Overexpression of the CBF2 transcriptional activator in Arabidopsis delays leaf senescence and extends plant longevity

Abstract

Leaf senescence is a programmed developmental process governed by various endogenous and exogenous factors, such as the plant developmental stage, leaf age, phytohormone levels, darkness, and exposure to stresses. It was found that, in addition to its well-documented role in the enhancement of plant frost tolerance, overexpression of the C-repeat/dehydration responsive element binding factor 2 ( CBF2) gene in Arabidopsis delayed the onset of leaf senescence and extended the life span of the plants by approximately 2 weeks. This phenomenon was exhibited both during developmental leaf senescence and during senescence of detached leaves artificially induced by either darkness or phytohormones. Transcriptome analysis using the Affymetrix ATH1 genome array revealed that overexpression of CBF2 significantly influenced the expression of 286 genes in mature leaf tissue. In addition to 30 stress-related genes, overexpression of CBF2 also affected the expression of 24 transcription factor (TF) genes, and 20 genes involved in protein metabolism, degradation, and post-translational modification. These results indicate that overexpression of CBF2 not only increases frost tolerance, but also affects other developmental processes, most likely through interactions with additional TFs and protein modification genes. The present findings shed new light on the crucial relationship between plant stress tolerance and longevity, as reported for other eukaryotic organisms.