Genetic architecture of maize yield traits dissected by QTL mapping and GWAS in maize

The study of yield traits can reveal the genetic architecture of grain yield for improving maize production.In this study, an association panel comprising 362 inbred lines and a recombinant inbred line population derived from X178 × 9782 were used to identify candidate genes for nine yield traits. High-priority overlap(HPO) genes, which are genes prioritized in a genome-wide association study(GWAS), were investigated using coexpression networks. The GWAS identified 51 environmentally stable SNPs in two environments and 36 pleiotropic SNPs, including three SNPs with both attributes. Seven hotspots containing 41 trait-associated SNPs were identified on six chromosomes by permutation. Pyramiding of superior alleles showed a highly positive effect on all traits, and the phenotypic values of ear diameter and ear weight consistently corresponded with the number of superior alleles in tropical and temperate germplasm. A total of 61 HPO genes were detected after trait-associated SNPs were combined with the coexpression networks. Linkage mapping identified 16 environmentally stable and 16 pleiotropic QTL.Seven SNPs that were located in QTL intervals were assigned as consensus SNPs for the yield traits.Among the candidate genes predicted by our study, some genes were confirmed to function in seed development. The gene Zm00001 d016656 encoding a serine/threonine protein kinase was associated with five different traits across multiple environments. Some genes were uniquely expressed in specific tissues and at certain stages of seed development. These findings will provide genetic information and resources for molecular breeding of maize grain yield.

The role of m6A modification in the biological functions and diseases

N6-methyladenosine(m6A)is the most prevalent,abundant and conserved internal cotranscriptional modification in eukaryotic RNAs,especially within higher eukaryotic cells.m6A modification is modified by the m6A methyltransferases,or writers,such as METTL3/14/16,RBM15/15B,ZC3H3,VIRMA,CBLL1,WTAP,and KIAA1429,and,removed by the demethylases,or erasers,including FTO and ALKBH5.It is recognized by m6A-binding proteins YTHDF1/2/3,YTHDC1/2 IGF2BP1/2/3 and HNRNPA2B1,also known as"readers".Recent studies have shown that m6A RNA modification plays essential role in both physiological and pathological conditions,especially in the initiation and progression of different types of human cancers.In this review,we discuss how m6A RNA methylation influences both the physiological and pathological progressions of hematopoietic,central nervous and reproductive systems.We will mainly focus on recent progress in identifying the biological functions and the underlying molecular mechanisms of m6A RNA methylation,its regulators and downstream target genes,during cancer progression in above systems.We propose that m6A RNA methylation process offer potential targets for cancer therapy in the future.