Assessing Huanglongbing Severity and Canopy Parameters of the Huanglongbing-Affected Citrus in Texas Using Unmanned Aerial System-Based Remote Sensing and Machine Learning.

Huanglongbing (HLB), also known as citrus greening disease, is a devastating disease of citrus. However, there is no known cure so far. Recently, under Section 24(c) of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), a special local need label was approved that allows the trunk injection of antimicrobials such as oxytetracycline (OTC) for HLB management in Florida.

Global citrus root microbiota unravels assembly cues and core members.

Introduction: Citrus is one of the most important fruit crops worldwide, and the root-associated microbiota can have a profound impact on tree health and growth.

Methods: In a collaborative effort, the International Citrus Microbiome Consortium investigated the global citrus root microbiota with samples collected from nine citrus-producing countries across six continents. We analyzed 16S rDNA and ITS2 amplicon sequencing data to identify predominant prokaryotic and fungal taxa in citrus root samples.

Inhibition of a conserved bacterial dual-specificity phosphatase confers plant tolerance to Liberibacter spp.

"Candidatus Liberibacter spp." are insect-vectored, fastidious, and vascular-limited phytopathogens. They are the presumptive causal agents of potato zebra chip, tomato vein clearing, and the devastating citrus greening disease worldwide.

Identification and Characterization of Potato Zebra Chip Resistance Among Wild Species.

Potato zebra chip (ZC) disease, associated with the uncultured phloem-limited bacterium, Liberibacter solanacearum (Lso), is transmitted by the potato psyllid . Potato ZC disease poses a significant threat to potato production worldwide. Current management practices mainly rely on the control of the psyllid to limit the spread of Lso.

An Overview of the Mechanisms Against " Liberibacter asiaticus": Virulence Targets, Citrus Defenses, and Microbiome.

Citrus Huanglongbing (HLB) or citrus greening, is the most destructive disease for citrus worldwide. It is caused by the psyllid-transmitted, phloem-limited bacteria " Liberibacter asiaticus" (Las). To date, there are still no effective practical strategies for curing citrus HLB.

Transcriptome Profiling of ' Liberibacter asiaticus' in Citrus and Psyllids.

' Liberibacter asiaticus' (Las) is an emergent bacterial pathogen that is associated with the devastating citrus huanglongbing (HLB). Vectored by the Asian citrus psyllid, Las colonizes the phloem tissue of citrus, causing severe damage to infected trees. So far, cultivating pure Las culture in axenic media has not been successful, and dual-transcriptome analyses aiming to profile gene expression in both Las and its hosts have a low coverage of the Las genome because of the low abundance of bacterial RNA in total RNA extracts from infected tissues.

Potato Zebra Chip: An Overview of the Disease, Control Strategies, and Prospects.

Potato ( L.) is an important food crop worldwide. As the demand for fresh and processed potato products is increasing globally, there is a need to manage and control devastating diseases such as zebra chip (ZC).

Metagenomic Analysis Reveals the Mechanism for the Observed Increase in Antibacterial Activity of Penicillin against Uncultured Bacteria Liberibacter asiaticus Relative to Oxytetracycline in Planta.

Citrus huanglongbing (HLB) is a devastating disease for the citrus industry. The previous studies demonstrated that oxytetracycline and penicillin are effective antibiotics against Liberibacter asiaticus (Las). However, since Las is uncultured, the mechanisms of action of antibiotics against Las are still unclear.

Citrus Vascular Proteomics Highlights the Role of Peroxidases and Serine Proteases during Huanglongbing Disease Progression.

Huanglongbing (HLB) is the most devastating and widespread citrus disease. All commercial citrus varieties are susceptible to the HLB-associated bacterium, Liberibacter asiaticus (Las), which resides in the phloem. The phloem is part of the plant vascular system and is involved in sugar transport.

Incidence, Severity, and Characterization of Phytophthora Foot Rot of Citrus in Texas and Implications for Disease Management.

-induced foot rot, also known as gummosis, is an important disease affecting citrus production worldwide. In Texas, the third-largest citrus-producing state in the United States, limited information is available on the etiology and epidemiology of foot rot in commercial orchards. This study comprises a survey of foot rot incidence and severity in Texas and the characterization of isolates associated with the disease.

Genome-wide analyses of Liberibacter species provides insights into evolution, phylogenetic relationships, and virulence factors.

'Candidatus Liberibacter' species are insect-transmitted, phloem-limited α-Proteobacteria in the order of Rhizobiales. The citrus industry is facing significant challenges due to huanglongbing, associated with infection from 'Candidatus Liberibacter asiaticus' (Las). In order to gain greater insight into 'Ca.

The RNA-Binding Protein CsrA Controls Virulence in by Regulating RelA, RcsB, and FlhD at the Posttranscriptional Level.

CsrA, an RNA-binding protein, binds to target transcripts and alters their translation or stability. In CsrA positively regulates the expression of type III secretion system (T3SS), exopolysaccharide amylovoran, and motility. In this study, the global effect of CsrA and its noncoding small RNA (ncsRNA) in was determined by RNA-seq, and potential molecular mechanisms of CsrA-dependent virulence regulation were examined.

The structure and function of the global citrus rhizosphere microbiome.

Citrus is a globally important, perennial fruit crop whose rhizosphere microbiome is thought to play an important role in promoting citrus growth and health. Here, we report a comprehensive analysis of the structural and functional composition of the citrus rhizosphere microbiome. We use both amplicon and deep shotgun metagenomic sequencing of bulk soil and rhizosphere samples collected across distinct biogeographical regions from six continents.

A Pathogen Secreted Protein as a Detection Marker for Citrus Huanglongbing.

The citrus industry is facing an unprecedented crisis due to Huanglongbing (HLB, aka citrus greening disease), a bacterial disease associated with the pathogen Liberibacter asiaticus (Las) that affects all commercial varieties. Transmitted by the Asian citrus psyllid (ACP), Las colonizes citrus phloem, leading to reduced yield and fruit quality, and eventually tree decline and death. Since adequate curative measures are not available, a key step in HLB management is to restrict the spread of the disease by identifying infected trees and removing them in a timely manner.

Lon protease modulates virulence traits in Erwinia amylovora by direct monitoring of major regulators and indirectly through the Rcs and Gac-Csr regulatory systems.

Lon, an ATP-dependent protease in bacteria, influences diverse cellular processes by degrading damaged, misfolded and short-lived regulatory proteins. In this study, we characterized the effects of lon mutation and determined the molecular mechanisms underlying Lon-mediated virulence regulation in Erwinia amylovora, an enterobacterial pathogen of apple. Erwinia amylovora depends on the type III secretion system (T3SS) and the exopolysaccharide (EPS) amylovoran to cause disease.

The RNA-binding protein CsrA plays a central role in positively regulating virulence factors in Erwinia amylovora.

The GacS/GacA two-component system (also called GrrS/GrrA) is a global regulatory system which is highly conserved among gamma-proteobacteria. This system positively regulates non-coding small regulatory RNA csrB, which in turn binds to the RNA-binding protein CsrA. However, how GacS/GacA-Csr system regulates virulence traits in E.

The bacterial alarmone (p)ppGpp activates the type III secretion system in Erwinia amylovora.

Unlabelled: The hypersensitive response and pathogenicity (hrp) type III secretion system (T3SS) is a key pathogenicity factor in Erwinia amylovora. Previous studies have demonstrated that the T3SS in E. amylovora is transcriptionally regulated by a sigma factor cascade.

Conserved aspartate and lysine residues of RcsB are required for amylovoran biosynthesis, virulence, and DNA binding in Erwinia amylovora.

In Erwinia amylovora, the Rcs phosphorelay system is essential for amylovoran production and virulence. To further understand the role of conserved aspartate residue (D56) in the phosphor receiver (PR) domain and lysine (K180) residue in the function domain of RcsB, amino acid substitutions of RcsB mutant alleles were generated by site-directed mutagenesis and complementation of various rcs mutants were performed. A D56E substitution of RcsB, which mimics the phosphorylation state of RcsB, complemented the rcsB mutant, resulting in increased amylovoran production and gene expression, reduced swarming motility, and restored pathogenicity.

Co-regulation of polysaccharide production, motility, and expression of type III secretion genes by EnvZ/OmpR and GrrS/GrrA systems in Erwinia amylovora.

The EnvZ/OmpR and GrrS/GrrA systems, two widely distributed two-component systems in gamma-Proteobacteria, negatively control amylovoran biosynthesis in Erwinia amylovora, and the two systems regulate motility in an opposing manner. In this study, we examined the interplay of EnvZ/OmpR and GrrS/GrrA systems in controlling various virulence traits in E. amylovora.

Alternative sigma factor RpoN and its modulation protein YhbH are indispensable for Erwinia amylovora virulence.

In Erwinia amylovora, ECF (extracytoplasmic functions) alternative sigma factor HrpL regulates the transcription of hrp (hypersensitive response and pathogenicity)-type III secretion system (T3SS) genes by binding to a consensus sequence known as the hrp box in hrp gene promoters. In turn, the expression of hrpL has been proposed to be positively controlled by alternative sigma factor 54 (σ(54)) (RpoN) and HrpS, a member of the σ(54) enhancer-binding proteins (EBPs). However, the function of RpoN has not been characterized genetically in E.

Xylella fastidiosa: a model for analyzing agricultural biosecurity.

The threat to national security posed by the hostile release of human pathogens has been extensively documented. However, conclusions regarding the menace that plant pests and pathogens pose to the national economy and food supply are less developed. Here we present a risk analysis for the arrival and spread of foreign plant pathogens into the U.

RNAi screen of endoplasmic reticulum-associated host factors reveals a role for IRE1alpha in supporting Brucella replication.

Brucella species are facultative intracellular bacterial pathogens that cause brucellosis, a global zoonosis of profound importance. Although recent studies have demonstrated that Brucella spp. replicate within an intracellular compartment that contains endoplasmic reticulum (ER) resident proteins, the molecular mechanisms by which the pathogen secures this replicative niche remain obscure.