Formation Time and Accumulation Intensity of HMW-GS and LMW-GS and the Relationship with SDS-sedimentation Volume in Winter Wheat

It is well known that different kinds of HMW-GS in wheat flour affect the bread-making quality, generally 1 and 2 * are better than null at Glu-1A , 7+8 is better than 7+9 at Glu-1B and 5+10 is superior to 2+12 at Glu-1D . It has been found that the quality of some cultivars with 5+10 was worse than that with 2+12, which was caused by accumulation of HMW-GS. However,how the quantities of both total HMW-GS and LMW-GS and individual subunits form, accumulate and cooperate in hard winter wheat, and how to affect the bread-making quality, which still remains a question. This study was conducted to investigate how the quantitative variation for HMW-GS and LMW-GS from their formation and accumulation intensity was associated with SDS-sedimentation volume. Six winter wheat cultivars with different qualities were grown in experimental fields at the farm of Shandong Agricultural University in 2001 with three replicates. HMW-GS and LMW-GS compositions were investigated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and densitometry. Initial formation time for HMW-GS was different among culitvars(Fig.1 and Table 2). Zone B of LMW-GS could be found on ten days after anthesis. More types and accumulation intensity of HMW-GS and LMW-GS were increased gradually along with the grain development. HMW-GS in winter wheat with strong gluten was completely formed within ten days after anthesis, while only partially formed in weak gluten wheat (Table 2). GMP in strong gluten wheat extremely increased (Fig.2) and individual HMW-GS accumulation (Fig.3) appeared rapidly during 25 days after anthesis to mature. The trend of accumulation of the same HMW-GS in cultivars with different qualities (Fig.4) was similar, but the quantities were different those of the cultivars with strong gluten were more than those of weak gluten. It appeared significantly positive correlation (Table 4) between HMW-GSs accumulation quantities and SDS-sedimentation volume. At mature, the correlations of the ratio of LMW-GS /HMW-GS in Zone C with the score at Glu-1 and SDS-sedimentation volume were significantly negative. Therefore the formation time and accumulation intensity of glutenin subunits correlated closely with SDS-sedimentation volume. These results suggest that when evaluating the wheat quality especially when the cultivars contain same subunits, only considering the score at Glu-1 is not enough, HMW-GS and LMW-GS formation time and accumulation intensity in Zone C should be more important.