THE POTENTIAL OF MICROSATELLITES FOR HIGH-THROUGHPUT GENETIC DIVERSITY ASSESSMENT IN WHEAT AND BARLEY

Microsatellite (SSR) profiles from 65 wheats and 135 barleys have been generated, involving 14 and 22 loci, respectively. The wheat and barl ey varieties were chosen to represent the bulk of the area sown to the se crops in the UK over the past 70 years. The profiling identified ge notypic mixtures in some seed samples. Null alleles were common in whe at, but rare in barley. We describe attempts to increase the efficienc y of data acquisition. High resolution agarose gel electrophoresis was unable to satisfactorily resolve 1-2 repeat unit differences in the c ommon size range for SSR loci, and was therefore unsuitable for mass s creening of allelic variants. Multiplex PCR was very dependent on the choice of primer combinations and seldom produced amplifications as co nsistently as when primer pairs were used individually. Background (no n-specific) amplification was common to many primer pairs, and this hi ndered the use of both multiplex PCR and multiple sample loading. Sequ ential sample loading was the most effective strategy, although this w as the least time-efficient of the measures used.