Stem-pitting caused by Citrus tristeza virus is associated with increased phloem occlusion.

Stem-pitting (SP) disease results from disruption of normal phloem and xylem development. In citrus, a characteristic manifestation of SP caused by Citrus tristeza virus (CTV) is phloem regeneration. We hypothesized that phloem regeneration occurs due to reduced functionality of CTV infected phloem cells.

Gene silencing of cathepsins B and L using CTV-based, plant-mediated RNAi interferes with ovarial development in Asian citrus psyllid (ACP), .

Kuwayama (Hemiptera: Liviidae) is a vector of the bacteria Liberibacter americanus (Lam) and Liberibacter asiaticus (Las), which are phloem-restricted and associated with the most important and destructive worldwide citrus disease, Huanglongbing (HLB). Currently, no cure for HLB has been described. Therefore, measures have focused on reducing populations.

Bacterial Pesticidal Protein Mpp51Aa1 Delivered via Transgenic Citrus Severely Impacts the Fecundity of Asian Citrus Psyllid, Diaphorina citri.

The Asian citrus psyllid (ACP) Diaphorina citri vectors the causative agent of citrus greening disease that has the capacity to decimate citrus production. As an alternative and more sustainable approach to manage D. citri than repeated application of chemical insecticides, we investigated the potential use of the bacteria-derived pesticidal protein, Mpp51Aa1, when delivered by transgenic Citrus sinensis cv.

Comparative transcriptome analysis of tree infected with stem pitting mutants provides new insight into the role of phloem regeneration in stem pitting disease.

Stem pitting is a complex and economically important virus-associated disease of perennial woody plants. Molecular mechanisms and pathways occurring during virus-plant interaction that result in this phenomenon are still obscure. Previous studies indicated that different (CTV) mutants induce defined stem pitting phenotypes ranging from mild (CTVΔp13) to severe (CTVΔp33) in trees.

Genetic Modification of for Expression of the Bacterial Pesticidal Protein Cry1Ba1.

The curry leaf tree, , is highly attractive to the Asian citrus psyllid, , which vectors the bacterial causative agent of citrus greening or huanglongbing disease. This disease has decimated citrus production in Florida and in other citrus-producing countries. As exhibits high affinity for feeding on young leaves of , transgenic expressing bacteria-derived pesticidal proteins such as Cry1Ba1 have potential for management when planted in or adjacent to citrus groves.

P33 Protein is Required for Efficient Transmission by the Aphid () (Kirkaldy).

Plant viruses are threatening many valuable crops, and (CTV) is considered one of the most economically important plant viruses. CTV has destroyed millions of citrus trees in many regions of the world. Consequently, understanding of the transmission mechanism of CTV by its main vector, the brown citrus aphid, () (Kirkaldy) may lead to better control strategies for CTV.

Functional study of CHS gene family members in citrus revealed a novel CHS gene affecting the production of flavonoids.

Background: Citrus flavonoids are considered as the important secondary metabolites because of their biological and pharmacological activities. Chalcone synthase (CHS) is a key enzyme that catalyses the first committed step in the flavonoid biosynthetic pathway. CHS genes have been isolated and characterized in many plants.

A 5'-proximal region of the Citrus tristeza virus genome encoding two leader proteases is involved in virus superinfection exclusion.

Superinfection exclusion (SIE), a phenomenon in which a primary virus infection prevents a secondary infection with the same or closely related virus, has been observed with various viruses. Earlier we demonstrated that SIE by Citrus tristeza virus (CTV) requires viral p33 protein. In this work we show that p33 alone is not sufficient for virus exclusion.

A viral protein mediates superinfection exclusion at the whole-organism level but is not required for exclusion at the cellular level.

Unlabelled: Superinfection exclusion (SIE), the ability of an established virus infection to interfere with a secondary infection by the same or a closely related virus, has been described for different viruses, including important pathogens of humans, animals, and plants. Citrus tristeza virus (CTV), a positive-sense RNA virus, represents a valuable model system for studying SIE due to the existence of several phylogenetically distinct strains. Furthermore, CTV allows SIE to be examined at the whole-organism level.

Citrus tristeza virus-based RNAi in citrus plants induces gene silencing in Diaphorina citri, a phloem-sap sucking insect vector of citrus greening disease (Huanglongbing).

A transient expression vector based on Citrus tristeza virus (CTV) is unusually stable. Because of its stability it is being considered for use in the field to control Huanglongbing (HLB), which is caused by Candidatus Liberibacter asiaticus (CLas) and vectored by Asian citrus psyllid, Diaphorina citri. In the absence of effective control strategies for CLas, emphasis has been on control of D.

Exploring the limits of vector construction based on Citrus tristeza virus.

We examined the limits of manipulation of the Citrus tristeza virus (CTV) genome for expressing foreign genes in plants. We previously created a vector with a foreign gene cassette inserted between the major and minor coat protein genes, which is position 6 from the 3' terminus. Yet, this virus has 10 3'-genes with several other potential locations for expression of foreign genes.

Agroinoculation of Citrus tristeza virus causes systemic infection and symptoms in the presumed nonhost Nicotiana benthamiana.

Citrus tristeza virus (CTV) naturally infects only some citrus species and relatives and within these it only invades phloem tissues. Failure to agroinfect citrus plants and the lack of an experimental herbaceous host hindered development of a workable genetic system. A full-genome cDNA of CTV isolate T36 was cloned in binary plasmids and was used to agroinfiltrate Nicotiana benthamiana leaves, with or without coinfiltration with plasmids expressing different silencing-suppressor proteins.

Survey of leafhopper species in almond orchards infected with almond witches'-broom phytoplasma in Lebanon.

Leafhoppers (Hemiptera: Auchenorrhyncha: Cicadellidae) account for more than 80% of all "Auchenorrhynchous" vectors that transmit phytoplasmas. The leafhopper populations in two almond witches'-broom phytoplasma (AlmWB) infected sites: Tanboureet (south of Lebanon) and Bourj El Yahoudieh (north of Lebanon) were surveyed using yellow sticky traps. The survey revealed that the most abundant species was Asymmetrasca decedens, which represented 82.

Marker-Assisted Selection of Tomato Genotypes with the I-2 Gene for Resistance to Fusarium oxysporum f. sp. lycopersici Race 2.

Fusarium vascular wilt, caused by Fusarium oxysporum f. sp. lycopersici, affects tomatoes worldwide.

Tolerance in Cucumber to Cucurbit yellow stunting disorder virus.

Cucurbit yellow stunting disorder virus (CYSDV), genus Crinivirus and family Closteroviridae, has emerged as a serious whitefly-transmitted virus of cucurbit crops, causing between 30 and 50% yield losses. Development of resistant cultivars represents an economically and environmentally sound approach to management of this disease. In all, 124 cucumber accessions were evaluated for reaction to CYSDV under high inoculum pressure over three growing seasons.