Comparative oxidation proteomics analyses suggest redox regulation of cytosolic translation in rice leaves upon Magnaporthe oryzae infection

Pathogen attack can increase plant levels of reactive oxygen species(ROS),which act as signaling molecules to activate plant defense mechanisms.Elucidating these processes is crucial for understanding redox signaling pathways in plant defense responses.Using an iodo-tandem mass tag(TMT)-based quantitative proteomics approach,we mapped 3362 oxidized cysteine sites in 2275 proteins in rice leaves.Oxidized proteins were involved in gene expression,peptide biosynthetic processes,stress responses,ROS metabolic processes,and translation pathways.Magnaporthe oryzae infection led to increased oxidative modification levels of 512 cysteine sites in 438 proteins,including many transcriptional regulators and ribosomal proteins.Ribosome profiling(Ribo-seq)analysis revealed that the oxidative modification of ribosomal proteins promoted the translational efficiency of many mRNAs involved in defense response pathways,thereby affecting rice immunity.Our results suggest that increased oxidative modification of ribosomal proteins in rice leaves promotes cytosolic translation,thus revealing a novel function of posttranslational modifications.Furthermore,the oxidation-sensitive proteins identified here provide a valuable resource for research on protein redox regulation and can guide future mechanistic studies.

Histone deacetylase HDA710 controls salt tolerance by regulating ABA signaling in rice

Plants have evolved numerous mechanisms that assist them in withstanding environmental stresses.Histone deacetylases(HDACs)play crucial roles in plant stress responses;however,their regulatory mechanisms remain poorly understood.Here,we explored the function of HDA710/OsHDAC2,a member of the HDAC RPD3/HDA1 family,in stress tolerance in rice(Oryza sativa).We established that HDA710 localizes to both the nucleus and cytoplasm and is involved in regulating the acetylation of histone H3 and H4,specifically targeting H4 K5 and H4 K16 under normal conditions.HDA710 transcript accumulation levels were strongly induced by abiotic stresses including drought and salinity,as well as by the phytohormones jasmonic acid(JA)and abscisic acid(ABA).hda710 knockout mutant plants showed enhanced salinity tolerance and reduced ABA sensitivity,whereas transgenic plants overexpressing HDA710 displayed the opposite phenotypes.Moreover,ABAand salt-stress-responsive genes,such as OsLEA3,OsABI5,OsbZIP72,and OsNHX1,were upregulated in hda710 compared with wild-type plants.These expression differences corresponded with higher levels of histone H4 acetylation in gene promoter regions in hda710 compared with the wild type under ABA and salt-stress treatment.Collectively,these results suggest that HDA710 is involved in regulating ABA-and salt-stress-responsive genes by altering H4 acetylation levels in their promoters.

Ustilaginoidea virens modulates lysine 2-hydroxyisobutyrylation in rice flowers during infection

The post-translational modification lysine 2-hydroxyisobutyrylation(K_(hib))plays an important role in gene transcription,metabolism,and enzymatic activity.K_(hib)sites have been identified in rice(Oryza sativa).However,the K_(hib)status of proteins in rice flowers during pathogen infection remains unclear.Here,we report a comprehensive identification of K_(hib)-modified proteins in rice flowers,and the changes in these proteins during infection with the fungal pathogen Ustilaginoidea virens.By using a tandem mass tag-based quantitative proteomics approach,we identified 2,891 K_(hib)sites on 964 proteins in rice flowers.Our data demonstrated that 2-hydroxyisobutyrylated proteins are involved in diverse biological processes.K_(hib)levels were substantially reduced upon infection with U.virens.Chromatin immunoprecipitation polymerase chain reaction(PCR)and reverse transcription quantitative PCR analyses revealed that histone K_(hib)is involved in the expression of disease-resistance genes.More importantly,most quantified sites on core histones H3 were downregulated upon U.virens infection.In addition,the histone deacetylases HDA705,HDA716,SRT1,and SRT2 are involved in the removal of K_(hib)marks in rice.HDA705 was further confirmed to negatively regulate rice disease resistance to pathogens U.virens,Magnaporthe oryzae,and Xanthomonas oryzae pv.oryzae(Xoo).Our data suggest that U.virens could modulate K_(hib)in rice flowers during infection.