Genetic Characterization Of Early Generation Lines Using SNPS Makers And Agronomic Traits For Resistance To Striga Improvement In Maize

The characterization of a greater number of lines hence potentially increase the efficiency of maize breeding programs. This study aims to assess the genetic variation and relationships existing within a population of 177 lines and the two parental lines, using 8,883 SNPs markers obtained from sequencing genotyping (GBS) and four agronomic traits. Two hundred S1 lines and four checks including the two parents have been evaluated under Striga hermonthica infestation in Benin Republic and Nigeria for two years during 2018 and 2019 growing seasons using 51 x 4 lattice design with two replicates. The UPGMA phylogeny, was used to group the progenies based on their genetic similarity. The tested lines have displayed high genetic variability for all the agronomic traits. Analysis molecular revealed that the polymorphism information content has been varied from 0.047 to 0.50, with average of 0.37, and 63% of the SNP makers were highly polymorphic. The population has displayed a moderate diversity with average genetic diversity of 0.44. The estimated genetic distance has been varied from 0.01 to 0.79 and the highest distance has been observed between the two parental lines. UPGMA clustering based on the Gower dissimilarity matrix grouped the 177 lines into two clusters (I and II) at 30% genetic similarity threshold. The estimated genetic distances between lines showed that all the progenies were genetically related to the two parental lines; and have the potential to provide new favorable alleles for the development of high-performing, Striga-resistant and/or Striga-tolerant maize populations

Agronomic Performance Of S1 Maize Lines Derived From A Bi-Parental Cross Under Infested And Striga Free Environments

Striga hermonthica, causes up to 100% yield loss in maize production in sub-Saharan Africa. Developing Striga resistant maize cultivars could be a major component of integrated Striga management strategies. This study aims at assessing the agronomic performance of S1 breeding lines in improving maize for Striga resistance. Two hundred S1 lines have been evaluated under artificial infestation Striga and Striga-free conditions in Benin for two years during 2018 and 2019 growing seasons using alpha-lattice design (51 x 4) with two replicates. Twelve agro-morphological and Striga adaptive traits have been assessed. The tested lines have displayed high genetic variability for most agronomic and Striga adaptive traits. The S1 lines exhibited high grain yield than their parents with averages of 2,552.72±593 kg ha-1 and 2,965.67±635.86 kg ha-1 under Striga artificial infestation and Striga-free conditions, respectively. Grain yield has displayed high positive and significant genetic and phenotypic correlations with ears per plant and high negative correlations with days to 50% silking, ears aspect, and Striga damage rating at 8 and 10 weeks after planting (WAP). Useful traits like ears per plant, days to 50% silking, ears aspect, number of emerged Striga plants and Striga rating at 10 WAP could assist for indirect selection under Striga conditions. Based on the selection index, a total of 15 S1 lines have been identified as top ranking and can be used as sources of resistance or tolerance genes to Striga and further improvement in maize breeding in future