Assessment of genetic diversity of wheat (Triticum aestivum L.) using physiological and molecular marker

Abstract

The study was conducted to assess genetic diversity in wheat using physiological and molecular breeding and to determine major allele frequency, genetic diversity index and polymorphic information content (PIC). Genomic DNA Purification Kit was used for DNA extraction. Total genomic DNA was extracted by Cetyltrimethylammonium Bromide (CTAB) method. Five functional markers and seven linked Random DNA Markers to the traits of interest were used for genotyping the bread wheat cultivars. The results indicated that the number of alleles range from 1- (Dreb-B1) to 9- (Xgwm577), genetic diversity index varied greatly among the loci from 0.0000 in case of Dreb-B1 to 0.8471 in case of Xgwm577. The Polymorphic Information Content (PIC) value were from 0.0000 (Dreb-B1) to 0.8296 (Xgwm577). The lowest genetic distances of 0.083 were recorded between accessions; 4402 and 4401, 4403 and 4401, 4403 and 4402, 4418 and 4417. Highest genetic distance was observed between accessions 4409 and 4412, accessions 4413 and 4412, accessions 4414 and 4412, accessions 4420 and 4412, accessions 4406 and 4412, and accessions 4408 and 4412 (0.750). Cluster analysis grouped the accessions into 5 groups at a genetic distance level of 0.15. Field trials were conducted at Lake Chad Research Institute Wheat Research Farm at Dadinkowa, Gombe State-Nigeria, during 2014/2015 and 2015/2016 dry seasons. Total of 24 wheat lines were used in this study. Heat stress was imposed through staggered sowing. Normal sowing (15th November) was non-stress and late sowing (6th January) resulted in heat stress at post-reproductive. The lines were laid out in Randomized Complete Block Design (RCBD) in triplicates in plots measuring 3 x 2 m with 6 rows and 30 cm row spacing apart. Data were analysed using analysis of variance. The result also indicated that means square from analysis of variance for the individual environment for growth and yield characters under normal and heat stressed condition indicated highly significant differences between genotypes. In conclusion, the yield attributes under heat stress is a good indicator of heat tolerant. In this study genotypes 4404, 4408, 4410, 4411, 4413, 4414, and 4420 were identified as top yielder as such could be explored for resistance lines against heat stress.