Biology subjects

Paolocci, F.

Publications and source records attributed to Paolocci, F..

3 recordsLinked to original sources

bioRxiv2025

It runs in the family: Discovery of enzymes in the oleuropein pathway in Olive (Olea europaea) by comparative transcriptomics

Olive (Olea europaea L.) is one of the most important crop trees, with olive oil being a key ingredient of the Mediterranean diet. Oleuropein, an oleoside-type secoiridoid, is the major determinant of flavor and quality of olive oil. Iridoid biosynthesis has been elucidated in Catharanthus roseus, which produces secologanin-type secoiridoids, but iridoid biosynthesis in other species remains unresolved. In this work, we sequenced RNA from olive fruit mesocarp of six commercial olive cultivars with varying oleuropein content, during maturation and ripening. Using this data we discovered three polyphenol oxidases with oleuropein synthase (OS) activity, a novel oleoside-11-methyl ester glucosyl transferase (OMEGT) synthesizing a potential intermediate in the route, and a 7-epi-loganic acid O-methyltransferase (7eLAMT). Interestingly, integrating transcriptomics data from 15 plant species from three iridoid-producing plant orders (Lamiales, Gentianales, and Cornales), and tissue expression panels from Jasminum sambac and Fraxinus excelsior, we discovered two 2-oxoglutarate dependent dioxygenases (named 7eLAS) that synthesize 7-epi-loganic acid; in contrast C. roseus 7-deoxy-loganic acid hydroxylase (7DLH), a known bottleneck in MIA production, is a cytochrome p450. This comparative co-expression method, which combines guilt by association and comparative transcriptomics approaches, can successfully leverage big datasets for untargeted discovery of enzymes. Key FindingsO_LIExpression of genes involved in iridoid biosynthesis, from the early MEP pathway to the last step of oleuropein biosynthesis, decreases during olive fruit maturation. C_LIO_LIWe discovered an oxoglutarate dependent dioxygenase, 7-epi-loganic acid synthase (7eLAS), catalyzing the stereoselective oxidation of 7-deoxy-loganic acid to 7-epi-loganic acid, in a reaction analogous to C. roseus 7-deoxy-loganic acid hydroxylase (7DLH), a cytochrome p450. C_LIO_LIWe report a 7-epi-loganic acid O-methyltransferase (7eLAMT) orthologous to Catharanthus roseus loganic acid O-methyltransferase and found a novel oleoside-11-methyl ester glucosyl transferase (OMEGT) synthesizing 7-{beta}-1-D-glucopyranosyl-oleoside-11-methyl ester, a potential intermediate in the oleuropein biosynthesis route. C_LIO_LIWe discovered three olive polyphenol oxidases that have oleuropein synthase (OS) activity, catalyzing the conversion of ligstroside to oleuropein. C_LI

biochemistry↗

bioRxiv2024

Co-cultivation with Azolla affects the metabolome of whole rice plant beyond canonical inorganic nitrogen fertilization

Azolla spp. are floating ferns used for centuries as biofertilizers to enrich the soil with inorganic nitrogen and improve rice yields. In this study, rice plants were grown together with Azolla by maintaining a low and constant concentration of inorganic nitrogen. We employed a combination of non-targeted metabolomics, chemometrics, and molecular networking to dissect the impact of Azolla co-cultivation on the metabolome of rice roots-and leaves. Our analyses revealed that Azolla releases a broad range of metabolites in the culture medium, mainly comprising small peptides and flavonoids. Moreover, in rice co-cultivated with Azolla, we observed a systematic response in the upregulation of metabolites that started from the roots and, over time, shifted to the leaves. During the early stages of co-cultivation, Azolla led to the accumulation of small peptides, lipids, and carbohydrates in roots, and flavonoid glycosides and carbohydrates in leaves of rice. Consistent with these results, transcriptomics analysis of rice roots indicated significant changes in the expression of genes coding for small peptide and lipid transporters, and genes involved in amino acid salvage and biosynthesis. Overall, our study highlights novel growth-promoting effects of Azolla on rice which could facilitate the development of sustainable techniques to increase yields. HighlightsThe aquatic fern Azolla synthesizes and releases a broad range of growth promoting metabolites (i.e. small peptides) that can be absorbed by the roots of co-cultivated rice plants

plant biology↗

bioRxiv2024

Co-cultivating rice plants with Azolla filiculoides modifies root architecture and timing of developmental stages

Strategies for increasing the yield of rice, the staple food for more than half of the global population, are needed to keep pace with the expected worldwide population increase, and sustainably forefront the challenges posed by climate change. In Southern-East Asian countries, rice farming benefits from the use of Azolla spp. for nitrogen supply. In virtue of the symbiosis with the nitrogen-fixing cyanobacterium Trichormus azollae, Azolla spp. are ferns that release nitrogen into the environment upon decomposition of their biomass. However, if and to what extent actively growing Azolla plants impact on the development of co-cultivated rice plantlets remains to be understood. Here, we show that actively growing Azolla filiculoides plants alter the architecture of the roots and accelerates the differentiation and proliferation of leaves and tillers in co-cultivated rice plants. These changes result from an intimate cross-talk between rice and A. filiculoides, in which hormones and other metabolites released by the fern in the growth medium trigger an alteration in the rice root transcriptome and the hormonal profiles of both roots and leaves. Overall, the present data let us argue that co-cultivation with A. filiculoides might prime rice plants to better deal with both abiotic and biotic stress. HighlightAzolla filiculoides alters the root transcriptome and hormonal balance in both roots and leaves of co-cultivated rice plantlets, thereby interfering with the progression of their developmental programs

plant biology↗