Sequence Variation Analysis Of Leaf-Angle-Related Genes Lg1 And ZmTAC1 And Their Association With Plant Architecture Related Traits In Maize (Zea Mays L.)

Maize(Zea mays L.)is the cereal with the largest harvested area and production in China.Its application has been greatly extended to the emergent domains such as the biofuels and chemical engineering materials.The improvements in maize production and quality are of great importance to ensure the food and energy security and to promote the development of animal husbandry and chemical industry.In the past century of maize cultivation,it is demonstrated that the increase of planting density is the essential origin of maize production.Hence,one of the most important task for the maize breeding is to enhance the traits related to the plant architecture and cultivate superior varieties that allow planting in high density.Among all the plant architecture related traits,the angle between the stem and leaf,i.e.the leaf angle,determines the spatial structure of maize and therefore the planting density.The investigations of the plant architecture related traits including leaf angle,the genetic variances of corresponding genes and elite allelic variations are extremely valuable for the control of the traits and genotypes of maize related to its planting density,and thus of key importance for the further incense of maize production in large scale.In this work,we constructed the inbred population of maize with 349 individuals that includes a wide range of genetic variances.The leaf angles and other traits related to plant architecture are measured.The genes Ig1 and ZmTAC1 are analyzed for the intrinsic genetic variances and linkage disequilibrium.We adopt the associated mapping approach to filter the sites with elite allelic variations.The main accomplishments from this study are introduced in the following items.a)We perform statistical analyses for the morphological diversity of the other plant architecture related traits,including leaf angle,plant height,ear height,leaf number above ear,tassel branch number and tassel branch length,in the population of 349 maize inbred lines.We observe large variation coefficients for the leaf angle and other traits.The differences are significant cross different environments or different taxa.These results show rich and significant variances in the phenotypes of all the traits.b)We analyze the nucleotide polymorphism and haplotype polymorphism in the sequences of genes lg1 and ZmTACly and observe abundant sites including SNPs and InDels.From the longer sequence in the coding region of gene lg1,52 SNPs and 31 InDels while 26 SNPs are filtered from the relatively shorter coding sequence of gene ZmTAC1.By sliding-window test,differences are observed for the genetic variances in different regions of the gene sequence.The variances in coding regions are relatively weaker than others and this indicates a larger selective pressure in the evolution.These results shows rich genetic variances for both the lg1 and ZmTAC1 sequences in the inbred population.c)We perform the associate mapping for the genes lg1 and ZmTACl with the plant architecture related traits including the leaf angle.Many SNPs that are related to these traits are filtered from the coding regions of the sequences.We find 19 sites that are significantly related to the leaf angle trait,of which some sites may have contribution up to 5?7%.We also find 10 other sites corresponding to other plant architecture related traits,with contributions ranging between 3?8%· The SNPs obtained in the lg1 gene are mostly related to the leaf angle while only a few are found for other traits,which shows that the function of lg1 gene mutation are relatively distinctive.On the other hand,in gene ZmTAC1,SNPs are obtained by associate mapping for all the plant architecture related traits,which shows noticeable effects from gene ZmTAC1 for all the spatial traits of maize.It is clearly manifested in our study that abundant genetic variances are observed in the genes lg1 and ZmTAC1 of maize,and they have significant effects in determining the traits related to the spatial structure.The associated mutation sites that are filtered can be utilized in the molecular breeding and marker assisted selections for the cultivation of maize variants with higher planting density and for the increment of maize production.