Defensin,an essential component of plant development,is indispensable in pathogen resistance.However,the molecular function of defensins under pathological conditions of Cytospora canker has not been characterized in ...Defensin,an essential component of plant development,is indispensable in pathogen resistance.However,the molecular function of defensins under pathological conditions of Cytospora canker has not been characterized in apple plants.The present study exhibits a detailed overview of the phylogeny and structure of 29 defensins(MdDEF)in apple.Expression analysis revealed that MdDEF genes were spatiotemporally diverse across apple tissues.Five MdDEF genes were found to be significantly up-regulated following a challenge with Cytospora mali.The transgenic overexpression of five defensin genes in apple calli enhanced resistance to C.mali.Among them,MdDEF30 was strongly induced and conferred the highest resistance level in vivo.Meanwhile,antifungal activity assays in vitro demonstrated that a recombinant protein produced from MdDEF30could inhibit the growth of C.mali.Notably,MdDEF30 promoted the accumulation of reactive oxygen species(ROS)and activated defense-related genes such as PR4,PR10,CML13,and MPK3.Co-expression regulatory network analysis showed that MdWRKY75 may regulate the expression of MdDEF30.Further yeast onehybrid(Y1H),luciferase,and chromatin Immunoprecipitation quantitative polymerase chain reaction(ChIPqPCR)assays verified that MdWRKY75 could directly bind to the promoter of MdDEF30.Importantly,pathogen inoculation assays confirmed that MdWRKY75 positively regulates resistance by transcriptionally activating MdDEF30.Overall,these results demonstrated that MdDEF30 promotes resistance to C.mali in apple plants and that MdWRKY75 regulates MdDEF30 expression during the induction of resistance,thereby clarifying biochemical mechanisms of resistance to C.mali in apple trees.展开更多
Since its discovery more than 110 years ago,Valsa canker has emerged as a devastating disease of apple in East Asia.However,our understanding of this disease,particularly the identity of the causative agents,has been ...Since its discovery more than 110 years ago,Valsa canker has emerged as a devastating disease of apple in East Asia.However,our understanding of this disease,particularly the identity of the causative agents,has been in a state of confusion.Here we provide a synopsis for the current understanding of Valsa canker and the taxonomy of its causal agents.We highlight the major changes concerning the identity of pathogens and the conflicting viewpoints in moving to“One Fungus=One Name”system for this group of fungal species.We compiled a list of 21 Cytospora species associated with Malus hosts worldwide and curated 12 of them with rDNA-ITS sequences.The inadequacy of rDNA-ITS in discriminating Cytospora species suggests that additional molecular markers,more intraspecific samples and robust methods are required to achieve reliable species recognition.展开更多
基金funded by the National Key R&D Program of China(2023YFD1401401)the China Agriculture Research System(CARS27)。
文摘Defensin,an essential component of plant development,is indispensable in pathogen resistance.However,the molecular function of defensins under pathological conditions of Cytospora canker has not been characterized in apple plants.The present study exhibits a detailed overview of the phylogeny and structure of 29 defensins(MdDEF)in apple.Expression analysis revealed that MdDEF genes were spatiotemporally diverse across apple tissues.Five MdDEF genes were found to be significantly up-regulated following a challenge with Cytospora mali.The transgenic overexpression of five defensin genes in apple calli enhanced resistance to C.mali.Among them,MdDEF30 was strongly induced and conferred the highest resistance level in vivo.Meanwhile,antifungal activity assays in vitro demonstrated that a recombinant protein produced from MdDEF30could inhibit the growth of C.mali.Notably,MdDEF30 promoted the accumulation of reactive oxygen species(ROS)and activated defense-related genes such as PR4,PR10,CML13,and MPK3.Co-expression regulatory network analysis showed that MdWRKY75 may regulate the expression of MdDEF30.Further yeast onehybrid(Y1H),luciferase,and chromatin Immunoprecipitation quantitative polymerase chain reaction(ChIPqPCR)assays verified that MdWRKY75 could directly bind to the promoter of MdDEF30.Importantly,pathogen inoculation assays confirmed that MdWRKY75 positively regulates resistance by transcriptionally activating MdDEF30.Overall,these results demonstrated that MdDEF30 promotes resistance to C.mali in apple plants and that MdWRKY75 regulates MdDEF30 expression during the induction of resistance,thereby clarifying biochemical mechanisms of resistance to C.mali in apple trees.
基金The National Natural Science Foundation of China(Grant No.U1903206)National Key Research and Development Project of China(Grant No.2018YFD0201404).
文摘Since its discovery more than 110 years ago,Valsa canker has emerged as a devastating disease of apple in East Asia.However,our understanding of this disease,particularly the identity of the causative agents,has been in a state of confusion.Here we provide a synopsis for the current understanding of Valsa canker and the taxonomy of its causal agents.We highlight the major changes concerning the identity of pathogens and the conflicting viewpoints in moving to“One Fungus=One Name”system for this group of fungal species.We compiled a list of 21 Cytospora species associated with Malus hosts worldwide and curated 12 of them with rDNA-ITS sequences.The inadequacy of rDNA-ITS in discriminating Cytospora species suggests that additional molecular markers,more intraspecific samples and robust methods are required to achieve reliable species recognition.
