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Project title: Analysis of chlorophyll breakdown as an early marker of leaf senescence

Objectives: Breakdown of chlorophyll with the accompanying loss of green colour is an important (early) process of leaf senescence. The aim of the ESR 5 project is to investigate chlorophyll breakdown in monocot crops. Together with the research of JU this will allow the development of diagnostic tools to monitor senescence onset and progression in cereals and grasses of agronomic relevance.

Description of work: During senescence, chlorophyll is metabolized to a species-specific set of chlorophyll catabolites accumulating in the vacuole. Preliminary analysis of senescent barley leaves indicate the presence of at least ten different non fluorescing catabolites (NCC), some of which have not been described before. Differences in abundance, timing of occurrence and nature of the catabolites will be investigated in different germplasm provided by the partners. Furthermore, together with biophysical methods established at JU analysis of chlorophyll catabolites will provide a robust screening method for mutants and varieties modulated in chlorophyll metabolism as an early marker of senescence. Orthologous genes of known steps of chlorophyll catabolism will be cloned from barley and/or ryegrass and their expression during crop development will be analyzed. This analysis will be particularly important for the characterization of transgenic plants and lines modulated in gene expression of senescence-related transcription factors provided by the partners. Selected chlorophyll catabolism genes might offer targets for genetic manipulation in order to modulate crop life span.

Deliverables: Identification and cloning of chlorophyll catabolism genes from barley and ryegrass; identification of chlorophyll catabolites as early markers of senescence