Abstract
BackgroundKernel weight, controlled by quantitative trait loci (QTL), is an important component of grain yield in maize. Cytokinins (CKs) participate in determining grain morphology and final grain yield in crops. ZmIPT2, which is expressed mainly in the basal transfer cell layer, endosperm, and embryo during maize kernel development, encodes an isopentenyl transferase (IPT) that is involved in CK biosynthesis.ResultsThe coding region of ZmIPT2 was sequenced across a panel of 175 maize inbred lines that are currently used in Chinese maize breeding programs. Only 16 single nucleotide polymorphisms (SNPs) and seven haplotypes were detected among these inbred lines. Nucleotide diversity (π) within the ZmIPT2 window and coding region were 0.347 and 0.0047, respectively, and they were significantly lower than the mean nucleotide diversity value of 0.372 for maize Chromosome 2 (P < 0.01). Association mapping revealed that a single nucleotide change from cytosine (C) to thymine (T) in the ZmIPT2 coding region, which converted a proline residue into a serine residue, was significantly associated with hundred kernel weight (HKW) in three environments (P <0.05), and explained 4.76% of the total phenotypic variation. In vitro characterization suggests that the dimethylallyl diphospate (DMAPP) IPT activity of ZmIPT2-T is higher than that of ZmIPT2-C, as the amounts of adenosine triphosphate (ATP), adenosine diphosphate (ADP), and adenosine monophosphate (AMP) consumed by ZmIPT2-T were 5.48-, 2.70-, and 1.87-fold, respectively, greater than those consumed by ZmIPT2-C. The effects of artificial selection on the ZmIPT2 coding region were evaluated using Tajima’s D tests across six subgroups of Chinese maize germplasm, with the most frequent favorable allele identified in subgroup PB (Partner B).ConclusionsThese results showed that ZmIPT2, which is associated with kernel weight, was subjected to artificial selection during the maize breeding process. ZmIPT2-T had higher IPT activity than ZmIPT2-C, and this favorable allele for kernel weight could be used in molecular marker-assisted selection for improvement of grain yield components in Chinese maize breeding programs.
Highlights
Kernel weight, controlled by quantitative trait loci (QTL), is an important component of grain yield in maize
More than 185 quantitative trait loci (QTL) underlying yield components including kernel row number (KRN), kernel number per row (KNPR), and hundred kernel weight (HKW) have been identified across the maize genome using various mapping populations (2012 November update to Gramene database), which has improved our understanding of the genetic basis of maize yield
KRN was significantly positively correlated with KNPR (P
Summary
Kernel weight, controlled by quantitative trait loci (QTL), is an important component of grain yield in maize. Grain yield is a complex quantitative trait, and is determined by several components including kernel number and kernel weight [2]. More than 185 quantitative trait loci (QTL) underlying yield components including kernel row number (KRN), kernel number per row (KNPR), and hundred kernel weight (HKW) have been identified across the maize genome using various mapping populations (2012 November update to Gramene database), which has improved our understanding of the genetic basis of maize yield. Grain size and kernel weight are important targets for artificial selection for high grain yield. QTL associated with TaGW2-6A Hap-6A-A for grain size [6] and TaCKX6-D1 [7] for grain weight have been identified and artificially selected from within Chinese wheat germplasm. Markers derived from QTL controlling similar components of grain yield in maize will be very useful for marker-assisted selection
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
