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CYTOGENETICS OF INTERGENERIC HYBRIDS BETWEEN DURUM WHEAT (TRITICUM TURGIDUM L.) WITH THINOPYRUM INTERMEDIUM AND SUB-SPECIES ACUTUM, GLAUCUM, PULCHERRIMUM, TRICHOPHORUM, VARNENSE

A. MUJEEB-KAZI¹, ALVINA GUL¹, SUMAIRA RIZWAN², MUHAMMAD FAROOQ², HADI BUX², IFTIKHAR AHMAD², JAVED IQBAL MIRZA², ROMAN DELGADO³, VICTOR ROSAS³ AND ALEJANDRO CORTES³

Abstract: Towards diversifying the germplasm base available for durum wheat (Triticum turgidum) the production and morpho-cytogenetic categorization of F₁ hybrid combinations between durum wheat cultivars and Thinopyrum intermedium and its sub-species (acutum, glaucum, pulcherrimum, trichophorum, varnense) are reported. All F₁ hybrids were mitotically stable with 2n=5x=35 chromosomes, expressed a co-dominant phenotype and exhibited mean meiotic metaphase I chromosomal associations, that in general, do not support alien genetic introgression into the A and / or B genomes of durum wheat via recombinational exchange. This F₁ perennial germplasm has formed the basis to generate backcross derivatives, amphiploids, and shall enable the application of genetic manipulation strategies for transferring useful genes from select combinations for durum wheat improvement. Backcross 1 derivatives (F₁ / durum wheat) were cytologically stable with 2n=7x=49 but exhibited poor self-fertility hampering their maintenance as genetic stocks.  Amphiploids however had good stability at the C-0 stage with 2n=10x=70 chromosomes, were self-fertile and set healthy seed progeny. Subsequent generations derived from C-0 seed gave derivatives that were closely true to the C-0 type in composition, as well as combinations that indicated genomic loss where all combinations possessed 56 chromosomal progeny. Aneuploidy, both hyper- and hypo-ploidy, was rampant across both the 56 and 70 chromosome progenies.

National Institute of Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan, ²National Agricultural Research Center (NARC), Park Road, Islamabad, Pakistan and ³International Maize and Wheat Improvement Center  (CIMMYT), Apartado Postal 6-641, Mexico D. F. 06600, Mexico