| In maize,kernel traits strongly impact overall grain yields,and it is known that sophisticated spatiotemporal programs of gene expression coordinate kernel development,so advancing our knowledge of kernel development can help efforts to improve grain yields.Here,using phenotype,genotype,and transcriptomics data of maize kernels at 5 and 15 days after pollination(DAP)for a large association mapping panel,we employed multiple quantitative genetics approaches-genome wide association studies(GWAS)as well as expression quantitative trait loci(eQTL)and quantitative trait transcript(QTT)analyses—to gain insights about molecular genetic basis of kernel development in maize.This resulted in the identification of 137 putative kernel length-related genes at 5 DAP,of which 43 are located in previously reported QTL regions.In addition,we also compared the gene regulatory networks of 5DAP with that of 15DAP,and found some interesting phenomena related to developmental stage-specific eQTLs,including the relatively longer distance between stage-specific eQTLs with their targets than those of stage-shared eQTLs,and the reverse effects of 324 eQTLs between the two stages.Beyond,we also revealed many multi-targets eQTLs that are specific at both stages,including one 15DAP-specific eQTL that regulating 53 genes.This eQTL overlaps the locus encoding a maize homolog of the recently described m6A methylation reader protein ECT2 from Arobidopsis.Notably,among the 53 genes associated with this putative epieQTL,10 are for the main storage proteins in the maize endosperm(zeins)and two are known regulators of zein expression or endosperm development(Opaque2 and ZmICE1).Collectively,beyond cataloging and characterizing genomic attributes of a large number of expression quantitative trait loci at the early stage of maize kernels,our study revealed several kernel-size related genes,which will give insights into the improvement of maize grain yields. |
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