Biology subjects

Ghanim, M.

Publications and source records attributed to Ghanim, M..

5 recordsLinked to original sources

bioRxiv2023

A cyclic adenosine monophosphate (cAMP)-specific phosphodiesterase interacts with begomovirus capsid proteins and modulates virus retention within its vector

Begomoviruses are whitefly-transmitted ss-DNA viruses infecting dicotyledonous plants and contribute to major economic losses to global crop production. Invasion and establishment of an aggressive species of B. tabaci, known as the B cryptic species, has severely constrained vegetable production in the southeastern and southwestern United States. Disruption of genes/pathways critical for whitefly mediated transmission can be effective for the management of begomoviruses. In this study, yeast two hybrid (Y2H)-based screening of B. tabaci cDNA library identified a cyclic adenosine monophosphate (cAMP)-specific phosphodiesterase (PDE4) of the whitefly as an interacting partner with capsid proteins (CPs) of old- and new-world begomoviruses. Interactions of PDE4 with begomovirus CPs were validated by GST-pull-down assays, co-immunoprecipitation, and co-immunolocalization in whitefly midgut. The PDE4 family of enzymes hydrolyze cAMP and regulate intracellular cAMP levels. This study revealed that elevation of cAMP within whitefly by chemically inhibiting or gene (PDE4) silencing resulted in increased retention and transmission of begomoviruses. Similarly, decreased cAMP levels resulted in reduced begomovirus retention. The results of this study demonstrate that whitefly mediated transmission of begomoviruses is regulated by intracellular cAMP by unknown mechanisms. ImportanceBegomoviruses, transmitted by the sweetpotato whitefly, (Bemisa tabaci Gennadius), are the causal agents of many economically important plant virus diseases. Lack of host plant resistance against begomoviruses, high whitefly abundance, and whiteflys ability to develop insecticide resistance rapidly often renders commonly used management practice ineffective. This study demonstrates how begomovirus retention within whitefly and its transmission can be modulated by altering cAMP expression of its insect vector. Naturally occurring bio-pesticides that target insect cAMPs are known. Our findings can lead to alternative strategies for the management of begomoviruses by targeting whitefly cAMP using chemicals, botanicals, or RNAi-based insecticides.

molecular biology↗

bioRxiv2022

Effects of calcium-regulated autophagy on Candidatus Liberibacter solanacearum in carrot psyllid midguts

Candidatus Liberibacter solanacearum (CLso) transmitted by the carrot psyllid, Bactericera trigonica causes carrot yellows in Israel, and has recently gained much importance due to the excessive economical loss. Understanding the interactions between CLso and the psyllid at the cellular level is fundamental for the disease management. Here, we demonstrate the role of calcium ATPase, cytosolic calcium and most importantly Beclin1 in regulating autophagy and its association with Liberibacter. Presence of CLso generates reactive oxygen species and induces the expression of the detoxification enzymes in the psyllid midguts. CLso also induces the expression of both sarco/endoplasmic reticulum Ca2+ pump (SERCA) and 1,4,5-trisphosphate receptors (ITPR) in the midguts, followed by high levels of calcium in the cytosol. Silencing these proteins individually disrupted the calcium levels in the cytosol leading to direct effects on autophagy and thus on Liberibacter. On the other hand, inhibiting Beclin1-phosphorylation through different calcium induced kinases altered the expression of autophagy and CLso abundance. This study establishes a direct correlation between cytosolic calcium levels, autophagy and CLso in the carrot psyllid midgut.

molecular biology↗

bioRxiv2021

Liberibacter solanacearum interacts with host psyllid vitellogenin with its membrane proteins

Candidatus Liberibacter solanacearum (CLso) haplotype D, transmitted by the carrot psyllid Bactericera trigonica is a major constraint in carrot production in Israel. Understanding the molecular interactions between the psyllid vector and CLso can facilitate non-chemical approaches for controlling CLso caused-diseases. In this study, we used CLso outer membrane protein (OmpA) and flagellin as baits to screen for psyllid interacting proteins in a yeast-two hybrid assay. We identified psyllid vitellogenin (Vg) protein to interact with both OmpA and flagellin of CLso. As Vg is often involved in innate immunity with its expression tightly linked to autophagy, a major component of the immune response in the cell, we also analyzed the expression of autophagy-related genes to further elucidate this interaction. We used the juvenile hormone (JH-III) to induce the expression of Vg, thapsigargin for suppressing autophagy, and rapamycin for inducing autophagy. The results revealed that Vg negatively regulates autophagy and vice versa. JH-III induced Vg expression significantly suppressed autophagy and, the levels of CLso significantly increased resulting in a significant mortality of the insect. Although the specific role of Vg remains obscure, the findings presented here identify Vg as an important component in the insect immune responses against CLso and may help in understanding the initial molecular response in the vector against Liberibacter.

molecular biology↗

bioRxiv2020

Non-transmissibility of Pepper whitefly borne vein yellows virus (PeWBVYV) by the Mediterranean species of Bemisia tabaci and identification of a candidate insect receptor protein for poleroviruses

Recent reports of transmission of poleroviruses by whiteflies is indicative of evolution of new virus-vector relationships. Pepper whitefly-borne vein yellows virus (PeWBVYV), was the first report of a polerovirus infecting pepper in Israel which was transmitted by whiteflies (MEAM1) and not aphids. This study reports the inability of the Mediterranean species (MED, Q biotype) of B. tabaci to transmit PeWBVYV. However we show that non-transmission of PeWBVYV by MED is not due to the lack of interaction with the GroEL protein of the Hamiltonella symbiont. Although not transmitted by MED, PeWBVYV was detected in its hemolymph, indicating its translocation across the MED midgut barrier. The aphid transmitted Pepper vein yellows virus 2 (PeVYV-2) was also detected in the hemolymph of MEAM1 whiteflies but PeWBVYV could not be detected in the aphid hemolymph. Interestingly, relative amounts of PeWBVYV in the hemolymph of the, MED was much lower than in hemolymph of MEAM1 whiteflies. We also identified a candidate receptor protein, complement component 1Q sub-complement binding protein (C1QBP) which interacts with the capsid proteins of PeWBVYV and PeVYV-2 but not with the whitefly transmitted Tomato yellow leaf curl virus by a yeast two-hybrid approach using the minor capsid protein (RTD) as bait to screen for interacting proteins against the whitefly cDNA library. C1QBP, is a known receptor of bacterial and viral pathogens but this is the first report of its interaction with a plant virus.

microbiology↗

bioRxiv2020

Biological activity of Ajuga iva extracts against the African cotton leafworm Spodoptera littoralis

The African cotton leafworm Spodoptera littoralis, a major crop pest worldwide, is controlled by chemical insecticides, leading to serious resistance problems. Ajuga plants contain phytoecdysteroids (analogs of arthropod steroid hormones that regulate metamorphoses) and clerodanes (diterpenoids exhibiting antifeedant activity). We analyzed phytoecdysteroids and clerodanes in leaf extracts of the Israeli Ajuga iva by LC-TOF-MS and TLC, and their efficiency at reducing S. littoralis fitness. Castor bean leaves were smeared with an aqueous suspension of dried methanolic crude extract of phytoecdysteroid and clerodanes from A. iva leaves (50, 100 and 250 {micro}g/{micro}l). First and third instars of S. littoralis larvae were fed with 1 treated leaf for 3 and 4 days, respectively. Mortality, larval weight gain, relative growth rate and survival were compared to feeding on control leaves. To evaluate and localize A. iva crude leaf extract activity in the insect gut, we used DAPI and phalloidin staining. Crude extract of A. iva leaves (50, 100 and 250 {micro}g/{micro}l) significantly increased mortality of first instar S. littoralis larvae (36%, 70% and 87%, respectively) compared to controls (6%). Third instar larval weight gain decreased significantly (by 52%, 44% and 30%, respectively), as did relative growth rate (-0.05 g/g day, compared to the relevant controls). S. littoralis larvae were further affected at later stages, with few survivors. Insect-gut staining showed that 250 {micro}g/{micro}l crude leaf extract reduces gut size, with relocation of nuclei and abnormal actin-filament organization. Our results demonstrate the potential of A. iva extract for alternative, environmentally safe insect-pest control. Key MessageInsects cause severe damage to numerous crops and their control relies on pesticides. Green control is becoming increasingly popular due to concerns about the negative impacts of pesticides on the environment. Phytoecdysteroids are found in Ajuga plants and affect a wide range of insects at very low concentrations. Here we demonstrate that crude extract from Ajuga iva alters the development of Spodoptera littoralis. Phytoecdysteroids may therefore be beneficial in IPM programs.

plant biology↗