Functions of EDS1-like and PAD4 genes in grapevine defenses against powdery mildew

The molecular interactions between grapevine and the obligate biotrophic fungus Erysiphe necator are not understood in depth. One reason for this is the recalcitrance of grapevine to genetic modifications. Using defense-related Arabidopsis mutants that are susceptible to pathogens, we were able to analyze key components in grapevine defense responses. We have examined the functions of defense genes associated with the salicylic acid (SA) pathway, including ENHANCED DISEASE SUSCEPTIBILITY 1 (EDS1), EDS1-LIKE 2 (EDL2), EDL5 and PHYTOALEXIN DEFICIENT 4 (PAD4) of two grapevine species, Vitis vinifera cv. Cabernet Sauvignon, which is susceptible to E. necator, and V. aestivalis cv. Norton, which is resistant. Both VaEDS1 and VvEDS1 were previously found to functionally complement the Arabidopsis eds1-1 mutant. Here we show that the promoters of both VaEDS1 and VvEDS1 were induced by SA, indicating that the heightened defense of Norton is related to its high SA level. Other than Va/VvEDS1, only VaEDL2 complemented Arabidopsis eds1-1, whereas Va/VvPAD4 did not complement Arabidopsis pad4-1. Bimolecular fluorescence complementation results indicated that Vitis EDS1 and EDL2 proteins interact with Vitis PAD4 and AtPAD4, suggesting that Vitis EDS1/EDL2 forms a complex with PAD4 to confer resistance, as is known from Arabidopsis. However, Vitis EDL5 and PAD4 did not interact with Arabidopsis EDS1 or PAD4, correlating with their inability to function in Arabidopsis. Together, our study suggests a more complicated EDS1/PAD4 module in grapevine and provides insight into molecular mechanisms that determine disease resistance levels in Vitis species native to the North American continent.     

Maslinic acid protects vascular smooth muscle cells from oxidative stress through Akt/Nrf2/HO-1 pathway

Maslinic acid (MA) is a natural triterpenoid widely distributed in edible and medicinal plants and has been demonstrated to possess bioactivity. However, its effect on vascular smooth muscle cells (VSMC) has not been explored yet. In this study, we found that heme oxygenase-1 (HO-1) expression was increased in VSMCs treated with MA. Furthermore, MA was found to induce Akt activation in a dose- and time-dependent manner. Wortmannin suppression of Akt was able to abolish HO-1 upregulation in VSMCs, suggesting the requirement of Akt activation for MA effect on HO-1. Further investigation indicated that Akt activation resulted in the elevated expression of Nrf2, a HO-1 promoter, in MA-treated VMSCs. Finally, we found that MA was able to protect VSMCs from oxidative stress induced by H₂O₂. Blocking the activation of Akt/Nrf2/HO-1 was able to compromise the protective effect of MA on VSMCs. Collectively, we provided evidence that MA protected VMSCs from oxidative stress through Akt/Nrf2/HO-1 pathway.     

First Report of Dragon Fruit (Hylocereus undatus) Anthracnose Caused by Colletotrichum truncatum in China

Anthracnose disease was detected from dragon fruit (Hylocereus undatus) at a market of Yuanjiang County, Yunnan Province, China. The results of pathogenicity test, morphology studies and sequence analyses based on ITS and β‐tubulin loci indicated that the disease was caused by Colletotrichum truncatum. The pathogen produced elliptic, yellow spots with chlorotic halos on the surface of the fruit, and the lesion become depressed gradually. Grey to black acervuli appeared on the lesion surface in concentric circles later. This is the first report of dragon fruit anthracnose caused by this pathogen in China.     

Unique WSPA protein from terrestrial macroscopic cyanobacteria can confer resistance to osmotic stress in transgenic plants

The terrestrial macroscopic cyanobacterium Nostoc commune exhibits remarkable resistance to desiccation stress. This species synthesizes abundant acidic water stress protein (WSPA) in cells upon desiccation and secretes it into the extracellular polysaccharide sheath upon rehydration. However, our knowledge about its cellular role in stress resistance is still rather limited. In this paper, we first revealed that WSPA also occurred in two other macroscopic cyanobacteria Nostoc flagelliforme and Nostoc sphaeroides, but it is more abundant in N. commune. The N. commune wspa1 gene was then heterologously expressed in Arabidopsis thaliana. Phenotypic observation found that WSPA1 conferred increased tolerance to osmotic stress in transgenic plants. The physiological indexes such as relative electrolyte leakage, malondialdehyde, proline accumulation and the maximal quantum efficiency of Photosystem II, were also improved in transgenic plants upon osmotic stress, compared to wild types. In addition, GFP fluorescence analysis of eGFP::wspa1 transgenic plant showed that WSPA1 was localized in the cytoplasm. Therefore, the role of WSPA revealed by this study mainly represented its intracellular function. In general, our research suggested that WSPA may act as a stress protein and involve cellular osmotic stress resistance.     

Association analysis of ERBB2 amplicon genetic polymorphisms and STARD3 expression with risk of gastric cancer in the Chinese population

The purpose of this study was to investigate whether risk of gastric cancer (GC) was associated with single nucleotide polymorphisms (SNPs) in a gene cluster on the chromosome 17q12-q21 (ERBB2 amplicon) in the Chinese Han population. We detected twenty-six SNPs in this gene cluster containing steroidogenic acute regulatory-related lipid transfer domain containing 3 (STARD3), protein phosphatase 1 regulatory subunit 1B (PPP1R1B/DARPP32), titin-cap (TCAP), per1-like domain containing 1(PERLD1/CAB2), human epidermal growth factor receptor-2 (ERBB2/HER2), zinc-finger protein subfamily 1A 3 (ZNFN1A3/IKZF3) and DNA topoisomerase 2-alpha (TOP2A) genes in 311 patients with GC and in 425 controls by Sequenom. We found no associations between genetic variations and GC risk. However, haplotype analysis implied that the haplotype CCCT of STARD3 (rs9972882, rs881844, rs11869286 and rs1877031) conferred a protective effect on the susceptibility to GC (P = 0.043, odds ratio [OR] = 0.805, 95% confidence intervals [95% CI] = 0.643–0.992). The STARD3 rs1877031 TC genotype endued histogenesis of gastric mucinous adenocarcinoma and signet-ring cell carcinoma (P = 0.021, OR = 2.882, 95% CI = 1.173–7.084). We examined the expression of STARD3 in 243 tumor tissues out of the 311 GC patients and 20 adjacent normal gastric tissues using immumohistochemical (IHC) analysis and tissue microarrays (TMA). The expression of STARD3 was observed in the gastric parietal cells and in gastric tumor tissues and significantly correlated with gender (P = 0.004), alcohol drinking (P < 0.001), tumor location (P = 0.007), histological type (P = 0.005) and differentiation (P = 0.023) in GC. We concluded that the combined effect of haplotype CCCT of STARD3 might affect GC susceptibility. STARD3 expression might be related to the tumorigenesis of GC in the Chinese population.     

A novel elicitor identified from Magnaporthe oryzae triggers defense responses in tobacco and rice

Key message

Our studies indicate a potential important elicitor candidate which can aid in the fight against a worldwide disease, rice blast.

Abstract

In this study, we report the purification, identification, characterization, and gene cloning of a novel hypersensitive response-inducing protein elicitor (MoHrip2) secreted from an important pathogenic fungus, Magnaporthe oryzae. The protein fraction was isolated from the culture filtrate of M. oryzae and identified by de novo sequencing. The elicitor-encoding gene mohrip2 was cloned following sequence comparison and PCR amplification. This 459-bp gene encodes a 152-residue polypeptide that contains an 18-residue signal peptide and exhibits a pI of 4.72 and an apparent molecular mass of 16 kDa. The hypothetical protein, MoHrip2, was expressed in Escherichia coli, and both the recombinant and the endogenous protein caused necrotic lesions in tobacco leaves. In addition to phenolic compound deposition and alkalization of the extracellular medium, MoHrip2 also induced hydrogen peroxide production and nitric oxide accumulation in tobacco cells. Moreover, rice seedlings treated with MoHrip2 exhibited pronounced resistance to M. oryzae compared with control seedlings.     

Overexpression of integrin-linked kinase (ILK) promotes glioma cell invasion and migration and down-regulates E-cadherin via the NF-κB pathway

Integrin-linked kinase (ILK) is a ubiquitously expressed serine/threonine protein kinase that has been implicated in cancer development, progression and metastasis. The aim of the present study was to characterize the role of ILK in glioma cell invasion and migration. We generated a recombinant eukaryotic expression vector containing the human ILK gene and transfected it into human glioma SHG-44 cells. Real-time PCR and western blot analysis were used to identify the stable transformants. The wound healing and Transwell invasion assays showed that ectopic overexpression of ILK in SHG-44 cells significantly promoted their migration and invasion capabilities in culture. This was accompanied by a decrease in expression of E-cadherin and an increase in expression of Snail and Slug. Moreover, the decrease in E-cadherin expression induced by ILK overexpression was greatly restored by the nuclear factor-κB (NF-κB) inhibitor BAY 11-7028 or small interfering RNA targeting NF-κB p65, indicating an involvement of NF-κB in ILK-induced down-regulation of E-cadherin. In conclusion, our data underscore a novel role for ILK in glioma invasion and metastasis processes, implicating potential for therapeutic interference.