The effect of additions of Aegilops longissima chromosomes on grain protein in common wheat

The effect of various chromosomes of Aegilops longissima when added to the common wheat cultivar 'Chinese Spring' was evaluated at two levels of nitrogen fertilization for absolute and relative amount of protein in the grain. All the added chromosomes of Ae. longissima increased protein percentage: protein increase by chromosomes D, C and A averaged 3.8% while that by chromosomes F, E, G and B averaged 1.7%. Addition lines F, D and C had a significantly higher protein weight per grain. On the other hand, lines A, E and G had reduced grain protein weight per grain as compared with that of 'Chinese Spring'. Line C carries the HMW glutenin and some of the gliadin subunits of Ae. longissima. The effect of this line, however, and obviously that of the other lines on protein content was through genes controlling the level of storage protein rather than through genes that code directly for these proteins. Nitrogen fertilization affected protein content and the relative amount of the various protein fractions in a similar manner in every addition line. When high levels of nitrogen fertilization were compared to low ones, the relative amount of the HMW glutenins remained constant while that of HMW gliadins increased and that of the LMW subunits decreased. In contrast to the nitrogen effect, increase in protein content by the addition of longissima chromosomes did not change the relative amounts of the various protein fractions.