Kalidas Upadhyaya

Bio: Kalidas Upadhyaya is an academic researcher from Mizoram University. The author has contributed to research in topics: Forest gardening & Geography. The author has an hindex of 4, co-authored 8 publications receiving 49 citations.

Current Developments and Challenges in Plant Viral Diagnostics: A Systematic Review

Abstract: Plant viral diseases are the foremost threat to sustainable agriculture, leading to several billion dollars in losses every year. Many viruses infecting several crops have been described in the literature; however, new infectious viruses are emerging frequently through outbreaks. For the effective treatment and prevention of viral diseases, there is great demand for new techniques that can provide accurate identification on the causative agents. With the advancements in biochemical and molecular biology techniques, several diagnostic methods with improved sensitivity and specificity for the detection of prevalent and/or unknown plant viruses are being continuously developed. Currently, serological and nucleic acid methods are the most widely used for plant viral diagnosis. Nucleic acid-based techniques that amplify target DNA/RNA have been evolved with many variants. However, there is growing interest in developing techniques that can be based in real-time and thus facilitate in-field diagnosis. Next-generation sequencing (NGS)-based innovative methods have shown great potential to detect multiple viruses simultaneously; however, such techniques are in the preliminary stages in plant viral disease diagnostics. This review discusses the recent progress in the use of NGS-based techniques for the detection, diagnosis, and identification of plant viral diseases. New portable devices and technologies that could provide real-time analyses in a relatively short period of time are prime important for in-field diagnostics. Current development and application of such tools and techniques along with their potential limitations in plant virology are likewise discussed in detail.

Enhancement of disease resistance, growth potential, and photosynthesis in tomato (Solanum lycopersicum) by inoculation with an endophytic actinobacterium, Streptomyces thermocarboxydus strain BPSAC147.

Abstract: Biotic stresses in plants have a significant impact on agricultural productivity. In the present study, in vivo experiments were conducted to determine the physiological responses of tomato (Solanum lycopersicum L.) seedlings by inoculation with an endophytic actinobacterium, Streptomyces thermocarboxydus isolate BPSAC147 under greenhouse conditions. Further, photochemical quantum yield of photosystem II (PSII) (Fv/Fm), photochemical quenching (qP) and non-photochemical (NPQ) were calculated in seedlings inoculated with S. thermocarboxydus (T1) and were compared with control (T0) plants. Furthermore, the electron transport rate (ETR) of PSII exhibited a significant increase in T1 plants, relative to T0 plants. These results indicate that inoculation of tomato seedlings with S. thermocarboxydus had a positive effect on the process of photosynthesis, resulting in enhanced chlorophyll fluorescence parameters due to increased ETR in the thylakoid membrane. GC-MS analysis showed significant differences in the volatile compounds in the different treatments performed under greenhouse conditions. The present study suggests that S. thermocarboxydus can be used as new biocontrol agent to control Fusarium wilt in tomato crops and enhance productivity by enhancing photosynthesis.

Plant Diversity in the Indigenous Home Gardens in the Eastern Himalayan Region of Mizoram, Northeast India

Abstract: The eastern Himalayan region of Northeast India is well known for its traditional home gardens, which are considered to play important roles in the maintenance of livelihoods of indigenous communities and conservation of biological diversity. This study determines the plant diversity in home gardens and their importance in conservation of plant genetic resources (PGR) through utilization. We studied 90 home gardens in detail located in six villages. Different aspects of the home gardens and plant species were observed directly and through discussion with the farmers. A total of 333 plant species (133 trees, 92 shrubs, and 108 herbs) belonging to 128 plant families with an average of 78 species per home garden were recorded. The size of home gardens ranged between 0.10 and 0.60 ha and showed significant (P<0.001) positive correlation between the garden size and plant species diversity. The species diversity index for trees, shrubs, and herbs was 4.76, 4.39, and 4.58, respectively. The species similarity within each life form was high with 50% for trees, 38% for shrubs, and 49% for herbs. Plant species in the home gardens could be grouped into 11 major use categories with the majority of plants in the medicinal or multiple use category. These home gardens are reservoirs of PGR and play a vital role in sustaining the livelihood of local inhabitants. They are also functioning as domestication and conservation centers of many crop relatives.

Decomposition Dynamics and Nutrient Release Pattern from Leaf Litters of Five Commonly Occurring Homegarden Tree Species in Mizoram, India

Abstract: Leaf litter decomposition and nutrient release patterns from five common multipurpose tree species—viz., Artocarpus heterophyllus, Mangifera indica, Areca catechu, Citrus sp., and Tamarindus indica...

Metagenomic Analysis of Bacterial Diversity in Traditional Fermented Foods Reveals Food-Specific Dominance of Specific Bacterial Taxa

Abstract: Traditional fermented foods have been recognized by various communities to be good for health since ancient times. There is a provincial legacy of traditional fermented foods among the ethnic population of North-East India. Fermented bamboo shoots (local name: Tuaither), soybeans (Bekang), and pork fat (Sa-um) are famous in the Mizoram state and represent a primary portion of the daily diet. These foods are prepared using methods based on cultural traditions inherited from previous generations, and prepared using a relatively uncontrolled fermentation process. Analysis of the bacterial diversity in these foods can provide important information regarding the flavor and texture of the final products of fermentation. Unfortunately, studies on the microbial composition and health benefits of such traditional fermented foods have rarely been documented. Therefore, the present study aims to highlight this bacterial diversity, along with the proximate composition of different traditional fermented foods (Tuaither, Bekang and Sa-um) primarily consumed in Mizoram state, India. Samples were collected on three different days of fermentation (3rd, 5th and 7th day), and bacterial diversity analysis was performed using the V3-V4 variable region of 16S rRNA gene with Illumina sequencing. Results revealed differences in the bacterial composition of dominant group members among all of the three food types. Firmicutes (82.72–94.00%), followed by Proteobacteria (4.67–15.01%), were found to dominate to varying degrees in all three of the fermented foods. However, at genus level high variation was observed in bacterial composition among these three different types of fermented foods. Lactobacillus (91.64–77.16%), Staphylococcus (52.00–17.90%), and Clostridium (72.48–55.40%) exhibited the highest relative abundances in the Tuaither, Bekang and Sa-um foods, respectively, in descending order from the 3rd to 7th day of fermentation. A few of the bacterial genera such as Lactobacilli were positively correlated with fermented bamboo shoot samples, and Staphylococcus was positively correlated with protein, carbohydrate and crude fiber content in soybean samples. In general, Tuaither, Bekang and Sa-um exhibited distinct differences in bacterial composition. This variation may be due to differences in the raw materials and/or methods used in the preparation of the different fermented food products. This is the first study to describe the bacterial composition of these traditional fermented foods using high-throughput sequencing techniques, and could help to drive research attention to comprehensive studies on improving understanding of the role of microbial communities in the preparation of traditional foods and their health benefits.

Scientific Opinion on the risk of Phyllosticta citricarpa (Guignardia citricarpa) for the EU territory with identification and evaluation of risk reduction options

Abstract: The Panel conducted a risk assessment of Phyllosticta citricarpa for the EU. P. citricarpa causes citrus black spot (CBS) and is absent from the EU. Under the scenario of absence of specific risk reduction options against P. citricarpa, the risk of entry of P. citricarpa was rated as likely for citrus plants for planting and citrus fruit with leaves, moderately likely for citrus fruit without leaves, unlikely for citrus leaves for cooking and very unlikely for Tahiti lime fruit without leaves. Establishment was rated as moderately likely because susceptible hosts are widely available and environmental conditions in many EU citrus-growing areas are suitable (with high uncertainty) for P. citricarpa ascospore production, dispersal and infection. Current fungicide treatments will not prevent establishment. Environmental favourability is increased by the use of sprinkler and micro-sprinkler irrigation in some EU citrus-growing locations. Spread with trade was rated as moderately likely. Model results indicate that CBS epidemics are most likely to develop in EU citrus-growing areas in late summer to early autumn and in some locations also in late spring to early summer. CBS is expected to affect mainly lemons and late-maturing sweet orange and mandarin varieties, with moderate negative consequences for the production of fresh fruit, but with environmental impact of additional fungicide treatments. Negative consequences would be minor for early-maturing citrus varieties and minimal for citrus for processing. Uncertainty concerning the consequences is high, mainly because of the lack of data on critical climate response parameters for the pathogen but also because information on impact in areas at the limits of the current distribution is scarce. Since eradication and containment are difficult, phytosanitary measures should focus on preventing entry. Current phytosanitary measures are evaluated to be effective, with the exception of pest-free production sites.

PGPR in Agriculture: A Sustainable Approach to Increasing Climate Change Resilience

Abstract: Growing environmental concerns are potentially narrowing global yield capacity of agricultural systems. Climate change is the most significant problem the world is currently facing. To meet global food demand, food production must be doubled by 2050; over exploitation of arable lands using unsustainable techniques might resolve food demand issues, but they have negative environmental effects. Current crop production systems are a major reason for changing global climate through diminishing biodiversity, physical and chemical soil degradation, and water pollution. The over application of fertilizers and pesticides contribute to climate change through greenhouse gas emissions (GHG) and toxic soil depositions. At this crucial time, there is a pressing need to transition to more sustainable crop production practices, ones that concentrate more on promoting sustainable mechanisms, which enable crops to grow well in resource limited and environmentally challenging environments, and also develop crops with greater resource use efficiency that have optimum sustainable yields across a wider array of environmental conditions. The phytomicrobiome is considered as one of the best strategies; a better alternative for sustainable agriculture, and a viable solution to meet the twin challenges of global food security and environmental stability. Use of the phytomicrobiome, due to its sustainable and environmentally friendly mechanisms of plant growth promotion, is becoming more widespread in the agricultural industry. Therefore, in this review, we emphasize the contribution of beneficial phytomicrobiome members, particularly plant growth promoting rhizobacteria (PGPR), as a strategy to sustainable improvement of plant growth and production in the face of climate change. Also, the roles of soil dwelling microbes in stress amelioration, nutrient supply (nitrogen fixation, phosphorus solubilization), and phytohormone production along with the factors that could potentially affect their efficiency have been discussed extensively. Lastly, limitations to expansion and use of biobased techniques, for instance, the perspective of crop producers, indigenous microbial competition and regulatory approval are discussed. This review largely focusses on the importance and need of sustainable and environmentally friendly approaches such as biobased/PGPR-based techniques in our agricultural systems, especially in the context of current climate change conditions, which are almost certain to worsen in near future.

PGPR Modulation of Secondary Metabolites in Tomato Infested with Spodoptera litura

Abstract: The preceding climate change demonstrates overwintering of pathogens that lead to increased incidence of insects and pest attack. Integration of ecological and physiological/molecular approaches are imperative to encounter pathogen attack in order to enhance crop yield. The present study aimed to evaluate the effects of two plant growth promoting rhizobacteria (Bacillus endophyticus and Pseudomonas aeruginosa) on the plant physiology and production of the secondary metabolites in tomato plants infested with Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae). The surface sterilized seeds of tomato were inoculated with plant growth promoting rhizobacteria (PGPR) for 3–4 h prior to sowing. Tomato leaves at 6 to 7 branching stage were infested with S. litura at the larval stage of 2nd instar. Identification of secondary metabolites and phytohormones were made from tomato leaves using thin-layer chromatography (TLC) and high performance liquid chromatography (HPLC) and fourier-transform infrared spectroscopy (FTIR). Infestation with S. litura significantly decreased plant growth and yield. The PGPR inoculations alleviated the adverse effects of insect infestation on plant growth and fruit yield. An increased level of protein, proline and sugar contents and enhanced activity of superoxide dismutase (SOD) was noticed in infected tomato plants associated with PGPR. Moreover, p-kaempferol, rutin, caffeic acid, p-coumaric acid and flavonoid glycoside were also detected in PGPR inoculated infested plants. The FTIR spectra of the infected leaf samples pre-treated with PGPR revealed the presence of aldehyde. Additionally, significant amounts of indole-3-acetic acid (IAA), salicylic acid (SA) and abscisic acid (ABA) were detected in the leaf samples. From the present results, we conclude that PGPR can promote growth and yield of tomatoes under attack and help the host plant to combat infestation via modulation in IAA, SA, ABA and other secondary metabolites.