MEIOTIC BEHAVIOR OF INTERSPECIFIC HYBRIDS BETWEEN HEXAPLOID AND TETRAPLOID WHEAT SPECIES

Abstract

Cytogenetic behavior of five wheat genotypes of Triticum aestivum (Shandweel 1, Misr 2 and Gemmiza 11) and T. durum (Benisouef 5 and Benisouef 6) in addition to their interspecific hybrids was studied. All five parental genotypes showed normal behavior in meiosis. Also, the interspecific hexaploid × hexaploid showed normal diploid pairing at diakinesis and metaphase I with average number ranged from 18.16 (C2) to 20.49 (RC2) and from 16.77 (C2) to 20.22 (C1) bivalents, respectively. And tetraploid × tetraploid showed normal diploid pairing at diakinesis and the average of bivalents were 13.95 and 13.98 for C10 and RC10 hybrids at metaphase I, respectively. So the normal decrease of laggards and micronuclei averages was recorded. Higher incidences of aberrant chromosomal structure such as the formation of univalent, laggards and micronuclei were observed in all the six interspecific pentaploid (hexaploid × tetraploid) which could be described as an abnormal compared to the six reciprocals hybrids (tetraploid × hexaploid) which were highly unexpected normality to form normal bivalents and a low frequency of laggards and micronuclei. Pollen grains of hexaploid × tetraploid hybrids were found to have markedly lower values of viability; ranged from 0.50 to 0.72, compared to parents and the other interspecific hybrids. Thus, the present study succeeded in proving that interspecific hybridization produced fertile pentaploid hybrids.