Biology subjects

Pitino, M.

Publications and source records attributed to Pitino, M..

6 recordsLinked to original sources

bioRxiv2026

Antimicrobial peptides expressed by plant-engineered 'symbiont' technology reduces titers and disease symptoms of "Candidatus Liberibacter solanacearum" in potato

Delivery of therapeutic biomolecules into plant vascular tissues remains a challenge in management of vector-borne plant pathogens. The symbiont concept uses reprogrammed Agrobacterium tumefaciens galls (called symbionts) to produce biomolecules while remaining connected to host vasculature. We evaluated whether symbionts expressing antimicrobial peptides (AMPs) suppress Candidatus Liberibacter solanacearum (CLso), the causal agent of potato zebra chip disease. Symbionts were engineered to express a Streptococcus mutans bacteriocin associated with bacterial membrane disruption (Blp-Sm), or an AMP isolated from finger lime and associated with resistance to citrus greening disease (MaSAMP). Effects of AMP-producing symbionts on CLso titers, infection incidence, pathogen movement, and disease symptoms were evaluated in tomato and potato. In tomato, neither AMP significantly reduced CLso titers or infection incidence. However, in potato, AMP-producing symbionts reduced CLso accumulation and movement from CLso-inoculated source shoots into non-inoculated sink shoots connected through underground tubers. Blp-Sm produced the strongest reduction in CLso accumulation and infection incidence in sink tissues. In separate assays where symbionts were established directly on potato seed tubers, MaSAMP significantly reduced CLso titers in stems and tubers and reduced zebra chip symptoms in tubers, despite no reduction of CLso titers in terminal leaves. These findings demonstrate that AMP-producing symbionts suppress vascular pathogen accumulation and movement within plants and highlight the symbiont concept as a potential platform for managing diseases caused by vascular-restricted pathogens. Further, they show the potato-CLso system is a promising infection model to both refine and improve symbiont technology, and to test additional AMPs for potency against related pathogens.

plant biology↗

bioRxiv2026

A scalable approach to inoculate plant viral vectors into plant tissue using non-pathogenic, transgenic galls

Vascular plant pathogens transmitted by insects inflict devastating economic losses on crops worldwide. By obstructing and usurping the natural flow of nutrients, plant infection by these pathogens drastically reduces yields, vigor and productivity. Treating fruit-bearing trees against persistent vascular pathogens poses a unique challenge, as systemic delivery of therapeutics must navigate the compartmentalized architecture of the trees vascular system under changing environmental conditions without disrupting fruit production or long-term tree health. Plant viruses have gained traction as a novel approach to deliver therapies to crop plants, including fruit trees, but delivery of viral vectors to orchards at scale remains a significant challenge. We tested whether transgenic galls can be used to systemically infect plants with a plant virus infectious clone. We combined the plant growth regulator gene cassette from Agrobacterium tumefaciens strain C58 with the wild-type strain of citrus yellow vein associated virus-1 (CY1) on a single plasmid within the T-DNA for plant cell transformation. Using EHA105, a disarmed strain of A. tumefaciens, we inoculated stems with these gall-forming plasmids and initiated systemic CY1 infection in citrus and Arabidopsis thaliana over three independent experiments. We provide proof-of-concept that transgenic galls, referred to as symbionts, can launch the systemic infection of CY1 in economically important and model plants. Symbiont delivery of therapeutic viral vectors is theoretically scalable from inoculation of mother trees within the nursery to millions of trees in the field and may be a valuable tool for the commercial delivery of therapeutic plant viral vectors.

plant biology↗

bioRxiv2025

The "Grove-First" Framework: Starting in the Grove to Find Therapies for Huanglongbing

Citrus greening disease, also known as huanglongbing (HLB), is the most serious vector-borne bacterial disease of citrus world-wide1,2. There is an immediate global need to provide the citrus industry with relief from HLB and a return to profitable citrus production. Standard screening methods for HLB therapeutic treatments typically involve various laboratory-based assays to select treatments with antimicrobial properties3, which then advance to greenhouse and eventually field testing in a workflow that takes multiple years. Unlike traditional lab-first screening, we present a design of experiments framework4,5, referred to as Grove-First, that rapidly screens treatments with regulatory-friendly profiles in commercial citrus groves using trunk injection to select treatments that improve tree health and fruit yield over the course of a single growing season. Using this framework, we identified candidate treatments with effects comparable to or better than the standard oxytetracycline (OTC) on visual tree-health and/or yield indices in an initial screen of HLB-positive 8-year-old Valencia sweet orange trees. Expanded trials in commercial citrus groves allowed us to validate the initial screening results at other locations and in other citrus varieties. Grove-First rapidly accelerated the identification and large-scale field testing of HLB therapies, some of which are available for growers to use immediately and others that require further field testing and/or regulatory actions.

plant biology↗

bioRxiv2023

Plant-derived, nodule-specific cysteine rich peptides inhibit growth and psyllid acquisition of 'Candidatus Liberibacter asiaticus', the citrus Huanglongbing bacterium

AbstractThe Asian citrus psyllid, Diaphorina citri, is a vector of Candidatus Liberibacter asiaticus (CLas), a gram-negative, obligate biotroph whose infection in Citrus species is associated with citrus greening disease, or Huanglongbing (HLB). Strategies to block CLas transmission by D. citri remain the best way to prevent the spread of the disease into new citrus growing regions. However, identifying control strategies to block HLB transmission poses significant challenges, such as the discovery and delivery of antimicrobial compounds targeting the bacterium and overcoming consumer hesitancy towards accepting the treatment. Here, we computationally identified and tested a series of 20-mer nodule-specific cysteine-rich peptides (NCRs) derived from the Mediterranean legume, Medicago truncatula Gaertn. (barrelclover) to identify those peptides that could effectively prevent or reduce CLas infection in citrus leaves and/or prevent CLas acquisition by the bacteriums insect vector, D. citri. A set of NCR peptides were tested in a screening pipeline involving three distinct assays: a bacterial culture assay, a CLas-infected excised citrus leaf assay, and a CLas-infected nymph acquisition assay that included D. citri nymphs, the only stage of D. citris life-cycle that can acquire CLas leading to the development of vector competent adult insects. We demonstrate that a subset of M. truncatula-derived NCRs inhibit both CLas growth in citrus leaves and CLas acquisition by D. citri from CLas-infected leaves. These findings reveal NCR peptides as a new class and source of biopesticide molecules to control CLas for the prevention and/or treatment of HLB.

plant biology↗

bioRxiv2022

Plant production of high affinity nanobodies that block SARS-CoV-2 spike protein binding with its receptor, human angiotensin converting enzyme

Nanobodies(R) (VHH antibodies), are small peptides that represent the antigen binding domain, VHH of unique single domain antibodies (heavy chain only antibodies, HcAb) derived from camelids. Here, we demonstrate production of VHH nanobodies against the SARS-CoV-2 spike proteins in the solanaceous plant Nicotiana benthamiana through transient expression and their subsequent detection verified through western blot. We demonstrate that these nanobodies competitively inhibit binding between the SARS-CoV-2 spike protein receptor binding domain and its human receptor protein, angiotensin converting enzyme 2 (ACE2). We present plant production of nanobodies as an economical and scalable alternative to rapidly respond to therapeutic needs for emerging pathogens in human medicine and agriculture.

bioengineering↗

bioRxiv2021

Quantification of new and archived Diaphorina citri transcriptome data using a chromosomal length D. citri genome assembly reveals the vector's tissue-specific transcriptional response to citrus greening disease

Background Huanglongbing (HLB) is the most serious disease of citrus. HLB is caused by the obligate, intracellular bacterium "Candidatus Liberibacter asiaticus" (CLas). CLas is transmitted by Diaphorina citri, the Asian citrus psyllid. Development of transmission blocking strategies to manage HLB relies on knowledge of CLas-D. citri interactions at the molecular level. Prior transcriptome analyses of CLas-infected and un-infected D. citri point to changes in psyllid biology due to CLas-infection. These studies relied on incomplete versions of the D. citri genome, lacked proper host plant controls, and/or were analyzed using different statistical approaches. Therefore, we used standardized experimental and computational approaches to identify differentially expressed genes in both CLas (+) and CLas (-) D. citri. The comparative analysis utilized the newest chromosomal length D. citri genome assembly Diaci_v3. In this work, we present a quantitative transcriptome analysis of excised heads, salivary glands, midguts and bacteriomes from CLas (+) and CLas (-) insects. Results Each organ had unique transcriptome profiles and responses to CLas infection. Though most psyllids were infected with CLas, CLas-derived transcripts were not detected in all organs. By analyzing the midgut dataset using both the Diaci_v1.1 and v3.0 D. citri genomes, we showed that improved genome assembly led to significant and quantifiable differences in RNAseq data interpretation. Conclusions Our results support the hypothesis that future transcriptome studies on circulative, vector-borne pathogens should be conducted at the tissue specific level using complete, chromosomal-length genome assemblies for the most accurate understanding of pathogen-induced changes in vector gene expression.

genomics↗