In our earlier paper (MGC, 1979, 53:108-111) we reported about the dominant mutation converting loose outer portions of opaque-2 endosperm into dense flint-like ones. Due to this flint shell high lysine corn improves its resistance to Fusarium diseases and low temperatures in soil at emergence (Doklady, WASHNIL, 1979, 5:3-5).
Table 1. Protein and lysine content in the endosperms of W70 line mutants
|Genotype||Endosperm type||Share of dense tissue of endosperm||Protein content (%)||Lysine content in protein|
|Integral endosperm||dense part of endosperm||Integral endosperm||dense part of endosperm|
|o2o2 sup sup||floury||0.0||9.8 ±0.52||---||3.68 ±0.046||---|
|o2o2 Sup Sup||modified||0.4||10.5±0.44||10.9±0.71||3.28±0.039||2.93±0.051|
|o2+o2+ sup sup||flint-floury||0.7||11.0±0.52||11.2±0.68||2.30±0.042||2.28±0.078|
The data on lysine and protein fractions distribution in different parts of a modified endosperm (Tables 1, 2) show a local specific effect of a suppressor. The major effect of the suppressor and a dominant allele of o2 gene results in intensification of zein synthesis. However, while the o2+ allele intensifies zein synthesis in an integral endosperm by 3.9 times, the suppressor in 3 doses increases it only by 2.2 times. Practically, the suppressor does not influence the total content of water-soluble proteins. The additional synthesis of zein mainly takes place in a dense portion of an endosperm for account of glutelin-3 fraction.
Table 2. Content of non-protein Lind protein nitrogen
in endosperm of W70 mutants
|albumins & globulins||zeins||glutelins||extractive||non-extractive residue|
|a dense part of modified endosperm||10.14||40.21||6.10||9.04||21.57||6.86||6.08|
At the same time considering the equal concentration of lysine in protein of floury and flinty parts of an endosperm (Table 1) the dominant allele of the o2 gene manifests in a similar way in all parts of an endosperm. In contrast to the suppressor the o2+ allele hampers synthesis of albumins and globulins greatly (Table 2).
A. S. Mashnenkov
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