Actin filament assembly in plants is a dynamic process, requiring the activity of more than 75 actin-binding proteins. Central to the regulation of filament assembly and stability is the activity of a conserved family of actin-depolymerizing factors (ADFs), whose primarily function is to regulate the severing and depolymerization of actin filaments. In recent years, the activity of ADF proteins has been linked to a variety of cellular processes, including those associated with response to stress. Herein, a wheat ADF gene, TaADF4, was identified and characterized. TaADF4 encodes a 139-amino-acid protein containing five F-actin-binding sites and two G-actin-binding sites, and interacts with wheat (Triticum aestivum) Actin1 (TaACT1), in planta. Following treatment of wheat, separately, with jasmonic acid, abscisic acid or with the avirulent race, CYR23, of the stripe rust pathogen Puccinia striiformis f. sp. tritici, we observed a rapid induction in accumulation of TaADF4 mRNA. Interestingly, accumulation of TaADF4 mRNA was diminished in response to inoculation with a virulent race, CYR31. Silencing of TaADF4 resulted in enhanced susceptibility to CYR23, demonstrating a role for TaADF4 in defense signaling. Using a pharmacological-based approach, coupled with an analysis of host response to pathogen infection, we observed that treatment of plants with the actin-modifying agent latrunculin B enhanced resistance to CYR23, including increased production of reactive oxygen species and enhancement of localized hypersensitive cell death. Taken together, these data support the hypothesis that TaADF4 positively modulates plant immunity in wheat via the modulation of actin cytoskeletal organization.
HZSM-5/SAPO-34 zeolite composites were prepared by hydrothermal synthesis (ZS-HS) and mechanical mixture (ZS-MM), respectively. ZS-HS showed higher propylene yield and better catalytic stability in ethanol conversion than ZS-MM as well as HZSM-5 and SAPO-34. In case of ZS-HS, SAPO-34 at least partially overlapped on HZSM-5, which resulted in the interfacial interaction of HZSM-5 and SAPO-34. Such interaction significantly modified the texture and the acidity of ZS-HS, which in turn affected its catalytic reactivity. ZS-HS showed the higher apparent formation rate of propylene, due to its moderate concentration and strength distribution of acid sites. Propylene, ethylene and butylenes might produce through the parallel reaction pathways and the common intermediate on ZS-HS.
1. Pleistocene climate changes played a significant role in the speciation of temperate insects. Cold-adapted species responding to past climatic events, however, remain rarely investigated in most groups of insects.2. We assessed the evolutionary history and speciation of the cold-adapted scorpionfly Cerapanorpa brevicornis (Hua and Li), endemic to the Qinling-Bashan Mountains and adjacent regions (QBMARs), based on one nuclear and three mitochondrial DNA gene markers.3. Two distinctly divergent lineages were found in C. brevicornis dating back to 0.56 Ma, approximately coinciding with the extra-long interglaciation (0.48-0.62 Ma) during the middle Pleistocene. Lineage I is widely distributed in the QBMARs, and Lineage II is confined to the 'sky islands' of the eastern Bashan Mountains (EBMs). The patch of 'alpine archipelagos' in the EBMs seems to function as interglacial microrefugia. In contrast, interglacial macrorefugia are located in the Qinling Mountains.4. These findings may highlight the essential role of postglacial warming in the speciation and generation of neo-endemic species through range contraction in cold-adapted species and may provide new insights into the mechanisms underlying the high endemism and species richness in the QBMARs.5. This study suggests that Lineage II can be treated as a good species acting as an indicator of climate change, and the 'sky islands' of the EBMs might be a high-priority region for alpine biodiversity conservation under global warming.
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