Lysine Content of Opaque‐2 Maize Kernels having Different Phenotypes¹

Abstract

Classification of homozygous opaque‐2 kernels of maize (Zea mays L.) in segregating progenies has been done on the assumption that the phenotype of these kernels is completely opaque. Certain lines in the S2 generation derived from opaque appearing S1 parents produced two phenotypic classes: (1) entirely opaque, and (2) modified opaque‐1/2 opaque : 1/2 translucent.Lysine content of 1/2 : 1/2 kernels was not different from opaque kernels on the same ear. Likewise the lysine content of translucent and opaque fractions of the endosperm from the 1/2 : 1/2 class was not different.High lysine corn with a high test weight and other desirable kernel characteristics may be produced by taking advantage of this opaque‐2 phenotypic expression.

Genetic control of kernel modification found in South African quality protein maize inbred lines

“…The discovery of the so-called "modified" 02 lines (Paez et al, 1969) created new hope for the utilisation of o2 maize. In modified 02 (mod-o2) kernels, modifier genes restore the endosperm to various degrees of normality.…”

Nonredundant Function of Zeins and Their Correct Stoichiometric Ratio Drive Protein Body Formation in Maize Endosperm

“…The poor agronomic properties associated with kernel opacity prevented implementation of o2, but subsequent breeding efforts led to the development of Quality Protein Maize (QPM) (Vasal et al, 1980;Geevers and Lake, 1992). QPM is a hardkernel o2 variety that retains the high levels of Lys and Trp (Paez et al, 1969;Ortega and Bates, 1983). QPM has low levels of a-zeins, like o2, but the 27-kD g-zein is increased 2-to 3-fold (Wallace et al, 1990;Geetha et al, 1991;Lopes and Larkins, 1991;Holding et al, 2011); the degree of endosperm vitreousness closely correlates with the level of 27-kD g-zein protein , and this increase causes the observed elevation in protein body number in QPM Moro et al, 1995) consistent with the proposed role of 27-kD g-zein in protein body initiation.…”

Pyrophosphate-Dependent Fructose-6-Phosphate 1-Phosphotransferase Induction and Attenuation of Hsp Gene Expression during Endosperm Modification in Quality Protein Maize

“…However, o2 was not commercially successful, due to the poor agronomic properties associated with its soft, opaque endosperm. Subsequently, breeding projects in Mexico (Vasal et al, 1980) and in South Africa (Geevers and Lake, 1992) led to the development of hard-kernel o2 varieties that retained the high levels of Lys and Trp (Paez et al, 1969;Ortega and Bates, 1983). These varieties, known as Quality Protein Maize (QPM), have been introgressed into many high-yielding maize inbreds and hybrids adapted to diverse growing conditions and are contributing to reducing protein deficiency disorders in humans and to more efficient livestock feeding.…”