Variations in Chiasma Frequencies and Terminalization in Interspecific F1 Hybrids of Tetraploid Wheats
1973 年 38 巻 4 号 p. 567-576
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1973 年 38 巻 4 号 p. 567-576
Comparative analysis of chiasma frequencies and terminalization in sixteen Fl hybrids of T. durum and T. dicoccum with nine species of 4n Triticum have been studied at late diplotene/diakinesis and metaphase. Total number of chiasmata per cell was found to be maximum in T. durum×T. dicoccoides at late diplotene and in T. durum×T. dicoccum at metaphase.
Variations in the number of bivalents with 0 to 5 chiasmata have also been studied at diplotene and metaphase. As many as five chiasmata per bivalent were noted in T. durum×T. dicoccoides. Similarly maximum number of bivalents with 4 chiasmata was observed in T. dicoccum×T. persicum at diplotene. This suggests random distribution and relatively lesser linear differentiation among the parental species. At metaphase maximum number of bivalents with 4 chiasmata was confirmed in T. durum×T. dicoccoides. On the contrary, highest number of univalents was noticed in T. dicoccum×T. durum (apart from T. timopheevi combinations). Maximum terminalization was observed in T. dicoccum×T. polonicum.
Correlation coefficients between total bivalents length and total number of chiasmata per PMC have also been worked out for both the stages. Significance of these values at 0.05 or even 0.01 level has been noted in some combinations. These comparative studies suggest that there are variations in respect of linear genetic differentiation among the corresponding parental homologues. This may indicate relative gradations of affinities or differences among species of 4n wheats.
