Two-step one-dimensional SDS-PAGE analysis of LMW subunits of glutelin : 1. Variation and genetic control of the subunits in hexaploid wheats.

A collection of 222 hexaploid wheat cultivars (including the 207 cultivars studied by Gupta and Shepherd in 1988) from 32 countries was analyzed for variation in the banding patterns of LMW subunits of glutenin using a modified two-step 1-D SDS-PAGE. Seventy percent ethanol at high temperature (≥50 °C) was used to selectively dissolve the native glutenins containing A, B, and C subunits and not the albumins and globulins (non-prolamins). This procedure allowed the glutenin subunits A, B and C to be separated in a background free of albumins and globulins, which normally overlap the B and C subunits (LMW subunits of glutenin). Although 40 different B and C subunits were detected, except where the cultivars carried a 1BL-1RS translocation or 1B/1R substitution, each cultivar exhibited from 7 to 16 subunits. These subunits could be divided into 20 band patterns which fell into three groups on the basis of their mutual exclusiveness, with 6, 9, and 5 patterns. Analysis of substitution lines revealed that the different patterns in these groups are controlled by genes on chromosomes 1A, 1B, and 1D, respectively. The least number of subunits was controlled by chromosome 1A and approximately 40% of the cultivars did not contain any band controlled by this chromosome. Thirteen of the cultivars were found to consist of two biotypes with respect to LMW subunits of glutenin. The genetic, evolutionary, and technological implications of these findings are discussed.