Subproject B06: Molecular Modulation of the WRKY regulatory network of leaf senescence

Principal investigator:

apl. Prof. Dr. Ulrike Zentgraf

Universität Tübingen

ZMBP, Allgemeine Genetik

Auf der Morgenstelle 28, 72076 Tübingen

Tel 07071 - 29 78833

Fax 07071 - 29 5042

ulrike.zentgrafspam prevention@zmbp.uni-tuebingen.de

Summary:

Senescence is a highly regulated process which aims at break-down and subsequent remobilization of macromolecule components of mature leaves, either for further growth or for deposition in developing fruits and seeds. It is programmed by endogenous cues like leaf or plant age; however, stress conditions can induce premature senescence. While developmental senescence tends to maximize seed quality and quantity, premature senescence describes an exit strategy, often resulting in severely decreased yields. Despite the agricultural importance of senescence, our knowledge on its regulatory mechanisms is still limited. In contrast to system biology approaches which characterize overall and genome-wide changes, we want to decipher the molecular mechanisms of this regulatory network starting from one point, namely the transcription factor WRKY53, which is tightly regulated by diverse mechanisms and is a convergence node between senescence and biotic and abiotic stress responses. In the last funding period we could already show that WRKY53 is part of a complex regulatory network between many different WRKY factors but also many other proteins which built up several layers of regulatory feedback loops which fine-tune this network. Activation or repression of specific target genes is controlled by homo- and heterodimerization as well as the redox state of the cells. In the next funding period we want to decipher the molecular mechanisms how WRKYs achieve specificity in dimerization, DNA-binding and redox regulation. What determines activator or repressor function of different WRKYs? How is the redox signal perceived? Moreover, as we have already identified a connection between early leaf development and senescence, we want to find out, whether a „leaf developmental memory“ exists, meaning if early leaf development is disturbed in specific phases, does this lead to a delay in senescence.