02113naa a2200289 a 450000100080000000500110000800800410001910000180006024501270007826000090020552013420021465000220155665000100157865000140158865000130160265300100161565300140162565300120163965300130165165300120166465300080167670000190168470000170170370000190172070000190173977300650175814782852018-07-13       1991    bl uuuu     u00u1 u    #d1 aGEETHA, K. B.  aOpaque-2 modifiers increase y-zein synthesis and alter its spatial distribution in maize endosperm.h[electronic resource]  c1991  aThrough the action of opaque-2 modifier genes, the soft, floury of opaque-2 mutants is converted to a vitreous phenotype. This change in endosperm texture is associated with a twofold to threefold increase in y-zein content. To investigate the effect of opaque-2 modifiers on the expression of y-zein genes, we analyzed the synthesis and distribution of y-zein protein and the level of y-zein mRNAs in developing endosperms of the inbreds W644 and W644o2, a modified opaque-2 mutant Poll 34 QP,, and their reciprocal F1 hybrids. We also characterized the number and organization of y-zein genes in these and related maize genotypes. Our studies show that opaque-2 modifiers are semidominant genes, resulting in a twofold to threefold increase in y-zein gene expression in both opaque-2 and normal genetic backgrounds. The increase in gene expression appears to e a conseguence of copies in modified as well as nonmodified genetic backgrounds. Ultrastructural studies showed that y-zein occurs in high concentration in the first few subaleurone cells of nonmodified endosperm, but high concentrations of y-zein occur in the subaleurone and central endosperm cells of modified opaque-2 mutants. The increased concentration and distribution of y-zein in modified endosperm are highly correlated with the activity of opaque-2 modifier genes.  amolecular biology  aMilho  aQualidade  aZea Mays  aMaize  aMolecular  aOpaco-2  aOpaque 2  aProtein  aQPM1 aLENDING, C. R.1 aLOPES, M. A.1 aWALLACE, J. C.1 aLARKINS, B. A.  tPlant Cell, Rockvillegv. 3, n. 11, p. 1207-1219, Nov. 1991.