QTL Mapping Of Vascular Bundle Related Traits In Maize Stem

Vascular bundle related traits are not noly related to the transportation of nutrients but also correlated with the lodging in maize?Zea mays L.?.Therefore,uncovering the genetic basis of vascular bundle related traits in stem may give guidance for breeding.In this study,a genome-wide association panel containing 248 diverse maize inbred lines and a recombined inbred lines population developed from a cross X178 and NX531 were used for genome wide association analysis and linkage mapping with high-throughput SNP markers for vascular bundle related traits and stalk pushing resistance,respectively.The main results are as follows:1.There were extensive natural variation for vascular bundle related traits in maize stem in both association mapping panel and RIL population.The broad-sense heritability of the number of small vascular bundle,vascular bundle and total vascular bundle in inbred lines population ranged from 84.53% to 91.96%.The simple correlation analysis indicated that stalk pushing resistance had significant negative correlation with the number of small vascular bundle,large vascular bundle and total vascular bundle per unit area in two populations.2.A total of 216 association SNP loci were identified associated with vascular bundle related traits,which were distributed on all chromosomes under both plant densities.130,86 SNP loci were detected associated with vascular bundle related traits under each plant density,respectively.The phenotypic variation denoted by each SNP ranged from1.11% to 30.27% and 1.03 to 27.63%,respectively.10,5 SNP loci were detected associated with stalk pushing resistance under each plant density,respectively.Meanwhile,a total of 31 repetitive SNP loci were detected simultaneously under both plant densities associated with the same trait.3.The linkage mapping results showed that a total of 30 QTLs were detected in RIL population on all chromosomes in RIL population.27 and 3 QTLs controlling vascular bundle related-traits and stalk pushing resistance were detected,which phenotypic variance explained by a QTL were 2.44%¹8.30% and 4.61%²4.80%,respectively.The physical interval for a QTL ranged from 0.92 Mb to 10.74 Mb,and the mean was 5.24 Mb.qNLVB6for the number of large vascular bundles and qNTVB6 for the number of total vascularbundles on chromosome 6 were identified located in the same genetic interval.qASVB10 for the average area of single small vascular bundle and qATSVB10 for total area of small vascular bundle on chromosome 10 were identified located in the same genetic interval.Moreover,9 QTLs phenotypic variation denoted more than 10% by each QTL were detected.4.Comparing the results of linkage mapping and association mapping,we found the SNP chr1₈019611 on chromosome 1 in Bin1.04 for the average area of single large vascular bundle was within the physical interval 6.60⁹.62 Mb of qALVB.There were two SNP chr7₁63784217 and chr7₁64199008 with phenotypic variation of 5.11% and17.74% on chromosome 7 in Bin7.04 mapped for the number of small vascular bundle per unit area within the physical interval of qN17 explaining 11.75% of the phenotypic variance about 196.59²06.88 Mb.5.11 candidate genes might be involve in the growth and development of plant and vascular patterning were identified,1 candidate genes might be associated with stalk mechanical strength in maize based on part of SNP associated with vascular bundle related traits and stalk pushing resistance.The correlation between vascular bundle related traits and stalk pushing resistance in maize stalk were discovered in this study.Genome-wide association study and linkage mapping were used to detect related traits loci and candidate genes which control vascular bundle related traits and stalk pushing resistance in maize stalk.These results will be of great significance in the future.