The present study was performed to investigate the effect of β-aminobutyric acid (BABA) treatment on defence activation in grape berries and to analyse its cellular mechanism. The results implied that BABA treatment at an effective concentration of 20 mM significantly inhibited gray mould rot caused by Botrytis cinerea in grape berries by inducing resistance. Accordingly, 20 mM BABA triggered a priming defence in grape suspension cells, since only the BABA-treated cells exhibited an accelerated ability for augmenting defence responses upon the pathogen inoculation. The primed cellular reactions were related to an early H2O2 burst, prompt accumulation of stilbene phytoalexins and activation of PR genes. Thus, we assume that 20 mM BABA can induce resistance to B. cinerea infection in intact grape berries perhaps via intercellular priming defence. Moreover, the BABA-induced priming defence is verified, because no negative effects on cell growth, anthocyanin synthesis, and quality impairment in either grape cells or intact berries were observed under low pathogenic pressure.
Authors:S. Hu, H. Shu, J.L. Yuan, J.Y. Gao, P.Y. Mu, C.Z. Ren, W. Sang, L.C. Guo, and H.B. Chen
The objective of this study was to evaluate the eﬀect of wheat–oat ﬂour ratio on the physical properties and β-glucan characteristics of extrudates. Results showed that increasing the wheat–oat ﬂour ratio resulted in a decrease in the water solubility index (r2=0.8567) and hardness (r2=0.9316), whereas the expansion ratio (r2=0.9307) and water absorption index (r2=0.9061) increased. Wheat ﬂour generally caused an increase in L values from 57.81 to 62.94 providing bright samples. Few cells were observed at high wheat–oat ﬂour ratios under a scanning electron microscope, and a smooth surface was noted. Meanwhile, the total (r2=0.9867) and soluble (r2=0.9848) β-glucan contents were inversely proportional to the wheat–oat ﬂour ratio. Extrudates with added wheat ﬂour had a high molecular weight, but wheat ﬂour had no signiﬁcant (P<0.05) eﬀect on the viscosity of β-glucan extracts. Conclusively, incorporation of wheat ﬂour at a wheat–oat ﬂour ratio of 2.33 provides ready-to-eat food based on whole oat ﬂour, on account of improving the texture and providing suﬃcient β-glucan contents (0.806 g/100 g) without signiﬁcantly aﬀecting β-glucan viscosity.
Authors:Z. Fang, D. Sun, J. Gao, M. Guo, L. Sun, Y. Wang, Y. Lıu, R. Wang, Q. Deng, D. Xu, and R. Gooneratne
Shewanella putrefaciens supernatant was found to increase the virulence factors of Vibrio parahaemolyticus by eﬃciently degrading its acylhomoserine lactone (AHL). To further reveal the regulation mechanism and its key degrading enzyme, a potential AHL-degrading enzyme acylase (Aac) from S. putrefaciens was cloned, and the inﬂuences of temperature, pH, protein modiﬁers, and metals on Aac were tested. Aac was signiﬁcantly inﬂuenced by temperature and pH, and exhibited the highest AHL-degrading activity at temperatures of 37 °C and pH of 8. Mg2+ and Fe2+ can further increase the AHL-degrading activity. 10 mM EDTA inhibited its activity possibly by chelating the co-factors (metals) required for Aac activity. Tryptophan and arginine were identiﬁed as key components for Aac activity that are critical to its AHL-degrading activity. This study provides useful information on Aac and for V. parahaemolyticus control.