Assessment of Crossability between Tetraploid and Hexaploid Wheat Genotypes and Evaluating their Hybrids for Salinity Tolerance

The present study aimed to investigate the crossability differences among three tetraploid durum and three hexaploid bread wheat genotypes and to study the chromosome number and meiotic behavior of their pentaploid F1 hybrids and F2 plants. The parental genotypes and their F1 hybrids were also evaluated for salinity tolerance at seedling stage under 0 and 100 mM NaCl concentrations. The results showed high significant differences in the crossability (%) among the interspecific crosses as well as between direct and reciprocal crosses. The crossability (%) was high when the tetraploid species were used as maternal parents (direct crosses). The pentaploid F1 hybrids had a chromosome complement of 35 chromosomes and showed abnormal meiotic behavior in different stages of meiosis. Cytogenetic analysis of F2 plants revealed high variations in chromosome number within and among the tested F2 populations, however some plants with 2n = 42 chromosomes were recorded. On the other hand, salinity stress affected durum wheat parents and their tetraploid hybrids higher than its effect on hexaploid wheat parents and their hexaploid hybrids for all studied traits. However, in general, pentaploid F1 hybrids showed moderate reductions for all studied traits compared to their parents. Additionally, they were more tolerant to salinity as compared to their tetraploid parents, suggesting that salinity tolerance genes of the bread wheat parents were transmitted to their pentaploid F1 hybrids. Thereby, the pentaploid hybrid strategy used in the present study could be an effective tool to transfer desirable genes and traits between tetraploid and hexaploid wheat species.