redox regulation; b-amylase; Drought stress; ABA; starch-maltose; Arabidopsis thaliana
Zanella Martina, Borghi Gian Luca, Pirone Claudia, Thalmann Matthias, Pazmino Diana, Costa Alex, Santelia Diana, Trost Paolo, Sparla Francesca (2016), beta-amylase 1 (BAM1) degrades transitory starch to sustain proline biosynthesis during drought stress, in JOURNAL OF EXPERIMENTAL BOTANY
, 67(6), 1819-1826.
Horrer Daniel, Fluetsch Sabrina, Pazmino Diana, Matthews Jack S. A., Thalmann Matthias, Nigro Arianna, Leonhardt Nathalie, Lawson Tracy, Santelia Diana (2016), Blue Light Induces a Distinct Starch Degradation Pathway in Guard Cells for Stomatal Opening, in CURRENT BIOLOGY
, 26(3), 362-370.
Thalmann Matthias, Pazmino Diana, Seung David, Horrer Daniel, Nigro Arianna, Meier Tiago, Koelling Katharina, Pfeifhofer Hartwig W., Zeeman Samuel C., Santelia Diana (2016), Regulation of Leaf Starch Degradation by Abscisic Acid Is Important for Osmotic Stress Tolerance in Plants, in PLANT CELL
, 28(8), 1860-1878.
Santelia Diana, Lawson Tracy (2016), Rethinking Guard Cell Metabolism, in PLANT PHYSIOLOGY
, 172(3), 1371-1392.
Hedhly Afif, Vogler Hannes, Schmid Marc W., Pazmino Diana, Gagliardini Valeria, Santelia Diana, Grossniklaus Ueli (2016), Starch Turnover and Metabolism during Flower and Early Embryo Development, in PLANT PHYSIOLOGY
, 172(4), 2388-2402.
Meekins David A., Raththagala Madushi, Auger Kyle D., Turner Benjamin D., Santelia Diana, Koetting Oliver, Gentry Matthew S., Kooi Craig W. Vander (2015), Mechanistic Insights into Glucan Phosphatase Activity against Polyglucan Substrates, in JOURNAL OF BIOLOGICAL CHEMISTRY
, 290(38), 23361-23370.
Santelia Diana, Trost Paolo, Sparla Francesca (2015), New insights into redox control of starch degradation, in CURRENT OPINION IN PLANT BIOLOGY
, 25, 1-9.
Seung David, Thalmann Matthias, Sparla Francesca, Abou Hachem Maher, Lee Sang Kyu, Issakidis-Bourguet Emmanuelle, Svensson Birte, Zeeman Samuel C., Santelia Diana (2013), Arabidopsis thaliana AMY3 Is a Unique Redox- regulated Chloroplastic alpha-Amylase, in JOURNAL OF BIOLOGICAL CHEMISTRY
, 288(47), 33620-33633.
Thalmann Matthias, Santelia Diana, Starch as a determinant of plant fitness under abiotic stress, in New Phytologist
One of the major challenges facing agriculture today is the global water shortage caused by increasing world population and worldwide climate change. The Intergovernmental Panel on Climate Change (IPCC) has concluded that elevated greenhouse gas concentrations are likely to lead to the general drying of the subtropics by the end of this century, creating widespread drought stress in agriculture (IPCC, 2007). Drought and salinity stress threaten the productivity of most field crops. In general, the primary response of plants to water deficit is the inhibition of shoot growth, allowing cellular essential solutes to be diverted from growth requirements to stress-related functions. However, since this growth arrest decreases plant size and hence limits yield potential, the development of crop plants able to withstand salt and drought stress is critical for yield stability.There is increasing evidence that the rapid mobilization of the starch reserve in the leaves in response to stress represents a short-term mechanism of survival, which aids plant fitness. The degradation of starch into soluble sugars sustains the central carbon metabolism in the production of osmoprotectans (sucrose and maltose) and energy generation, limiting the negative effects of stress on plant growth and yield. Thus, the pathway of starch degradation represents an emerging target for genetic engineering of drought stress tolerance. We have recently obtained solid evidence that the Arabidopsis ß-amylase 1 (BAM1), which releases maltose from the exposed nonreducing ends of glucan chains in starch, is a key enzyme involved in the stress-induced degradation of starch in the light. On the contrary, BAM1 is not required for normal nighttime leaf starch degradation when plants are grown under standard conditions. Among the different Arabidopsis ß-amylase isoforms (nine in total), BAM1 is unique in that it displays a very peculiar gene expression profile and is the only one to be redox regulated, possibly explaining why BAM1 has a critical role in starch metabolism only under certain conditions. Up till now, however, the molecular mechanisms that integrate such a multiple level of regulation are poorly characterized and their physiological relevance for BAM1 function in planta has not been investigated. The research we propose will focus on the characterization, at the molecular and biochemical level, of the mechanisms driving BAM1 activity in response to stress, including transcriptional regulation, post-translational modifications, and the functional interaction of BAM1 with other proteins of the starch degradation pathway. The work described in this proposal will take a combination of in vivo and in vitro approaches. The identification of Trans-regulatory elements involved in BAM1 transcriptional regulation will mainly take advantage of the Arabidopsis protoplasts transactivation assay, in combination with other standard methods, such as electrophoresis mobility shift assay and chromatin immunoprecipitation. In addition, we will generate a set of transgenic plants and multiple bam1 mutant combinations for in depth molecular phenotyping, including the analysis of carbon partitioning by “pulse-chase” 14CO2-labelling experiments, starch and sugars accumulation, gene expression levels and enzyme activities. These investigations have the potential to identify, for the first time, novel factors linking stress signaling and the control of carbohydrate metabolism. The manipulation of these factors is a powerful tool for bioengineering complex metabolic pathways in plants.