Fitness of F1 hybrids between 10 maternal wild soybean populations and transgenic soybean

Abstract

The releasing of transgenic soybeans (Glycine max (L.) Merr.) into farming systems raises concerns that transgenes might escape from the soybeans via pollen into their endemic wild relatives, the wild soybean (Glycine soja Sieb. et Zucc.). The fitness of F1 hybrids obtained from 10 wild soybean populations collected from China and transgenic glyphosate-resistant soybean was measured without weed competition, as well as one JLBC-1 F1 hybrid under weed competition. All crossed seeds emerged at a lower rate from 13.33–63.33%. Compared with those of their wild progenitors, most F1 hybrids were shorter, smaller, and with decreased aboveground dry biomass, pod number, and 100-seed weight. All F1 hybrids had lower pollen viability and filled seeds per plant. Finally, the composite fitness of nine F1 hybrids was significantly lower. One exceptional F1 hybrid was IMBT F1, in which the composite fitness was 1.28, which was similar to that of its wild progenitor due to the similarities in pod number, increased aboveground dry biomass, and 100-seed weight. Under weed competition, plant height, aboveground dry biomass, pod number per plant, filled seed number per plant, and 100-seed weight of JLBC-1 F1 were lower than those of the wild progenitor JLBC-1. JLBC-1 F1 hybrids produced 60 filled seeds per plant. Therefore, F1 hybrids could emerge and produce offspring. Thus, effective measures should be taken to prevent gene flow from transgenic soybean to wild soybean to avoid the production F1 hybrids when releasing transgenic soybean in fields in the future.

Fitness and Ecological Risk of Hybrid Progenies of Wild and Herbicide-Tolerant Soybeans With EPSPS Gene

“…In contrast to the results of this study, Kuroda et al (2013) suggested that the hybrid progeny of cultivated and wild soybeans contain some artificial domestication genes, so the fitness of hybrid progeny of cultivated and wild soybeans may be lower than that of wild soybeans. When transgenic soybeans with the EPSPS gene (developed by Nanjing Agricultural University) were crossed with wild soybeans from 10 different regions, the seed germination percentage, plant height, biomass, pods per plant, and 100-seed weight of F 1 were lower than those of wild soybeans, indicating that the gene transfer was not conducive to the survival of hybrid offspring in natural environments ( Liu et al, 2021 ).…”

“…However, the relevant national authorities need scientific and technical support in making decisions on whether to approve the industrialization of transgenic soybeans and in managing the resulting environmental risks (especially controlling the introduction of foreign genes into wild soybeans). To date, there have been four studies conducted on the fitness of hybrid progeny between EPSPS- transgenic and wild soybeans, of which one study showed that the fitness of F 1 hybrids of them in different regions was lower than that of wild soybeans ( Liu et al, 2021 ). The results of the remaining three showed that, compared to wild soybeans, the fitness of those expressing the EPSPS gene did not change significantly in the absence of glyphosate and was even significantly higher than that of wild soybeans in some fitness parameters, indicating that wild soybeans expressing the EPSPS gene may be more invasive than their wild soybean parents ( Guan et al, 2015 ; Kan et al, 2015 ; Yook et al, 2021 ).…”

The role of intraspecific crop-weed hybridization in the evolution of weediness and invasiveness: cultivated and weedy radish (Raphanus sativusL.) as a case study

“…When hybridization occurs, the hybrid lineages harbor alleles from both progenitors, and the process of introgression will depend on the fitness of the hybrids relative to their parents (Mercer et al, 2007; Presotto et al, 2019). Hybrids commonly exhibit intermediate phenotypes and reduced fitness compared to their parents (Mercer et al, 2006; Sahoo et al, 2010; Hooftman et al, 2015; Martin et al, 2019; Yue et al, 2021), with nonviable or sterile offspring in extreme cases (Rieseberg et al, 2007). If novel alleles reduce hybrid fitness, these alleles may not prevail or introgress.…”

The role of intraspecific crop–weed hybridization in the evolution of weediness and invasiveness: Cultivated and weedy radish (Raphanus sativus) as a case study

“…When hybridization occurs, the hybrid lineages harbor alleles from both progenitors, and the process of introgression will depend on the fitness of the hybrids relative to their parents (Mercer et al, 2007; Presotto et al, 2019). Hybrids commonly exhibit intermediate and maladapted phenotypes and reduced fitness compared to their parents (Mercer et al, 2006; Sahoo et al, 2010; Hooftman et al, 2015; Martin et al, 2019; Yue et al, 2021), with nonviable or sterile offspring in extreme cases (Rieseberg et al, 2007). If novel alleles reduce hybrid fitness, these alleles may not prevail or introgress.…”