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Citrus greening/yellow shoot disease/HLB, caused by Candidatus liberibacter asiaticus, showing mosaic/mottling pattern on leaves, stunting of plants, de-shape, pre-mature fruit drop and yellowing of reticulate venation as characteristic symptoms, is the most concerned disease prevailing in citrus groves of Punjab, Pakistan. For the detection of pathogen and downstream studies, a high-quality DNA is required. In citrus, due to the variety of species, different age groups in plants, thick waxy cuticle of leaves, high production of phenolics, polysaccharides and other compounds, it is very difficult to extract good quality DNA from leaves and especially from main midrib where the fastidious bacterium is residing. CTAB and SDS are two devised methods for the extraction of total genomic DNA from citrus leaves while the current research suggests some modified protocols for the detection of DNA from infected/healthy samples. 100mg leaf midrib sample was crushed in liquid nitrogen, homogenized in 500µl CTAB, incubated at 60°C in water bath for 45 minutes, centrifuged at 12000rpm for 5 minutes, supernatant was transferred to new tube and 5µl RNase-A was added, incubated at 37°C for 20 minutes. Equal volume of chloroform/isoamyl alcohol (24:1) was added, vortexed for 5 minutes, centrifuged for 2 minutes at 12000rpm for phase separation and upper phase was transferred to new tube where 500µl of chilling isopropanol was added, kept at -20°C for 15 minutes, centrifuged at 12000rpm, pallet was washed twice with 70% ethanol. CTAB method was modified by increasing the incubation time i.e., 45 minutes for cell lysis in water bath for determination the variation in quality of DNA and the amount of beta mercaptethanol was also doubled from the normal one. Modified protocols have been proved excellent for the extortion of total genomic DNA from citrus. In SDS, addition of TE buffer, RNAase, Isoamylalcohol: Chloroform (24:1) along with 20% SDS and 2M Sodium Acetate gave high quality DNA from citrus leaves. Hence, DNA was extracted by four different ways but the modified CTAB and SDS methods gave improved quality DNA as confirmed by its quantification through nanophotometer. The DNA was quantified by nanophotometer and presence was observed on gel documentation apparatus. Hence, DNA was found suitable for PCR and RFLP analysis and long-term storage on -80 °C. [ABSTRACT FROM AUTHOR]

Evaluation of various wheat varieties against Karnal bunt disease showed that seven cultivars were susceptible, and the same number were moderately susceptible. Fourteen varieties among all were highly resistant whereas nineteen depicted resistant response against the Nevossia indica. Sowing time showed a varying response on disease incidence while the fungicidal chemistries showed that shelter and dolomite were the best at the dose of 45 ug/ml and 100 ug/ml and while 100 µg/ml of Antracol and Alert+ also demonstrate similar results. Protection application of dolomite and shelter showed 62 and 64% decrease in the incidence of Karnal Bunt disease. As eradicative spray dolomite and shelter were used and their application lead to 39 and 41% reduction of disease respectively. Antracol was found least effective as curative spray with 24.07% against the Karnal Bunt disease comparatively. Hence, breeding resistant varieties is the need of the hour for the management of the wheat crop as it is cheaper, safe, and environment friendly approach not only for the farmer, climate and the country. Current research open avenues to exploit more ways for the Karnal bunt management by adopting biological control strategies. [ABSTRACT FROM AUTHOR]

In vitro studies were carried out for the isolation, identification, biochemical, cultural and physiological characterization of Xanthomonas oryzae pv. oryzae. Biochemical and diagnostic tests proved X. oryzae pv. oryzae as a gram negative bacterium that showed luxurious growth on a new modified yeast sucrose calcium carbonate nutrient agar (YSCNA) medium with maximum average recovery of (83.50). The bacterium produced bright yellow, circular and slightly raised bacterial colonies on tested media compared to previously tested media used for the isolation and multiplication. The pathogen showed best growth at 30°C and pH of 7.0 with mean (94.50) and (103.75) bacterial colonies. [ABSTRACT FROM AUTHOR]

Biological control is described as the suppression of one or more populations of plant pathogens using introduced or resident living species rather than disease-resistant host plants. This can be accomplished by the use of microbial biological control agents (MBCAs) where they biologically control plant pathogens interacting with their hosts via a range of modes of action. Overuse of pesticides has had a negative impact on the climate in recent decades that gave rise to human health issues. This posed a dire need to explore alternative strategies that are comparatively safe, environmental, and monetarily feasible. The employment of MBCAs is found to be a highly effective way to regulate several diseases of the exiting flora caused mainly by nematode infestation and bacterial or fungal pathogens. Microbial inoculants suppress a particular form of plant disease or regulate soils so that plant-associated species and native soil can work together to suppress the disease. Microbes, such as bacteria, protozoa, algae, and fungi, frequently interact with plants in several ways including protocooperation, mutualism, commensalism, rivalry, neutralism, amensalism, predation, and parasitism. These interactions are cascades of highly regulated metabolic events that combine various kinds of action. Compounds such as enzymes, signaling compounds, and other interfering metabolites are released in situ at low levels during the interaction. Pseudomonas, Erwinia, Bacillus, Agrobacterium, Rahnella, Lysobacter, Myxobacteria, Enterobacter, and Streptomyces are some of the bacterial genera that have major biocontrol potential to mitigate crop plant diseases. Several species, including P. fluorescens, P. putida, P. cepacia, P. aureofaciens, P. tolaasii, P. fluorescens (strains A1, BK1, TL3B1, A506, and B10), Erwinia herbicola, B. cereus (strain UW85), Agrobacterium radiobacter (strain K84), Rahnella aquatilis have been proved beneficial against various crop diseases. Likewise, Trichoderma harzianum, Glomus fasciculatum, G. macrocarpum, and Pisolithus tinctorius are known to induce plant defense response against phytotoxic effects caused by different pathogenic strains. This review highlights the role of MBCAs against pathogenic microorganisms and their mode of action in terms of the ability to enhance plant defense systems for their improved growth. [ABSTRACT FROM AUTHOR]