CYTOGENETICS OF SOME TRITICUM AESTIVUM AND T. TURGIDUM x AEGILOPS VARIABILIS INTERGENERIC HYBRIDS AND THEIR DERIVED AMPHIPLOIDS

摘要

Amongst alien germplasms that provide much needed genetic diversity for resistance to leaf-blotch (caused by Cochliobolus sativus) and karnal bunt (caused by Tilletia indica) is the tertiary gene pool tetraploid Aegilops variabilis (2n=4x=28; UUSS) resource. In order to exploit this species potential, it is crucial that intergeneric hybrids are first produced from which stable genetic stocks are developed for subsequent agricultural utilization. The hybridization of several durum and bread wheat cultivars with Ae. variabilis is reported herein which have yielded cytologically characterized normal F, hybrids (2n=4x=28, ABUS or 2n=5x=35, ABDUS). These upon colchicine treatment have generated fertile octoploid and decaploid amphiploids. The amphiploidsin all cases possessed aneuploidy that was more pronounced with bread wheat cultivars (2n=10x=70, AABBDDUUSS). Durum amphiploid combinations had more normal 56 chromosome plant types with perfect bivalent meiosis (2n=8x=56, AABBUUSS and 28 bivalents across variable ring and rod associations). Reported here is the cytogenetics of these intergeneric hybrid cross combinations that have enabled the production of a novel genetic resource in the form of fertile amphiploids that hold the potential to addressfuture work on improving wheat cultivars for resistance to C. sativus and T. indica.