Fitness Of Hybrids Between Glyphosate-Resistant Transgenic Soybean And Wild Soybean(JSCZ、LNTL) And Their Effect On Soil Bacterial Communities

Wild soybean（Glycine soja Sieb.et Zucc.）is the ancestor of cultivated soybean（Glycine max（Linn.）Merr.）.Both of them belong to G chromosome group with the same number of chromosomes（2n=40）.Therefore,introgression can occur between them under natural conditions.China is an origin and genetic diversity center for wild soybean.Wild soybean is widely distributed in China and its distribution area is highly overlap with cultivated soybean.If herbicide-resistant gene introgressed into wild soybean and hybrids which have high fitness,this will be cause harmness to the ecological environment and also destroy the genetic diversity of wild soybeans.The previous research clarified the sexual compatibility between transgenic soybean（T14R 1251-70）and wild soybean（JSCZ、LNTL）,and the fitness of hybrid F₁under non-competitive conditions was evaluated,but the fitness of the hybrids in different habitats and the effects of hybrids on soil bacterial community have not been studied.In this paper,based on the previous research,the fitness of two hybrid F₂and F₃was studied under four planting conditions（Pured-Wasteland（PW）,Pured-Farmland（PF）,Mixed-Wasteland（MW）,Mixed-Farmland（MF））,and the effects of JSCZ F₂and JSCZ F₃on soil bacterial community were analyzed.The purpose is to provide more experimental data for the risk assessment of gene flow from herbicide-resistant transgenic soybean to wild soybean,and to provide a theoretical basis for the environmental safety assessment of the herbicide-resistant transgenic soybean.Main results were as follows:（1）Fitness of F₂hybridsThe emergence rate of JSCZ F₂was 84.5%,which was significantly higher than that of wild soybean,and the emergence rate of LNTL F₂was 77.5%,which was significantly lower than that of wild soybean.In terms of vegetative growth indicators,there was no significant difference in plant height between JSCZ F₂and wild soybean under four planting conditions,but LNTL F₂was significantly taller than wild soybean.The dry above-ground biomass of JSCZ F₂was significantly lower than wild soybean under PW and PF,and significantly greater than wild soybean under MW and MF;LNTL F₂was significantly greater than wild soybean under four planting conditions.In terms of reproductive growth indicators,such as the number and weight of pods,seeds,filled seeds per plant of JSCZ F₂were significantly lower than wild soybean under PW and PF,but under MW and MF,JSCZ F₂were significantly greater than wild soybean.The weight of pods,seeds,filled seeds per plant of LNTL F₂were significantly greater than wild soybean under four planting conditions.The total fitness of JSCZ F₂was significantly lower than wild soybean under PW and PF,but there was no significant difference between JSCZC F₂with wild soybean under MW and MF.The total fitness of LNTL F₂was similar to wild soybean under four planting conditions.The hardness rate and dormancy of the two F₂seeds were significantly lower than the corresponding wild soybean.The thickness of palisade layer and the content of K and Ca in JSCZ F₂seed coat were significantly lower than those of wild soybean.The thickness of osteosclereid layer and content of Ca in palisade layer of LNTL F₂seed coat was significantly higher or lower than that of wild soybean.In summary,the fitness of JSCZ F₂was greater than wild soybean under MW and MF,and the fitness of LNTL F₂was greater than wild soybean under the four planting conditions.Therefore,JSCZ F₂and LNTL F₂may has a higher survival and reproduction ability under the natural environmental conditions.（2）Fitness of F₃hybridsThe emergence rate of JSCZ F₃was 82.5%,which was significantly higher than that of wild soybean,and the emergence rate of LNTL F₃was no significant difference with wild soybean.In terms of vegetative growth indicators,the plant height of JSCZ F₃was significantly lower than wild soybean,but LNTL F₃was significantly taller than wild soybean under four planting conditions.The dry above-ground biomass of JSCZ F₃was significantly lower than wild soybean under PW and PF and significantly greater than wild soybean under MW and MF;the dry above-ground biomass of LNTL F₃was significantly higher than wild soybean under four planting conditions.In terms of reproductive growth indicators,the number and weight of pods,seeds,filled seeds per plant of JSCZ F₃were significantly lower than wild soybean under under PW and PF,but under MW and MF,the number of pods,seeds,filled seeds per plant of JSCZ F₃were significantly greater than wild soybean.The number and weight of pods,seeds,filled seeds per plant of LNTL F₃were significantly greater than wild soybean under four planting conditions.The total fitness of JSCZ F₃was significantly lower than wild soybean under PW and PF,but there was no significant difference between JSCZC F₃with wild soybean under MW and MF.The total fitness of LNTL F₃was 1.35～1.39,which was significantly higher than wild soybean under four planting conditions.Therefore,JSCZ F₃and LNTL F₃may has a higher ability to survive and reproduce under natural environmental conditions.（3）Effects of JSCZ F₂and JSCZ F₃on soil bacterial communityThere was no significant difference on soil bacterial diversity,relative abundance of dominant bacterial（Proteobacteria,Sphingobacteriales,Pseudomonas）between F₂and wild soybean and transgenic soybean under PW and PF,but these of F₂were significantly higher than that of parents or equivalent to transgenic soybean under MW and MF.The bacterial diversity of F₃was significantly higher than that of wild soybean,and was significantly lower than or similar to that of transgenic soybeans under PW and PF;but the bacterial diversity of F₃was similar to wild soybean and transgenic soybean under MW and MF.The relative abundance of Proteobacteria,which was the dominant bacterial phylum,was significantly lower in F₃than in wild soybean and transgenic soybean under PW and PF,and similar to parents or significantly higher than wild soybean under MW and MF.The relative abundance of Sphingobacteriales and Pseudomonas,which was the dominant bacterial order/genus,was significantly higher in F₃than in parents or similar to transgenic soybean under PF and MF,and similar to parents or significantly higher than transgenic soybean under PW and MW.The results showed that the two F₂and F₃hybrids had higher survival and reproduction ability under natural conditions,and the soil bacterial communities of JSCZ F₂and JSCZ F₃were obviously different from wild soybean and transgenic soybean under different planting conditions.Therefore,it is worthy to be further studied that the possible ecological risk caused by gene flow from herbicide-resistant transgenic soybean to wild soybean.