The antioxidant protein ZmPrx5 contributes resistance to maize stalk rot

Maize(Zea mays L.)stalk rot is a devastating disease worldwide,causing severe yield losses.Although previous studies have focused on the genetic dissection of maize resistance to stalk rot,the mechanisms of resistance remain largely unknown.We used a comparative proteomics approach to identify candidate proteins associated with stalk rot resistance.Statistical analyses revealed 763 proteins differentially accumulated between Fusarium graminearum and mock-inoculated plants.Among them,the antioxidant protein ZmPrx5,which was up-accumulated in diseased plants,was selected for further study.ZmPrx5 transcripts were present in root,stalk,leaf,ear,and reproductive tissues.The expression of ZmPrx5 in three inbred lines increased significantly upon F.graminearum infection.ZmPrx5 was localized in the cytoplasm.Compared to control plants,maize plants overexpressing ZmPrx5 showed increased resistance to F.graminearum infection,and ZmPrx5 mutant plants were more susceptible than wild-type plants.Defense-associated pathways including plant–pathogen interactions,phenylalanine metabolism,and benzoxazinoid and flavonoid biosynthesis were suppressed in ZmPrx5 homozygous mutant plants compared with wild-type plants.We suggest that ZmPrx5 positively regulates resistance against stalk rot in maize,likely through defense-oriented transcriptome reprogramming.These results lay a foundation for further research on the roles of Prx5 subfamily proteins in resistance to plant fungal diseases,and provide a potential genetic resource for breeding disease-resistance maize lines.

Senome-wide Association Studies in Maize： Praise and Stargaze

Genome-wide association study （GWAS） has become a widely accepted strategy for decoding genotype- phenotype associations in many species thanks to advances in next-generation sequencing （NGS） technol- ogies. Maize is an ideal crop for GWAS and significant progress has been made in the last decade. This review summarizes current GWAS efforts in maize functional genomics research and discusses future prospects in the omics era. The general goal of GWAS is to link genotypic variations to corresponding dif- ferences in phenotype using the most appropriate statistical model in a given population. The current re- view also presents perspectives for optimizing GWAS design and analysis. GWAS analysis of data from RNA, protein, and metabolite-based omics studies is discussed, along with new models and new popula- tion designs that will identify causes of phenotypic variation that have been hidden to date. The joint and continuous efforts of the whole community will enhance our understanding of maize quantitative traits and boost crop molecular breeding designs.

Large-Scale Discovery of Non-conventional Peptides in Maize and Arabidopsis through an Integrated Peptidogenomic Pipeline

Non-conventional peptides(NCPs),which include small open reading frame-encoded peptides,play critical roles in fundamental biological processes.In this study,we developed an integrated peptidogenomic pipeline using high-throughput mass spectra to probe a customized six-frame translation database and applied it to large-scale identification of NCPs in plants.A total of 1993 and 1860 NCPs were unambiguously identified in maize and Arabidopsis,respectively.These NCPs showed distinct characteristics compared with conventional peptides and were derived from introns,3′UTRs,5′UTRs,junctions,and intergenic regions.Furthermore,our results showed that translation events in unannotated transcripts occur more broadly than previously thought.In addition,we found that dozens of maize NCPs are enriched within regions associated with phenotypic variations and domestication selection,indicating that they potentially are involved in genetic regulation of complex traits and domestication in maize.Taken together,our study developed an integrated peptidogenomic pipeline for large-scale identification of NCPs in plants,which would facilitate global characterization of NCPs from other plants.The identification of large-scale NCPs in both monocot(maize)and dicot(Arabidopsis)plants indicates that a large portion of plant genome can be translated into biologically functional molecules,which has important implications for functional genomic studies.

Ascorbate peroxidase 1 confers resistance to southern corn leaf blight in maize

Southern corn leaf blight (SCLB), caused by Bipolarismaydis, is one of the most devastatingdiseases affecting maize production. However,only one SLCB resistance gene, conferring partialresistance, is currently known, underscoring theimportance of isolating new SCLB resistancerelatedgenes. Here, we performed a comparativeproteomic analysis and identified 258 proteinsshowing differential abundance during the maizeresponse to B. maydis. These proteins included anascorbate peroxidase (Zea mays ascorbate peroxidase1 (ZmAPX1)) encoded by a gene locatedwithin the mapping interval of a previously identifiedquantitative trait locus associated with SCLBresistance. ZmAPX1 overexpression resulted inlower H_(2)O_(2) accumulation and enhanced resistanceagainst B. maydis. Jasmonic acid (JA)contents and transcript levels for JA biosynthesisand responsive genes increased in ZmAPX1-overexpressing plants infected with B. maydis,whereas Zmapx1 mutants showed the oppositeeffects. We further determined that low levels of H_(2)O_(2) are accompanied by an accumulation of JAthat enhances SCLB resistance. These resultsdemonstrate that ZmAPX1 positively regulatesSCLB resistance by decreasing H_(2)O_(2) accumulationand activating the JA-mediated defensesignaling pathway. This study identified ZmAPX1as a potentially useful gene for increasing SCLBresistance. Furthermore, the generated datamay be relevant for clarifying the functions ofplant APXs.

Ligand deprivation activates receptor signaling

Signaling peptides,together with their receptor kinases and proteins,are involved in a wide range of processes related to plant growth,development,and stress responses.In Arabidopsis,over 1000 different peptides and 251 leucine-rich repeat receptorkinases(LRR-RKs)were identified.

O2-ZmGRAS11 coordinates cell expansion and endosperm filling

Maize(Zea mays),a major crop for food and feed,is grown world-wide with a high annual yield.The grain size and weight of maize are mainly determined by starch and storage proteins that are actively synthesized during endosperm filling.During early endo-sperm development,the maize endosperm undergoes a series of cell division,differentiation,and expansion events.Cell division and expansion determine the number and size of endosperm cells,respectively,influencing the final grain size and yield.While cell division mainly occurs during early endosperm development,cell expansion occurs continuously,particularly during the endo-sperm filling stage when starchy endosperm cells are enlarged with storage metabolites.Despite several key genes involved in the regulation of either endosperm filling or cell expansion being identified,how these two processes are coordinated remains elusive.