| In order to understand the genetic differences between high molecular weight glutenin subunit (HMW-GS) 7OE+8* and 17+18 which were encoded by Glu-B1al and Glu-B1i, the genetic differences between low molecular weight glutenin subunit (LMW-GS) which were encoded by Glu-A3e and Glu-A3c, as well as the interaction between different sites in HMW-GS and between HMW-GS and LMW-GS, four near-isogenic lines (NILs) of Kefeng 6 (subunits 5 + 10 and 2 + 12 were located at Glu-D1 locus while subunits 7OE + 8* and 17 + 18 were located at Glu-B1 locus) and Longmai 19 (subunits 5 + 10 and 2 + 12 were located at Glu-D1 locus while subunits Glu-A3c and Glu-A3e were located at Glu-A3 locus) were obtained by 6 times of continuous selective backcross, respectively. Based on comprehensive quality analysis of these NILs,we studied and discussed the problems above and got the following conclusions:For the NILs of Kefeng 6 with HMW-GS 7OE+8* and 17+18, the 2-year results showed that the differences of grain protein content and dry gluten content which could reflect the quantity of protein were small. The gluten index reflecting the quality of protein was increased 7.6% and there was an significant difference (P<0.01). The positive effects on gluten index of subunit 7OE+8* were more obvious in the backround of subunit 5+10 than that of 2+12 in Glu-D1. Compared with the NILs of Kefeng 6 with subunit 17+18,the Zeleny sedimentation value, sedimentation value/dry gluten, development time and breakdown time of Kefeng 6 with subunit 7OE+8* were 5.5%, 8.4%, 32.8% and 8.1% higher respectively. There were all statistically significant difference (P<0.01). The positive effects on these parameters of subunit 7OE+8* were more obvious in the backround of subunit 5+10 than that of 2+12 in Glu-D1. The test results of alveogram and extensogram were similar. Compared with the NILs with subunit 17+18, the NILs with subunit 7OE+8* were all improved in the P and W value of alveogram as well as the maximum resistance and the area of extensogram, and there were all significant difference statistically (P<0.01). The positive effects on gluten strength of subunit 7OE+8* were more obvious in the backround of subunit 5+10 than that of 2+12. The Multi-comparison results of 4 NILs of Kefeng 6 showed that the contributions of these subunits to gluten strength are in the following order: 7OE+8* > 17+18, 5+10 > 2+12, 5+10 > 7OE+8*, and the parameters of extension area and W value were basically the same between subunits 7OE+8* and 5+10 in 2009.The results of Longmai 19 NILs in 2010 showed that the differences of protein content and dry gluten content between LMW-GS Glu-A3c and Glu-A3e NILs were less. Compared with the NILs of Longmai 19 with subunit Glu-A3e, the gluten index, Zeleny sedimentation value and sedimentation value/dry gluten of Longmai 19 with subunit Glu-A3c were 14.0%, 15.7% and 17.0% higher respectively. There were all statistically significant difference (P<0.01). The positive effects on these parameters of subunit Glu-A3c were more obvious in the backround of subunit 5+10 than that of 2+12. In the backround of subunit 5+10, the stability and breakdown time of the NILs with subunit Glu-A3c were 26.8% and 17.9% higher than those of the NILs with subunit Glu-A3e. While there two parameters were basically the same in the background of subunit 2+12. The value of NILs with subunits Glu-A3c in L and W of alveogram were 11.7% and 17.4% higher respectively, and there were all significant difference statistically (P<0.01). From the extensogram parameter data we could see that the maximum resistance and the area of NILs with subunit Glu-A3c were 32.4% and 32.8% higher respectively,and there were significant difference statistically (P<0.01). The positive effects on the parameters of W value, maximum resistance and the area of subunit Glu-A3c were more obvious in the backround of subunit 2+12 than that of 5+10. The Multi-comparison results of 4 NILs of Longmai 19 showed that the contributions of these subunits to gluten strength are in the following order: Glu-A3c > Glu-A3e,5+10 > 2+12,5+10 > Glu-A3c, and Glu-A3c was slightly larger than 5+10 in gluten index.These studies above showed that subunit 7OE +8* located in Glu-B1 locus contributed much to the gluten strength at present, and its contribution to baking quality is next to subunit 5+10 located at Glu-D1 locus. The subunit 7OE +8* should be widely used in current strong gluten wheat breeding while the Glu-A3e encoding LMW-GS should be tried to avoid using in strong gluten wheat varieties. |
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