Genetic variation in lysine and protein content in corn seed

Abstract

The lysine and protein content of corn seed was determined for inbred lines and crosses among inbred lines, to gain a better understanding of the genetic variation of these characters. Lysine content was determined by an automatic amino acid analyzer. Protein content was estimated by means of a Coleman nitrogen analyze. Other methods of lysine determinations were investigated, but none proved satisfactory. The genetic variation among a group of 55 inbred lines was investigated. A 6x6 diallel cross experiment was conducted to study the nature of the genetic variation. Crosses of two different sources of opaque -2, o (line underneath) ₂, to four inbred lines were used to determine the effect of genetic background on the expression of the o (line underneath) ₂ gene in the one dose level. The o (line underneath) ₂ gene is known to have a major effect on lysine content in corn seed. Selfed progeny of homozygous o (line underneath) ₂ segregates obtained from crosses of 10 inbred lines to one source of o (line underneath) ₂ were used to detect differences in the genetic background of the inbred lines that affect the expression of the homozygous o (line underneath) ₂. The genetic variation among inbred lines was found to be highly significant for protein content and for lysine content expressed as a per cent of either protein or seed weight. A positive correlation of +0.46 was found for lysine, expressed as a per cent of seed, and per cent protein; whereas, a negative correlation of -0.44 was found for g. lys./100 g protein and per cent protein....