Genetic Analysis Of Heterosis For Maize Yield And Important Agronomic Traits

Maize(Zea mays L.)is not only the largest food crop in the world,but also an important feed,energy and processing raw materials crop.Maize plays an important role in food security.Heterosis is a phenomenon in which hybrids exhibit superior phenotypes,such as enhanced biomass production,development rate,grain yield,and quality,relative to their parents.Heterosis utilization is very essential for maize breeding.Studying the genetic mechanism of heterosis is helpful for its utilization in plant breeding.In this study,A recombinant inbred line population(RIL),which was developed from a cross between Z58 and HD568,and a test-cross population,which was developed from across between RIL and four tester(Z58 HD568 Mo17 and B73),were planted at Xinxiang in 2015(?),2016(?)and Gongzhuling in 2016(?).Maize traits of the RIL population and its parents,including plant height(PH),ear height(EH),ear length(EL),ear diameter(ED),rows number(RN),kernel number per row(KR),yield per plant(GYP)and hundred grain weight(HKW)were investigated.Using a high-density SNP map,QTL mapping was performed to detect genetic factors associated with heterosis in the RIL population.The results of the study are as follows:1.The mid-parent heterosis of plant height was higher than ear height;Genetic environment and the interaction effect among different factors had powerful impact on PH and EH(P?0.05);The broad sense heritability(h~2)of PH and EH were 91.35%and 88.99%respectively;In environment I,The genetic model for PH is F-2,which is additive effect controlled by three major genes;In environment?and?,The genetic model for PH is G-0,which is three pairs additive–epistasis major genes and additive–epistasis ploggenes.In environment?and?,the genetic model for EH is F-2,which is additive effect of the three main genetic controlled by three major genes,in environment?the genetic model is G-0,which is the three pairs additive–epistasis major genes and additive–epistasis ploggenes.2.Using the phenotypic data and BLUP value of plant height and ear height heterosis in three environments,one stability QTL control PH and EH was identified in the marker interval SNP0178-SNP0180,and it's also the main-effect heteosis loci(HL)for PH.In total,9 main-effect HL for PH and two main-effect HL for EH were identified;Three main-effect HL for PH,and three main effect HL for EH were identified using BLUP value.3.The broad sense heritability of yield and its related traits range from 0.47-0.94.GYP shows strong heterosis.Using the phenotypic data of the three environment and BLUP value,three stable HL for yield and its related traits were identified,and their marker intervals are SNP1197-SNP1195(EL),SNP1392-SNP1391(ED)and SNP1393-SNP1392(HKW,EL),corresponding to maize chromosome 4,5 and 5,respectively;In total,three main-effect HL for GYP,one main-effect HL for RN and two main-effect HL for KR were detected;Using BLUP predicted value,three main-effect HL for HKW and one main-effect HL for ED were detected.