Expression profi les of ten pathogenesis-related(PR) genes during plant defense against Fusarium, Yellow dwarf virus(YDV) aphid-transmitted and Hessian fly(Hf) were compared temporally in both resistant and susceptible genotypes following pathogen infection or insect infestation. Quantitative real-time PCR(qRT-PCR) revealed that PR1, PR2, PR3, PR5, PR6, PR8, PR9, and PR15 appeared to be induced or suppressed independently in response to Fusarium, YDV aphid-transmitted or Hf during the interactions. The PR gene(s) essential to defense against one organism may play little or no role in defense against another pathogen or pest, suggesting the alternative mechanisms may be involved in different interactions of wheatFusarium, wheat-YDV aphid-transmitted and wheat-Hf. However, strong up- or down-regulation of PR12 and PR14 encoding low molecular membrane acting protein, defensin and lipid transfer protein(LTP), respectively, had been detected after either pathogen infection or insect infestation, therefore showed broad responses to pathogens and insects. It was postulated that low molecular proteins such as defensins and LTPs might play a role in the early stages of pathogenesis in the signaling process that informs plants about the attack from biotic stresses. In addition, a synergistic action between different PR genes might exist in plants to defense certain pathogens and insects on the basis of comprehensive expression profi ling of various pathogenesis-related genes revealed by qRT-PCR in this study.
Fusarium head blight(FHB),caused primarily by Fusarium graminearum,is a destructive disease of wheat throughout the world.However,the mechanisms of host resistance to FHB are still largely unclear.Deoxynivalenol(DON)produced by F graminearum which enhances the pathogen to spread could be converted into inactive form D3 G by UDP-glycosyltransferases(UGTs).A DON responsive UGT gene,designated as TaUGT4,was first cloned from wheat in this study.The putative open reading frame(ORF) of TaUGT4 was 1386 bp,encoding 461 amino acids protein.TaUGT4 was placed on chromosome 2D using a set of nulli-tetrasomic lines of wheat cultivar Chinese Spring(CS).When fused with eGFP at C terminal,TaUGT4 was shown to localize in cytoplasm of the transformed tobacco cells.The transcriptional analysis revealed that TaUGT4 was strongly induced by F graminearum or DON in both of FHB-resistant cultivar Sumai 3 and susceptible cultivar Kenong 199,especially in Sumai 3 under DON treatment.Similar increase of TaUGT4 expression was observed in Sumai 3 and Kenong 199 in response to salicylic acid(SA) treatment.But interestingly,the transcripts level of TaUGT4 in Sumai 3 showed significantly higher than that in Kenong 199 after treated with methyl jasmonate(MeJA).According to the expression patterns,TaUGT4 might lead to different effects between FHB-resistant genotype and susceptible genotype in the process against F graminearum inoculation.It had also been discussed in this paper that JA signaling pathway might play a significant role in the resistance against F.graminearum compared to SA signaling pathway.
MA XinDU Xu-yeLIU Guo-juanYANG Zai-dongHOU Wen-qianWANG Hong-weiFENG De-shunLI An-feiKONG Ling-rang
Gliadins are the major components of storage proteins in wheat and play an important role in determining the extensibility properties of dough.In the present work,six novel full-length γ-gliadin genes were cloned from the C genome of Aegilops markgrafii using a PCR-based strategy.Analysis of the deduced amino acid sequences showed that the cloned genes had primary structures that were similar,but not identical,to published γ-gliadins from other wheat-related species.The lengths of the open reading frames(ORFs)ranged from 909 to 963 bp,and the repetitive and glutamine-rich domains were mainly responsible for the size of the proteins.An extra cysteine residue was present in the repetitive domain of sequence JX566513.All amino acid sequences of γ-gliadin genes from Ae.markgrafii were searched for the five peptides identified as T cell stimulatory epitopes in celiac disease(CD)patients.Peptide Gliγ-3 was present in sequences JX566513 and JX566514.Peptide Gliγ-5 was present only in JX566513.The otherγ-gliadins contained no toxic epitopes.These results provide information to better understand the use of Ae.markgrafii in wheat breeding and the evolutionary relationship of theγ-gliadin genes in Ae.markgrafii and other Triticeae species.
