Changes in the promoter of a defender against apoptotic cell death gene affect its expression in upland cotton

Abstract

AbstractThe DAD1 (defender against apoptotic cell death) gene is a negative regulator of programmed cell death. It plays important roles in plant growth, development, environmental adaptation, and aging. We examined whether and how the expression of DAD1 gene is affected by the promoter changes in the allotetraploid upland cotton (Gossypium hirsutum L.). We compared the expression status of the genes in the leaves of an elite cultivar and a wild variety of G. hirsutum, and cloned and analyzed a 1.3‐kb promoter region of the genes in two cotton types. Results revealed that the expression of a subgenomic homoeolog of DAD1 (DAD1 At ) was significantly upregulated in leaves of the cultivated cotton when compared with that in a wild cotton. In addition, we identified 18 variations, including 14 single nucleotide polymorphisms and four indels between the promoters of the two cotton types. We detected at least 10 of 18 variations in the promoters related to possible cis‐regulatory elements. Further transient tobacco assays using heterogeneous DAD1 At promoter::GUS fusion showed that the activity of the DAD1 At promoter in the cultivated cotton was stronger than that in the wild cotton, which suggested a dynamic change in the DAD1 At promoter during genetic divergence of the two cottons. This study provides an example of how gene expression could be affected by specific changes in the gene promoter.