Identifcation and segregation of two closely linked major QTLs for kernel row number in advanced maize–teosinte populations

Abstract

Kernel row number (KRN) is a crucial factor infuencing maize yield and serves as a signifcant target for maize breeding. The use of wild progenitor species can aid in identifying the essential traits for domestication and breeding. In this study, teosinte (MT1) served as the donor parent, the inbred maize line of Mo17 was used as the recurrent parent, we identifed a major quantitative trait locus (QTL) for KRN, designatedqKRN2, into two closely linked loci,qKRN2-1and qKRN2-2. Here, fne mapping was performed to investigate two QTLs,qKRN2-1andqKRN2-2, within a genomic range of 272 kb and 775 kb, respectively. This was achieved using a progeny test strategy in an advanced backcross population, with the two QTLs explaining 33.49% and 35.30% of the phenotypic variance. Molecular marker-assisted selection resulted in the development of two nearly isogenic lines (NILs),qKRN2-1andqKRN2-2, which difered only in the segment containing the QTL. Notably, the maize (Mo17) alleles increased the KRN relative to teosinte by approximately 1.4 and 1.2 rows for qKRN2-1andqKRN2-2, respectively.Zm00001d002989encodes a cytokinin oxidase/dehydrogenase and its expression in the immature ears exhibited signifcant diferences among theqKRN2-1NILs. In situ hybridization localizedZm00001d002989 to the primordia of the inforescence meristem and spikelet pair meristems, is predicted to be the causal gene ofqKRN2-1. The fndings of this study deepen our understanding of the genetic basis of KRN and hold signifcant potential for improv ing maize grain yields.