Citrus fruit production occupies a place of considerable importance in the economy of the world including Pakistan. Tristeza disease caused by Citrus Tristeza Virus (CTV) exists in various forms that may or may not cause symptoms in the plants. The bioactive compounds and antioxidants are naturally present in plants and provide a defense mechanism that is generally accelerated in response to a stress. The objective of the present study was to target and analyze the citrus plants that were CTV positive to observe the changes in the enzymatic and non-enzymatic antioxidants of citrus (Sweet Oranges only). It was observed that in response to CTV infection, both the non-enzymatic antioxidants (total flavonoid, ascorbic acid, phenolic acid) and enzymatic antioxidants (catalase, superoxide dismutase and peroxidase) activities showed an increasing trend overall. The profiling of antioxidants in response to a viral infection may help in the discovery of new biomarkers that can be used as a monitoring tool in disease management.
Melia azedarach L. belongs to one of the most versatile medicinal plants family meliaceae (mahogany) which has great attraction for researchers. The plant was selected for research because it was one of the least explored members. The presence of saponin, alkaloids, tannins and flavonoids in the leaves extracts of plant indicated its medicinal value. These compounds have pharmacological effects against cancer, viral and malarial infections that are one of the main causes of deaths. With passage of time most of bacterial strains develop resistance against traditional medicines so they are needed to be upgraded or replaced. There is a need to develop antimicrobial agents with more effectiveness and minimum side effects. There are some reports from last two decades that Melia azedarach is a potential source of novel antibodies. Its extracts have both antioxidant and antimicrobial activities. Powdered leaves of M. azedarach were extracted with methanol and extract was preliminary examined by phytochemical tests and thin layer chromatography. The different concentrations of extracts showed good antibacterial activities against three pathogenic bacterial strains Staphylococcus aureus, Escherichia coli and Bacillus thuringiensis. The results indicated that M. azedarach L. could be an effective source of herbal medicines against infectious diseases.
An updated real-time multiplex quantitative polymerase chain reaction (qPCR) assay was designed and validated for the simultaneous detection of three ‘Candidatus Liberibacter species’ (CLsp), Ca. Liberibacter asiaticus (CLas), africanus (CLaf) and americanus (CLam), associated with the Huanglongbing (HLB) disease of citrus. The multiplex assay was designed based on the previously published qPCR assay by Li et al., 2006, taking into consideration all available CLsp 16S rRNA gene sequences in the GenBank and the MIQE guidelines and workflow for qPCR optimization, which became available after 2006. When using the updated multiplex CLsp qPCR assay compared to singleplex qPCR, no significant increase in Cq values was detected. The specificity and sensitivity of the updated qPCR assay was optimal and measuring the intra and inter assay variations confirmed the reproducibility and repeatability of the assay. The assay was also successfully used with a large number of diverse samples, at independent laboratories in four countries, thus demonstrating its transferability, applicability, practicability, and robustness as different qPCR reaction conditions or instruments had a minor effect on Cq values. This updated multiplex CLsp qPCR assay can be used in a variety of citrus surveys, germplasm, or nursery stock programs that require different pathogen detection tools for their successful operation. Keywords: Citrus greening disease, COX internal DNA control; validation; citrus germplasm; budwood; citrus nursery, citrus survey, regulatory diagnostics, Citrus Clonal Protection Program (CCPP), National Clean Plant Network (NCPN)
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