Search for: All records

We describe the Harder–Narasimhan filtration of the Hodge bundle for Teichmüller curves in the nonvarying strata of quadratic differentials appearing in the work of Dawei Chen and Martin Möller [Ann. Sci. ’Ec. Norm. Sup’er. (4) 47 (2014), pp. 309–369]. Moreover, we show that the Hodge bundle on the nonvarying strata away from the irregular components can split as a direct sum of line bundles. As applications, we determine all individual Lyapunov exponents of algebraically primitive Teichmüller curves in the nonvarying strata and derive new results regarding the asymptotic behavior of Lyapunov exponents. 

ABSTRACT Global understanding of how plant diversity responds to multiple, co‐occurring global change drivers (e.g., elevated CO₂, climate change, and nitrogen addition) remains fragmented, largely due to the highly context‐dependent nature of responses and disparate experimental evidence. To address this, we conducted a global meta‐analysis synthesising 6832 control‐treatment comparisons from 465 studies. We found that for individual drivers, elevated CO₂had no effect on species richness, whereas increased precipitation enhanced it. In contrast, warming, decreased precipitation, and nitrogen addition generally reduced richness, with nitrogen addition consistently decreasing Shannon diversity and Pielou evenness. When drivers combined, warming‐driven losses were offset by elevated CO₂and increased precipitation and those of nitrogen addition were counteracted by both increased and decreased precipitation. Interaction analyses further revealed that additive effects between drivers predominated, though significant antagonisms emerged for specific pairs. Importantly, these responses were strongly context‐dependent, being mediated by a combination of site‐specific conditions (i.e., local climate, soil, and background diversity) and experimental methodologies (i.e., treatment duration, intensity, and plot and sampling area). Our synthesis underscores that predicting future biodiversity trajectories necessitates that models evolve beyond main effects to explicitly represent both multi‐driver interactions and the critical, often‐dominant, moderating role of local contexts and experimental conditions. 

Developmental plasticity is critical for plants to adapt to constantly changing environments. Plant root hairs display dramatic plasticity under different environments and therefore play crucial roles in defense against environmental stressors. Here, we report the isolation of an Arabidopsis mutant, salinity over-sensitive mutant 1-1 (som1-1), also exhibiting root hair developmental defects. Map-based cloning and allelic analyses confirmed that som1-1 is a new mutant allele of SPIRRIG (SPI), which encodes a Beige and Chediak Higashi (BEACH) domain-containing protein. SPI has been reported to facilitate actin dependent root hair development by temporally and spatially regulating the expression of BRICK1 (BRK1), a subunit of the SCAR/WAVE actin nucleating promoting complex. Our living cell imaging examinations revealed that salt stress induces an altered actin organization in root hair that mimics those in the spi mutant, implying SPI may respond to salt stress induced root hair plasticity by modulating actin cytoskeleton organization. Furthermore, we found BRK1 is also involved in root hair developmental change under salt stress, and overexpression of BRK1 resulted in root hairs over-sensitive to salt stress as those in spi mutant. Moreover, based on biochemical analyses, we found BRK1 is unstable and SPI mediates BRK1 stability. Functional loss of SPI results in the accumulation of steady-state of BRK1. 

This work elucidates a route to mesoporous magnetic materials with co-continuous morphologies from block copolymer self-assembly. The co-continuous structure impacts the magnetic behavior compared to non-structured chemically-identical materials. 

SUMMARY Trichome development is a fascinating model to elaborate the plant cell differentiation and growth processes. A wealth of information has pointed to the contributions of the components associated with cell cycle control and ubiquitin/26S proteasome system (UPS) to trichome morphogenesis, but how these two pathways are connected remains obscure. Here, we report that HECT‐type ubiquitin ligase KAKTUS (KAK) targets the cyclin‐dependent kinase (CDK) inhibitor KRP2 (for kip‐related protein 2) for proteasome‐dependent degradation during trichome branching in Arabidopsis. We show that over‐expression ofKRP2promotes trichome branching and endoreduplication which is similar tokakloss of function mutants. KAK directly interacts with KRP2 and mediates KRP2 degradation. Mutation ofKAKresults in the accumulation of steady‐state KRP2. Consistently, inkak pKRP2:KRP2‐GFPplants, the trichome branching is further induced compared with the single mutant. Taken together, our studies bridge the cell cycle control and UPS pathways during trichome development and underscore the importance of post‐translational control in epidermal differentiation. 

Abstract The Arabidopsis (Arabidopsis thaliana) TRANSPARENT TESTA GLABRA2 (TTG2) gene encodes a WRKY transcription factor that regulates a range of development events like trichome, seed coat, and atrichoblast formation. Loss-of-function of TTG2 was previously shown to reduce or eliminate trichome specification and branching. Here, we report the identification of an allele of TTG2, ttg2-6. In contrast to the ttg2 mutants described before, ttg2-6 displayed unique trichome phenotypes. Some ttg2-6 mutant trichomes were hyper-branched, whereas others were hypo-branched, distorted, or clustered. Further, we found that in addition to specifically activating R3 MYB transcription factor TRIPTYCHON (TRY) to modulate trichome specification, TTG2 also integrated cytoskeletal signaling to regulate trichome morphogenesis. The ttg2-6 trichomes displayed aberrant cortical microtubules (cMTs) and actin filaments (F-actin) configurations. Moreover, genetic and biochemical analyses showed that TTG2 could directly bind to the promoter and regulate the expression of BRICK1 (BRK1), which encodes a subunit of the actin nucleation promoting complex suppressor of cyclic AMP repressor (SCAR)/Wiskott–Aldrich syndrome protein family verprolin homologous protein (WAVE). Collectively, taking advantage of ttg2-6, we uncovered a function for TTG2 in facilitating cMTs and F-actin cytoskeleton-dependent trichome development, providing insight into cellular signaling events downstream of the core transcriptional regulation during trichome development in Arabidopsis.