Assessment of salinity tolerance and SSR profile differentiation in nine maize genotypes (Zea mays L)

The low productivity of maize in Iraq is resulting from many factors that relate to insufficient knowledge of the genetic sources of germplasm used for crop improvement. A major goal of this project was to find the phenotypic, and genotypic variations by using salinity stress and Simple sequence repeat markers among nine maize geno- types. Genetic variation for salt tolerance was assessed in nine maize genotypes using four salinity levels (control, 50, 100, and 150 mM NaCl). Seedling of each genotype was compared to their growth under control and saline conditions. Salt stress (sodium chloride) markedly reduced the germination percentage, shoot and root lengths and fresh and dry masses. However, Dhqan, Fajr 265, Talar were considered as tolerant genotypes while Medium 791 defined as sensitive genotype. Genotypic analysis was carried out using 18 SSR primers. A total of 46 polymorphic alleles were perceived among the maize genotypes with a range of 1–7 polymorphic bands were detected with size ranging from (90 to 500 bp) along the different maize genotypes. Polymorphism information content, marker index and gene diversity ranged from 0.178 to 0.788, 8.900 to 68.800, and 0.198 to 0.815, respectively. Dendrograms were constructed based on total microsatellite polymorphism, and nine genotypes were grouped into three major clusters. The analysis of molecular variance results revealed 17 and 83% of the total variation between and within populations (local and Iranian). The results confirmed the efficiency of SSR (Simple Sequence Repeat) markers in the detection of genetic variation among maize genotypes

Exploring chemical composition and genetic dissimilarities between maize accessions

The capacity of maize (Zea mays L.) accessions to tolerate drastically extreme conditions in Iraq, contributes to thecharacterization of the genetic resources for germplasm management and the identification of the finest genotypesfor genetic improvement. Therefore, breeding maize program requires knowledge of genetic variation andgenetic structure. A total of 25 maize accessions from three regions (Iraq-Sulaimani, Iraq-Erbil and Iran-Sanandaj)were genotyped by chemical and phytochemical components and simple sequence repeats (SSR) markers to evaluategenetic diversity, population composition and the relationships between genetic and chemical compositiondissimilarities. In terms of proximate and phytochemical parameters, the maize accessions exhibited large significantdisparity, in which oil, phenol contents and 2,2-diphenyl-1-picrylhydrazyl (DPPH) characteristic appeared tobe the most discriminating features of maize accessions. Altogether, 18 SSR markers produced 77 polymorphicalleles across the 25 samples, and the chosen SSR was extremely informative with polymorphic information content(PIC) varied from 0.91 (Bnlg1890) to 0.37 (Umc1630 and Bnlg1189), as well as gene diversity (ranging from0.48 to 0.91, with an average of 0.75) illustrating the broad genetic variability of the accessions investigated.Molecular variance assessment (AMOVA) showed that there was only 21% genetic variation among populations.Pairwise PhiPT distance (0.10 to 0.31) stated high population distinctions among the populations investigated. Inaddition, the accessions from three regions were differentiated into seven clusters by both methods; clusteringand population structure analysis and the accessions are not grouped in term of geographic locations. Both chemicalcomposition and SSR markers differentiated 25 maize accessions. The results of the Mantel test exhibited asignificant positive linkage between chemical components and SSR matrices. The results of this research revealedthat maize accessions have a broad genetic diversity that provides a source of new and unique alleles that arehelpful for maize breeding programs to address the continuing and future significant challenges and determiningcollections of well-known cultivars and disparities between them