Susceptible Varieties Research Articles

Dicer-Like Protein 4 and RNA-Dependent RNA Polymerase 6 Are Involved in Tomato Torrado Virus Pathogenesis in Nicotiana benthamiana.

Tomato torrado virus (ToTV) is a type member of the Torradovirus genus in the Secoviridae family known to cause severe necrosis in susceptible tomato varieties. ToTV also infects other Solanaceae plants, including Nicotiana benthamiana, where it induces distinctive disease symptoms: plant growth drop with the emergence of spoon-like malformed systemic leaves. Virus-induced post-transcriptional gene silencing (PTGS) is significant among plant defense mechanisms activated upon virus invasion. The PTGS, however, can be counteracted by suppressors of RNA silencing commonly found in viruses, which efficiently disrupt the antiviral defense of their host. Here, we addressed the question of PTGS antiviral activity and its suppression in N. benthamiana during ToTV infection-a phenomenon not described for any representative from the Torradovirus genus so far. First, we showed that neither the Vp26-a necrosis-inducing pathogenicity determinant of ToTV-nor other structural viral proteins limited the locally induced PTGS similar to p19, a well-characterized potent suppressor of RNA silencing of tombusviruses. Moreover, by employing wild-type and transgenic lines of N. benthamiana with suppressed Dicer-like 2 (DCL2), Dicer-like 4 (DCL4), Argonaute 2 and RNA-dependent RNA polymerase 6 (RDR6) proteins, we proved their involvement in anti-ToTV defense. Additionally, we identified DCL4 as the major processor of ToTV-derived siRNA. More importantly, our results indicate the essential role of the Suppressor of Gene Silencing 3 (SGS3)/RDR6 pathway in anti-ToTV defense. Finally, we conclude that ToTV might not require a potent RNA silencing suppressor during infection of the model plant N. benthamiana.

Searching new targets for the control of Black Rot: following the role of host factors modulating the infection process of Phyllosticta ampelicida.

Black Rot is a grapevine disease caused by the ascomycete Phyllosticta ampelicida. Neglected so far, this is developing into a pertinent problem in organic viticulture as resistant varieties are still lacking. Here, we follow cellular details of the infection process in the susceptible vinifera variety Müller-Thurgau and screen the ancestral European wild grapevine (V. vinifera sylvestris) for resistance to Black Rot. Using a standardized infection assay, we follow fungal development using LTSEM and quantify key stages on different hosts using fluorescence microscopy. There is considerable variation in susceptibility, which is associated with more rapid leaf maturation. Hyphal growth on different carbon sources shows a preference for pectins over starch, cellulose or xylans. In the resistant sylvestris genotypes Ketsch 16 and Ketsch 18 we find that neither spore attachment nor appressorium formation, but hyphal elongation is significantly inhibited as compared to Müller-Thurgau. Moreover, defence-related oxidative burst and accumulation of phenolic compounds is stimulated in the resistant genotypes. We arrive at a model, where more rapid maturation of the cell wall in these sylvestris genotypes sequesters pectins as major food source and thus block hyphal elongation. This paves the way for introgression of genetic factors responsible for cell wall maturation into V. vinifera to develop Black Rot-resistant varieties of grapevine.

Transcriptomic datasets of Verticillium wilt resistant and non-resistant Gossypium barbadense varieties during pathogen inoculation

Cotton is a significant cash crop and the primary source of natural fiber globally. Among the numerous diseases encountered in cotton production, Verticillium wilt is one of the most serious, caused by the pathogen Verticillium dahliae (V. dahliae). Unfortunately, there are no effective targeted methods to combat this disease. Genomic resources for Verticillium wilt resistance primarily exist in Gossypium barbadense (G. barbadense). Regrettably, there have been limited transcriptomic comparisons between V. dahliae-resistant and -susceptible varieties of G. barbadense due to the scarcity of susceptible resources. In this study, we conducted a transcriptome analysis on both V. dahliae-resistant and -susceptible varieties of G. barbadense at the 0, 12, 24 and 48 hours after V. dahliae inoculation. This comparative transcriptome analysis yielded high-quality data and offered new insights into the molecular mechanisms underlying cotton’s resistance against this destructive pathogen.

Contribuição do QuitoMax® no metabolismo hormonal e enzimático em tomate sob estresse salino

ABSTRACT Salinity stress severely restricts plant nutrition and hinders biochemical and physiological processes crucial for growth. In several crop systems bioactive products which confer growth promotion, are applied as a sustainable alternative for contributing to food security. The aim of this work was to evaluate the biochemical contribution of QuitoMax® to hormonal and enzymatic metabolism in tomato under saline stress. Three treatments were applied: saline without QuitoMax®, nonsaline + QuitoMax® and saline + QuitoMax®. A tolerant (Amalia) and a susceptible (Claudia) tomato variety were used as experimental models. The normalized difference vegetation index (NDVI) was measured as a morphological variable, and peroxidase (POD), glutamine synthetase (GS) and nitrate reductase (NR) enzyme activities were determined. Gibberellic (GA) and abscisic acid (ABA) concentrations were also determined. Due to the effects of QuitoMax®, the plants maintained high NDVI values even under saline conditions. A decrease in POD and GS activity and an increase in NR activity were also found. The GA concentration in the leaves was higher in the tolerant variety when QuitoMax® was applied than in the saline treatment but lower in the susceptible variety. The opposite behavior was found when the ABA concentration was quantified. This study demonstrates the protective action of QuitoMax® under salinity stress on tomato crops in both tolerant and susceptible varieties. In crux, QuitoMax® can be opted as a shotgun approach to tackle salinity in tomato.

Reaction of potato cultivars to Potato Cyst Nematodes (Globodera rostochiensis and G. pallida) under greenhouse conditions in Kenya

Several measures have been recommended in the control of potato cyst nematodes (PCN) with resistant potato cultivars being considered as the most practical and affordable for smallholder potato farmers in Kenya. However, the level of resistance in locally grown potato varieties is yet to be established. The aim of this study was to screen Kenyan potato cultivars against PCN under greenhouse conditions. Eleven potato cultivars namely Shangi, Dutch Robijn, Sherekea, Nyota, Roseline tana, Tigoni, Unica, Asante, Chulu, Kenya Mpya and Arka were screened with Desiree (susceptible variety), Manitou (resistant cultivar) as controls. For each potato cultivar, there were two sets of plants with the first set being inoculated with 50 cysts, while the second batch was nematode-free. The treatments were arranged in a completely randomized design with three replications. A scale of 1-9, with 9 indicating the highest level of resistance was used in the assessment of disease severity. Nematode infestation caused a reduction in root mass across the 11 cultivars from 20 to 100% compared to uninoculated controls. Reproductive index of PCN viable eggs across the 11 cultivars was <1 compared to control (Desiree). Potato cultivars Shangi, Tigoni, Dutch, Chulu, Asante, Unica, Arka, Kenya Mpya, and Roseline Tana had a severity score of 1-3 (>95%), hence were considered to be susceptible to PCN. The cultivars Sherekea and Nyota had a severity score of 4-6 (<25%) and hence were considered partially resistant to PCN. The findings of this study provides a basis of integrating partially resistant potato cultivars into PCN management in smallholder farms. Keywords: Cyst viable eggs, reproductive index, resistance, susceptible, smallholder farmers, severity score.

Genetic variations among the isolates of Bipolaris Maydis based on phenotypic and molecular markers

Abstract Maydis leaf blight, caused by Bipolaris maydis, is an important disease of maize crop in Khyber Pakhtunkhwa (KP) Pakistan. Fifteen isolates of the pathogen, collected across KP, were studied for variability based on phenotypic and molecular markers. Significant variability among the isolates was observed when assessed using phenotypic traits such as radial growth, spore concentration, fungicide sensitivity and virulence. The isolates were classified into six culture groups based on colour, texture and margins of the colony. Conidial morphology was also variable. These were either straight or slightly curved and light to dark brown in colour. Fungicide test showed significant variation in the degree of sensitivity against Carbendazim. Isolate Bm8 exhibited maximum radial growth on carbendazim spiked plates. Conversely, isolate Bm15 showed the lowest radial growth. Variations in virulence pattern of the isolates were evident when a susceptible maize variety Azam was inoculated with spores of B. maydis. Genetic variability amongst the isolates was also estimated by RAPD as well as sequencing of ITS region. The RAPD dendrogram grouped all the isolates into two major clusters. Average genetic distance ranged from 0.6% to 100%, indicating a diverse genetic gap among the isolates. Maximum genetic distance was found between isolates Bm9 and Bm10 as well as Bm2 and Bm8. Conversely, isolates Bm13 and Bm15 were at minimum genetic distance. Phylogenetic dendrogram based on sequencing of ITS region grouped all the isolates into a single major cluster. The clusters in both the dendrogram neither correlate to the geographical distribution nor to the morphological characteristics.

Impact of managing yellow rust (Puccinia striiformis f.sp. tritici) by the use of fungicide sprays and resistant varieties on the physiochemical qualities of bread wheat

AbstractYellow rust disease caused by Puccinia striiformis f. sp. tritici is one of the major threats to wheat production in Ethiopia. In this paper, the impact of yellow rust on the physical qualities of bread wheat was studied. For this purpose, combinations of four bread wheat varieties (Digalu, Hidase, Danda'a, and Honkolo) and two fungicides (Nativo SC 300 and Tilt® 250E.C.) were tested at two different hotspot areas (Albazar and Alicho) in the Silte Zone, Southern Ethiopia, under natural epidemics of the disease during the 2018 growing season. A randomized complete block design in factorial arrangement with three replications was used to set up the experiment. A significant (p < .01) increase in hectoliters weight and wet gluten content were observed due to the application of Nativo SC 300; however, grain protein content did not respond significantly (p > .01) at both locations. Wheat varieties with high yellow rust severity exhibited maximum values of area under the disease progress curve and physical quality loss percentage (%). The highly susceptible wheat variety Digalu exhibited the highest values of hectoliter weight losses (%), and the actual losses ranged from 5.5% to 29.5%. Except for grain protein content, there was a significant negative correlation between the values of terminal rust severity, average coefficient infection, and area under the disease progress curve and that of hectoliters weight and wet gluten content, with correlation coefficients ranging from −0.85** to −0.33**. It is possible to improve the physiochemical properties of bread wheat through the application of foliar fungicides by selecting the appropriate genotypes that have an acceptable level of resistance to yellow rust.

Transcriptome-based analysis of candidate gene markers associated with resistance mechanism to Phytophthora melonis that causes root and crown rot in pumpkin.

Root and crown rot incited by an oomycete, Phytophthora melonis, causes significant yield losses in commercial pumpkin (Cucurbita pepo) production worldwide. Currently, resistant cultivars and knowledge of molecular mechanism of C. pepo against P. melonis are scarce. Here, we analysed the quantitative gene expression changes of 10 candidate gene markers (bHLH87, ERF014, HSF, MYB, PR-1, WRKY21, CPI, POD, PSK, SGT) in pumpkin roots and leaves at three time points (h post-inoculation, hpi) following inoculation with P. melonis in two resistant (Ghelyani and Tanbal), and two susceptible (Marmari and Khoreshti) varieties of pumpkin. Gene expression using quantitative real time PCR along a time course revealed the strongest transcriptomic response at 48 and 72hpi in resistant genotypes, 1.1-2.7-fold in roots and leaves, respectively, with a high significant correlation (r=0.857**-0.974**). We also found that CPI, PSK, SGT1 and POD act as a dual regulator that similarly modulate immunity not only against P. melonis, but also against other diseases such as early blight (Alternaria cucumerina), powdery mildew (Podosphaera xanthii), downy mildews (Pseudoperonospora cubensis), and pathogenic plant nematodes (Meloidogyne javanica). Furthermore, significantly higher activities of the ROS scavenging defence enzymes, catalase (1.6-fold increase) and peroxidase (6-fold increase) were observed in the roots of resistant cultivars at different hpi compared with non-inoculated controls. In addition, the biomass growth parameters including leaf and root length, stem and root diameter, root fresh weight and volume were significantly different among studied genotypes. Cumulatively, the transcriptome data provide novel insights into the response of pumpkins for improving pumpkin breeding to P. melonis.

Exploring the biochemical dynamics in faba bean (Vicia faba L. minor) in response to Orobanche foetida Poir. parasitism under inoculation with different rhizobia strains.

In Tunisia, Orobanche foetida Poir. is considered an important agricultural biotic constraint on faba bean (Vicia faba L.) production. An innovative control method for managing this weed in faba bean is induced resistance through inoculation by rhizobia strains. In this study, we explored the biochemical dynamics in V. faba L. minor inoculated by rhizobia in response to O. foetida parasitism. A systemic induced resistant reaction was evaluated through an assay of peroxidase (POX), polyphenol oxidase (PPO) and phenyl alanine ammonialyase (PAL) activity and phenolic compound and hydrogen peroxide (H2O2) accumulation in faba bean plants infested with O. foetida and inoculated with rhizobia. Two rhizobia strains (Mat, Bj1) and a susceptible variety of cultivar Badi were used in a co-culture Petri dish experiment. We found that Mat inoculation significantly decreased O. foetida germination and the number of tubercles on the faba bean roots by 87% and 88%, respectively. Following Bj1 inoculation, significant decreases were only observed in O. foetida germination (62%). In addition, Mat and Bj1 inoculation induced a delay in tubercle formation (two weeks) and necrosis in the attached tubercles (12.50% and 4.16%, respectively) compared to the infested control. The resistance of V. faba to O. foetida following Mat strain inoculation was mainly associated with a relatively more efficient enzymatic antioxidative response. The antioxidant enzyme activity was enhanced following Mat inoculation of the infected faba bean plant. Indeed, increases of 45%, 67% and 86% were recorded in the POX, PPO and PAL activity, respectively. Improvements of 56% and 12% were also observed in the soluble phenolic and H2O2 contents. Regarding inoculation with the Bj1 strain, significant increases were only observed in soluble phenolic and H2O2 contents and PPO activity (especially at 45 days after inoculation) compared to the infested control. These results imply that inoculation with the rhizobia strains (especially Mat) induced resistance and could bio-protect V. faba against O. foetida parasitism by inducing systemic resistance, although complete protectionwas not achieved by rhizobia inoculation. The Mat strain could be used as a potential candidate for the development of an integrated method for controlling O. foetida parasitism in faba bean.

Disturbed nutrient accumulation and cell wall metabolism in panicles are responsible for rice straighthead disease.

Rice straighthead disease substantially reduces crop yield, posing a significant threat to global food security. Dimethylarsinic acid (DMA) is the causal agent of straighthead disease and is highly toxic to the reproductive tissue of rice. However, the precise physiological mechanism underlying DMA toxicity remains unknown. In this study, six rice varieties with varying susceptibility to straighthead were utilized to investigate the growth performance and element distribution in rice panicles under DMA stress through pot experiments, as well as to explore the physiological response to DMA using transcriptomic methods. The findings demonstrate significant variations in both DMA accumulation and straighthead sensitivity among cultivars. The susceptible varieties exhibited higher DMA accumulation indices and displayed typical symptoms of straighthead disease, including erect panicles, deformed rachides and husks, and reduced seed setting rate and grain yield when compared to the resistant varieties. Moreover, DMA addition promoted mineral nutrients to accumulate in rachides and husks but less in grains. DMA showed preferential accumulation in rice grains with a distribution pattern similar to that of Copper (Cu) and zinc (Zn) within the panicle. Transcriptome analyses underscored the substantial impact of DMA on gene expression related to mineral metabolism. Notably, DMA addition significantly up-regulated the expression of pectin methylesterase, pectin lyase, polygalacturonase, and exogalacturonase genes in Nanjingxiangzhan, while these genes were down-regulated or weakly expressed in Ruanhuayou 1179. The alteration of pectin metabolic pathways induced by DMA may lead to abnormality of cell wall assembly and modification, thereby resulting in deformed rice panicles.

Functional Analysis of Amino Acid Transporter Genes ACYPI000536 and ACYPI004320 in Acyrthosiphon pisum.

In recent years, pea aphids have become major pests of alfalfa. Our previous study found that "Gannong 5" is a highly aphid-resistant alfalfa variety and that "Lie Renhe" is a susceptible one. The average field susceptibility index of "Gannong 5" was 31.31, and the average field susceptibility index of "Lie Renhe" was 80.34. The uptake and balance of amino acids in insects are usually dependent on amino acid transporters. RT-qPCR was used to detect the relative expression levels of seven amino acid transporter differential genes in the different instar pea aphids fed on resistant and susceptible alfalfa varieties after 24 h, and two key genes were selected. When pea aphids fed on "Gannong 5", the expression of ACYPI004320 was significantly higher than that in pea aphids fed on "Lie Renhe"; however, the expression of ACYPI000536 was significantly lower than that in pea aphids fed on "Lie Renhe". Afterward, the RNA interference with pea aphid ACYPI000536 and ACYPI004320 genes was performed using a plant-mediated method, and gene function was verified via liquid chromatography-mass spectrometry and pea aphid sensitivity to aphid-resistant and susceptible alfalfa varieties. The results showed that the down-regulation of the ACYPI000536 gene expression led to an increase in the histidine and lysine contents in pea aphids, which, in turn, led to an increase in mortality when pea aphids fed on the susceptible variety "Lie Renhe". The down-regulation of the ACYPI004320 gene expression led to an increase in phenylalanine content in pea aphids, which, in turn, led to a decrease in mortality when pea aphids fed on the resistant variety "Gannong 5".

ASSESSMENT OF DIFFERENT TOMATO VARIETIES AND CHEMOTHERAPEUTIC COMPOUNDS FOR CONTROLLING ROOT ROT DISEASE CAUSED BY RHIZOCTONIA SOLANI

Solanum lycopersicum L., commonly known as tomato, is a vital vegetable crop with significant nutritional value but is susceptible to various pathogens causing diseases. Among all of these, Rhizoctonia solani-induced root rot is a highly destructive disease affecting tomato production and quality. This study aimed to identify resistant tomato varieties and effective chemical strategies for root rot management. Ten tomato varieties and advanced lines were evaluated under field conditions, and disease incidence was recorded. Nadir (11.80%) and Sundar (18.43%) exhibited resistance with the lowest disease incidence, while To-1057 f1 (25.87%), Ahmar (32.13%), and Litth-879-2 f3 (36.77%) showed moderate resistance. Moderately susceptible varieties included Rio-grandi (40.67%), Salar (47.90%), and Naqeeb (52.83%), while FS-2187 (75.90%) and Litth-861-4-17 (80.93%) were susceptible and highly susceptible, respectively. Additionally, six fungicides were tested under in-vitro and greenhouse conditions, with Dolomite, Nativo, and Evicine exhibiting the best performance. Further evaluation of these fungicides in field conditions confirmed Evicine effectiveness in reducing disease incidence. These findings emphasize the need for future research and development of resistant tomato cultivars and recommend the use of Evicine as an effective treatment against Rhizoctonia solani for disease management.

Proteomics Analysis to Explore the Resistance Genes of Silkworm to Bombyx mori Nuclear Polyhedrosis Virus.

The resistance of silkworms to Bombyx mori nuclear polyhedrosis virus (BmNPV) is controlled by a major dominant gene and multiple modifying genes. Given the presence of modified genes, it is difficult to determine the main gene by positional cloning. In this study, the main anti-BmNPV gene of BmNPV-resistant silkworm variety N was introduced into the susceptible variety Su to breed the near-isogenic line SuN with BmNPV resistance. The infection process of BmNPV in the hemolymph of Su and SuN was analyzed using the cell analysis system TissueFAXS PLUS. According to the law of infection and proliferation, hemolymph was extracted every 6 h for two-dimensional electrophoresis (2-DE) analysis and quantitative real-time polymerase chain reaction (qRT-PCR). Seven DEPs were found in comparisons between Su and SuN by 2-DE analysis. Among them, acid phosphatase, storage protein, and phenoloxidase can prevent pathogen invasion, which may play a role against BmNPV. Polyamine oxidase plays an important role in energy metabolism, which may be indirectly involved in the process of resisting BmNPV. Most of the transcriptional expression profiles of the seven DEPs were consistent with the 2-DE results. This study can provide a reference for the identification of anti-BmNPV genes and the breeding of BmNPV-resistant silkworm varieties.

Effects of Major Fungal Pathogens on Growth and Yield of Improved and Local Sorghum Genotypes under Field Trials in Lower Eastern Kenya

Sorghum is a climate resilient cereal that offers food and nutrition security for the arid and semi-arid lands (ASALs). Its production potential is however limited by fungal diseases. A study on the effects of major fungal diseases on sorghum growth and yield and identification of tolerant genotypes is critical for sustainable sorghum production. A total of 14 germplasms were analyzed under a two-seasonal field trial laid out in Randomized Complete Block Design with four replications at two different agro-ecological zones within Kenya’s ASALs. A spreader row technique using a highly susceptible variety and natural infections was used for fungal inoculation. Ten plants randomly sampled and tagged from two inner rows in each plot, were used to asses plant growth, yield, and diseases. Diseases were identified using identification keys, visual symptoms, and signs and effects scored through disease severity (DS) and disease incidence (DI). Identified diseases included anthracnose, leaf blight, rust, gray leaf spot, ladder leaf spot, oval leaf spot, downy mildew, and covered kernel smut. Higher DS (>7.0) and DI (>50%) were recorded in anthracnose, leaf blight, and leaf rust across most genotypes. The significant (P≤0.01) negative correlations between DS and days to 50% flowering, number of green leaves, leaf area and panicle width indicated potential disease inhibition of sorghum growth. Correlations between DS and dry biomass, grain yield and grain weight were also negative but insignificant (P>0.05) implying no disease effects on sorghum yield. Improved genotypes had the least foliar and panicle infections and produced significantly higher grain yield (>2.0 t/ha) compared to local varieties with lower yield (<1.5t/ha) and higher foliar and panicle symptoms. The improved genotypes were thus classified as tolerant to fungal diseases and could be used to support resistance breeding programs as a sustainable management strategy for improved sorghum production in ASALs of Kenya.

Screening of Promising Maize Varieties Against Maize Weevil (Sitophilus zeamais Motschulky) Under Storage Condition

The maize weevil (Sitophilus zeamais Motschulsky) causes significant quantitative and qualitative losses during storage. To identify resistant varieties of maize against this pest, an experiment was conducted in a Completely Randomized Design (CRD) with 11 varieties in free and no-choice conditions. The study measured weight loss, mean bored grain, debris, and weevil numbers at 30, 60, and 90 days. The findings showed that BG13Y-POP, Manakamana-7, and RML-19/RML-6 were the most resistant varieties, with weight loss percentages of 1.99%, 1.47%, and 1.74%, respectively, and final weevil numbers of 104, 72, and 73. Ganesh-2 and ZM-401 were the most susceptible varieties, with weight losses of 7.34% and 6.05%, respectively. The maximum debris weight was found in RML-761/RL-105 (1.98 g), while the minimum was found in Manakamana-7 (0.26 g). The highest number of bored grains was observed in Ganesh-2 (81), while the lowest number was observed in Rampur-4 (51). Similarly, ZM-401 (158) and Ganesh-2 (165) exhibited the highest weevil population, while the lowest count was found in Rampur-4 (72). Overall, using resistant varieties, such as Manakamana-7, BG13Y-POP, and RML-19/RML-6, can be an effective approach for reducing post-harvest losses from weevil infestation.

VdPT1 Encoding a Neutral Trehalase of Verticillium dahliae Is Required for Growth and Virulence of the Pathogen.

Verticillum dahliae is a soil-borne phytopathogenic fungus causing destructive Verticillium wilt disease. We previously found a trehalase-encoding gene (VdPT1) in V. dahliae being significantly up-regulated after sensing root exudates from a susceptible cotton variety. In this study, we characterized the function of VdPT1 in the growth and virulence of V. dahliae using its deletion-mutant strains. The VdPT1 deletion mutants (ΔVdPT1) displayed slow colony expansion and mycelial growth, reduced conidial production and germination rate, and decreased mycelial penetration ability and virulence on cotton, but exhibited enhanced stress resistance, suggesting that VdPT1 is involved in the growth, pathogenesis, and stress resistance of V. dahliae. Host-induced silencing of VdPT1 in cotton reduced fungal biomass and enhanced cotton resistance against V. dahliae. Comparative transcriptome analysis between wild-type and mutant identified 1480 up-regulated and 1650 down-regulated genes in the ΔVdPT1 strain. Several down-regulated genes encode plant cell wall-degrading enzymes required for full virulence of V. dahliae to cotton, and down-regulated genes related to carbon metabolism, DNA replication, and amino acid biosynthesis seemed to be responsible for the decreased growth of the ΔVdPT1 strain. In contrast, up-regulation of several genes related to glycerophospholipid metabolism in the ΔVdPT1 strain enhanced the stress resistance of the mutated strain.

Diversity of halotolerant endophytes from wheat (Triticum aestivum) and their response to mitigate salt stress in plants

Soil salinity is one of the major limiting factors that decline crop production. About 20% of irrigated land soil is presently affected by high salinity worldwide reducing the crop yield by 20–50%. Endophytes play an important role in coping with the salinity stress in plants. In present study, 224 bacterial endophytes exhibiting discrete salt tolerance ranging from 0.5 M to 4.0 M were isolated from the shoot and root of wheat. Endophytic isolates showed varying salt tolerance potential and only a few (7.14%) possess the capability to tolerate high salt concentration (≥3.0 M NaCl). The 16S rRNA gene sequence exhibited 65 discrete OTUs recovered from the root (53.85%) and shoot tissue (46.15%) of the wheat plant. The 16S rRNA gene sequencing revealed the majority of phylum were Firmicutes (81.54%), Proteobacteria (13.85%), and Actinobacteria (4.62%) and dominated by Bacillus (63.08%), Priestia (13.85%), Pseudomonas (10.77%), Exiguobacterium and Curtobacterium (3.08% each). Moreover, this study is the first report for the abundance of certain bacterial species as endophytes from wheat cultivated under saline-affected regions like Bacillus australimaris, B. vallismortis, B. haynesii, Rossellomorea marisflavi, Exiguobacterium undae, Curtobacterium pusillum. The selected endophytes significantly reduced the detrimental influence of salt stress and enhanced various growth parameters like root length, shoot length, fresh weight, and dry weight of salt susceptible wheat variety ‘HD 2733’ as compared to the control. The present study might be beneficial to restore soil fertility and reduce the loss of crop productivity under saline stress conditions.

Effectiveness of Integrated Management on Fusarium-Nematode wilt Complex Disease of Banana cv. Ney Poovan (AB): Insights from a Field Study

Banana (Musa spp.) belongs to the family Musaceae is the most important fruit crop in the world, serving as a staple food and source of income in many developing countries. There are several diseases recorded on Banana causing serious losses. Wilt complex disease caused by Fusarium oxysporum f. sp. cubense and Radopholus similis is considered as a serious threat Banana cultivation. A field experiment was conducted in a randomised complete block design with susceptible Banana variety Nay Poovan (AB) to manage the fungal-nematode wilt complex using treatments of bioagents, organic amendments and chemicals in individual as well as in integrated approach. The experiment results revealed that, Carbendazim (262.73 cm) treated plants had good plant height and it was on par with combined treatments. Among combination treatments, T11 (Neem cake + FYM +T. viride + + P. fluorescens +P. lilacinus + Carbofuran + stem injection of Carbendazim at 5,7,9 months) gave maximum plant height (118.00, 195.27 and 262.60 cm). The least plant height was recorded in control 89.60 cm, 140.00 cm and 188.00 cm at 90, 180 days after planting and at harvest respectively. The final population of R. similis in soil was lowest in T11 (Neem cake + FYM, T. viride+P. fluorescens+P. lilacinus + Carbofuran + stem injection of Carbendazim at 5,7,9 months) (6.33 /200 cc soil), followed by T6 (T. viride + P. lilacinus) (26.33 /200 cc soil), whereas control treatment has maximum (1382.00 /200 cc soil). Regarding wilt incidence, the plants treated with Neem cake + FYM, T. viride+P. fluorescens+P. lilacinus + Carbofuran + stem injection of Carbendazimat 5, 7, 9 months (T11) recorded less incidence (11.12%) as compared to the maximum wilt incidence of 88.89 per cent in control treatment. The next best treatment was T10 (Carbendazim 17.67 %). Individual application the maximum number of hands per bunch, bunch weight and total yield per hectare was recorded in T10(Carbendazim) 13.80, 12.75 kg and 45.75 t/ha), T2(P. Fluorescens) (9.67, 9.73 kg and 36.05 t/ha) and least was recorded in T9 (Carbofuron) (8.75, 8.25 kg and 32.50 t/ha) compare to control. Among the combined treatments, the maximum number of hands per bunch (19.75), bunch weight (16.80 kg) and total yield per hectare (26.33 t/ha) was recorded in treatment T11 (Neem cake + FYM, T. viride+P. fluorescens+P. lilacinus + Carbofuran + stem injection of Carbendazim at 5, 7, 9 months). The economic analysis revealed that, the T11 had recorded a maximum benefit cost ratio of 4.26 followed by T10 – Carbendazim (3.96) percent incidence and the least benefit cost ratio was recorded by control (1.23).

The integrated disease management of early blight in organically grown tomato under hill condition of Sikkim, India

Tomato (Lycopersicon esculentum Mill.) is the most widely cultivated vegetable crop in the world and early blight caused by Alternaria spp. is one of the major production constraints. Survey was conducted during kharif seasons of 2018-19 &2019-20 in four districts of Sikkim. Maximum early blight disease severity was recorded in south district of Sikkim. Pathogenicity test of isolates collected from different location were established. Morphological, cultural, and molecular identification of the pathogen reveal pathogen as Alternaria spp. Five different bio-control agents i.e., Trichoderma harzianum, T. Viride, Pseudomonas fluorescens, Bacillus subtilis and Bacillus cereus were evaluated against the test pathogens. Among the bio-control agents tested, Trichoderma harzianum (74.89%) and Trichoderma viride (69.41%) showed maximum percent growth inhibition. Open field experiment was conducted with eleven treatments formulated by integrating the different organic inputs, biocontrol agents and copper-based fungicide as chemical check. Organic treatment T9 {Susceptible Variety + Soil treatment with Trichoderma harzianum @1:25(1kg Trichoderma + 25 Kg of FYM) + cow dung slurry 10% + Nimbicidine 0.3% + Panchagavya 10% + Cow Urine 10%} consistently showed the best result among the bioresources tested. Keywords: Tomato, Organic, Bio agent and Integrated disease management

Cotton microbiome profiling and Cotton Leaf Curl Disease (CLCuD) suppression through microbial consortia associated with Gossypium arboreum

The failure of breeding strategies has caused scientists to shift to other means where the new approach involves exploring the microbiome to modulate plant defense mechanisms against Cotton Leaf Curl Disease (CLCuD). The cotton microbiome of CLCuD-resistant varieties may harbor a multitude of bacterial genera that significantly contribute to disease resistance and provide information on metabolic pathways that differ between the susceptible and resistant varieties. The current study explores the microbiome of CLCuD-susceptible Gossypium hirsutum and CLCuD-resistant Gossypium arboreum using 16 S rRNA gene amplification for the leaf endophyte, leaf epiphyte, rhizosphere, and root endophyte of the two cotton species. This revealed that Pseudomonas inhabited the rhizosphere while Bacillus was predominantly found in the phyllosphere of CLCuV-resistant G. arboreum. Using salicylic acid-producing Serratia spp. and Fictibacillus spp. isolated from CLCuD-resistant G. arboreum, and guided by our analyses, we have successfully suppressed CLCuD in the susceptible G. hirsutum through pot assays. The applied strains exhibited less than 10% CLCuD incidence as compared to control group where it was 40% at 40 days post viral inoculation. Through detailed analytics, we have successfully demonstrated that the applied microbes serve as a biocontrol agent to suppress viral disease in Cotton.