Ricerc@Sapienza

The research activity of Dr. Pontiggia mainly focuses on the role of the cell wall in plant development and resistance to pathogens. By using a complementary approach based on genetic, biochemical and molecular biology techniques, she has contributed to understanding how pectin modifications play a role in maintaining a proper balance between plant defense and development. Also the impact of the plant cell wall modifications in the use of plant biomass for industrial applications and biofuel production was an interest of the applicant.
Dr. Pontiggia’s research activity started with the study of molecular mechanisms regulating plant-pathogen interactions, particularly the structure-function relationships of the fungal enzymes polygalacturonase (PG) and its plant-derived protein inhibitors (PGIP). She was involved in the cloning, purification, and biochemical characterization of PG from Colletotrichum lupini and PGIPs from bean, wheat and Arabidopsis. During fungal infection, the action of PGs results in the accumulation of fragments of plant cell wall fragments [i.e., oligogalacturonides (OGs)], which are crucial for the induction of defense responses. The Applicant has provided an
important contribution to the finding that pectin degradation not only activates in vivo defense responses but also regulates growth and hormonal responses.
On the other hand, Dr. Pontiggia’s studies on plant biomass production and modification for biotechnological purposes have elucidated that the controlled expression in planta of the pectic enzymes pectate lyase 1 of Pectobacterium carotovorum improves the saccharification of the cell wall without interfering with the plant development (US patent US8637734B2).
Furthermore, she played a fundamental role in the detection and measurement of OGs in vivo by developing an “ad hoc” carbohydrate analysis methodologies by HPLC-PAD and mass spectrometry (MALDI-TOF and LC-MS/MS). She characterized the levels of OGs in transgenic plants overexpressing a chimeric protein capable of producing OGs, (named “OG-machine plants”) and studied how OGs regulate the plant growth/defense trade off. “OG-machine plants” are more resistant to pathogens but also show reduced growth according to the notion that the growth/defense trade-off is conditioned by a hormonal imbalance where salicylic acid (SA) is involved. Indeed, Dr. Pontiggia showed by LC MS/MS analysis that SA levels are higher in these plants. Notably, the gene coding for a chimeric OG-machine protein, under the control of an inducible promoter, may be used to obtain crop plants with normal growth and enhanced resistance to pathogens. (US patent US20180002705A1.)
Dr. Pontiggia also contributed to the discovery that plants produce oxidized OGs, which are inactive in inducing defense responses, suggesting that OG-mediated processes are finely regulated in a redox-dependent manner. By LC-MS/MS analysis, she identified enzymes involved in OGs oxidation and contributed to their biochemical characterization. In addition to oxidation of OGs, it was proved that oxidation of cellodextrins (other cell wall-derived elicitors of defense responses) also contributes to a homeostatic regulation mechanism of plant immunity.
Another scientific interest of Dr. Pontiggia is the quantitative and functional proteomic and phospho-proteomic analysis of plants during growth and defence. She was successful in the identification of membrane proteins induced by OGs  and in determining the profiles of microsomal proteins expressed during tomato fruit ripening, particularly the proteins involved in the synthesis and modification of cell walls.
Throughout all her scientific and academic career, Dr. Pontiggia was enormously fascinated by plants and their ability to be sessile organisms able to cope with external stresses. Her intention is to continue to study mechanisms governing the physiology of plants and their interaction with the environment.
Daniela Pontiggia follows Einstein's rule in her research activity: "We can't solve problems by using the same kind of thinking we used when we created them." Her 'non-linear' educational, professional and academic background has given both creative thinking, helping to ask the right questions, and many skills that aid in looking for answers