Involvement of facultative apomixis in inheritance of EPSPS gene amplification in glyphosate-resistant Amaranthus palmeri

• Published in: Planta 2014, Vol.239 (1), p.199-212
• Main Authors: Ribeiro, Daniela N, Pan, Zhiqiang, Duke, Stephen O, Nandula, Vijay K, Baldwin, Brian S, Shaw, David R, Dayan, Franck E
• Format: Article
• Language: English
• Subjects: 3-Phosphoshikimate 1-Carboxyvinyltransferase - genetics; 3-Phosphoshikimate 1-Carboxyvinyltransferase - metabolism; Agriculture; Amaranth; Amaranthus - drug effects; Amaranthus - genetics; Amaranthus palmeri; Apomixis; Apomixis - drug effects; Apomixis - genetics; Biomedical and Life Sciences; Complementary DNA; correlation; Drug Resistance - genetics; Ecology; Enzymatic activity; enzyme activity; Females; Forestry; Gene Amplification; Gene Dosage; Gene Expression Regulation, Plant; genes; Genetic Variation; Genomics; Glycine - analogs & derivatives; Glycine - pharmacology; Glyphosate; Herbicides - pharmacology; Inhibitory concentration 50; Life Sciences; Metagenomics; nuclear genome; Original Article; parents; Plant Proteins - genetics; Plant Proteins - metabolism; Plant reproduction; Plant Sciences; Plants; reciprocal crosses; Seeds; Sex chromosomes
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s00425-013-1972-3

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.