title: Involvement of facultative apomixis in inheritance of EPSPS gene amplification in glyphosate-resistant Amaranthus palmeri.
abstract: The inheritance of glyphosate resistance in two Amaranthus palmeri populations (R1 and R2) was examined in reciprocal crosses (RC) and second reciprocal crosses (2RC) between glyphosate-resistant (R) and -susceptible (S) parents of this dioecious species. R populations and Female-R × Male-S crosses contain higher 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene copy numbers than the S population. EPSPS expression, EPSPS enzyme activity, EPSPS protein quantity, and level of resistance to glyphosate correlated positively with genomic EPSPS relative copy number. Transfer of resistance was more influenced by the female than the male parent in spite of the fact that the multiple copies of EPSPS are amplified in the nuclear genome. This led us to hypothesize that this perplexing pattern of inheritance may result from apomictic seed production in A. palmeri. We confirmed that reproductively isolated R and S female plants produced seeds, indicating that A. palmeri can produce seeds both sexually and apomictically (facultative apomixis). This apomictic trait accounts for the low copy number inheritance in the Female-S × Male-R offsprings. Apomixis may also enhance the stability of the glyphosate resistance trait in the R populations in the absence of reproductive partners.
authors.affiliation: Department of Plant and Soil Sciences, Mississippi State University, Starkville, MS, 39762, USA.
authors.forename: Daniela N
authors.initials: DN
authors.lastname: Ribeiro
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Pan
authors.forename: Stephen O
authors.initials: SO
authors.lastname: Duke
authors.forename: Vijay K
authors.initials: VK
authors.lastname: Nandula
authors.forename: Brian S
authors.initials: BS
authors.lastname: Baldwin
authors.forename: David R
authors.initials: DR
authors.lastname: Shaw
authors.forename: Franck E
authors.initials: FE
authors.lastname: Dayan
mesh_terms: D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase / Q000235:genetics* / Q000378:metabolism; D027721:Amaranthus / Q000187:drug effects* / Q000235:genetics*; D060832:Apomixis / Q000187:drug effects / Q000235:genetics*; D004351:Drug Resistance / Q000235:genetics; D005784:Gene Amplification; D018628:Gene Dosage; D018506:Gene Expression Regulation, Plant; D014644:Genetic Variation; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology; D006540:Herbicides / Q000494:pharmacology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D000097797:Glyphosate
chemical_list: D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase; D005998:Glycine; D006540:Herbicides; D010940:Plant Proteins; D000097797:Glyphosate