Adverse environmental conditions, including high temperature, often affect the growth and production of crops worldwide. F-box protein, a core component of the Skp1-Cullin-F-box (SCF) E3 ligase complex, plays an important role in abiotic stress responses. A previously cloned gene from wheat, TaFBA1, encodes a homologous F-box protein. A Yeast two-Hybrid (Y2H) assay showed that TaFBA1 interacted with other SCF proteins. We found that the expression of TaFBA1 could be induced by heat stress (45°C). Overexpression of TaFBA1 enhanced heat stress tolerance in transgenic tobacco, because growth inhibition was reduced and photosynthesis increased as compared with those in the wild type (WT) plants. Furthermore, the accumulation of H2O2, O2-, and carbonyl protein decreased and cell damage was alleviated in transgenic plants under heat stress, which resulted in less oxidative damage. However, the transgenic plants contained more enzymatic antioxidants after heat stress, which might be related to the regulation of some antioxidant gene expressions. The qRT-PCR analysis showed that the overexpression of TaFBA1 upregulated the expression of genes involved in reactive oxygen species (ROS) scavenging, proline biosynthesis, and abiotic stress responses. We identified the interaction of TaFBA1 with Triticum aestivum stress responsive protein 1 (TaASRP1) by Y2H assay and bimolecular fluorescence complementation (BiFC) assay. The results suggested that TaFBA1 may improve enzymatic antioxidant levels and regulate gene expression by interacting with other proteins, such as TaASRP1, which leads to the enhanced heat stress tolerance seen in the transgenic plants.

Study design: Previous works suggested that neutralizing intratumoral lactic acidosis combined with glucose deprivation may deliver an effective approach to control tumor. We did a pilot clinical investigation, including a nonrandomized (57 patients with large HCC) and a randomized controlled (20 patients with large HCC) studies. Methods: The patients were treated with transarterial chemoembolization (TACE) with or without bicarbonate local infusion into tumor. Results: In the nonrandomized controlled study, geometric mean of viable tumor residues (VTR) in TACE with bicarbonate was 6.4-fold lower than that in TACE without bicarbonate (7.1% [95% CI: 4.6%–10.9%] vs 45.6% [28.9%–72.0%]; p<0.0001). This difference was recapitulated by a subsequent randomized controlled study. TACE combined with bicarbonate yielded a 100% objective response rate (ORR), whereas the ORR treated with TACE alone was 44.4% (nonrandomized) and 63.6% (randomized). The survival data suggested that bicarbonate may bring survival benefit. Conclusion: Bicarbonate markedly enhances the anticancer activity of TACE.Clinical trail registration: ChiCTR-IOR-14005319.DOI: http://dx.doi.org/10.7554/eLife.15691.001

U-box E3 ubiquitin ligases play important roles in the ubiquitin/26S proteasome machinery and in abiotic stress responses. TaPUB1-overexpressing wheat (Triticum aestivum L.) were generated to evaluate its function in salt tolerance. These plants had more salt stress tolerance during seedling and flowering stages, whereas the TaPUB1-RNA interference (RNAi)-mediated knock-down transgenic wheat showed more salt stress sensitivity than the wild type (WT). TaPUB1 overexpression upregulated the expression of genes related to ion channels and increased the net root Na + efflux, but decreased the net K + efflux and H + influx, thereby maintaining a low cytosolic Na + /K + ratio, compared with the WT. However, RNAi-mediated knock-down plants showed the opposite response to salt stress. TaPUB1 could induce the expression of some genes that improved the antioxidant capacity of plants under salt stress. TaPUB1 also interacted with TaMP (Triticum aestivum α-mannosidase protein), a regulator playing an important role in salt response in yeast and in plants. Thus, low cytosolic Na + / K + ratios and better antioxidant enzyme activities could be maintained in wheat with overexpression of TaPUB1 under salt stress. Therefore, we conclude that the U-box E3 ubiquitin ligase TaPUB1 positively regulates salt stress tolerance in wheat.

E3 ligases play significant roles in plant stress tolerance by targeting specific substrate proteins for post-translational modification. In a previous study, we cloned TaPUB1 from Triticum aestivum L., which encodes a U-box E3 ligase. Real-time polymerase chain reaction revealed that the gene was up-regulated under drought stress. To investigate the function of TaPUB1 in the response of plants to drought, we generated transgenic Nicotiana benthamiana (N. benthamiana) plants constitutively expressing TaPUB1 under the CaMV35S promoter. Compared to wild type (WT), the transgenic plants had higher germination and seedling survival rates as well as higher photosynthetic rate and water retention, suggesting that the overexpression of TaPUB1 enhanced the drought tolerance of the TaPUB1 overexpressing (OE) plants. Moreover, less accumulation of reactive oxygen species (ROS) and stronger antioxidant capacity were detected in the OE plants than in the WT plants. To characterize the mechanisms involved, methyl viologen (MV) was used to induce oxidative stress conditions and we identified the functions of this gene in the plant tolerance to oxidative stress. Our results suggest that TaPUB1 positively modulates plant drought stress resistance potential by improving their antioxidant capacity.

High salinity is one of the most severe environmental stresses and limits the growth and yield of diverse crop plants. We isolated a gene named TaPUB1 from wheat (Triticum aestivum L. cv HF9703) that encodes a novel protein containing a U-box domain, the precursor RNA processing 19p (Prp19) superfamily and WD-40 repeats. Real-time reverse transcription-PCR analysis showed that TaPUB1 transcript accumulation was up-regulated by high salinity, drought and phytohormones, suggesting that it plays a role in the abiotic-related defense response. We overexpressed TaPUB1 in Nicotiana benthamiana to evaluate the function of TaPUB1 in the regulation of the salt stress response. Transgenic N. benthamiana plants (OE) with constitutively overexpressed TaPUB1 under the control of the Cauliflower mosaic virus 35S (CaMV 35S) promoter exhibited a higher germination rate, less growth inhibition, less Chl loss and higher photosynthetic capacity than wild-type (WT) plants under salt stress conditions. These results demonstrated the increased tolerance of OE plants to salt stress compared with the WT. The OE plants had lower osmotic potential (OP), reduced Na+ toxicity and less reactive oxygen species accumulation compared with the WT, which may be related to their higher level of osmolytes, lower Na+/K+ ratio and higher antioxidant enzyme activities under salt stress conditions. Consistent with these results, the up-regulated expression of osmic- and antioxidant-related genes in OE plants indicated a role for TaPUB1 in plant salt tolerance.

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