Bcl-xL transformed peanut (Arachis hypogaea L.) exhibits paraquat tolerance
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The human Bcl-xL gene was transformed into peanut cultivar Georgia Green via microprojectile bombardment. Following selection on hygromycin-containing medium and regeneration, eighty hygromycin-resistant callus clusters were recovered. Southern blot analysis of ten fertile lines revealed multiple insertions of the Bcl-xL transgene in most lines. Western blot analysis of primary plants and T1 progenies demonstrated detectable levels of Bcl-xL expression in four transgenic lines. We could not detect Bcl-xL protein in other tested lines even though transcripts were identified by RT-PCR and northern blot. Three of the western-positive transgenic lines either were sterile or the progenies lost the expressive copy of Bcl-xL. Only T1 progenies from line BX25-4-2a-19 continued to express an intermediate level of Bcl-xL. This line demonstrated paraquat tolerance at the 5 μM level. Tolerance to salt of T1 and T2 seeds from seven other transgenic lines also was tested, but no tolerance was found in these lines. A high level of Bcl-xL transgene expression may be deleterious to plant growth and development even though the gene may confer tolerance to other abiotic and biotic stresses such as drought and pathogens.
KeywordsBcl-xL Arachis hypogaea L. Genetic transformation Paraquat tolerance
Support for this work was provided by the USDA Multicrop Aflatoxin Elimination Program and the National Peanut Foundation. We thank Evelyn P. Morgan for her technical assistance and Benjamin G. Mullinix for his help on statistical analysis. We also thank Marty Dickman, Texas A & M University and IDUN Pharmaceuticals (now part of Pfizer) for providing the Bcl-xL gene.
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