UV-B (280-315 nm)is an integral part of solar radiation and can act either as a stress inducer or as a developmental signal. In recent years, increasing attention has been paid to the low-fluence UV-B-induced photomorphogenic response and several key players in this response have been identified, which include UVR8 (a UV-B-specific photoreceptor), COP1 (a WD40-repeat-containing RING finger protein), HY5 (a basic zipper transcription factor), and RUP1/2 (two UVR8-interacting proteins). Here we report that Arabidopsis SALT TOLERANCE (STO/BBX24), a known regulator for light signaling in plants, defines a new signaling component in UV-B-mediated photomorphogenesis. The bbx24 mutant is hypersensitive to UV-B radiation and becomes extremely dwarfed under UV-B treatment. By contrast, BBX24 overexpression transgenic lines respond much more weakly to UV-B than the bbx24 and wild-type plants. BBX24 expression is UV-B-inducible and its accumulation under UV-B requires COP1. Co-immunoprecipitation experiments indicate that BBX24 interacts with COP1

Vps21 plays a role in autophagy in addition to its role in endocytosis. Individual deletions of members of the endocytic Vps21 module, including a GEF and four effectors, result in autophagy defects and accumulation of autophagosomal clusters. Therefore the endocytic Vps21 module regulates autophagy.

Trs130 is a specific component of the TRAPP II (Transport protein particle II) complex, which functions as a guanine exchange factor (GEF) for Rab GTPases Ypt31/32. Ypt31/32 is known to be involved in autophagy, although the precise mechanism has not been thoroughly studied. In this study, we investigated the potential involvement of Trs130 in autophagy and found that both the cytoplasm-to-vacuole targeting (Cvt) pathway and starvation-induced autophagy were defective in a trs130ts (trs130 temperature-sensitive) mutant. Mutant cells could not transport Atg8 and Atg9 to the preautophagosomal structure/ phagophore assembly site (PAS) properly, resulting in multiple Atg8 dots and Atg9 dots dispersed in the cytoplasm. Some dots were trapped in the trans-Golgi. Genetic studies showed that the effect of the Trs130 mutation was downstream of Atg5 and upstream of Atg1, Atg13, Atg9 and Atg14 on the autophagic pathway. Furthermore, overexpression of Ypt31 or Ypt32, but not of Ypt1, rescued autophagy defects in trs130ts and trs65ts (Trs130-HA Trs120-myc trs65Δ) mutants. Our data provide mechanistic insight into how Trs130 participates in autophagy and suggest that vesicular trafficking regulated by GTPases/GEFs is important in the transport of autophagy proteins from the trans-Golgi to the PAS.

Expression of integrin β1 is regulated by the mechanical stiffness of the ECM, and correlates with the invasion and metastasis events of HCC in patients with cirrhosis.

Two photoproducts of DNA damage, i.e. cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts (6-4PPs), induced by UV-B radiation in suspension-cultured tobacco cells were quantified by enzymelinked immunosorbent assay (ELISA) with monoclonal antibodies. CPDs and 6-4PPs were induced in tobacco cells by UV-B radiation. Photorepair of CPDs was faster than that of 6-4PPs. UV-B radiation induces formation of CPDs and 6-4PPs even at 0°C, but low temperature significantly decreases the UV-Binduced (in contrast to UV-C-induced) formation of CPDs and 6-4PPs. Low temperature also retarded the removal of CPDs and 6-4PPs under white light, and almost no photorepair of CPDs and 6-4PPs was detected at 0°C. When purified DNA from tobacco cells grown in darkness was irradiated with UV-B, formation of CPDs and 6-4PPs took place at the same speed at different temperatures. It indicated that formation of CPDs and 6-4PPs induced by UV-B was temperature-independent in a non-cellular system. Based on our results for suspension-cultured tobacco cells, not only the photorepair but also UV-B-induced formation of CPDs and 6-4PPs are temperature-dependent.

The Arabidopsis radical-induced cell death1 (rcd1) mutant is sensitive to ozone fumigation and apoplastic superoxide, but tolerant to methyl viologen. In the present article, we report that the rcd1 mutant is also tolerant to supplementary UV-B radiation. The rcd1-1 mutant exhibits less accumulation of TT dimers, increased hypocotyl growth inhibition and higher accumulation of flavonoids under supplemental UV-B radiation. Moreover, the expression of HY5 (elongated hypocotyl5) is increased in the mutant after UV-B treatment. Gene expression downstream of UV-B signaling reveals that COP1 (constitutively photomorphogenic1)-regulated genes have an elevated expression in rcd1-1 mutant under UV-B radiation, while expression of UVR8 (UV resistance locus 8)-regulated and HY5-independent genes are not changed. Interestingly, the expression of RCD1 genes is not significantly changed by UV-B radiation. Previous study has shown that STO protein is interacting with RCD1 in vitro. Here, we found the mRNA level of STO (salt tolerance) is greatly increased in rcd1-1 mutant after UV-B radiation. However, UV-B-induced HY5 and CHS expression is partially inhibited in sto mutant. Based on the above results, it is deduced that the RCD1, working together with STO, is involved in Arabidopsis UV-B signaling.

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A greenhouse pot experiment was conducted to study the impact of arbuscular mycorrhizal fungi−Glomus versiforme (Gv) and Rhizophagus intraradices (Ri) on the growth, Cd uptake, antioxidant indices [glutathione reductase (GR), ascorbate peroxidase (APX), superoxide dismutase (SOD), catalase (CAT), ascorbate (ASA), glutathione (GSH) and malonaldehyde (MDA)] and phytochelatins (PCs) production of Lonicera japonica in Cd-amended soils. Gv and Ri significantly increased P acquisition, biomass of shoots and roots at all Cd treatments. Gv significantly decreased Cd concentrations in shoots and roots, and Ri also obviously reduced Cd concentrations in shoots but increased Cd concentrations in roots. Meanwhile, activities of CAT, APX and GR, and contents of ASA and PCs were remarkably higher in Gv/Ri-inoculated plants than those of uninoculated plants, but lower MDA and GSH contents in Gv/Ri-inoculated plants were found. In conclusion, Gv and Ri symbiosis alleviated Cd toxicity of L. japonica through the decline of shoot Cd concentrations and the improvement of P nutrition, PCs content and activities of GR, CAT, APX in inoculated plants, and then improved plant growth. The decrease of shoot Cd concentrations in L. japonica inoculated with Gv/Ri would provide a clue for safe production of this plant from Cd-contaminated soils.