Diallel Analysis Of Metabolic Traits In Maize Kernels

Maize is the largest grain crop in China,with the highest total yield and the most economical and industrial uses.Maize kernels are rich in a variety of metabolites,which are closely related to the nutritional composition,physiology and biochemistry of maize.Metabolites,as the link between genotype and phenotype,and the characteristics of quantitative traits,have been widely used for functional gene mining and phenotype prediction.However,the genetic model of metabolites themselves has not been studied.Diallel cross is an essential genetic design in classical quantitative genetics and an effective method for studying genetic models and combining ability.Here,we used E28,Zheng58,Chang7-2,Mo17 and Zi330,the parents of Zhongdan2,Danyu13 and Zhengdan95 8,as the test materials.And we used 52 diallel cross design to perform genetic analysis for the kernel metabolites of 5 test parents as well as their 20 reciprocal hybrids.With non-targeted metabolic profiling techniques,208 metabolites and their content in maize kernels were determined and analyzed.The main research results are as follows:1.The 208 identified metabolites were annotated and divided into ten categories,of which the number of amino acid metabolites was the highest.The cluster analysis and principal component analysis showed that there were differences in the metabolite contents of the parent and hybrid,and some metabolites had strain characteristics.2.The ANOVA analysis of metabolites was carried out on 5 test parents and 20 reciprocal hybrids,and 166 metabolites had significant differences between the test materials.Further analysis of combining ability was carried out,and the results showed that there were significant differences in general combining ability（GCA）among 134 metabolites,160 metabolites with significant differences between special combining ability（SCA）,and 28 metabolites with significant differences between reciprocal crosses（REC）.3.Griffing’s Method 1 Model I was used to estimate GCA,SCA of 166 significant metabolites.The results showed that the metabolites of P1（E28）and P2（Zheng58）exhibited more positive GCA than negative GCA,while the metabolites of P3（Chang7-2）,P4（Mol7）and P5（Zi330）exhibited more negative GCA than positive GCA.The hybrid combination with the largest number of positive SCA metabolites was P2x P4（Zheng58×Mo17）,and the combination with the largest number of negative SCA was P1× P5（E28×Zi330）.4.The genetic model analysis of 138 significant metabolites was performed using Hayman’s method,and the results showed that 34%of the metabolites followed the additivedominant model,and 46.3%of metabolites did not follow the additive-dominant model and may have epistatic effects.Genetic model analysis was carried out on 28 metabolites with significant differences between reciprocal.The results showed that 4 metabolites followed the additive-dominant model at reciprocal hybrids,1 metabolite followed the additivedominant model at obverse cross,and 9 metabolites followed the additive-dominant model at inverse cross.The results not only facilitate understanding the genetic basis of maize kernels at the metabolic level,but also provide novel ideas for genetic improvement of maize.