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Double mutation in Eleusine indica α‐tubulin increases the resistance of transgenic maize calli to dinitroaniline and phosphorothioamidate herbicides
Author(s) -
Anthony Richard G.,
Hussey Patrick J.
Publication year - 1999
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.1999.00484.x
Subject(s) - eleusine indica , biology , eleusine , mutation , tubulin , transgene , microtubule , botany , genetically modified crops , cross resistance , dimer , genetics , gene , weed , agronomy , finger millet , physics , nuclear magnetic resonance
Summary The repeated use of dinitroaniline herbicides on the cotton and soybean fields of the southern United States has resulted in the appearance of resistant biotypes of one of the world's worst weeds, Eleusine indica . Two biotypes have been characterized, a highly resistant (R) biotype and an intermediate resistant (I) biotype. In both cases the resistance has been attributed to a mutation in α‐tubulin, a component of the α/β tubulin dimer that is the major constituent of microtubules. We show here that the I‐biotype mutation, like the R‐biotype mutation shown in earlier work, can confer dinitroaniline resistance on transgenic maize calli. The level of resistance obtained is the same as that for E. indica I‐ or R‐biotype seedlings. The combined I‐ and R‐biotype mutations increase the herbicide tolerance of transgenic maize calli by a value close to the summation of the maximum herbicide tolerances of calli harbouring the single mutations. These data, taken together with the position of the two different mutations within the atomic structure of the α/β tubulin dimer, imply that each mutation is likely to exert its effect by a different mechanism. These mechanisms may involve increasing the stability of microtubules against the depolymerizing effects of the herbicide or changing the conformation of the α/β dimer so that herbicide binding is less effective, or a combination of both possibilities.