Ricerc@Sapienza

1. Regulation of elicitor-induced defense responses in plants. Plants have evolved the ability to detect invading microbes by perceiving elicitor, called Pathogen- and Damage-Associated Molecular Patterns (PAMPs and DAMPs), that trigger PAMP-Triggered Immunity (PTI). Examples of PAMPs and DAMPs are chitin, the major structural component of fungal cell walls, and oligogalacturonides (OGs), pectin fragments released from the plant cell wall by fungal polygalacturonases (PGs), respectively. We have previously characterized the main components of the signaling pathways linking perception of OGs to activation of downstream responses. Moreover, we have investigated the role of LysM-containing receptor-like kinases in modulating defense responses, and demonstrated that chimeric PAMP receptors can be engineered to obtain plants more resistant to infections. Activation of PTI is costly and, in the absence of pathogen pressure, might reduce fitness. For instance, accumulation of high levels of OGs in Arabidopsis plants expressing a fusion between a fungal PG and a PG-inhibiting protein leads to growth reduction. On the other hand, plants treated with elicitors acquire a “primed” status, and respond more efficiently to subsequent infections. Current research aims to characterize the mechanisms underlying this phenomenon and the trade-off between defense and growth in plants.

2) Impact and mode of action of cell wall modifications on plant growth and defense. Plants cell walls are the first line of defense against pathogen attack and regulate growth under physiological and stress conditions. Plant cells constantly monitor cell wall integrity to adjust growth and modulate defenses. We have shown that plants expressing a fungal PG constitutively express defense responses and are more resistant to infections, but are severly impaired in growth. These growth defects are partly dependent on apoplastic peroxidases that cause the accumulation of reactive oxygen species (ROS). Current research focuses on the elucidation of the interactions between ROS and resistance to pathogens upon loss of cell wall integrity, and on the identification of novel elements of the pathways linking cell damage, growth reduction and defenses.

3) Biotechnological approaches to exploit lignocellulosic sugars. Lignocellulosic biomass is a promising source of sustainable biofuels and chemicals, but its use  is hampered by its recalcitrance to enzymatic deconstruction. Current research in the lab aims to find biotechnological solutions to improve conversion of biomasses into simple sugars, both modifying the plant cell wall composition and searching for novel sources of degrading enzymes. We are also studying how to use lignocellulosic sugars to grow microalgae in mixotrophy, with the aim of producing biodiesel and nutraceuticals.