玉米氮效率QTL定位和候选基因筛选OA北大核心CSTPCD

[Objective]Genetic improvement for efficient utilization of maize nutrients represents a crucial method to ensure national food security.Exploring quantitative trait locus(QTL)and related candidate genes of nitrogen use efficiency can provide a theoretical basis for improving the efficiency of nitrogen fertilizer in maize and cultivating high-yield and high-efficiency maize varieties.[Method]In this study,QTL mapping analysis in one recombinant inbred line(RIL)population constructed by KA105 and KB024 was performed for grain yield under two different nitrogen treatments,including the derived traits partial factor productivity from applied nitrogen(PFPN),low nitrogen tolerance coefficient(LNTC)and nitrogen agronomic efficiency(NAE).Concurrently,integrating the seedling transcriptome data of the parent KA105 under nitrogen treatment,differentially expressed genes were identified,and candidate genes associated with maize nitrogen use efficiency were mined through co-expression analysis.Subsequently,the selected candidate genes were validated using qRT-PCR.[Result]Through mapping analysis,a total of 36 QTLs distributed across different chromosomes were detected,explaining 1.63%to 17.26%of the phenotypic variation.Among these,eight major QTLs with a phenotypic variation explanation rate exceeding 10%were identified,along with seven genetically stable QTLs commonly identified across different traits or environments.Notably,qNNGYP1 located on chromosome 1 has been repeatedly detected in previous studies,with a phenotypic explanation rate of up to 11.73%.Additionally,other QTLs(qNNGYP1,qPFPN1)co-located in this interval across different environments,suggesting it as a focal region for further investigation.Combining transcriptome data of seedlings under low nitrogen stress,39 differentially expressed genes within these QTL intervals were identified,and 6 key genes were identified through co-expression network prediction.The result of qRT-PCR indicated that the expression trends of the candidate genes under both nitrogen treatments were consistent with the transcriptome data.Specifically,GRMZM2G366873 was involved in the regulation of auxin homeostasis and may participate in maize responses to low nitrogen stress,drought stress,and boron stress through auxin signal transduction,also regulating ear length.GRMZM2G414192 was involved in the response of the photosynthetic system to low nitrogen stress and was regulated by brassinosteroids.GRMZM2G414043 was associated with maize grain length and biomass,while GRMZM2G040642 may be involved in the long-distance signal transduction of nitrogen.[Conclusion]In summary,a total of 36 QTLs were identified,distributed across chromosomes 1,4,5,7,8,and 9,including eight major QTLs(PVE＞10%).The candidate genes GRMZM2G366873,GRMZM2G414192,GRMZM2G414043,and GRMZM2G040642 were identified as potential genes for maize nitrogen efficiency.