Overexpression of AtSZF2 from Arabidopsis Showed Enhanced Tolerance to Salt Stress in Soybean

Plants have adapted to environmental challenges by expressing many plant genes in response to the stresses. Among those genes, CCCH zinc finger proteins are involved in abiotic and biotic stresses. Transgenic soybean plants overexpressing AtSZF2 were produced to investigate that its ectopic overexpression enhanced salt stress tolerance by Agrobacterium-mediated transformation using half-seed explants. Sixteen transgenic lines were chosen to analyze for T-DNA insertion and transcription levels, and most of them were confirmed as positive. In further analysis with Southern blot, stable transformation event and copy number were confirmed. Following high salinity stress on the detached leaf and whole plant of two transgenic lines (#4 and #6) revealed that the ectopic expression of AtSZF2 was correlated with stress tolerance in phenotype, ion leakage and chlorophyll content with statistical significance. In another test with 20% PEG treatment, similar tolerance of transgenic plants was observed with lower ion leakage and higher chlorophyll content, indicating that the damage of cell membrane was prevented in transgenic plants. Finally, expression of various abiotic stress-responding genes was detected by reverse transcriptase and quantitative real-time PCR analysis with the transgenic plants. It could be proposed that introduction of AtSZF2 resulted in the modulation of ABA/stress responsive gene expression in transgenic soybean plants and make them tolerant against salt stress. Considering soybean as a salt-sensitive crop and importance of salt stress tolerance in specific farming region, the introduction of AtSZF2 may provide an approach for crop improvement in soybean breeding.