Abstract
Stalk lodging resistance, which is mainly measured by stem diameter (SD), stalk bending strength (SBS), and rind penetrometer resistance (RPR) in maize, seriously affects the yield and quality of maize (Zea mays L.). To dissect its genetic architecture, in this study multi-locus genome-wide association studies for stalk lodging resistance-related traits were conducted in a population of 257 inbred lines, with tropical, subtropical, and temperate backgrounds, genotyped with 48,193 high-quality single nucleotide polymorphisms. The analyses of phenotypic variations for the above traits in three environments showed high broad-sense heritability (0.679, 0.720, and 0.854, respectively). In total, 423 significant Quantitative Trait Nucleotides (QTNs) were identified by mrMLM, FASTmrEMMA, ISIS EM-BLASSO, and pLARmEB methods to be associated with the above traits. Among these QTNs, 29, 34, and 48 were commonly detected by multiple methods or across multiple environments to be related to SD, SBS, and RPR, respectively. The superior allele analyses in 30 elite lines showed that only eight lines contained more than 50% of the superior alleles, indicating that stalk lodging resistance can be improved by the integration of more superior alleles. Among sixty-three candidate genes of the consistently expressed QTNs, GRMZM5G856734 and GRMZM2G116885, encoding membrane steroid-binding protein 1 and cyclin-dependent kinase inhibitor 1, respectively, possibly inhibit cell elongation and division, which regulates lodging resistance. Our results provide the further understanding of the genetic foundation of maize lodging resistance.
Highlights
Lodging is one of the most important factors threatening grain yield in maize, and can result in reduced photosynthesis, nutrient transportation, and grain quality (Remison and Dele Akinleye, 1978)
To further understand the molecular basis of lodging-related traits, we focused on the candidate genes that were directly associated with the common Quantitative Trait Nucleotides (QTNs)
Our study demonstrated that improved efficiency and accuracy could be achieved by a combination of the new multi-locus methods for identification of lodging resistance-related QTNs in maize
Summary
Lodging is one of the most important factors threatening grain yield in maize, and can result in reduced photosynthesis, nutrient transportation, and grain quality (Remison and Dele Akinleye, 1978). Previous studies on crop morphological traits showed that plant stem diameter (SD), stalk bending strength (SBS), and rind penetrometer resistance (RPR) are closely associated with stalk lodging in the field (Kashiwagi et al, 2008; Hu et al, 2012, 2013). These three traits are significantly negatively correlated with stalk lodging rate in the field (Ling, 2008).
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