Abstract
Gene transfer from transgenic crops to their weedy relatives may introduce undesired ecological consequences that can increase the fitness and invasiveness of weedy populations. Here, we examined the rate of gene flow from abiotic stress-tolerant transgenic rice that over-express AtCYP78A7, a gene encoding cytochrome P450 protein, to six weedy rice accessions and compared the phenotypic performance and drought tolerance of their hybrids over generations. The rate of transgene flow from AtCYP78A7-overexpressing transgenic to weedy rice varied between 0% and 0.0396%. F1 hybrids containing AtCYP78A7 were significantly taller and heavier, but the percentage of ripened grains, grain numbers and weight per plant were significantly lower than their transgenic and weedy parents. The homozygous and hemizygous F2 progeny showed higher tolerance to drought stress than the nullizygous F2 progeny, as indicated by leaf rolling scores. Shoot growth of nullizygous F3 progeny was significantly greater than weedy rice under water-deficient conditions in a rainout shelter, however, that of homozygous F3 progeny was similar to weedy rice, indicating the cost of continuous expression of transgene. Our findings imply that gene flow from AtCYP78A7-overexpressing transgenic to weedy rice might increase drought tolerance as shown in the pot experiment, however, increased fitness under stressed conditions in the field were not observed for hybrid progeny containing transgenes.
Highlights
Gene transfer from transgenic crops to their weedy relatives may introduce undesired ecological consequences that can increase the fitness and invasiveness of weedy populations
Decreases in the tiller numbers per plant, grain numbers per panicles, and percent seed fertility was observed for the hybrids between transgenic herbicide-resistant rice and weedy rice compared to their parental lines[8] Chun et al.[9] have reported that the homozygous F2 progeny of herbicide-resistant transgenic rice and weedy rice were considerably taller and produce more grains per plant compared to their parental transgenic and weedy relatives
Transgenic hybrids with the AtCYP78A7 gene were detected with Geojeaengmi 20, Gunsanaengmi 1, Boeunaengmi 5, Muanaengmi 15, and Hwaseongaengmi 1, but not with Yesanaengmi 3
Summary
Gene transfer from transgenic crops to their weedy relatives may introduce undesired ecological consequences that can increase the fitness and invasiveness of weedy populations. We examined the rate of gene flow from abiotic stress-tolerant transgenic rice that over-express AtCYP78A7, a gene encoding cytochrome P450 protein, to six weedy rice accessions and compared the phenotypic performance and drought tolerance of their hybrids over generations. Our findings imply that gene flow from AtCYP78A7-overexpressing transgenic to weedy rice might increase drought tolerance as shown in the pot experiment, increased fitness under stressed conditions in the field were not observed for hybrid progeny containing transgenes. The rate of gene flow from transgenic crops to their related species is not high, the introgression of a transgene may introduce potential ecological consequences that can elevate the fitness and invasiveness of those weedy/wild populations[2,3,4,5,6]. It is important to investigate the performance of hybrids resulting from gene flow between drought-tolerant transgenic crops and their weedy relatives because a transgene might confer diverse beneficial traits (including drought tolerance) to the hybrids
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