QTL Mapping Of Maize Plant Height QPh10 And Transcriptome Heterosis Analysis Based On Chromosomal Fragment Substitution Line

Maize is an important crop for food,economy and feed in China.Plant height?PH?,an important agronomic trait for maize production,is highly correlated with the lodging resistance and planting density.In this study,a chromosomal fragment substitution line CL137,which was constructed with Ye478 as the recurrent parent and Qi319 as the donor parent was used as the male parent to crossed with Ye478 to construct the F₂ segregating population.The polymorphic Indel markers were developed based on the re-sequencing data of Qi319 and Ye478.Then plant height QTL on chromosome 10 was identified in two environments.Meanwhile,we used several typical inbred lines to produce hybrid,then combined with 13 hybrids and their parents'transcriptome data to analysis the gene expression patterns,construct the gene expression network between plant height and yield,and then mine hub gene.The main results are as follows:1.In 2017,the QTL of PH was mapped between the markers mk7-bnlg1655,corresponding to the83.86-85.34 Mb interval of the B73 genome?RefGen?v3?,the physical distance was about 1.5 Mb,and the phenotypic variation explanation?PVE?was 7.57%.In 2018,the QTL of PH was mapped between the markers mk5-bnlg1655,corresponding to the 82.76-85.34 Mb interval of the B73 genome,the physical distance was about 2.5 Mb,and the PVE was 5.75%.Notably,the genetic effects of qPH10were mainly additive effects.This study also annotated the function genes in the position interval and predicted candidate genes GRMZM2G133529 and GRMZM2G125977 may control plant height.2.It was found that the number of genes expressed in hybrids was more than that in inbred lines,indicating that the number of genes expressed in hybrids might be the cause of heterosis.Using gene expression data to calculate Euclidean distance,we found that there was a significant positive correlation?r=0.97,P<0.01?between genetic distance and the number of differential genes between the corresponding parents of the hybrid,that is,the farther the genetic distance,the more differential genes between parents.3.The DEGs between hybrids and parents mainly showed non-additive?92.2%?expression pattern,and the non-additive expression pattern mainly showed partial dominance;a few DEGs showed complete dominance or super dominance respectively.These genes could be clustered into four different types.Cluster1 and cluster2 were the types which hybrids performance was between parents,cluster1was the down type,cluster2 was the up type,and most of genes were of this two type;cluster3was the type which hybrids was lower than parents;cluster4 was the type which hybrids was higher than parents.4.Go?Gene Ontology?and KEGG?Kyoto Encyclopedia of Genes and Genomes?analysis showed that the up-regulated genes had a great influence on heterosis of plant height and ear height,and these genes were mainly enriched in GO terms such as positive regulation of cell cycle and regulation of mitotic cell division.KEGG pathway analysis showed that these genes were mainly enriched in 10pathways,and the core pathway map00520 corresponds to the metabolism of amino sugar and nucleotide sugar.These results suggest that mitosis and expression of cell cycle related genes may play an important role in plant height heterosis,and we should pay close attention to the relationship between carbohydrate metabolism and heterosis.5.After WGCNA?Weighted Gene Co-expression Network Analysis?analysis,3513 DEGs obtained by 13 hybrids and their parents were divided into 19 modules.The red,blue and brown modules were highly correlated with plant height and ear height phenotypes.The hub gene Zm00001d030772 in the blue module was related to ceramide metabolism,and can participate in important life activities such as programmed cell death,differentiation and proliferation.The change of plant height is generally caused by the difference of internode length and internode number,which is reflected in the change of cell number and cell size at the cell level.It was speculated that the gene may affect the cell differentiation and proliferation,and then control plant height heterosis.