ALDH2C4 regulates cuticle thickness and reduces water loss to promote drought tolerance.

In Arabidopsis thaliana, ALDH2C4 encodes coniferaldehyde dehydrogenase, which oxidizes coniferaldehyde to ferulic acid. Drought stress is one of the important abiotic stresses affecting plant growth. However, the role of ferulic acid in drought resistance is unknown. To investigate the contribution of ferulic acid to cuticle composition and drought resistance, we used two Arabidopsis aldh2c4 mutant lines. Compared with wild-type (WT) leaves, ferulic acid contents were significantly lower (by more than 50 %) in mutants. The mutants also had lower amounts of cutin and wax, primarily due to reductions in C18:2 dioic acid and alkanes, respectively. Furthermore, the leaves of the mutant plants exhibited greater rates of water loss and released chlorophyll faster than WT leaves when immersed in 80 % ethanol, indicating a defective cuticle barrier. The growth of aldh2c4 mutants was severely inhibited, and their leaves showed a higher degree of wilting relative to the WT plants under drought conditions. In aldh2c4 complementation lines, the growth inhibition of the mutant plants under drought stress was alleviated. Taken together, our results demonstrate that ferulic acid plays an important role in the composition and structural properties of the cuticle and that a ferulic acid deficiency in the cutin leads to reduced drought tolerance.

Plant Salinity Sensors: Current Understanding and Future Directions.

Salt stress is a major limiting factor for plant growth and crop yield. High salinity causes osmotic stress followed by ionic stress, both of which disturb plant growth and metabolism. Understanding how plants perceive salt stress will help efforts to improve salt tolerance and ameliorate the effect of salt stress on crop growth. Various sensors and receptors in plants recognize osmotic and ionic stresses and initiate signal transduction and adaptation responses. In the past decade, much progress has been made in identifying the sensors involved in salt stress. Here, we review current knowledge of osmotic sensors and Na+ sensors and their signal transduction pathways, focusing on plant roots under salt stress. Based on bioinformatic analyses, we also discuss possible structures and mechanisms of the candidate sensors. With the rapid decline of arable land, studies on salt-stress sensors and receptors in plants are critical for the future of sustainable agriculture in saline soils. These studies also broadly inform our overall understanding of stress signaling in plants.

Root Na+ Content Negatively Correlated to Salt Tolerance Determines the Salt Tolerance of Brassica napus L. Inbred Seedlings.

Soil salinization is a major environmental stressor that reduces the growth and yield of crops. Maintaining the balance of ions under salinity is vital for plant salt tolerance; however, little is known about the correlation between the salt tolerance of crops and the ion contents of their roots and shoots. Here, we investigated the poorly understood salt-tolerance mechanisms, particularly regarding ion contents (particularly Na+), in Brassica napus subsp. napus L., an agriculturally important species. Twenty B. napus inbred lines were randomly chosen from five salt-tolerance categories and treated with increasing concentrations of NaCl (0-200 mmol) for this work. We found that the root Na+ content is the most correlated limiting factor for the salt tolerance of B. napus; the higher the salt tolerance, the lower the root Na+ content. Correspondingly, the Ca2+/Na+ and K+/Na+ ratios of the roots were highly correlated with B. napus salt tolerance, indicating that the selective absorption ability of these ions by the roots and their translocation to the shoots play a pivotal role in this trait. These data provide a foundation for the further study of the molecular mechanisms underlying salt tolerance and for breeding salt-tolerant B. napus cultivars.

miRNA-574-5p downregulates ZNF70 and influences the progression of human esophageal squamous cell carcinoma through reactive oxygen species generation and MAPK pathway activation.

There is growing evidence shown that microRNAs (miRNAs) are associated with cancer and can play a role in human cancers as oncogenes or tumor suppressor genes. miRNA-574-5p is a candidate oncogene in various types of cancer, but little is known about biological functions of miR-574-5p in esophageal squamous cell carcinoma (ESCC). In this study, we observe that the expression of miR-574-5p is not only increased in human ESCC tissues but also remarkably increased in cell lines correlates with ZNF70. In vitro, we explored the role of miR-574-5p in ESCC progression via transfection of the miR-574-5p inhibitor into ECA-109 cells. The results show miR-574-5p serve as a tumor promoter regulating cells proliferation and apoptosis in ESCC through mitochondrial-mediated reactive oxygen species (ROS) generation and MAPK pathways. Furthermore, ZNF70 has been proved to as a functional target for miR-574-5p to regulate cells poliferation and apoptosis. In summary, these results suggest that miR-574-5p serves as tumor promoter to promote proliferation and inhibit apoptosis of ESCC cells by targeting ZNF70 via mitochondrial-mediated ROS generation and MAPK pathways. The miR-574-5p/ZNF70 pathway provides a new insight into the molecular mechanisms that the occurrence and development of ESCC and it provides a novel therapeutic target for ESCC.

[Dynamic expression of toll like receptor 2 and 4 in a rat model of myocardial ischemia/reperfusion injury].

OBJECTIVE: To explore the role of toll-like receptor 2 (TLR2) and toll-like receptor 4 (TLR4) in myocardial ischemia/reperfusion injury (MI/RI) by observing the dynamic expression changes at mRNA and protein levels early after myocardial ischemia/reperfusion (I/ R). METHODS: The Wistar rats were randomly divided into Sham and I/R group (n = 42), and killed according to different reperfusion time (1, 2, 4, 6, 12, 24 h and 7 d). Structural and morphous changes of myocytes were observed under optical microscope. The mRNA and protein levels of TLR2 and TLR4 were detected using real-time PCR (RT-PCR). Monocyte chemokine protein-1 (MCP-1) and interleukine-6 (IL-6) mRNA levels were measured by reverse transcriptase-polymerase chain reaction (rt-PCR). RESULTS: (1) With the extension of reperfusion time, the myocardial infarct size increased smoothly, and reached the plateau at 4 h, then stayed in the platform. After reperfusion for 7 d, the ventricular had been remodeled. (2) At the beginning of reperfusion, myocardial structure showed no significant change in Sham group, but had different degrees of injury in I/R group. In rats of the group reperfused for 7 d the left ventricular remodeling could be visible. (3) Compared to sham group,TIR2, TLR4, MCP-1, IL-6 mRNA level were increased in myocardium in I/R group. TLR2 and TLR4 both peaked at 4 h of reperfusion, IL6 peaked at 6 h, followed by a gradually decrease. TLR4 and IL-6 mRNA levels rose again at 7 d. MCP-1 level in I/R group remained fairly with sham group at the beginning of reperfusion, and markedly elevated at 7 d. CONCLUSION: Expression of TLRs mRNA in myocardium during early after myocardial ischemia/reperfusion increased rapidly and activated TLRs might play an important role in MI/RI through promoting the generation of inflammatory factors. At the late reperfusion, TLRs levels raise again and the expression of inflammatory factors increase once again, Those may probably affect the remodeling of ventricular, and injure myocardial structure and function.

Deficiency of phytochrome B alleviates chilling-induced photoinhibition in rice.

PREMISE OF THE STUDY: Food crops of tropical origins, such as rice, are often cultivated in areas with suboptimal temperature regimes. The rice phytochrome B-deficient mutant (phyB) is tolerant of chilling temperatures compared with the wild type (WT) under low irradiance, and unsaturated fatty acids (USFAs) of membrane lipids have been shown to play an important role in chilling resistance. However, the relationship between phytochrome B and membrane lipids has not been empirically investigated. • METHODS: We assessed various photosynthesis indexes in phyB and WT rice: chlorophyll content, maximal photochemical efficiency (Fv/Fm) of photosystem II (PSII), the quantum yield of PSII electron transport (ΦPSII), the percentage of oxidizable P700 (P700), nonphotochemical quenching (NPQ), and the de-epoxidized ratio of xanthophyll cycle (A+Z)/(V+A+Z). We also analyzed the ultrastructure and fatty acid desaturases (FADs) and glycerol-3-phosphate acyltransferase (GPAT) genes of the chloroplasts using transmission electron microscopy and real-time PCR. • RESULTS: After a chilling treatment of 24 h, chloroplast damage and USFA content reduction were more severe in the WT than in the phyB mutant. Genes involved in the synthesis of USFAs in membranes such as FADs and GPAT were more stable in phyB than in WT. Chlorophyll content, Fv/Fm, ΦPSII, and P700 decreased more slowly under chilling stress and recovered more rapidly under optimal conditions in phyB than in WT. The (A+Z)/(V+A+Z) and NPQ increased more rapidly in phyB than in the WT after 24 h of chilling treatment. • CONCLUSIONS: Phytochrome B deficiency in rice with more stabilized chloroplast structure and higher USFA content in membrane lipids could alleviate chilling-induced photoinhibition.