Open AccessPopulation genetics structure of glyphosate‐resistant J ohnsongrass ( S orghum halepense L . P ers) does not support a single origin of the resistance
Author(s) -
Fernández Luis,
Haro Luis Alejandro,
Distefano Ana J.,
Carolina Martínez Maria,
Lía Verónica,
Papa Juan C.,
Olea Ignacio,
Tosto Daniela,
Esteban Hopp Horacio
Publication year - 2013
Publication title -
ecology and evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.17
H-Index - 63
ISSN - 2045-7758
DOI - 10.1002/ece3.671
Subject(s) - glyphosate , genetics , population , biology , microbiology and biotechnology , medicine , environmental health
Single sequence repeats ( SSR ) developed for S orghum bicolor were used to characterize the genetic distance of 46 different S orghum halepense ( J ohnsongrass) accessions from A rgentina some of which have evolved toward glyphosate resistance. Since Johnsongrass is an allotetraploid and only one subgenome is homologous to cultivated sorghum, some SSR loci amplified up to two alleles while others (presumably more conserved loci) amplified up to four alleles. Twelve SSR providing information of 24 loci representative of Johnsongrass genome were selected for genetic distance characterization. All of them were highly polymorphic, which was evidenced by the number of different alleles found in the samples studied, in some of them up to 20. UPGMA and Mantel analysis showed that Johnsongrass glyphosate‐resistant accessions that belong to different geographic regions do not share similar genetic backgrounds. In contrast, they show closer similarity to their neighboring susceptible counterparts. D iscriminant A nalysis of P rincipal C omponents using the clusters identified by K ‐means support the lack of a clear pattern of association among samples and resistance status or province of origin. Consequently, these results do not support a single genetic origin of glyphosate resistance. Nucleotide sequencing of the 5‐enolpyruvylshikimate‐3‐phosphate synthase ( EPSPS ) encoding gene from glyphosate‐resistant and susceptible accessions collected from different geographic origins showed that none presented expected mutations in aminoacid positions 101 and 106 which are diagnostic of target‐site resistance mechanism.