Abstract
BackgroundMaize is one of the most important staple crops and is widely grown throughout the world. Stalk lodging can cause enormous yield losses in maize production. However, rind penetrometer resistance (RPR), which is recognized as a reliable measurement to evaluate stalk strength, has been shown to be efficient and useful for improving stalk lodging-resistance. Linkage mapping is an acknowledged approach for exploring the genetic architecture of target traits. In addition, genomic selection (GS) using whole genome markers enhances selection efficiency for genetically complex traits. In the present study, two recombinant inbred line (RIL) populations were utilized to dissect the genetic basis of RPR, which was evaluated in seven growth stages.ResultsThe optimal stages to measure stalk strength are the silking phase and stages after silking. A total of 66 and 45 quantitative trait loci (QTL) were identified in each RIL population. Several potential candidate genes were predicted according to the maize gene annotation database and were closely associated with the biosynthesis of cell wall components. Moreover, analysis of gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway further indicated that genes related to cell wall formation were involved in the determination of RPR. In addition, a multivariate model of genomic selection efficiently improved the prediction accuracy relative to a univariate model and a model considering RPR-relevant loci as fixed effects.ConclusionsThe genetic architecture of RPR is highly genetically complex. Multiple minor effect QTL are jointly involved in controlling phenotypic variation in RPR. Several pleiotropic QTL identified in multiple stages may contain reliable genes and can be used to develop functional markers for improving the selection efficiency of stalk strength. The application of genomic selection to RPR may be a promising approach to accelerate breeding process for improving stalk strength and enhancing lodging-resistance.
Highlights
Maize is one of the most important staple crops and is widely grown throughout the world
The rind penetrometer resistance (RPR) values evaluated in multiple stages, environments and recombinant inbred line (RIL) populations exhibited normal distributions, and the difference between the smallest and largest values ranged from 1.90- to 3.33-fold for each stage (Additional file 1: Figure S1)
The RPR values in the seven stages were classified into three groups, and the largest cluster consisted of AS10, AS20, AS30, AS40 and 10 to 50 days after silking (AS50), which belong to the reproductive growth phase
Summary
Maize is one of the most important staple crops and is widely grown throughout the world. Stalk lodging can seriously influence photosynthesis and substance transportation, and annually causes reductions in maize yield ranging from 5 to 20% worldwide [1] Several factors, such as genetics, natural conditions, field management, diseases and insect pests, can result in weak plant standability and stalk lodging [2,3,4,5,6]. Several approaches have been developed to measure stalk strength, including stalk bending strength, As for the genetic architecture of RPR, previous studies have used association and linkage mapping to identify quantitative trait loci (QTL) with the purpose of. A range of significantly associated loci related to RPR have been detected in genome-wide association study (GWAS) for maize nested association mapping panel and natural population, further indicating the great genetic complexity of RPR [28, 29]. The predictive ability needs to be improved to be able to predict stalk strength in a GS strategy for practical breeding programs
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