Genome-wide association mapping and genomic prediction of stalk rot in two mid-altitude tropical maize populations

Maize stalk rot reduces grain yield and quality.Information about the genetics of resistance to maize stalk rot could help breeders design effective breeding strategies for the trait.Genomic prediction may be a more effective breeding strategy for stalk-rot resistance than marker-assisted selection.We performed a genome-wide association study(GWAS)and genomic prediction of resistance in testcross hybrids of 677 inbred lines from the Tuxpe?o and non-Tuxpe?o heterotic pools grown in three environments and genotyped with 200,681 single-nucleotide polymorphisms(SNPs).Eighteen SNPs associated with stalk rot shared genomic regions with gene families previously associated with plant biotic and abiotic responses.More favorable SNP haplotypes traced to tropical than to temperate progenitors of the inbred lines.Incorporating genotype-by-environment(G×E)interaction increased genomic prediction accuracy.

A molecular framework for signaling crosstalk between jasmonate and ethylene in anthocyanin biosynthesis,trichome development,and defenses against insect herbivores in Arabidopsis

The phytohormones ethylene(ET)and jasmonate(JA)regulate plant development,growth,and defense responses;however,the molecular basis for their signaling crosstalk is unclear.Here,we show that JA-ZIM-domain(JAZ)proteins,which repress JA signaling,repress trichome initiation/branching and anthocyanin accumulation,and inhibit the transcriptional activity of the basic helix-loop-helix(bHLH)-MYBmembers(GLABRA3(GL3)-GL1 and TRANSPARENT TESTA 8(TT8)-MYB75)of WD-repeat/bHLH/MYB(WBM)complexes.The ET-stabilized transcription factors ETHYLENEINSENSITIVE3(EIN3)and EIN3-LIKE1(EIL1)were found to bind to several members of WBM complexes,including GL3,ENHANCER OF GLABRA3(EGL3),TT8,GL1,MYB75,and TRANSPARENT TESTA GLABRA1(TTG1).This binding repressed the transcriptional activity of the b HLH-MYB proteins and inhibited anthocyanin accumulation,trichome formation,and defenses against insect herbivores while promoting root hair formation.Conversely,the JA-activated b HLH members GL3,EGL3,and TT8 of WBM complexes were able to interact with and attenuate the transcriptional activity of EIN3/EIL1 at the HOOKLESS1 promoter,and their overexpression inhibited apical hook formation.Thus,this study demonstrates a molecular framework for signaling crosstalk between JA and ET in plant development,secondary metabolism,and defense responses.