Amaranthus hybridus can be pollinated frequently by A. tuberculatus under field conditions

Abstract

Recent studies have confirmed that weedy Amaranthus species are capable of interspecific hybridization, and such hybridization may foster the evolution of herbicide resistance. However, the extent to which hybridization among these species occurs in nature is unknown. The purpose of this study was to determine the frequency under field conditions at which A. hybridus, a monoecious and predominantly selfpollinated species, would be pollinated by A. tuberculatus, a dioecious species. To do this, parents carrying different alleles at the ALS locus, which encodes a herbicide target site, were used. Male A. tuberculatus parents were homozygous for a dominant herbicide-insensitive allele, while A. hybridus parents were homozygous for a sensitive form. Hybrid progeny therefore could be detected via herbicide selection. Mean hybridization frequencies between 0.4 and 2.3% were obtained, depending on the proximity between parents (P ¼ 0.02). The robustness of the hybrid selection assay was verified using a molecular marker and DNA content analyses. Using these techniques, more than 99% of the progeny that survived the herbicide were confirmed to be hybrids. Frequencies obtained in this study were many times higher than the generally expected rate of mutation. Therefore, even minimal fertility in hybrid progeny would support the view that hybridization could play a role in adaptive evolution of weedy Amaranthus species. Heredity (2005) 94, 64-70.

The origin of Darwin hybrid tulips analyzed by flow cytometry, karyotype analyses and genomic in situ hybridization

“…In the present study, however, we demonstrated that all of the Darwin hybrid tulips tested have two copies of the T. gesneriana genome and one copy of the T. fosteriana genome, indicating that T. gesneriana has supplied the diploid gamete. Lefeber (1960) Relative DNA content Flow cytometry has been frequently used for hybrid identification (Nakamura et al, 2005;Trucco et al, 2005). In this study, the relative DNA content of diploid …”

Rapid Assay Evaluation of Plant Response to Protoporphyrinogen Oxidase (Protox)-Inhibiting Herbicides

“…], 30 to 40 seed heads from putative R plants in a composite sample is recommended Davis et al 2008). Collecting a large sample size for self-pollinated species is done by other research groups (Davis et al 2010;Weaver 2001 (Trucco et al 2005). Collecting a large number of samples is unnecessary for species with outcrossing mating behavior.…”

Morphological Characterization of <i>Amaranthus palmeri</i> x <i>A. spinosus</i> Hybrids

“…Sauer, with the transfer of glyphosate resistance [3], and with A. tuberculatus, with the transfer of ALS resistance [4]. Transfer of ALS resistance from A. tuberculatus to A. hybridus has also been confirmed [5].…”