs the major sugar storage compartment. Functional analysis of SWEET2 activity in yeast showed low uptake activity for the glucose analog 2-deoxyglucose, consistent with a role in the transport of glucose across the tonoplast. Loss-of-function sweet2 mutants showed reduced tolerance to excess glucose, lower glucose accumulation in leaves, and 15-25% higher glucose-derived carbon efflux from roots, suggesting that SWEET2 has a role in preventing the loss of sugar from root tissue. SWEET2 root expression was induced more than 10-fold during Pythium infection. Importantly, sweet2 mutants were more susceptible to the oomycete, showing impaired growth after infection. We propose that root-expressed vacuolar SWEET2 modulates sugar secretion, possibly by reducing the availability of glucose sequestered in the vacuole, thereby limiting carbon loss to the rhizosphere. Moreover, the reduced availability of sugar in the rhizosphere due to SWEET2 activity contributes to resistance to Pythium. [ABSTRACT FROM AUTHOR]

Soybean accounts for more than half of the global production of oilseed and more than a quarter of the protein used globally for human food and animal feed. Soybean domestication involved parallel increases in seed size and oil content, and a concomitant decrease in protein content. However, science has not yet discovered whether these effects were due to selective pressure on a single gene or multiple genes. Here, re-sequencing data from >800 genotypes revealed a strong selection during soybean domestication on GmSWEET10a. The selection of GmSWEET10a conferred simultaneous increases in soybean-seed size and oil content as well as a reduction in the protein content. The result was validated using both near-isogenic lines carrying substitution of haplotype chromosomal segments and transgenic soybeans. Moreover, GmSWEET10b was found to be functionally redundant with its homologue GmSWEET10a and to be undergoing selection in current breeding, leading the the elite allele GmSWEET10b , a potential target for present-day soybean breeding. Both GmSWEET10a and GmSWEET10b were shown to transport sucrose and hexose, contributing to sugar allocation from seed coat to embryo, which consequently determines oil and protein contents and seed size in soybean. We conclude that past selection of optimal GmSWEET10a alleles drove the initial domestication of multiple soybean-seed traits and that targeted selection of the elite allele GmSWEET10b may further improve the yield and seed quality of modern soybean cultivars. [ABSTRACT FROM AUTHOR]

It has long been recognized that stomatal movement modulates CO2 availability and as a consequence the photosynthetic rate of plants, and that this process is feedback-regulated by photoassimilates. However, the genetic components and mechanisms underlying this regulatory loop remain poorly understood, especially in monocot crop species. Here, we report the cloning and functional characterization of a maize (Zea mays) mutant named closed stomata1 (cst1). Map-based cloning of cst1 followed by confirmation with the clustered regularly interspaced short palindromic repeats (CRISPR)/ CRISPR associated protein 9 system identified the causal mutation in a Clade I Sugars Will Eventually be Exported Transporters (SWEET) family gene, which leads to the E81K mutation in the CST1 protein. CST1 encodes a functional glucose transporter expressed in subsidiary cells, and the E81K mutation strongly impairs the oligomerization and glucose transporter activity of CST1. Mutation of CST1 results in reduced stomatal opening, carbon starvation, and early senescence in leaves, suggesting that CST1 functions as a positive regulator of stomatal opening. Moreover, CST1 expression is induced by carbon starvation and suppressed by photoassimilate accumulation. Our study thus defines CST1 as a missing link in the feedback-regulation of stomatal movement and photosynthesis by photoassimilates in maize. [ABSTRACT FROM AUTHOR]

Highlights: [•] DB induced apoptosis and suppressed the growth of human non-Hodgkin lymphoma cells. [•] Mitochondrial membrane potential was decreased by DB. [•] DB activated FADD, caspases in the death receptor pathway. [ABSTRACT FROM AUTHOR]

• Air-water two-phase flow tests were carried out in a 3 × 3 rod bundle channel. • Global and local void fraction data were measured, benchmarked and validated. • PDF, FFT, averages and standard deviations were obtained for dynamic analysis. • Local/global void distributions under different flow conditions were presented. • A set of empirical correlations for estimating local void fractions were proposed. In this study, the vertical upward air–water two-phase flow tests have been carried out to investigate the distribution of local and global void fractions in a rod bundle channel under low-flow conditions. The height of the rod bundle channel is about 5 m, and the channel cross section is comprised of a 52 × 52 mm rectangular casing and 3 × 3 circular rods. The rods with a diameter of 11.5 mm and a pitch of 15.4 mm were set as a rectangular array. Four sets of non-intrusive conductivity sensors were built to measure the local and global void fractions of various gaps within the rod bundle channel. The tests were operated at low flow conditions: j g = 0.016–0.92 m/s and j f = 0.02–0.05 m/s, which covered the possible flow regimes of bubbly, cap-bubbly and cap-turbulent flows. The measured global void fraction were benchmarked with existing one-dimensional drift-flux model, and the local void fractions have been summed up by regions and compared with the global void fraction for validation. The dynamic characteristics of local/global void fractions have been analyzed with probability density function (PDF) and fast Fourier transform (FFT), and the distributions and variations of averaged void fraction against test conditions have been presented. Furthermore, the empirical correlations for estimating the local void fractions have been proposed, which can successfully estimate the local void distribution from global void fraction with limited errors. The present results and correlations can be a reference for future development and modification of detailed two-phase flow models in the rod bundle geometry. [ABSTRACT FROM AUTHOR]