A mutation of the Ph gene which normally suppresses heterogenetic chromosome pairing was obtained in cultivar 'Cappelli' of Triticum turgidum L. em Morris et Sears var. durum. The chromosomes of 'Cappelli,' the Ph− mutant, and another 'Cappelli' line suspected to have a duplication of part of arm 5Bq (5BL) were C-banded. Compared with arm 5Bq of the parental cultivar, the 5Bq arm of the Ph− mutant was shorter owing to a deletion of one of two interband regions in the middle of the arm. In the line suspected to have a duplication, the 5Bq arm was longer than in 'Cappelli' and the interband region that was absent in Ph− was twice as long. An interchange between sister chromatids or homologous chromosomes is suggested to be responsible for the deletion and tandem duplication of the chromosome region. The C-band patterns are used to infer the approximate location of the Ph gene in the 5Bq arm.Key words: wheat, C-band, deletion, duplication, Triticum, 5B chromosome.
Determination of the absorption constant in the interband region by photocurrent measurements
