II.27 Linkage of spontaneous mutant seedling lethal genes with genetic male sterile genes.
M.M. Rahman and R.F. Eslick. Kentucky State University, Frankfort, Kentucky 40601 and Dept. of Plant and Soil Science, Montana State University, Bozeman, Montana 59715, respectively.
In BGN5, Rahman and Eslick (1975), reported the recombination values for a number of seedling lethal genes and genetic male sterile genes previously assigned to chromosomes.
In Table 1 we report on observed genetic ratios of nine spontaneously occurring seedling lethal genes. We have designated these genes "spontaneously" as they were collected from the nursery plots at Bozeman prior to the use of mutagens at Bozeman and before previously assigned seedling lethal genes were grown at Bozeman. The objective of these studies was to evaluate the usefulness of these genes for genetic male sterile systems of hybrid barley production.
Table 1. Gene symbols and monohybrid ratios for nine spontaneous seedling lethal mutants.
Three of the genes may be classified as xantha (xan), 5 as albino (alb), and 1 as virescent (y). All are inherited in a monogenic fashion, Table 1.
Data presented in Table 2 are enumeration data from crosses of the seedling lethal genes with a number of male sterile genes. The interaction chi-square reported is calculated as the chi-square for the expected 1:2:2:4 ratio minus the chi-square for the 1:2 expected ratio for Msg msg, minus the expected 1:2 ratio for the seedling lethal gene Aa. When one of the expected 1:2 ratios yielded a significant chi-square (P <.05), "distorted" is noted in the recombination column.
Examination of the data of Table 2 will indicate that xan,,g is on chromosome 5, xan,,h is on chromosome 3, and xan,,i is on chromosome 1. A small population would indicate that alb,,o may be on chromosome 7. The gene alb,,o segregated independently of markers on the other chromosomes. alb,,p is on chromosome 2. R.T. Ramage (correspondence) has induced this mutant in coupling with msg 2. Crosses with alb,,q frequently led to distorted ratios; however, linkage was shown with orange lemma, oo, on chromosome 6, Table 3. alb,,r was not located; however, no crosses involving genes on chromosome 6 were made. alb,,s was not located but no crosses involving chromosome 2 and 6 were made. Crosses with y,,d consistently gave distorted ratios. This is rather surprising in view of the good fit to a 3:1 ratio reported in Table 1. Genes on chromosomes 2 and 6 were not tested with y,,d.
Table 3. Recombination of some of the spontaneous seedling lethal genes with orange lemma, oo.
References:
Rahman, M.M (1973) Balanced male sterile-lethals systems for hybrid barley production. Ph.D. thesis, Montana State University, Bozeman, Montana, 59715, pp. 1-93
Rahman, M.M. and R.F. Eslick (1975) Linkage of male sterile genes with seedling lethal genes. BGN5:42-44.
