Genome-wide analysis of NDR1/HIN1-like genes in pepper(Capsicum annuum L.)and functional characterization of CaNHL4 under biotic and abiotic stresses

Plant NDR1/HIN1-like(NHL)genes play an important role in triggering plant defenses in response to biotic stresses.In this study,we performed a genome-wide identification of the NHL genes in pepper(Capsicum annuum L.)and characterized the functional roles of these CaNHL genes in response to abiotic stresses and infection by different pathogens.Phylogenetic analysis revealed that CaNHLs can be classified into five distinct subgroups,with each group containing generic and specific motifs.Regulatory element analysis showed that the majority of the promoter regions of the identified CaNHLs contain jasmonic acid(JA)-responsive and salicylic acid(SA)-responsive elements,and transcriptomic analysis revealed that CaNHL genes are expressed in all the examined tissues of pepper.The CaNHL1,CaNHL4,CaNHL6,CaNHL10,CaNHL11,and CaNHL12 genes were significantly upregulated under abiotic stress as well as in response to different pathogens,such as TMV,Phytophthora capsici and Pseudomonas syringae.In addition,we found that CaNHL4 localizes to the plasma membrane.CaNHL4-silenced pepper plants display significantly increased susceptibility to TMV,Phytophthora capsici and Pseudomonas syringae,exhibiting reduced expression of JA-related and SA-related genes and reduced ROS production.However,transient overexpression of CaNHL4 in pepper increases the expression of JArelated and SA-related genes,enhances the accumulation of ROS,and inhibits the infection of these three pathogens.Collectively,for the first time,we identified the NHL genes in pepper and demonstrated that CaNHL4 is involved in the production of ROS and that it also regulates the expression of JA-related and SA-related genes in response to different pathogens,suggesting that members of the CaNHL family play an essential role in the disease resistance of pepper.

On-resin peptide modification of methionine residue by employing 2-bromoacetate derivatives

On-resin peptide modification renders an easy-to-operate method that combines solid-phase peptide synthesis efficiency and avoids tedious purification procedures. Herein, we report the transition-metal-free and redox-neutral approach for solid-phase Met diversification with substrate diversity, which could be applied to synthesize cyclic peptides of different sizes.

A Phytophthora capsici RXLR Effector Targets and Inhibits a Plant,PPlase to Suppress Endoplasmic Reticulum-Mediated Immunity

Phytophthora pathogens secrete a large arsenal of effectors that manipulate host processes to create an environment conducive to pathogen colonization. However, the underlying mechanisms by which Phytophthora effectors manipulate host plant cells still remain largely unclear. In this study, we report that PcAvr3a12, a Phytophthera capsici RXLR effector and a member of the Avr3a effector family, suppresses plant immunity by targeting and inhibiting host plant peptidyl-prolyl cis-trans isomerase （PPlase）. Overexpression of PcAvr3a 12 in Arabidopsis thaliana enhanced plant susceptibility to P. capsici. FKBP15-2, an endoplasmic reticulum （ER）-Iocalized protein, was identified as a host target of PcAvr3a12 during early P. capsici infection. Analyses of A. thaliana T-DNA insertion mutant （fkbp15-2）, RNAi, and overexpression lines consistently showed that FKBP15-2 positively regulates plant immunity in response to Phytophthora infection. FKBP15-2 possesses PPlase activity essential for its contribution to immunity but is directly suppressed by PcAvr3a12. Interestingly, we found that FKBP15-2 is involved in ER stress sensing and is required for ER stress-mediated plant immunity. Taken together, these results suggest that P. capsici deploys an RXLR effector, PcAvr3a12, to facilitate infection by targeting and suppressing a novel ER-Iocalized PPlase, FKBP15-2, which is required for ER stress-mediated plant immunity.