Characteristics Of GMP And Protein Component Formation In Wheat With Different HMW-GS

Twenty-five wheat genotypes were used to analyze the relationships among GMP content, protein content, HMW-GS subunit and HMW-GS accumulation. The experiments mainly studied the dynamics of GMP content, protein and its component content in grains of wheat varieties with different HMW-GS subunits, investigated the effects of nitrogen application on grain protein,protein component and GMP content. The main results were as follows:1. Different wheat genotypes might have the same subunits of HMW-GS, but the accumulation was different. The subunits of HMW-GS in wheat grains with lower- protein content were usually"N, 7+8/7+9, 2+ 12"; but those with higher protein content were usually"1, 7+8/7+9, 5+10". GMP and protein content in grains with the same HMW-GS subunits could still be significantly different. HMW-GS accumulation amount in grains might be one of the important factors affecting grain quality. HMW-GS accumulation amount was positively correlated with grain protein, GMP and gluten contents as well as GMP/Pr ratio. GMP content had a very significant relation with gluten and protein contents as well as GMP/Pr ratio. Grain protein content was very significantly correlated with dry and wet gluten contents, and significantly related to GMP/Pr ratio.2. None of any HMW-GS subunit could be found within ten days after anthesis. HMW-GS began to appear on 15th day after anthesis, then more types of HMW-GS could be found until 25th day after anthesis. The subunits and accumulation amount of HMW-GS at maturity were quite stable.3. The dynamics of GMP, protein and protein components contents were analyzed in wheat varieties with"2+12"or"5+10"HMW-GS subunits. GMP content in varieties with HMW-GS subunit"5+10"was greater than that in varieties with HMW-GS subunit"2+12"at middle and late grain filling stages. The changes of GMP content were similar among the varieties with the same HMW-GS subunits. GMP content was greatest at maturity. The change of GMP content was consistent with that of GMP/Pr ratio; Grain protein content showed a "high - low - high" tendency, but the minimum value appeared at the different time among the varieties with different HMW-GS subunits. The minimum grain protein content in the variety with HMW-GS subunit"5+10"appeared earlier than that with HMW-GS subunit"2+12". The changes of grain protein component contents were not different between varieties with"5+10"and"2+12"HMW-GS subunits. It was suggested that HMW-GS subunit"5+10"could be taken as an indicator of good quality for strong-gluten wheat, while HMW-GS subunit"2+12"for weak-gluten wheat.4. The effects of nitrogen on HMW-GS accumulation, GMP content, and protein content were studied in Yangmai 13 with HMW-GS subunit"2+12", and Yannong 19 with HMW-GS subunit"5+10". With the increase of N application amount or top dressing N ratio, GMP, protein and protein components contents increased correspondingly, but the increase amount differed among varieties with different HMW-GS subunits.