Expression of A/B zeins in single and double maize endosperm mutants
1992
Paulis, J.W. (National Center for Agricultural Utilization Research, Peoria IL (USA). USDA-ARS) | Bietz, J.A. | Bogyo, T.P. | Nelsen, T.C. | Darrah, L.L. | Zuber, M.S.
Zeins, the major endosperm proteins in maize (Zea mays L.), are deficient in the essential amino acids lysine and tryptophan. Some mutant genes, like opaque-2 (o2) and floury-2 (fl2), reduce the levels of A- and B-zeins, thereby improving maize's nutritional value. Other mutants, such as amylose-extender (ae), floury-1 (fl1), soft starch (h), dull-1 (du), shrunken-1 (sh1), sugary-1 (su1), sugary-2 (su2), and waxy (wx), primarily affect starch composition, but also alter zein compostition. The effects of some of these mutant genes on A/B-zein composition and the interactions of these genes in double- mutant combinations were studied. Zeins in the extracts from endosperm prolamins of inbred B37, ten near-isogenic single mutants, and most double-mutants, were fractionated by reversed-phase high-performance liquid chromatography (RP-HPLC) into 22-24 peaks. Of the resulting 22 major peaks the areas of 16 (per mg endosperm) were significantly affected by individual mutant genes relative to the zein composition of the normal inbred. In combination these genes exhibited significant epistatic interactions in regulating the expression of individual A/B zeins. The o2 gene, alone and in combination with other mutant genes, significantly decreased the amounts of many individual zeins. The effect of the o2 gene was the greatest of all the genes examined. Various clustering techniques, eg. principal component analysis, were used to see if mutant effects could be grouped. 3-dimensional scatter graphs were constructed based on the first three principal components. For the single mutants, these showed no relationships to gene actions; for the double mutants, however, this techniques showed that four single mutants, o2, sh1, su1 and su2, had the greatest effects on zein composition when combined with each other and with the remaining six single mutants.
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