Relationship Between Heterosis and Genetic Distance Determined by SSR Markers in Oriental Tobacco

Abstract

Hybrid cultivars could be beneficial to achieve high leaf yields while maintaining good quality properties in oriental tobacco. Identification of parents constitutes a major part of a hybrid breeding program. The aim of the present study was to determine the relationship between the genetic distance of parents determined by simple sequence repeats (SSR) markers and heterosis levels in hybrids produced from those parents for leaf yield and quality properties in oriental tobacco. Twenty-one hybrids produced by half diallel crossing among seven tobacco genotypes used in oriental tobacco production in Turkey were grown along with their parents in three locations in 2012 and 2013. Twenty-nine SSR markers were used to determine genetic distances among seven tobacco genotypes. A total of 80 alleles were produced by all twenty-nine markers. Average number of observed alleles per polymorphic marker was 2.96. Twenty-seven of 80 alleles were observed in only one of the seven parents. The polymorphic information content of markers varied from 0.215 to 0.810 (average 0.480). Mid-parent heterosis levels ranged from 18.03 to 42.00% for leaf number, between -19.75 and 38.06% for leaf width, between -17.51 and 36.25% for leaf length, between -34.38 and 76.12% for leaf yield, between -78.30 and 154.01% for sugar content and between -45.40 and 143.29% for nicotine content. Heterosis levels were correlated with genetic distances between parents for leaf number in Erbaa 2012 and Tokat 2012 locations, for leaf width in Erbaa 2013 location, for leaf length in Erbaa 2013 location, and for leaf yield in Tokat 2012 location only. SSR markers were very effective to determine genetic distance of oriental tobacco, and only two markers could distinguish all seven genotypes used in the study. The findings indicated that genetic distance determined by SSR markers used in the present study is not sufficient to predict hybrid performance in oriental tobacco.