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Abstract

As alternatives to chemical insecticides, entomopathogenic fungi or wild plants and their secondary metabolites are being used. These biocontrol agents are significant because of their biodegradability, specificity, eco-friendliness, and utility as agents to reduce insecticide resistance. In this study five ethyl acetate extracts of locally isolated fungal strains ( Talaromyces atroroseus, Fusarium chlamydosporum, Talaromyces stipitatus, Trichoderma lixii, Beauveria bassiana) as well as alkaloid extract of Haloxylon salicornicum were extracted and investigated as biocontrol agents against cotton mealybug Phenacoccus solenopsis. The results indicated that all extracts had toxic effects against P. solenopsis except the extract of T. stipitatus. The LC50 values and toxicity index indicated that the alkaloid extract of H. salicornicum was the most toxic one (26 ppm) after 72 hours of treatment followed by the extracts of F. chlamydosporum (77 ppm), then B. bassiana (84 ppm) and T. lixii (118 ppm). On the other hand, there were significant changes in tested insect enzyme activities (amylase, lipase, glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), and acetyl choline esterase (AchE) as well as total proteins and lipids in the insects treated with the alkaloid extract of H. salicornicum, and ethyl acetate extracts of F. chlamydosporum and B. bassiana after 24 hours of treatment compared to the control. GC/MS analyses of fungal extracts indicated that there were some bioactive compounds like hexadecanoic acid, octadecanoic acid, and tetradecanoic acid. In addition, the anabasine compound was found as a major constituent of the alkaloid extract of H. salicornicum and identified by 1H NMR and GC/MS analysis. In conclusion, according to this study, it was recommended that the alkaloid extract of H. salicornicum and the ethyl acetate extracts of F. chlamydosporum, B. bassiana, and T. lixii be used as alternatives to chemical insecticides for controlling the cotton mealybug P. solenopsis.
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Authors and Affiliations

Reda R.H. Abdullah
1
Ahmed Ramadan El-Rokh
2

  1. Cotton Pesticides Evaluation Research Department, Plant Protection Research Institute, Agriculture Research Center, Dokki, Giza, Egypt
  2. Piercing Sucking Pests Research Department, Plant Protection Research Institute, Agricultural Research Center, Dokki, Giza, Egypt
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Abstract

In our previous Genome-wise Association Study we found that Cystic Fibrosis Transmem- brane Conductance Regulator gene (CFTR) is a candidate gene for sperm motility in fresh semen of Holstein-Friesian bulls. Since in cows thawed semen is commonly used for the artificial insem- ination (AI) we have decided to find out whether functional polymorphism within CFTR gene coding sequence is associated with selected parameters of thawed sperm, including their motility evaluated by computer-assisted sperm analysis (CASA), the activity of three antioxidant enzymes: glutathione peroxidase (GPx) catalase (CAT), superoxide dismutase (SOD), ATP con- tent and integrity of sperm membranes. One hundred twenty Holstein Friesian bulls kept in uni- form environmental conditions (one AI company) were included in the study. Significant associ- ations between genotypes of missense mutation within exon 11 of the CFTR gene (Met468Leu) and the activity of antioxidant enzymes and sperm mitochondrial function were revealed. No effect of CFTR genotypes on sperm motility was observed. Significant differences in CAT and SOD activity were found between AA and TT homozygous individuals. Bulls with TT genotype had the lowest activity of both antioxidant enzymes. The same bulls also showed the lowest num- ber of sperm with active mitochondria. Our results demonstrate that missense mutation Met468Leu within CFTR gene is associated with antioxidant enzyme activity and mitochondrial function of bovine thawed sperm without affecting their motility.

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Authors and Affiliations

S. Kaminski
D.M. Hering
W. Kordan
M. Lecewicz
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Abstract

Leaf scald, caused by the necrotrophic fungus Monographella albescens, is one of the main threats to rice (Oryza sativa L.) around the world. This disease decreases yields in rice by up to 30% because of dead leaf tissue, damaged seeds, and sterile flowers. Currently, there is limited knowledge about the molecular mechanisms involved in rice plant resistance against this pathogen. For this purpose, six commercial cultivars of rice were primarily screened for M. albescens infection and development. Dasht and Salari were found to be the most resistant and susceptible to M. albescens infection, respectively. The plants were kept in a greenhouse at 29 ± 2°C during the day and 26 ± 2°C at night with a relative air humidity of 85 ± 5%. Forty-five days after sowing, the plants with three biological replications were inoculated by transferring a PDA disc (0.3 cm2) containing M. albescens mycelia to the middle third of the 7th, 8th, and 9th completely open leaves. The leaves were collected 24, 48, 72, 96 and 120 hai. Leaf samples were also collected from the non-inoculated plants (0 h) to serve as controls. Real-time quantitative PCR (RT-qPCR) showed rapid induction and significant accumulation of jasmonic acid (JA) and ethylene (ET) responsive genes such as lipoxygenase (LOX), allene oxide synthase 2 (Aos2), jasmonic acid carboxyl methyltransferase 1 (JMT1) and ACC synthase 1 (ACS1) in the resistant Dasht cultivar after infection with M. albescens. Furthermore, the transcripts of salicylic acid (SA) responsive phenyl alanine ammonia lyase 1 (PAL1) and nonexpressor of pathogenesis-related genes 1 (NPR1) genes were induced in the incompatible interaction. The activities of the defense enzymes superoxide dismutase (SOD), peroxidase (POX) and glutathione reductase (GR) increased strongly in Dasht in response to M. albescens infection. In addition, there was an increase in the H2O2 levels in the leaves of the Dasht cultivar during the infectious period of M. albescens associated with the enhancement of catalase (CAT) activity as well as higher levels of malondialdehyde (MDA). This is the first study on the interaction between rice and M. albescens at the molecular level. It can contribute to understanding how rice responds to pathogen infection, as well as assist with future research plans of molecular breeding regarding the tolerance to leaf scald disease.

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Authors and Affiliations

Dariush Ebadi Almas
Atefeh Rahmani Kamrodi

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