Inter-Specific Variations in Chiasma Frequencies and Terminalization in Emmer Wheats
1972 年 37 巻 2 号 p. 225-234
詳細
1972 年 37 巻 2 号 p. 225-234
Comparative analysis of chiasma frequencies and terminalization in nine tetraploid species of Triticum have been studied at late diplotene/diakinesis and metaphase. Total number of chiasmata per cell was found to be maximum in T. timopheevi and wild species T. dicoccoides and minimum in cultivated species (T. dicoccum). Similar trends for mean number of chiasmata per 100μ of bivalent length were noted.
Variations in the number of bivalents with zero to four chiasmata do exist among the species studied. Maximum number of bivalents with four chiasmata was noted in T. timopheevi suggesting random distribution and least linear differentiation among wild wheats. This situation has been further confirmed from the highest proportion of interstitial chiasmata both at late diplotene and metaphase in T. timopheevi and T. dicoccoides. Cultivated species like T. dicoccum had maximum number of bivalents with zero to one chiasma.
Correlation coefficients between total bivalent length and total number of chiasmata per PMC were found to be significant at 0.05 or even 0.01 level. These comparative studies on chiasma frequencies, distribution and terminalization suggest that individual species differ in respect of linear genetic differentiation of their homologues.
