Biology subjects

Diretto, G.

Publications and source records attributed to Diretto, G..

4 recordsLinked to original sources

bioRxiv2026

Hydroxylated monoterpenes mimic bacterial attack to trigger jasmonate-dependent self-amplifying immunity in tomato

Hydroxylated monoterpenes (HMTPs) are emitted during resistant tomato-Pseudomonas syringae interactions and confer antibacterial resistance, yet their integration into immune signalling remains poorly understood. Here we show that HMTPs act as endogenous mimics of pathogen attack that engage canonical defence pathways in tomato. Using -terpineol as a representative HMTP, we demonstrate that this volatile activates MPK kinase-, calcium- and reactive oxygen species (ROS)-dependent signalling, promotes jasmonate and salicylic acid accumulation, and induces pathogen-like stomatal immunity independently of abscisic acid. Functional analyses revealed that HMTPs biosynthesis depends on ROS and jasmonate signalling, and HMTPs further promote their own accumulation, establishing a self-reinforcing feed-forward mechanism. Moreover, in vitro oxidative conditions drive chemical remodelling and selective interconversion among HMTPs, contributing to volatile diversification and favouring the accumulation of highly bioactive hydroxylated forms. Consistently, deuterium-labelled linalool is incorporated into plant metabolism and converted into deuterated -terpineol in planta, providing direct evidence for volatile interconversion. Together, our findings establish HMTPs as dynamic amplifiers of tomato antibacterial immunity and key actors in pathogen-associated signalling.

plant biology↗

bioRxiv2022

Dually biofortified cisgenic tomatoes with increased flavonoids and branched-chain amino acids content

Higher dietary intakes of flavonoids may have a beneficial role in cardiovascular disease prevention. Additionally, supplementation of branched-chain amino acids (BCAAs) in vegan diets can reduce risks associated to their deficiency, particularly in older adults, which can cause loss of skeletal muscle strength and mass. Most plant-derived foods contain only small amounts of BCAAs and those plants with high levels of flavonoids are not eaten broadly. Here we describe the generation of metabolically-engineered cisgenic tomatoes enriched in both flavonoids and BCAAs. In this approach, coding and regulatory DNA elements, all derived from the tomato genome, were combined to obtain a herbicide-resistant version of an acetolactate synthase (mSlALS) gene expressed broadly, and a MYB12-like transcription factor (SlMYB12) expressed in a fruit-specific manner. The mSlALS played a dual role, as a selectable marker as well as being key enzyme in BCAA enrichment. The resulting cisgenic tomatoes were highly enriched in Leucine (21-fold compared to wild type levels), Valine (9-fold), Isoleucine (3-fold), and concomitantly biofortified in several antioxidant flavonoids including kaempferol (64-fold) and quercetin (45-fold). Comprehensive metabolomic and transcriptomic analysis of the biofortified cisgenic tomatoes revealed marked differences to wild type and could serve to evaluate the safety of these biofortified fruits for human consumption.

bioengineering↗

bioRxiv2022

Combination of the Systemin peptide with the beneficial fungus Trichoderma afroharzianum T22 improves plant defense responses against pests and diseases

Trichoderma spp. are among the most widely used plant beneficial fungi in agriculture. A novel approach to enhance their effectiveness in plant defense is to use the fungi in combination with bioactive molecules including plant-derived compounds. Here, we show that plant treatment with Trichoderma afroharzianum (strain T22) and Systemin (Sys), a tomato plant peptide active in triggering plant defense, confers protection against the fungal pathogens Fusarium oxysporum, Botrytis cinerea and the insect pest Tuta absoluta. The observed defensive response was associated with increased accumulation of metabolites and transcripts involved in the Jasmonic acid (JA) pathway. Our findings suggest that the innovative combination of T. afroharzianum T22 and Sys can result in a more effective and robust control of different biotic stress agents.

genetics↗

bioRxiv2019

Efficient production of saffron crocins and picrocrocin in Nicotiana benthamiana using a virus-driven system

Crocins and picrocrocin are glycosylated apocarotenoids responsible, respectively, for the color and the unique taste of the saffron spice, known as red gold due to its high price. Several studies have also shown the health-promoting properties of these compounds. However, their high costs hamper the wide use of these metabolites in the pharmaceutical sector. We have developed a virus-driven system to produce remarkable amounts of crocins and picrocrocin in adult Nicotiana benthamiana plants in only two weeks. The system consists of viral clones derived from tobacco etch potyvirus that express specific carotenoid cleavage dioxygenase (CCD) enzymes from Crocus sativus and Buddleja davidii. Metabolic analyses of infected tissues demonstrated that the sole virus-driven expression of C. sativus CsCCD2L or B. davidii BdCCD4.1 resulted in the production of crocins, picrocrocin and safranal. Using the recombinant virus that expressed CsCCD2L, accumulations of 0.2% of crocins and 0.8% of picrocrocin in leaf dry weight were reached in only two weeks. In an attempt to improve apocarotenoid content in N. benthamiana, co-expression of CsCCD2L with other carotenogenic enzymes, such as Pantoea ananatis phytoene synthase (PaCrtB) and saffron {beta}-carotene hydroxylase 2 (BCH2), was performed using the same viral system. This combinatorial approach led to an additional crocin increase up to 0.35% in leaves in which CsCCD2L and PaCrtB were co-expressed. Considering that saffron apocarotenoids are costly harvested from flower stigma once a year, and that Buddleja spp. flowers accumulate lower amounts, this system may be an attractive alternative for the sustainable production of these appreciated metabolites.

plant biology↗