Identification of WHIRLY1 as a Factor Binding to the Promoter of the Stress- and Senescence-Associated Gene HvS40

HvS40 is a marker gene for leaf senescence in barley. It is expressed during dark-induced as well as age-dependent senescence and in response to biotic and abiotic stress factors. Its expression is also induced by hormones involved in the control of stress responses and senescence processes. Run-on-transcription assays with isolated nuclei showed that its expression during dark-induced senescence is regulated at the transcriptional level. Its promoter contains two elicitor response elements (ERE) consisting of two W-boxes. Binding of proteins to these motifs changed during senescence. A 24-kDa protein binding to ERE2 of nonsenescent leaves was identified as WHIRLY1.