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.
Authors:K.J. Deng, J.P. Zhou, X.H. Wu, G. Sun, T. Wang, A.T. Tang, X.L. Zheng, and Y. Zhang
It is well demonstrated that wheat-rye 1BL/1RS translocated chromosome leads to some valuable novel traits such as disease resistance, high yield and functional stay-green after anthesis. To understand the physiological mechanism of 1BL/1RS translocation responsible for osmotic stress, two wheat cultivars, CN12 and CN17, carrying the translocated chromosome and MY11 without the translocated chromosome were employed in the study. During 5-day osmotic stress, fresh weight inhibition, chlorophyll content, soluble protein content, MDA concentration, antioxidant enzymes activity and free polyamines content were examined. CN12 and CN17, especially cultivar CN17, registered greater biomass and minor oxidative damage compared with their wheat parent. Meanwhile, the concentration of Spd and Spm in CN17 was significantly higher than the others. In addition, we found a positive correlation of fresh weight inhibition (FWI) and Put concentration, and a negative one with the parameters (Spd + Spm): Put ratio, indicating the importance of higher polyamine (Spd and Spm) accumulation on the adaptation to osmotic stress. Therefore, we proposed that the accumulation of higher polyamines (Spd and Spm) should play an important role on the adaptation of 1BL/1RS translocation lines to osmotic stress and might be important factors for the origin of novel traits introduced by 1BL/1RS.
Authors:J. P. Zhou, Y. Cheng, L. L. Zang, E. N. Yang, C. Liu, X. L. Zheng, K. J. Deng, Y. Q. Zhu, and Y. Zhang
In this study, a new substitution line, 12-5-1, with 42 chromosomes that was derived from BC3F2 descendants of the hybridization between Triticum aestivum cv. CN19 and Aegilops biuncialis was created and reported. The 12-5-1 was immune to both powdery mildew and stripe rust and has stable fertility. Multi-color fluorescence in situ hybridization indicated that 12-5-1 was a substitution line 1Mb(1B). The seed storage protein electrophoresis showed that 12-5-1 presented high molecular weight glutenin subunits (2 + 12) of CN19 and a new subunit designated as M which apparently originated from parent Ae. biuncialis, and absent 7 + 8 subunits. Additionally, the flour quality parameters showed that the protein content, Zeleny sedimentation value, wet gluten content, and grain hardness and mixing time of 12-5-1 were signifiantly higher than those of its parent CN19. Moreover, 5 pairs of the chromosome 1Mb-specifi polymerase chain reaction-based landmark unique gene markers, TNAC1021, TNAC1026, TNAC1041, TNAC1-02 and TNAC1-04, were also obtained. The new substitution line 1Mb(1B) 12-5-1 could be a valuable source for wheat improvement, especially for wheat end product quality and resistance to disease.