RESUMO
Stress adaptation in plants involves altered expression of many genes through complex signaling pathways. To achieve the optimum expression of downstream functional genes, we expressed AtbHLH17 (AtAIB) and AtWRKY28 TFs which are known to be upregulated under drought and oxidative stress, respectively in Arabidopsis. Multigene expression cassette with these two TFs and reporter gene GUS was developed using modified gateway cloning strategy. The GUS assay and expression analysis of transgenes in transgenic plants confirmed the integration of multigene cassette. The transgenic lines exhibited enhanced tolerance to NaCl, Mannitol and oxidative stress. Under mannitol stress condition significantly higher root growth was observed in transgenics. Growth under stress and recovery growth was substantially superior in transgenics exposed to gradual long term desiccation stress conditions. We demonstrate the expression of several downstream target genes under various stress conditions. A few genes having either WRKY or bHLH cis elements in their promoter regions showed higher transcript levels than wild type. However, the genes which did not have either of the motifs did not differ in their expression levels in stress conditions compared to wild type plants. Hence co-expressing two or more TFs may result in upregulation of many downstream target genes and substantially improve the stress tolerance of the plants.
Assuntos
Adaptação Fisiológica , Proteínas de Arabidopsis/genética , Arabidopsis/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Proteínas de Ligação a DNA/genética , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Estresse Fisiológico , Fatores de Transcrição/genética , Arabidopsis/crescimento & desenvolvimento , Secas , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Raízes de Plantas/genética , Raízes de Plantas/crescimento & desenvolvimento , Regiões Promotoras Genéticas , Cloreto de Sódio/farmacologia , Regulação para CimaRESUMO
Large number of primary transgenic events were generated in groundnut by an Agrobacterium mediated, in planta transformation method to assess the efficacy of cry1AcF against the Spodoptera litura. The amplification of required size fragment of 750 bp with npt II primers and 901 bp with cry1AcF gene primers confirmed the integration of the gene. The expression of the cry gene was ascertained by ELISA in T2 generation, and the maximum concentration of cry protein in transgenic plants reached approximately 0.82 µg/g FW. Further, Southern blot analysis of ten T2 transgenic plants proved that transgene had been integrated in the genome of all the plants and Northern analysis of the same plants demonstrated the active expression of cry1AcF gene. The highest mean % larval mortalities 80.0 and 85.0 with an average mean % larval mortalities 16.25 (n = 369) and 26.0 (n = 80) were recorded in T1 and T2 generations, respectively. Segregation analysis of the selected lines in the T3 generation demonstrated homozygous nature. This clearly proved that though there is considerable improvement in average mean % larval mortality in T2 generation, the cry1AcF gene was effective against S. litura only to some extent.
