Exploring combined effect of elevated CO2 and temperature on Fusarium wilt development of chickpea

Fusarium wilt (FW) caused by Fusarium oxysporum f. sp. ciceris (Foc) is one of the major diseases in chickpea. Under changing climatic scenario, elevated CO2 (eCO2) (550 and 700 ppm) and temperature (25°C, 30°C and 35°C) have potential impact on plant resistance mechanisms and pathogen virulence. Hence, the present study was aim to assess the impact of eCO2 and temperature on FW incidence and disease progression in two chickpea cultivars, JG 62 (susceptible) and WR 315 (resistant). Irrespective of temperature, the incubation period was delayed in eCO2 when compared to ambient. In case of combined effect, the maximum disease incidence was found in 30°C combined with 700 ppm as well as ambient CO2 conditions. To quantify the pathogen load and expression of several defence responsive genes in chickpea and virulence-related genes in Foc, qPCR study was employed. As compared to the eCO2, the expression of defence and virulence response genes in chickpea inoculated seedlings was highly up-regulated in ambient CO2 conditions irrespective of temperatures. The results suggested that among different defence-related genes studied, peroxidise gene was highly expressed in WR 315 cultivar, there by restricting the Foc colonization, by providing an evidence of efficient defense mechanism in the resistant cultivar. Moreover, in JG 62 the pathogenicity-causing secreted in xylem (SIX 14) gene was highly expressed as it mainly helps in colonization of Foc by defeating its defense in susceptible cultivar, which helps in providing more insights in understanding the compatible and incompatible interactions between chickpea and Fo

Risk assessment and preparedness: an encounter to agricultural transboundary pests and diseases

The transboundary crop pest and disease (P&D) outbreaks over large geographical regions jeopardizes the food security and have broad economic, social and environmental impacts. The climate change accelerated transboundary P&D are responsible for food chain catastrophes and upsurge of minor pest into major. Such accelerated events require more attention on a greater scale to strengthen food security and protect the livelihoods of poor and most vulnerable countries of the world. The ICRISAT, Center of Excellence on Climate Change Research for Plant Protection (CoE-CCRPP) is a joint initiative with Department of Science and Technology and ICRISAT to study impact of climate change on agriculture P&D in an inclusive manner with key audience (adaptation funding entities, planners, policymakers and practitioners) at national and regional level (NARS, ARIs and CGIAR). The CoE-CCRPP emphasis is on mapping the potential pest risk distribution and forecasting; short and medium term climate resilient pest management practices; as well as capacity building of various stakeholders on climate resilient agriculture. The ICRISAT center, further focus to determine and establish priority pest indicators ranking, risk assessment and distribution, socio-economics of P&D to assist in enhancement of pest policies, pre-emptive breeding, improved P&D monitoring and surveillance to strengthen global efforts to alleviate P&D complications on sustainable agriculture and food security

Evolution of polygonal crack patterns in mud when subjected to repeated wetting-drying cycles

The present paper demonstrates how a natural crack mosaic resembling a random tessellation evolves with repeated 'wetting followed by drying' cycles. The natural system here is a crack network in a drying colloidal material, for example, a layer of mud. A spring network model is used to simulate consecutive wetting and drying cycles in mud layers until the crack mosaic matures. The simulated results compare favourably with reported experimental findings. The evolution of these crack mosaics has been mapped as a trajectory of a 4-vector tuple in a geometry-topology domain. A phenomenological relation between energy and crack geometry as functions of time cycles is proposed based on principles of crack mechanics. We follow the crack pattern evolution to find that the pattern veers towards a Voronoi mosaic in order to minimize the system energy. Some examples of static crack mosaics in nature have also been explored to verify if nature prefers Voronoi patterns. In this context, the authors define new geometric measures of Voronoi-ness of crack mosaics to quantify how close a tessellation is to a Voronoi tessellation, or even, to a Centroidal Voronoi tessellation

Improving fault ride-through of three phase voltage source inverter during symmetrical fault using DC link fault current limiter

The majority of distributed generation (DG) units utilize three phase voltage source inverter (VSI) to exchange electric power with the utility grid. The VSI employs semiconductor devices (SDs) with limited current withstand capabilities which are very vulnerable during grid faults. However, to ensure a secure and reliable operation of power systems at high penetration level of the DGs, most of the new grid codes worldwide require that the VSIs must have fault ride-through (FRT) capability. This paper presents a DC link fault current limiter (DLFCL) based VSI FRT scheme to improve its FRT capability. In the proposed scheme, the DLFCL is connected in series with the DC side of the VSI to limit the output current during symmetrical grid fault. The DLFCL does not have considerable effect on the VSI performance during the normal operation, whereas it limits the output current in all phases to the safe area operation of the SDs of the inverter. The effectiveness of the proposed scheme is validated through the simulation studies in PSCAD/EMTDC software

Exploring combined stress incited disease dynamics of chickpea x dry root rot interation

Dry root rot (DRR) of chickpea caused by Rhizoctonia bataticola (Rb) has become an emerging threat to chickpea production. Under field conditions, the disease becomes highly aggressive, coincides with higher temperatures and decrease in soil moisture content (SMC). Thus establishing a sound relation between various climatic factors and DRR is necessary to design a rational strategy for combating this disease. Hence, the present study aims to quantify the roles of temperature, soil moisture and Rb as combined stress for causing infection and subsequent disease progression in chickpea. The results proved that a significant relationship exists between the biotic and abiotic elements in predisposing chickpea to DRR. Out of two temperatures (25°C and 35°C) and two soil moisture content (60% and 80% SMC) tested, the combination of high temperature (35°C) and low SMC (60%) was successful in inciting early disease symptoms in the chickpea cultivars tested. The disease severity based on percent susceptibility index (derived from modified 0-9 rating scale) and percent loss in root biomass also provided similar insights, where plants grown under the above combination displayed higher degree of root rot than the combination of low temperature (25°C) and high SMC (80%). A high positive correlation was observed between disease severity, temperature at 35°C and SMC at 60%, whereas, a negative correlation was realized for temperature at 25°C and SMC at80%. Results of the real-time qPCR based absolute quantification for fungal propagules present in the root tissues sampled at different time points also corroborated with the above finding

Catalysing the host plant resistance: An insight into phyto-hormone mediated ISR against dry root rot of chickpea

Dry root rot (DRR) of chickpea caused by Rhizoctonia bataticola has become a serious concern to chickpea production. Changing climatic elements like frequent low soil moisture stress and high temperature are among the probable factors increasing DRR incidence in chickpea. Management of the DRR is challenging, owing to its wide host range, lack of resistant sources and uneconomical chemical control measures. Therefore, an alternate resistance management approach against this disease may be achieved by exploitation of host plant resistance through phyto-hormone mediated induced systemic resistance (ISR). The present study aims to identify the role of phyto-hormones in inducing systemic resistance against chickpea DRR. Two Phytohormones Methyl Jasmonic Acid (MeJA) and Salicylic Acid (SA) were used in this study to induce systemic resistance (ISR) against DRR. Of them MeJA was proved to be a robust in playing vital role in inducing resistance against targeted pathogen. The disease severity based on per-cent disease susceptibility index (derived from modified 0-9 rating scale) showed that plants treated with MeJA 50ppm displayed lower degree of DRR severity than the other subtreatments viz., MeJA at 25ppm and 75ppm. Also, the fungal propagule concentrations present in the root tissues sampled at different time points were analogous with theabove findings. A high positive correlation was observed in the results from real-time qPCR based absolute quantification

Synthesis of isopongaflavone

540-54

Use of Genomic Approaches in Understanding the Role of Actinomycetes as PGP in Grain Legumes

The advancement in molecular technologies has given a breakthrough to explore the untapped and novel microbial isolates for characterization in every aspect as we can consider microbes as an important primary natural store house for key secondary metabolites and enzymes. Actinomycetes are the most fruitful source ofmicroorganisms for all types of bioactive secondary metabolites, including agroactive-antibiotic molecules that are best recognized and most valuable for their role in agriculture and industries. In agriculture, actinomycetes are used as biocontrol agents against some pests and pathogenic organisms as well as plant growth-promoting (PGP) agents for crops. Use of different molecular methods, e.g., metagenomics, metatranscriptomics, genetic fingerprinting, proteogenomics, and metaproteomics, are more significant for classifying and discovering the immense diversity in microbial population and for understanding their interactions with other abiotic and biotic environmental elements. The opportunity of accessing inexpensive sequencing techniques has led to the assemblies of copious genomic data for actinomycetes, such as Streptomyces and related species, with the goal of discovering novel bioactive metabolic and their utility as PGP; however, the use of actinomycetes in agriculture using genomic approaches is in its initial stages