Exogenous abscisic acid alleviates zinc uptake and accumulation in Populus × canescens exposed to excess zinc.

A greenhouse experiment was conducted to study whether exogenous abscisic acid (ABA) mediates the responses of poplars to excess zinc (Zn). Populus × canescens seedlings were treated with either basal or excess Zn levels and either 0 or 10 µm ABA. Excess Zn led to reduced photosynthetic rates, increased Zn accumulation, induced foliar ABA and salicylic acid (SA), decreased foliar gibberellin (GA3 ) and auxin (IAA), elevated root H2 O2 levels, and increased root ratios of glutathione (GSH) to GSSG and foliar ratios of ascorbate (ASC) to dehydroascorbate (DHA) in poplars. While exogenous ABA decreased foliar Zn concentrations with 7 d treatments, it increased levels of endogenous ABA, GA3 and SA in roots, and resulted in highly increased foliar ASC accumulation and ratios of ASC to DHA. The transcript levels of several genes involved in Zn uptake and detoxification, such as yellow stripe-like family protein 2 (YSL2) and plant cadmium resistance protein 2 (PCR2), were enhanced in poplar roots by excess Zn but repressed by exogenous ABA application. These results suggest that exogenous ABA can decrease Zn concentrations in P. × canescens under excess Zn for 7 d, likely by modulating the transcript levels of key genes involved in Zn uptake and detoxification.

Identification and Functional Prediction of Poplar Root circRNAs Involved in Treatment With Different Forms of Nitrogen.

Circular RNAs (circRNAs) are a class of noncoding RNA molecules with ring structures formed by covalent bonds and are commonly present in organisms, playing an important regulatory role in plant growth and development. However, the mechanism of circRNAs in poplar root responses to different forms of nitrogen (N) is still unclear. In this study, high-throughput sequencing was used to identify and predict the function of circRNAs in the roots of poplar exposed to three N forms [1 mM NO3 - (T1), 0.5 mM NH4NO3 (T2, control) and 1 mM NH4 + (T3)]. A total of 2,193 circRNAs were identified, and 37, 24 and 45 differentially expressed circRNAs (DECs) were screened in the T1-T2, T3-T2 and T1-T3 comparisons, respectively. In addition, 30 DECs could act as miRNA sponges, and several of them could bind miRNA family members that play key roles in response to different N forms, indicating their important functions in response to N and plant growth and development. Furthermore, we generated a competing endogenous RNA (ceRNA) regulatory network in poplar roots treated with three N forms. DECs could participate in responses to N in poplar roots through the ceRNA regulatory network, which mainly included N metabolism, amino acid metabolism and synthesis, response to NO3 - or NH4 + and remobilization of N. Together, these results provide new insights into the potential role of circRNAs in poplar root responses to different N forms.

Physiological characteristics and RNA sequencing in two root zones with contrasting nitrate assimilation of Populus × canescens.

Different root zones have distinct capacities for nitrate (NO3-) uptake in Populus species, but the underlying physiological and microRNA (miRNA) regulatory mechanisms remain largely unknown. To address this question, two root zones of Populus × canescens (Ait.) Smith. with contrasting capacities for NO3- uptake were investigated. The region of 0-40 mm (root zone I) to the root apex displayed net influxes, whereas the region of 40-80 mm (root zone II) exhibited net effluxes. Concentrations of NO3- and ammonium (NH4+) as well as nitrate reductase activity were lower in zone II than in zone I. Forty one upregulated and twenty three downregulated miRNAs, and 576 targets of these miRNAs were identified in zone II in comparison with zone I. Particularly, growth-regulating factor 4 (GRF4), a target of upregulated ptc-miR396g-5p and ptc-miR396f_L + 1R-1, was downregulated in zone II in comparison with zone I, probably contributing to lower NO3- uptake rates and assimilation in zone II. Furthermore, several miRNAs and their targets, members of C2H2 zinc finger family and APETALA2/ethylene-responsive element binding protein family, were found in root zones, which probably play important roles in regulating NO3- uptake. These results indicate that differentially expressed miRNA-target pairs play key roles in regulation of distinct NO3- uptake rates and assimilation in different root zones of poplars.

Abscisic acid enhances lead translocation from the roots to the leaves and alleviates its toxicity in Populus × canescens.

To shed light on physiological mechanisms underlying abscisic-acid (ABA)-mediated lead (Pb) uptake, translocation and detoxification, we exposed Populus × canescens saplings to either 0 or 3 mM Pb2+ in combination with either 0 or 10 µM exogenous ABA. Pb was taken up by the roots and accumulated mainly in the cortex. A fraction of the Pb in the roots was translocated to the leaves, thereby resulting in decreased photosynthesis and biomass. Pb accumulation caused a burst of reactive oxygen species (ROS), with higher concentrations of total thiols, glutathione, and ascorbate in the roots and/or leaves. Exogenous ABA stimulated Pb uptake, decreased Pb deposition in the cortex, and enhanced Pb vascular loading in the roots. Exogenous ABA alleviated the Pb-induced reductions in photosynthesis and root biomass, and decreased Pb-triggered ROS overproduction in the roots and/or leaves. Correspondingly, exogenous ABA stimulated the mRNA levels of a few genes involved in Pb uptake, transport, and detoxification, including NRAMP1.4, ABCG40, FRD3.1, PCS1.1, and ABCC1.1. These results suggest that exogenous ABA enhances Pb uptake and translocation, and alleviates Pb toxicity in poplars through the ABA-induced movement of Pb from the root cortex to the vascular stele, and transcriptionally regulated key genes involved in Pb tolerance.

Sulfur nutrition stimulates lead accumulation and alleviates its toxicity in Populus deltoides.

Sulfur (S) can modulate plant responses to toxic heavy metals, but the underlying physiological and transcriptional regulation mechanisms remain largely unknown. To investigate the effects of S supply on lead (Pb)-induced toxicity in poplars, Populus deltoides monilifera (Aiton) Eckenw. saplings were exposed to 0 or 50 µM Pb together with one of the three S concentrations (0 (low S), 100 (moderate S) or 1500 (high S) µM Na2SO4). Populus deltoides roots absorbed Pb and it was partially translocated to the aerial organs, thereby decreasing the CO2 assimilation rate and leaf growth. Lead accumulation in poplars caused the overproduction of O2- and H2O2 to induce higher levels of total thiols (T-SH) and glutathione (GSH). Lead uptake by the roots and its accumulation in the aerial organs were repressed by low S application, but stimulated by high S supply. Lead-induced O2- and H2O2 production were exacerbated by S limitation, but alleviated by high S supply. Moreover, the concentrations of S-containing antioxidants including T-SH and GSH were reduced in S-deficient poplars, but increased in high S-treated plants, which corresponded well to the changes in the activities of enzymes involved in S assimilation and GSH biosynthesis. The transcript levels of both genes encoding sulfate transporters, i.e., SULTR1.1 and SULTR2.2, were elevated by low S application or high S supply in the roots, and the transcriptional upregulation of both genes was more pronounced under Pb exposure. Furthermore, the mRNA levels of several genes involved in S assimilation and the biosynthesis of GSH and phytochelatins, i.e., ATPS1, ATPS3, GSHS1, GSHS2 and PCS1, were upregulated in poplar roots with high S supply, particularly under Pb exposure. These results indicate that a high S supply can stimulate Pb accumulation and reduce its toxicity in poplars by improving S assimilation and stimulating the biosynthesis of S-containing compounds including T-SH and GSH.

Effects of Shugan Jianpi Formula () on myeloid-derived suppression cells-mediated depression breast cancer mice.

OBJECTIVE: To observe the intervention effect of Shugan Jianpi Formula (, SGJPF) on a breast cancer mouse model with depression and investigate the underlying mechanism of SGJPF in preventing the development of breast cancer. METHODS: The breast cancer model was induced by inoculation of breast cancer cells, the depression model was induced by chronic stress stimuli, and the depression cancer model was established by combining the two factors. The mice were divided into 7 groups: normal control, depression model, tumor model, depression tumor model, SGJPF, chemotherapy, and SGJPF+chemotherapy groups. The last 3 groups were depression breast cancer mice and treated respectively with SGJPF, chemotherapy drug gemcitabine (GEM), and SGJPF alongside GEM. The condition of the mice was evaluated by the expression of 5-hydroxytryptamine in hippocampus after the sucrose water test and open field test, weight change, and survival time. Tumor growth was monitored with in vivo imaging. Flow cytometry was used to analyze the level of myeloid-derived suppression cell (MDSC) in the mouse spleen, T cell subsets, and the early apoptosis of CD8+ T cells. RESULTS: The SGJPF+GEM group had the highest inhibition rate and the longest survival time (P<0.01). The MDSC level and the apoptosis rate of CD8+ T cells was the highest in the SGJPF+GEM group (P<0.05). CONCLUSIONS: Depressive disorders and tumor growth could suppress the immune function of mice to different degrees, and the microenvironment in late 4T1 inflammatory breast cancer may play an important role in the pathological process. SGJYF could regulate the immune microenvironment by reducing CD8+ T lymphocyte apoptosis and tumor cell activity, increasing immune surveillance capability, and inhibiting MDSC proliferation, thus prolonging the survival time of tumor-bearing mice.

Comprehensive treatment with Chinese medicine in patients with advanced non-small cell lung cancer: A multicenter, prospective, cohort study.

OBJECTIVE: To determine whether additional Chinese medicine (CM) could prolong survival and improve the quality of life (QOL) in patients with advanced non-small cell lung cancer (NSCLC) compared with Western medicine (WM) alone. METHODS: This was a multicenter, prospective cohort study. A total of 474 hospitalized patients with stage III-IV NSCLC were recruited and divided into 2 groups. Patients in the WM group received radiotherapy, chemotherapy, and optimal supportive therapy according to the National Comprehensive Cancer Network (NCCN) guidelines. In the integrative medicine (IM) group, individualized CM (Chinese patent medicines and injections) and WM were administered. The primary end point was overall survival, and the secondary end points were time to disease progression, adverse events, and QOL. Follow-up clinical examinations and chest radiography were performed every 2 months. RESULTS: The median survival was 16.60 months in the IM group and 13.13 months in the WM group (P<0.01). The incidences of loss of appetite, nausea, and vomiting in the IM group were significantly lower than those in the WM group (P<0.05). The QOL based on Functional Assessment of Cancer Therapy-Lung in the IM group was markedly higher than that in the WM group at the fourth course (P<0.05). CONCLUSIONS: Additional CM may prolong survival and improve the QOL patients with NSCLC. The adverse effects of radio- and chemotherapy may be attenuated as CM is used in combination with conventional treatments.