ZENG1, LINGHE AND WM. VANCE BAIRD.* Horticulture Department, Box 340375, Clemson University, Clemson, SC 29634-0375; 1 U.S.D.A./A.R.S Salinity Laboratory - Plant Group, Riverside, CA. - Inheritance of antimicrotubule drug resistance in goosegrass [Eleusine indica (L.) Gaertn.]
The genetic basis of antimicrotubule drug resistance was investigated
using pre-emergence dinitroaniline herbicides on three biotypes of
goosegrass. Using physical emasculation, reciprocal crosses were made
between inbred lines of the wild type/susceptible (S), the
intermediately resistant (I) and the highly resistant (R) biotypes.
F1 hybrids were identified by isoenzyme analysis. A non-destructive
root-growth bioassay was developed to determine the dinitroaniline
response phenotype (DRP) of mature F1 hybrids.
F2 and F3 populations were generated by selfing.
A seedling radicle-growth bioassay was used to determine the DRP of
F2 and F3 progenies. Analysis of the DRP in
F1 hybrids indicated that "resistance" was
recessive to "susceptibility" (i.e., S>I>R). This was true
irrespective of which biotype/phenotype served as the pollen donor,
thus ruling out any effect due to inheritance of a cytoplasmic factor.
Segregation analysis of the F2 and F3 progenies
confirmed the dominance of "susceptibility". Furthermore,
the segregation of "susceptibility" to
"resistance" phenotypes in the F2 and
F3 progenies best fit a 3:1 inheritance pattern (i.e.,
3S:1R, 3S:1I, and 3I:1R). These data are consistent with the DRP
being inherited as a single gene trait. The proposed designation for
the nuclear locus is Drp. There were at least three alleles at
this locus; such that Drps was dominant to
Drpi which was dominant to Drpr.
The research was supported by USDA-NRI grant 95-37315-2152.
Key words: dinitroaniline, goosegrass, herbicide resistance, oryzalin