| Abstract: | Grain of op-2 Maya have a higher total protein content in bothendosperm and germ than normal maize. In large grain, differencesin total grain protein are due mainly to the endosperm whilein small grain, differences are due to the germ, particularlythe scutellum which is larger in op-2 kernels. Reserve proteincomposition was distinct: op-2 endosperms showed an increasein the proportions of albumins, globulins, and the glutelinG3 fraction which was accompanied by a marked decrease in zeincontent in comparison with normal endosperms. During endosperm depletion there was a net increase in the salt-solublefraction prior to day 3 from imbibition; glutelins and zeinhowever decreased throughout, the former being degraded at initiallyfaster rates. In general, regardless of protein composition,the most abundant fraction was utilized most rapidly. Water uptake during imbibition was greater in op-2 grain, thoughno differences in axis growth in terms of dry weight or laminaarea were apparent at the end of reserve degradation. In bothnormal and op-2 seedlings, protein was mobilized both earlierand faster than endosperm dry matter and the shoot, principallythe first leaf lamina, received more reserve nitrogen than theroot. |
