|Dong, Chao - Nanjing Agricultural University|
|Ma, Yuanchun - Jiangsu University|
|Cheng, Zong-ming - University Of Tennessee|
Submitted to: Environmental and Experimental Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/23/2017
Publication Date: 7/24/2017
Citation: Dong, C., Ma, Y., Wisniewski, M.E., Cheng, Z. 2017. Meta-analysis of the effect of overexpression of CBF/DREB family genes on drought stress response. Environmental and Experimental Botany. 142:1-14.
Interpretive Summary: There is a critical need to improve the stress tolerance of crops given the anticipated changes in climate and increases in population that are projected. Genetic transformation of crop plants with a specific transcription factor gene (DREB or CBF), i.e. one that is responsible for inducing the expression of other genes in response to a stimulus, has been demonstrated to elevate the expression of many stress-responsive genes and increase stress tolerance to drought and low temperature. The degree of the response has varied between experiments and unwanted impacts on growth have also been observed. There is a need to better understand the impact of the overexpression on stress tolerance and many other plant parameters across many independent experiments. There is also a need to understand how experimental variables, such as the source of the donor gene, the species of the recipient, and the method of stress assessment, etc., impacts the overall effect of the genetic modification on plant performance. In the current study, meta-analysis, a statistical procedure, was used to evaluate the noted parameters across numerous independent data sets. The results clearly identified the impact of experimental variables on the effect of overexpression of a DREB transcription factor on a variety of physiological parameters and the overall effect of overexpression on drought tolerance. These data can be used to optimize genetic transformation and stress evaluation studies. A similar approach will be used to examine the impact of the overexpression of a CBF transcription factor on freezing tolerance across multiple, independent experiments.
Technical Abstract: Transcription factors C-repeat/dehydration-responsive element binding proteins (CBF/DREB) play an important role in plant response to abiotic stresses. Over-expression of various CBF/DREB genes in diverse plants have been reported, but inconsistency of gene donor, recipient genus, parameters used in evaluting the transgenic plants have made it difficult to elucidate the complex physiologicial mechanisms by which DREBs impact drought tolerance. We performed a meta-analysis to categorize the response of plant parameters involved in drought tolerance in DREB-overexpressed plants and to evaluate experimental variables that affects transgenic plant performance. The results from across different studies indicated that 8 and 2 of 13 measured parameters exhibited a significant response by increasing or decreasing values by 25% or more in drought-stressed and in non-stressed, control plants, respectively. Among the examined moderating variables, promoters, type of media and stress, donor genus, and recipient genus significatnly affected the extent of DREBs influence. In plants subjected to drought stress, the overexpression of DREB genes derived from Arabidopsis led to greater increases in Fv/Fm (maximum quantum efficiency of photoystem II), relative water content, and proline content. These findings should guide future research on the function of the DREB genes in plant drought tolerance and the use of genetic engineering in drought tolerance breeding.