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The protein quality of maize (Zea mays L.) can be improved by replacing normal Opaque2 alleles with nonfunctional recessive alleles (o2). Homozygous o2 kernels have increased levels of lysine and tryptophan. Unfortunately, the asso- ciated soft texture of the o2 kernels causes poor yield and susceptibility to diseases and insects. Breeding has resulted in the development of o2 genotypes with improved endosperm hardness; such genotypes are referred to as quality protein maize (QPM). Quality protein maize germplasm is utilized in breeding programs worldwide and has been competitive in yield trials. To under- stand the genetics of endosperm modifi cation, a population of 146 recombinant inbred lines (S 5 to S 7 ) derived from a cross between the o2 inbred B73o2 and the QPM inbred CML161 was evaluated in two Texas locations from 2004 to 2006. The endosperm traits texture, opacity, and vitreousness were highly affected by inbred line genotype, were highly correlated with each other, and exhibited high broad-sense heritabil- ity. Relative content of the essential amino acids lysine, tryptophan, and methionine were also highly affected by the inbred line genotype, and exhibited high broad-sense heritability. Negative correlation was observed between endosperm texture traits and amino acid contents. Favor- able responses to selection can be expected for both endosperm texture modifi cation and rela- tive content of the essential amino acids if they are effi ciently monitored. |
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