Biology subjects

Aly, R.

Publications and source records attributed to Aly, R..

5 recordsLinked to original sources

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↗

bioRxiv2019

Mutagenesis of two homologs ATP Binding cassette protein in tomato by CRISPR/Cas9 provide resistance against the plant parasite Phelipanche aegyptiaca

Plant parasitic weed Phelipanche aegyptiaca and Orobanche spp. are obligate plant parasites that cause heavy damage to agricultural crop plants. Germination of the parasite seeds require exposure to specific chemical known as strigolactone [SL]. The plant hormone SL is derived from plant carotenoids via cleavage by CCD7 and CCD8 enzymes and exuded by the host roots to the rhizosphere. Here, we provide evidence that CRISPR/Cas9 mediated targeted mutagenesis of two homologues ATP Binding cassette (ABC) protein in tomato (Solyc08g067610 and Solyc08g067620), significantly reduced the germination of the parasitic weed P.aegyptiaca. Constructs harboring specific single guide RNA were prepared and targeted against conserved region in the above tomato genes (Solyc08g067610 and Solyc08g067620). Selected T0-mutated tomato plants showed different type of deletions at both locuses. Furthermore, genotype analysis of T1 plants showed that the introduced mutations stably inherited to next generation with no identified off-targets. Mutated tomato lines, showed more branching, enhanced growth of axillary buds, reduced length of primary stems and significantly reduced development of the parasitic weed P. aegyptiaca as compared to wild type plants. Moreover, in ABCCas9 mutants the expression level of the genes (CCD8 and MAX1) related to SL biosynthesis were decreased, without alteration in the root extract orobanchol [SL] as compared to control plants. Development of genetic resistance based on genome editing of host key genes are novel approaches for enhancing host-parasite resistance. The current study offers insights into ABC protein homologs and mutagenesis of ABC protein that could be used in the development of efficient method to reduce parasitic weed germination.

plant biology↗

bioRxiv2019

Development of specific molecular markers to distinguish and quantify broomrape species in a soil sample from infected field

Broomrapes (Orobanche and Phelipanche) are obligate holoparasites that cause heavy damage to numerous crops, reducing the yield and its quality. The parasite develops in the soil and exerts the greatest damage prior to its emergence; therefore the majority of field loss may occur before diagnosis of infection. Because of the parasite tiny seed size (200 to 300 m) and dormancy for several decades in the field, it is very difficult to diagnose the parasite by conventional methods. Therefore, to restrict the parasite seeds spread and contamination to other commercial fields, development of DNA-based molecular markers to identify and quantify broomrape species in a soil sample is much needed. In this study, we developed a specific molecular marker (RbcL-M) based on rbcL (large subunit of the ribulose-bisphosphate carboxylase) gene from Orobanche crenata to differentiate between Orobanche crenata and Orobanche cumana. Likewise, a specific marker (ITS100) based upon unique sequences in the internal transcribed spacer (ITS) regions of the nuclear ribosomal DNA of Phelipanche aegyptiaca to quantify three species of the parasite (P. aegyptiaca, O. crenata and O. cumana) in a soil sample was developed. Genomic DNA was extracted from soil samples artificially infested with broomrape seeds or tissue of P. aegyptiaca, O. cumana and O. crenata and subjected to PCR analysis. RbcL-M marker successfully amplified a PCR product (1300bp) when O. crenata seeds or tissues (collected from several locations in Israel) were added to the soil samples. The same marker amplified a PCR product (1000bp) when O. cumana seeds or tissues were added to the soil samples. RbcL-M marker did not amplify soil samples with seeds or tissues of P. aegyptiaca or any soil-borne DNA. Furthermore, using ITS-100 marker and Real-Time PCR analysis, allowed quantitative diagnostic of the parasite in a soil sample from infected sunflower field. As expected the universal internal control primer (UCP-555) amplified a PCR product (555bp) when genomic DNA extracted from soil samples with or without broomrape tissues. The development of an efficient, simple and robust molecular marker to detect and distinguish between broomrape species, has a significant insights on assessment the level of infestation and planning eradication program to the parasite in a field crop.

molecular biology↗

bioRxiv2019

Genome-Scale reconstruction of Paenarthrobacter aurescens TC1 metabolic model towards the study of atrazine bioremediation

Atrazine is an herbicide and pollutant of great environmental concern that is naturally biodegraded by microbial communities. The efficiency of biodegradation can be improved through the stimulating addition of fertilizers, electron acceptors, etc. In recent years, metabolic modelling approaches have become widely used as an in silico tool for organism-level phenotyping and the subsequent development of metabolic engineering strategies including biodegradation improvement. Here, we constructed a genome scale metabolic model, iRZ960, for Paenarthrobacter aurescens TC1 - a widely studied atrazine degrader - aiming at simulating its degradation activity. A mathematical stoichiometric metabolic model was constructed based on a published genome sequence of P. aurescens TC1. An Initial draft model was automatically constructed using the RAST and KBase servers. The draft was developed into a predictive model through semi-automatic gap-filling procedures including manual curation. In addition to growth predictions under different conditions, model simulations were used to identify optimized media for enhancing the natural degradation of atrazine without a need in strain design via genetic modifications. Model predictions for growth and atrazine degradation efficiency were tested in myriad of media supplemented with different combinations of carbon and nitrogen sources that were verified in vitro. Experimental validations support the reliability of the models predictions for both bacterial growth (biomass accumulation) and atrazine degradation. Predictive tools, such as the presented model, can be applied for achieving optimal biodegradation efficiencies and for the development of ecologically friendly solutions for pollutant degradation in changing environments.

bioinformatics↗

bioRxiv2018

Use of a visible reporter marker- myb-related gene in crop plants to minimize herbicide usage against weeds

Weeds, a main threat to agricultural productivity worldwide, are mostly controlled by herbicides. To minimize herbicide usage by targeting it to weedy areas, we developed a new image-based methodology for robust weed detection that relies on manipulating the crop plants leaf hue, without affecting crop fitness. We generated transgenic tobacco (Nicotiana tabacum Xanthi) lines overexpressing anthocyanin pigment as a traceable marker that differentiates transgenes from the surrounding weeds at an early stage. Transformation with the anthocyanin VlmybA1-2 gene produced purple-colored leaves. Subsequent gene silencing with vector pTRV2:VlmybA1-2 significantly reduced anthocyanin pigments in tobacco leaves 40 days after agroinfiltration, with a concomitant reduction in VlmybA1-2 transcript levels. Purple hue faded gradually, and there were no fitness costs in terms of plant height or leaf number in the silenced vs. non-silenced tobacco transgenes. These results could lead to a new sustainable weed-control method that will alleviate weed-related ecological, agricultural and economic issues.

plant biology↗