Overexpression of DmDREBa Gene Significantly Enhances Low Temperature Tolerance in Transgenic Tobacco
Many environmental factors such as drought,salt stress,hormones and low/high temperature influence the growth and development of plants.It has been found that DREB transcription factors play important roles in plants against different abiotic stresses.In this study,DmDREBa (GenBank accession No.EF490996),a DREB-like gene isolated from chrysanthemum was overexpressed in tobacco plants by mediation of Agrobacterium tumefaciens under the control of the constitutive promoter CaMV 35S,and 43 transgenic tobacco plants were obtained by PCR method.9 transgenic tobacco plants were randomly selected to perform RT-PCR investigation and 7 plants indicated RNA transcripts accumulation.The southern blot result showed that 1-3 copies of DmDREBa were randomly inserted.The tolerance of transgenic tobacco plants was increased comparing with the wild type tobacco plants under low temperature condition.The water loss of transgenic tobacco was less than wild type plants after natural transpiration.Moreover,the density of the stomata in the epidermis was observed.The result showed that the numbers of stomata in upper or lower epidermis of transgenic plants were reduced comparing to wild type tobacco.The result of t test demonstrated that the differences between the upper and lower epidermis of transgenic plants and wild type were significant.Furthermore,the conent of malondialdehyde (MDA) in transgenic plants was lower than that in wild type tobacco plants at lower temperature condition,which indicated the tolerance ability of transgenic plants was increased.All these results indicated that DmDREBa improved tolerance ability of trangenic tobacco plants to the lower temperature stress.This research will provide a very useful reference for functional analysis of DREB genes in chrysanthemum in the future.
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