Delineation of molecular interactions of plant growth promoting bacteria induced β-1,3-glucanases and guanosine triphosphate ligand for antifungal response in rice: a molecular dynamics approach

Background The plant growth is influenced by multiple interactions with biotic (microbial) and abiotic components in their surroundings. These microbial interactions have both positive and negative effects on plant. Plant growth promoting bacterial (PGPR) interaction could result in positive growth under normal as well as in stress conditions. Methods Here, we have screened two PGPR’s and determined their potential in induction of specific gene in host plant to overcome the adverse effect of biotic stress caused by Magnaporthe grisea, a fungal pathogen that cause blast in rice. We demonstrated the glucanase protein mode of action by performing comparative modeling and molecular docking of guanosine triphosphate (GTP) ligand with the protein. Besides, molecular dynamic simulations have been performed to understand the behavior of the glucanase-GTP complex. Results The results clearly showed that selected PGPR was better able to induce modification in host plant at morphological, biochemical, physiological and molecular level by activating the expression of β-1,3-glucanases gene in infected host plant. The docking results indicated that Tyr75, Arg256, Gly258, and Ser223 of glucanase formed four crucial hydrogen bonds with the GTP, while, only Val220 found to form hydrophobic contact with ligand. Conclusions The PGPR able to induce β-1,3-glucanases gene in host plant upon pathogenic interaction and β-1,3-glucanases form complex with GTP by hydrophilic interaction for induction of defense cascade for acquiring resistance against Magnaporthe grisea. Graphical abstract

IOT BASED MOLECULAR MARKERS FOR DISEASE RESISTANCE STUDIES IN RICE - STRATEGY AND CHALLENGES

Rice production is constrained by diseases of fungal, bacterial and viral origin. The Internet of Things (IoT) – network of interconnected devices - is an application for disease related uses, collection of data, processing for testing and monitoring. This review article aims about how IoT can track and allows disease resistance studies in in Oryza species. Among them Xanthomonas oryzae, Magnaporthe grisea, RYMV (Rice yellow mottle virus), and brown planthopper causes the high yield losses. Disease resistance genes are identified and they are screened by the SSR (simple sequence repeats), RAPD (Randomly Amplified Polymorphic DNA) and RFLP (restriction fragment length polymorphisms) analysis.

Impact of climate change on pests of rice and cassava.

Climate change is exacerbating food insecurity, and its negative impacts will worsen over time. This is happening via several pathways, among which plant pests are a leading cause. To contribute to more evidence-based decisions and policies, a team from the Food and Agriculture Organization of the United Nations (FAO) carried out a comprehensive literature review on rice (Oryza sativa) and cassava (Manihot esculenta), the major pests and diseases affecting them, and the impact of climate change on the latter. Rice is the major staple crop for about half the world's population. Most studies conclude that pest pressure will increase on rice under future climate change. There are a lot of pests of rice, among which brown planthopper (Nilaparvata lugens) is the most important pest. Leaf blast disease caused by fungus Magnaporthe grisea is the most significant disease, with losses of up to USD 66 billion dollars per year that are equivalent to the amount needed to feed 60 million people. Cassava is the major staple crop and crucial for food security in many countries of the world. A study has shown that cassava production will vary from -3.5% to +17.5% within Africa under 2030 climate projections. Unfortunately, as other crops, cassava will be vulnerable to pests and diseases. Over a third of attainable cassava yield is lost every year to pests and disease alone.

Asymmetric Synthesis of Nodulones C & D by Chemoenzymatic Approach gives Insight into their Biosynthesis

The first asymmetric total synthesis of fungal secondary metabolites, (R)-nodulone C (4) and trans-nodulone D (5) has been reported through the chemoenzymatic approach. The strategy utilizes NADPH-dependent naphthol reductases of Magnaporthe grisea for the reduction of putative biosynthetic substrates, synthesized non-enzymatically in multiple steps. A dihydronaphthalenone 32 and cis-nodulone D (30) has also been synthesized chemoenzymatically. The work implies for similar steps during the biosynthesis of nodulones and their analogs with the involvement of tetrahydroxynaphthalene reductase related enzyme(s).

Antioxidant, Antifungal and Aphicidal Activity of Triterpenoids Spinasterol, 22,23-Dihydrospinasterol From Colocynthis (Citrullus Colocynthis L.) Leaves

Terpenoids from natural plants resources are valuable for diverse biological activities which exhibited important part in medical and agrochemicals industry. This study aimed to assess the antioxidant, antifungal and aphicidal activity of a mixture of Spinasterol, 22,23-dihydrospinasterol from Citrullus colocynthis leaves. 1, 1-diphenyl-2-picrylhydrazyl (DPPH) was used to assess the antioxidant activity whereas, antifungal activity was tested by mycelium growth inhibition assay on three pathogenic fungi Magnaporthe grisea, Rhizoctonia solani and Phytophthora infestans. Aphicidal activity against adults of Myzus persicae was also determined via In-vitro and In-vivo assays. The outcome of the study exposed that Spinasterol, 22, 23-dihydrospinasterol afforded moderate antioxidant activity even at lower concentrations i.e. 19.98, 31.52, 36.61 and 49.76% at 0.78, 3.0, 12.5 and 50µgmL− 1 respectively. However, reasonable fungicidal activity of Spinasterol, 22; 23-dihydrospinasterol was recorded as being EC50 values 129.5 and 206.1µgmL− 1 against R. solani and M. grisea respectively. On the other hand, Boscalid and Carbendazim being a positive control proved highly effective against all fungi except for M. grisea and P. infestans with EC50 values 868 and 272109µgmL− 1 respectively. The significant insecticidal activity was afforded via residual as well as greenhouse assay being LC50 values as 42.46, 54.86, 180.9 µgmL− 1 and 32.71, 42.46 and 173.8µgmL− 1 at 72, 48 and 24 h respectively. Moreover, antioxidant activity of Spinasterol, 22,23-dihydrospinasterol presented strong positive correlation versus antifungal and insecticidal activity. Spinasterol, 22,23-dihydrospinasterol possess good antioxidant and aphicidal activity with moderate fungicidal activity which could be a suitable candidate as an alternative to synthetic pesticidal agents.

Expression Patterns and Functional Analysis of E3 Ubiquitin Ligase Genes in Rice

Background: E3 ubiquitin ligases involve in many processes, containing the response to biotic and abiotic stresses. However, the functions of E3 ubiquitin ligases in rice were rarely studied.Results: In this research, 11 E3 ubiquitin ligase genes were selected and the function analysis was done in rice. These 11 E3 ubiquitin ligase genes showed different expression patterns under different treatments. The BMV:Os06g13870- infiltrated seedlings showed decreased resistance to Magnaporthe grisea (M. grisea) when compared with BMV:00-infiltrated seedlings, while BMV:Os04g34030- and BMV:Os02g33590-infiltrated seedlings showed increased resistance. They involved in the resistance against M. grisea maybe by regulating the accumulation of reactive oxygen species (ROS) and expression levels of defense-related genes. The BMV:Os06g34390-infiltrated seedlings showed decreased tolerance to drought stress while BMV:Os02g33590-infiltraed seedlings showed increased tolerance, maybe through regulating proline content, sugar content and drought-responsive genes’ expression. BMV:Os05g01940-infiltrated seedlings showed decreased tolerance to cold stress by regulating malondial dehyde (MDA) content and cold-responsive genes’ expression.Conclusion: These results showed that E3 ubiquitin ligases involved in the resistance to biotic and abiotic stresses in rice.

Pearl Millet Blast Pathogen Virulence Study and Identification of Resistance Donors on Virulent Isolate

Pearl Millet leaf Blast caused by Pyricularia grisea [teleomorph: Magnaporthe grisea], is spreading at an alarming rate in the major Pearl millet growing geographies of India effecting grain yield and green fodder yield. Blast isolates collected from Jaipur, Alwar and Toopran regions of India and virulence study conducted to identify the most virulent isolate among the three isolates. Artificial screening for Blast conducted on a raised bed method utilising uniform Blast Nursery (UBN) method. Eleven Pearl Millet genotypes (ICMB01333, ICMB03444, ICMB03555, ICMB06111, ICMB95444, ICMB11666, ICMB14333, ICMB14666, ICMB97111, ICMR12888 and ICMR06444) were screened with three blast isolates utilising artificial screening method. Among the eleven genotypes, ten genotypes were showing susceptible to Jaipur isolate indicating that the Jaipur isolate having highest virulence among the three isolates. To identify Blast resistant donors for Jaipur isolate, a set of 93 genotypes containing of 45 maintainer lines and 48 restorer lines were screened under both UBN and field conditions (Jaipur, Rajasthan). Among all the lines evaluated, five lines are showing resistant reaction for Jaipur isolate with disease score less than 1.9. ICMR06444 from restorer background and IC414K14B5, IC594K16B5, RBB037 and IC6912K18B from maintainer background are identified as resistant lines. Identified lines can be utilised in pearl millet hybrid breeding programme.

Deciphering Genotype-By-Environment Interaction for Target Environmental Delineation and Identification of Stable Resistant Sources Against Foliar Blast Disease of Pearl Millet

Once thought to be a minor disease, foliar blast disease of pearl millet, caused by Magnaporthe grisea, has recently emerged as an important biotic constraint for pearl millet production in India. The presence of a wider host range as well as high pathogenic heterogeneity complicates host–pathogen dynamics. Furthermore, environmental factors play a significant role in exacerbating the disease severity. An attempt was made to unravel the genotype-by-environment interactions for identification and validation of stable resistant genotypes against foliar blast disease through multi-environment testing. A diversity panel consisting of 250 accessions collected from over 20 different countries was screened under natural epiphytotic conditions in five environments. A total of 43 resistant genotypes were found to have high and stable resistance. Interestingly, most of the resistant lines were late maturing. Combined ANOVA of these 250 genotypes exhibited significant genotype-by-environment interaction and indicated the involvement of crossover interaction with a consistent genotypic response. This justifies the necessity of multi-year and multi-location testing. The first two principal components (PCs) accounted for 44.85 and 29.22% of the total variance in the environment-centered blast scoring results. Heritability-adjusted genotype plus genotype × environment interaction (HA-GGE) biplot aptly identified “IP 11353” and “IP 22423, IP 7910 and IP 7941” as “ideal” and “desirable” genotypes, respectively, having stable resistance and genetic buffering capacity against this disease. Bootstrapping at a 95% confidence interval validated the recommendations of genotypes. Therefore, these genotypes can be used in future resistance breeding programs in pearl millet. Mega-environment delineation and desirability index suggested Jaipur as the ideal environment for precise testing of material against the disease and will increase proper resource optimization in future breeding programs. Information obtained in current study will be further used for genome-wide association mapping of foliar blast disease in pearl millet.