The Journal of Heredity 1990:81(3):201-204
© 1990 The American Genetic Association 81:201-204
research-article |
Internode Length in Lathyrus odoratus L.: The Expression and Interaction of Genes L and Lb
From the Department of Plant Science, University of Tasmania Hobart, Australia
Address reprint requests to Dr. Ross, Department of Plant Science. University of Tasmania, Hobart 7001, Australia.
Abstract
A recessive allele that causes semidwarf stature in the sweet pea, Lathyrus odoratus L., was identified and designated lb. The recessive allele for dwarf habit, l, is epistatic to the Lb-lb pair of alleles in the sense that a clear dihybrid F2 segregation ratio of 9 tall (L- Lb-): 3 semidwarf (L- Iblb): 4 dwarf (II —) was obtained. However, a quantitative effect of lb was detected in the dwarf (II) class. The lb allele had its maximum effect in the upper internodes, which, in semidwarf plants, were only about 56% as long as those of wild-type (tall) plants. In contrast, the effect of I was obvious soon after shoot emergence, and internode length in dwarf plants rapidly fell to less than half that of tall plants. The shorter internodes of dwarf and semidwarf plants resulted from a reduction in both the length and the number of epidermal cells per internode. Compared with tall plants, dwarf (II) plants had smaller and more ovate leaves with shorter petioles, the foliage was darker green in color, the node of flower initiation was reduced slightly, and branching was increased markedly. In contrast, the effect of lb was confined largely to internode length, although some increase in basal branching also was noted in semidwarf plants.