Periodic Reporting for period 1 - LEAF-OF-LIFE (Photosynthetic energy balance, chloroplast integrity, carbon flow and epigenetic regulation of isoprenoid biosynthesis during leaf development and senescence)
Période du rapport: 2017-06-01 au 2019-05-31
Main results: (1) isoprene-emitting leaves of Arabidopsis and poplars senesced early (relative to non-emitting lines) (2) isoprene emission significantly altered leaf and plant phenotype, induced different temporal (leaf age-specific) changes in photosynthesis, while showing photosynthetic stability under short-term stresses, (3) Isoprene-emission led to greater abundance of cytokinins in healthy mature leaves (genomic impact is being analysed).
Implications and exploitation of results from LEAF-OF-LIFE:
Faster growth, shortening of leaf lifespan, hastening of flowering and quicker completion of plant lifecycle in isoprene-emitting individuals reveals a significant new role for isoprene (mediated via cytokinin signalling) in altering leaf and plant life-history strategy. This leads to new genomic and metabolic targets to improve plant performance under stress and alter plant phenotype and productivity by manipulating constitutive and exogenous volatile hydrocarbons. The main research paper (to be communicated) will also reassess the evolutionary significance of constitutive volatile hydrocarbon emission, while new independent research projects (emanating from LEAF-OF-LIFE) have begun conducting trials with crop plants.
(a) LEAF-OF-LIFE is the first attempt to understand the relationship between photosynthesis, isoprenoid metabolism and the rate of leaf senescence. The current view sees volatiles as both means and ends of abiotic stress response, and LEAF-OF-LIFE provides a major reappraisal of volatile hydrocarbons as regulators of plant development, a progress beyond the state-of-the art.
(b) LEAF-OF-LIFE successfully combines annual and perennial plant model systems to investigate the constraints on leaf and plant senescence. State-of-the art in plant senescence research is dominated by functional characterisation of select genes, transcriptional factors and enzymes. LEAF-OF-LIFE combines leaf age-specific genomic analysis, photosynthesis and metabolite characterisation to show how the process (senescence) impacts isoprenoid metabolism and in turn how presence of some isoprenoids shape phenotype to determine the course of senescence. This will be seen as a significant break-away from conventional template to understand senescence.
These fundamental advances in our knowledge of isoprene-cytokinin relationships in leaf development and senescence have significant implications for volatile hydrocarbon and hormone interactions overall in altering plant development, phenotype, reproductive senescence and productivity. The sequencing results (in preparation) and analyses will provide further insights into the genomic regions and transcription factors responsible for isoprene-CK mediated changes in leaf and organismal life history. We have reached an evolutionary dead-end in our quest to enhance food grain productivity both due to spatial (plant body architecture and land availability) and temporal (minimum ~70 to 90-day life cycle) limitations. New insights into volatile and hormone interactions regulating leaf senescence obtained during LEAF-OF-LIFE have informed experiments involving crop plants (commenced at CNR), where novel sustainable avenues to maintain productivity are being addressed using volatile and hormone interactions. Results of LEAF-OF-LIFE prompted the MSCA candidate and his host to take a lead role in several new proposals and projects, which take the legacy of LEAF-OF-LIFE forward.