Pioneering Nit Gene Exploitation to Develop Molecular Diagnostic Assay for Rapid Detection of Cotton Root Rot Incitant, Macrophomina phaseolina (Tassi) Goid, in Field Soil.

Cotton root rot caused by Macrophomina phaseolina pose a significant threat to cotton production, leading to substantial yield and quality losses. Early and accurate diagnosis of this pathogen in soil is crucial for effective disease management. This study presents a pioneering investigation into the utilization of the nit gene encoding nitrilase for the development of a molecular diagnostic assay aimed at the rapid detection of M. phaseolina in field soils. The methodology involved the design and validation of primers targeting the Nit gene sequence, followed by the optimization of PCR conditions for efficient amplification. Leveraging state-of-the-art molecular techniques, the assay offers a novel protocol to accurately identify the presence of M. phaseolina in soil with high sensitivity and specificity. The specificity of the designed primers was confirmed through PCR amplification using DNA from M. phaseolina and other related fungi. Sensitivity tests demonstrated that the PCR assay reliably detected M. phaseolina DNA at concentrations as low as 1 ng. Furthermore, the performance of the diagnostic assay was rigorously evaluated using field soil samples with a known status of M. phaseolina infection, demonstrating its reliability and efficacy in real-world scenarios. This study introduces a novel molecular marker for the detection of M. phaseolina and offers a rapid and efficient means for screening M. phaseolina in large soil samples with minimal time and manpower.

Unravelling the synergistic interaction of Thrips tabaci and newly recorded, Thrips parvispinus with Alternaria porri (Ellis.) Cif., inciting onion purple blotch.

Onion purple blotch is the most indispensable foliar disease of crop and has become a major concern for farmers and research fraternity. An attempt to investigate the role of injury in parasitism by Alternaria porri indicated that disease incidence and severity enhance considerably with injury. Thrips injured plants inoculated with A. porri presented 100% incidence and 52-72% severity while mechanically injured plants inoculated with A. porri showed 60-70% incidence and 28-34% severity. The uninjured plants showed considerably less disease incidence (30-40%) and severity (10-16%). Injured inoculated plants presented reduced leaf length and leaf area while the leaf diameter remained unaffected. The lesion number, lesion length and size was substantially enhanced with concomitant infestation of pest and pathogen. Thrips tabaci injury led to more pronounced symptoms of purple blotch compared to Thrips parvispinus injury. There was substantial decrease in photosynthetic rate and chlorophyll content with stress imposed on plant whilst the relative stress injury was enhanced. The induction of injury and inoculation of A. porri had an impact on the concentration of total phenolics, total soluble sugars, total proteins and hydrogen peroxide in onion leaves. A. porri combined with injury caused a more pronounced decrease in total soluble sugars and total protein content while enhancement in total phenolics and hydrogen peroxide content compared to uninjured plants. The dynamic nature of morpho-physiological and biochemical changes owing to stress conditions imposed on onion plant adds an extra layer of complexity in understanding the onion plant physiology and their ability to work out in response to challenging environment conditions.