MOLECULAR CHARACTERIZATION OF THE TUBULIN-RELATED GENE FAMILIES IN HERBICIDE-RESISTANT AND SUSCEPTIBLE GOOSEGRASS (ELEUSINE INDICA)

Goosegrass, wide spread throughout the tropics and subtropics, is one of the most noxious weeds known, Recently, biotypes of goosegrass have been found resistant to the dinitroaniline herbicides. An alteration in the structure/composition of a tubulin protein has been postulated as an explanation for the hyperstable microtubules and the resistant p henotype. Our study was initiated to investigate the structure of the alpha (alpha)-, beta (beta)- and gamma (gamma)-tubulin related gene se quences in resistant, intermediately resistant, and susceptible biotyp es, Heterologous tubulin gene clones were used as probes of restrictio n endonuclease-digested genomic DNA from each biotype, to determine ge ne size and copy number and to screen for restriction fragment length polymorphisms, The tubulin genes are organized into gene families, The re are three to five alpha-tubulin genes, four to seven beta-tubulin g enes, and four to eight gamma-tubulin genes, There was no evidence of multiple copies or tandem repeats of any individual gene sequence, Alt hough RFLPs were observed, no significant difference in the banding pa ttern between the resistant and the susceptible biotypes was found for either alpha-, beta-, or gamma-tubulin gene families, Therefore, it i s unlikely that the difference between the herbicide-response phenotyp es can be attributed to large deletions or insertions in a tubulin gen e.