Preliminary Genetic Studies of the Phenotype of Betaine Deficiency in Zea mays L. 1
AUTOR(ES)
Rhodes, David
RESUMO
Glycinebetaine-deficient inbreds of Zea mays do not exhibit a general deficiency of nitrogenous solutes; the total free amino acid levels of betaine-deficient lines are not significantly less than those of inbreds which exhibit >100-fold higher betaine levels. Betaine-deficient inbreds are characterized by extremely low betaine: total free amino acid ratios (<0.0015). Highly significant correlations are demonstrated between the expected mid-parent and observed betaine:amino acid ratios of 30 hybrids of known pedigree. In 12 hybrids constructed from a betaine-deficient male parent (inbred 1506), the observed betaine:amino acid ratios of the hybrids are proportional to the betaine:amino acid ratios of the female parents (r = 0.83). Two hybrids, 1146 × 1074 and 1146 × 1506, were chosen for further genetic analysis. The common female parent (1146) and inbred 1074 both exhibit betaine:amino acid ratios of 0.090, a value which is approximately 90-fold greater than the betaine:amino acid ratio of inbred 1506. Hybrid 1146 × 1074 exhibits almost exactly twice the betaine:amino acid ratio of hybrid 1146 × 1506. If inbred 1506 is homozygous recessive for a single nuclear gene responsible for the phenotype of betaine deficiency, and if inbreds 1146 and 1074 are homozygous dominant for this allele, then this twofold difference in betaine:amino acid ratio must be associated with the homozygous dominant and heterozygous conditions, respectively, for 1146 × 1074 and 1146 × 1506. Evidence is presented from both greenhouse and field evaluations of F2 populations of these hybrids that a single nuclear recessive gene is most likely responsible for the phenotype of betaine-deficiency in inbred 1506. Approximately 25% of the F2 segregants from 1146 × 1506 exhibited extremely low betaine:amino acid ratios (<0.0015), whereas 0% of the F2 segregants from 1146 × 1074 exhibited this phenotype. The segregation patterns with respect to betaine:amino acid ratio suggest a 1:2:1 segregation ratio for homozygous recessive:heterozygous:homozygous dominant individuals within the 1146 × 1506-F2 population.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1055532Documentos Relacionados
- Recombination in ZEA MAYS L. II. Cytogenetic Studies of Recombination in Reciprocal Crosses
- In Vitro Gibberellin A1 Binding in Zea mays L. 1
- Abscisic Acid Biosynthesis in Isolated Embryos of Zea mays L. 1
- Regulation of Assimilatory Sulfate Reduction by Cadmium in Zea mays L. 1
- Sterol Accumulation and Composition in Developing Zea mays L. Kernels 1