Cloning, Characterization and Chromosome Localization of Two Powdery Mildew Resistance-Related Gene Sequences from Wheat

Reverse_transcription Polymerase Chain Reaction (RT_PCR) was performed using cDNAs as templates from wheat_ Haynaldia villosa 6VS/6AL translocation line and 'Yangmai 5' induced with fungus Erysiphe graminis , and degenerate primers designed based on the conserved amino acid sequences of known plant disease_resistance genes. The cDNA sequences encoding cyclophilin_like and H +_ATPase_like genes were first isolated and characterized in wheat. The putative amino acid sequences of the two clones showed that they were highly homologous to those of cyclophilin proteins and H +_ATPases isolated from other plants. Thus they were designated as Ta_Cyp and Ta_MAH . The obvious expression differences could be observed between wheat_ H. villosa 6VS/6AL translocation line and susceptible wheat cultivar 'Yangmai 5', implying that the two genes may be related with the resistance of wheat_ H. villosa 6VS/6AL translocation line to disease. Southern blot indicated that the wheat genome contained 2-3 copies of Ta_Cyp gene and one copy of the Ta_MAH gene. Chinese Spring nulli_tetrasomic line analysis located the Ta_Cyp homologous genes on wheat chromosome 6A, 6B and 6D. Southern blot using Ta_Cyp clone as a probe showed that the polymorphic bands existed among the H. villosa , amphiploid of Triticum durum _ H. villosa , wheat_ H. villosa 6VS/6AL translocation line and 'Yangmai 5', suggesting that Ta_Cyp homologies exist in wheat genome as well as on the short arm of chromosome 6V in H. villosa .

Recent improvements of actuator line-large-eddy simulation method for wind turbine wakes

In a large wind farm,the wakes of upstream and downstream wind turbines can interfere with each other,affecting the overall power output of the wind farm.To further improve the numerical accuracy of the turbine wake dynamics under atmosphere turbulence,this work proposes some improvements to the actuator line-large-eddy simulation(AL-LES)method.Based on the dynamic k-equation large-eddy simulation(LES),this method uses a precursor method to generate atmospheric inflow turbulence,models the tower and nacelle wakes,and improves the body force projection method based on an anisotropic Gaussian distribution function.For these three improvements,three wind tunnel experiments are used to validate the numerical accuracy of this method.The results show that the numerical results calculated in the far-wake region can reflect the characteristics of typical onshore and offshore wind conditions compared with the experimental results.After modeling the tower and nacelle wakes,the wake velocity distribution is consistent with the experimental result.The radial migration velocity of the tip vortex calculated by the improved blade body force distribution model is 0.32 m/s,which is about 6%different from the experimental value and improves the prediction accuracy of the tip vortex radial movement.The method proposed in this paper is very helpful for wind turbine wake dynamic analysis and wind farm power prediction.

Cloning of a Resistance Gene Analog from Wheat and Development of a Codominant PCR Marker for Pm21

To Investigate the mechanism of resistance to wheat （Triticum aestivum L.） powdery mildew, suppression subtractlve hybridization was conducted between an isogenic resistant line carrying Pm21 and its recurrent parent Yangmal 5 to Isolate the resistance relative genes. A cDNA fragment specifically expressed in the resistant line was obtained and its full length was cloned by in silico cloning and RT-PCR. This gene encoded a deduced protein of 219 amino acids with a leucine-rich repeat （LRR） motif, often found In plant resistance genes, and was designated as Ta-LRR2. Ta-LRR2 had an increased expression level in the resistant line after Inoculation with Erysiphe graminis DC. f. sp. tritici Marchal. PCR analysis with different cytogenetlc stocks suggested that Ta-LRR2 was specifically associated with chromosome arms 6VS and 6AS. Linkage analysis further showed that Ta-LRR2 could be used as a resistance gene analog polymorphism marker of Pm21 for marker-assisted selection in germplasm enhancement and breeding practice. Moreover, how to Isolate Pm21 based on the Information obtained for Ta-LRR2 is discussed.