Root-dip Method Research Articles

Fermented botanical fertilizer controls bacterial wilt of tomatoes caused by Ralstonia pseudosolanacearum.

This study demonstrates the effect of fermented botanical product (FBP) on Ralstonia pseudosolanacearum-induced bacterial wilt disease and unravels its action mechanism. Soaking with diluted FBP solutions (0.1%-0.5%) significantly suppressed bacterial wilt in tomato plants, and FBP-treated tomato plants grew well against R. pseudosolanacearum infection. Growth assays showed that FBP had no antibacterial effect but promoted R. pseudosolanacearum growth. In contrast, few or no R. pseudosolanacearum cells were detected in aerial parts of tomato plants grown in FBP-soaked soil. Subsequent infection assays using the chemotaxis-deficient mutant (ΔcheA) or the root-dip inoculation method revealed that FBP does not affect pathogen migration to plant roots during infection. Moreover, FBP-pretreated tomato plants exhibited reduced bacterial wilt in the absence of FBP. These findings suggest that the plant, but not the pathogen, could be affected by FBP, resulting in an induced resistance against R. pseudosolanacearum, leading to a suppressive effect on bacterial wilt.

Effects of nanoparticle applications on seedling survival and morphological characteristics in Scots pine afforestation

This study was conducted in the afforestation area, using bare-root 2+0-year-old Scots pine seedlings from Kastamonu. The study aimed to determine the impact of nanoparticle (NP) applications on seedling morphological characteristics and seedling survival success. Three different concentrations (low, medium, high) and four different nanoparticle types [Fe₃O₄, CuO, ZnO, TiO2] were applied to the plant root-dipping method in the study. The effects of NP treatments on seedling height (SH), root collar diameter (RCD), stem fresh weight (SFW), root new weight (RFW), seedling fresh weight (SEFW), root dry weight (RDW), stem dry weight (SDW), seedling dry weight (SEDW), sturdiness quotient (SI), root: shoot ratio (R/S), and seedling survival in the field were evaluated. The study results revealed that NP types significantly affected all seedling variables except RFW, SDW, RDW, and SEDW, and NP doses significantly affected all seedling variables except RFW. The binary interaction effects of NP types and doses had a significant effect on all seedling variables, and higher values were obtained compared to the control treatment. Medium and high NP doses were more effective in seedling growth than low doses; the percentage of seedling survival was 61.4% in the control treatment and 95% in the TiO2-Medium NP treatment combination.

First Vanilla planifolia High-Density Genetic Linkage Map Provides Quantitative Trait Loci for Resistance to Fusarium oxysporum.

Fusarium oxysporum f. sp. radicis-vanillae (Forv), the causal agent of root and stem rot disease, is the main pathogen affecting vanilla production. Sources of resistance have been reported in Vanilla planifolia G. Jackson ex Andrews, the main cultivated vanilla species. In this study, we developed the first high-density genetic map in this species with 1,804 genotyping-by-sequencing (GBS)-generated single nucleotide polymorphism (SNP) markers using 125 selfed progenies of the CR0040 traditional vanilla cultivar. Sixteen linkage groups (LG) were successfully constructed, with a mean of 113 SNPs and an average length of 207 cM per LG. The map had a high density with an average of 5.45 SNP every 10 cM and an average distance of 1.85 cM between adjacent markers. The first three LG were aligned against the first assembled chromosome of CR0040, and the other 13 LG were correctly associated with the other 13 assembled chromosomes. The population was challenged with the highly pathogenic Forv strain Fo072 using the root-dip inoculation method. Five traits were mapped, and 20 QTLs were associated with resistance to Fo072. Among the genes retrieved in the CR0040 physical regions associated with QTLs, genes potentially involved in biotic resistance mechanisms, coding for kinases, E3 ubiquitin ligases, pentatricopeptide repeat-containing proteins, and one leucine-rich repeat receptor underlying the qFo72_08.1 QTL have been highlighted. This study should provide useful resources for marker-assisted selection in V. planifolia.

Characterisation and pathogenicity of Verticillium dahliae isolates associated with Verticillium wilt of tomato in the Limpopo Province of South Africa

In the Limpopo Province of South Africa, the sustainable production of tomatoes is threatened by a soilborne disease known as Verticillium wilt. Limited information is available regarding the Verticillium species involved, their genetic diversity and aggressiveness. Therefore, a pathogen survey was conducted in the three major tomato production regions in Limpopo (six fields in the Lowveld and two fields each in the Highveld and Soutpansberg). Verticillium dahliae was identified as the only Verticillium species associated with Verticillium wilt of tomatoes. Conventional vegetative compatibility group (VCG) testing identified 38 isolates as VCG 4B and two isolates as VCG 2B. Pathotype-genotype specific PCR analysis indicated that all the isolates belonged to the non-defoliating pathotype, specifically genotype C. These characteristics allowed for the classification of almost all the isolates from the Lowveld, Highveld and Soutpansberg regions into clonal lineage 4B (38 isolates). The exception was for two isolates from the Lowveld that belonged to lineage 2B824. Based on a race-specific PCR analysis, all 40 isolates belonged to race 2. Sequencing of the race-specific PCR amplicon revealed the presence of two haplotypes namely I and II. Evaluation of seven inoculation methods (agar plug, millet, node-inoculation, root-dip, sand-bran, soil-drench and toothpick methods) using three isolates showed that the root-dip method was the only method that consistently identified all the isolates as pathogenic based on disease severity as well as an increase in plant height. Assessment of the aggressiveness of the 40 characterised V. dahliae isolates showed that the isolates varied in aggressiveness to the cv. Floradade.

First report in China of Fusarium humuli as a causative agent of Chinese yam wilt.

Wilt is one the most serious soil-born fungal diseases of Chinese yam (Dioscorea polystachya Turczaninow cv. Tiegun), affecting plant production in many growing regions in Jiangxi province, China. The average annual incidence of wilt is 45-80%. In 2020, affected plants with wilt symptoms including withered and dried leaves, vascular discoloration, and brown necrotic stem lesions at the soil line or in the crown of the plant (Figure 1A-D) were collected from the Ruichang, Yongfeng and Taihe production areas (four fields per location) in Jiangxi province. A total of fifteen isolates were recovered from the infected stem tissues of Chinese yam and purified by single spore cultures on PDA growth medium. The fifteen isolates were similar in morphology so isolate JXRC11 was selected to be representative of the group. Pure fungal colonies of JXRC11were found to be round, white, with margin entire (Figure 1E). Macroconidia with 3-5 septations were straight to slightly curved, 23.8-40.3 µm in length and 2.6-3.9 µm in width, with predominantly 5-septate macroconidia on carnation leaf agar (CLA) (Figure 1F). However, neither microconidia or chlamydospores were observed on CLA. The morphological characteristics of the isolate were consistent with the description observed previously for Fusarium humuli species complex (Wang et al. 2019). To confirm morphological identification, ITS, CAM, TEF-1α, RPB1 and RPB2 were amplified using the primers ITS5/ITS4 (White et al. 1990), CL1/CL2A (O'Donnell et al. 2000), EF1/EF2 (O'Donnell et al. 1998), Fa/G2R (O'Donnell et al. 2010), and 5f2/11ar (O'Donnell et al. 2010), respectively. BLASTn analysis of the ITS sequence (GenBank accession no. MZ768912), EF-1α (MZ824669), CAM (MZ824670), RPB1 (MZ824672) and RPB2 (MZ824673) alignment showed 99.55%, 99.68%, 99.85%, 97.61% and 99.76% identity to those of F. humuli CQ1039 (MK280845, MK289570, MK289712, MK289840 and MK289724), respectively. Multilocus phylogenetic analyses showed that the sequences of ITS, CAM, EF-1α, RPB1, and RPB2 of the isolate belonged to the incarnatum clade (FIESC-33) of the F. incarnatum-equiseti species complex with an independent branch (Figure 2). Pathogenicity tests were conducted on one-month-old Chinese yam seedlings using a seedling root dip method (Li et al. 2013). The roots and rhizomes of seedlings grown to two meters in height were dipped into spore suspensions (1×106 spores/mL) of isolate JXRC11 for 30 min and then transferred into 20 cm diameter plastic pots containing steam-sterilized soil and placed in a greenhouse under 12 h photoperiod. After 15 d, the inoculated seedlings showed typical wilt symptoms similar to those observed in farm fields, whereas the control remained unaffected (Figure 1G-H). The pathogen was then re-isolated from the infected plants, the re-isolations were identified as F. humuli by sequencing EF-1α, fulfilling the Koch's postulates. It has been reported that the pathogen F. oxysporum Schlecht causes Fusarium wilt in five species of Dioscorea (Nwankiti and Arene, 1978). Moreover, at least 5 species of Fusarium were identified as a causative agent of Chinese yam wilt (Fang et al. 2020). To our knowledge, this is the first report of Fusarium wilt disease on Chinese yam caused by a member of the F. humuli in Jiangxi, China. This report will contribute to developing management strategies to control the disease.

Effects of melatonin applications on Anatolian black pine (Pinus nigra J. F. Arnold. subsp. pallasiana (Lamb.) Holmboe) afforestation performance in semi-arid areas

Melatonin, a substantial hormone, is a natural antioxidant agent that functions as a protector against the harmful effects of free radicals. Studies have found that “exogenous melatonin” applications have a positive effect on the growth and development of plants. This study investigated the adaptation of the seedlings that were transported from the nursery to the afforestation site for the process of planting. In 2019 the 2+0 aged bare-rooted Kastamonu/Taşköprü Anatolian Black pine seedlings, which are suitable for planting in semi-arid areas, were selected as research materials. Four different doses of “exogenous melatonin” (250, 500, 1000, and 1500 μM) were administered through two different methods (root-dipping and needle-spraying). Morphological seedling characteristics and bioactive chemical variables were measured for the control group and the seedlings treated with different doses of melatonin. Antioxidant enzyme activities were identified. When both the needle-spraying and root-dipping methods for melatonin application were evaluated in terms of morphological and biochemical variables, the best results were determined in low doses (250 to 500 μM). The results suggest that melatonin provides support to the metabolic process for the resistance of seedlings to low temperatures and semi-arid climatic conditions.

First Report of Verticillium Wilt Caused by Verticillium dahliae in Grafted Tomato in Taiwan.

Grafted tomato (Solanum lycopersicum L.) is widely used to manage soil-borne diseases (Lee et.al 2010). In Taiwan, grafting on eggplant (S. melongena L.) rootstock have been extensively used to reduce bacterial wilt in tomato production. In July 2019, wilting plants were found at a cherry tomato farm (~ 0.5 ha) located at Miaoli County. About 10% tomatoes of cv. 'Mint Shine' grafted onto the eggplant rootstock displayed wilt symptoms. Numerous leaflets with chlorosis, inter-vein yellowing, V-shaped necrotic lesions and withered leaves were observed on the affected plants. Some plants eventually wilted and died. A cut at the grafting site revealed the vascular discolorations on both scion (tomato) and rootstock (eggplant). A fungus with a compact whitish colony was consistently isolated from the symptomatic vascular tissue by using acidified potato dextrose agar (PDA) plates. Two isolates, Ve2 from eggplant and Ve4 from tomato, grown on PDA plates were characterized. Both Ve2 and Ve4 grow slowly (ca. 2.6 mm/day at 28 oC) and shared almost identical cultural and morphological characteristics. They first showed whitish mycelium and cream color in reverse within 1 week. Later, numerous microsclerotia developed evenly over the colony and the reverse color turned dark black. Microscopic observations revealed hyaline hyphae with black, elongated, irregularly spherical microsclerotia measuring 31.3 to 71.5 × 16.8 to 49.0 µm (average 50.4 × 28.5 µm) on a 3-week-old PDA culture. Abundant hyaline, single-celled, ellipsoida conidia measuring 2.7 to 4.7 × 0.9 to 3.2 µm (average 3.7 × 1.9 µm) and verticillate conidiophores were observed. The fungus was identified as Verticilium dahliae based on the consistent morphological characteristics (Hawksworth et. al 1970). To confirm the identity, the internal transcribed spacer regions of ribosomal DNA, amplified by PCR with universal primers ITS4/ITS5 (White et.al 1990), were sequenced. Both strains shared the same sequences (GenBank MZ734460; MZ736637), and BLASTn searching was 100% identical to many records of V. dahliae including an ex-epitype CBS130341. Pathogenicity was tested on 3-week-old seedlings of tomato cv. 'Bonny best' and eggplant cv. 'Longship' by a root dip method (Bhat & Subbarao 2007). Eighteen plants arranged into three replications were inoculated for each host-isolate combination, and incubated in the greenhouse at 25±3℃. The pathogenicity test was repeated two times, with the result that both isolates were pathogenic to tomato and eggplant. Both isolates induced wilt symptoms in all inoculated plants within 14 days post-inoculation (DPI). Severe leaf drop, wilting and vascular discoloration in all inoculated eggplant whereas slight yellowing and mildly stunt growth in tomato were observed at 21 DPI. Koch's postulates were fulfilled by re-isolating the same fungus from both infected tomato and eggplant. All uninoculated plants remained health and no V. dahliae was isolated from them. To our knowledge, this is the first report of V. dahliae and Verticilium wilt of grafted tomato caused by this pathogen in Taiwan. This pathogen affects over 400 plant species and has resulted in significant economic losses in many regions of world (Subbarao 2020). It is important to investigate the distribution and extent of damage caused by this emerging pathogen on Solanaceous or other crops.

Evaluation of artificial inoculation methods to determine resistance reaction to dry root rot and black root rot disease in mulberry (Morus spp.)

Root rot disease of mulberry is a widespread soil-borne disease, which can cause serious damage and huge economic loss to mulberry production in India. Efficient and reliable screening methods are prerequisites to evaluate the disease-resistant germplasm accessions for developing a cultivar’s resistance to root rot. A multifactor experiment with four replications was established to evaluate four different inoculation techniques namely, colonized sorghum grains (CSG), colonized toothpick, root dip (RD), and syringe inoculation using pathogenic isolates of three fungal pathogens; Fusarium solani, F. oxysporum (dry root rot) and Lasiodiplodia theobromae (black root rot) against known resistant and susceptible mulberry germplasm accessions under glasshouse conditions. In addition, all the methods of evaluating resistance were compared and the results indicated that CSG and RD methods of inoculation for dry and black root rot were stable in their pathogenic effect. Also, these two methods were easy to screen and more convenient than other methods.

First Report of Sanqi (Panax notoginseng) Root Rot Caused by Pythium vexans in China.

Sanqi (Panax notoginseng (Burk.) F. H. Chen) is a precious traditional Chinese herbal medicine. During April of 2021, a root rot disease with approximate 15% incidence was observed on 2-year-old Sanqi plants in a field of Zhouning (27º12' N, 119°33' E), Fujian Province of China. The disease symptoms included severe stunting, leaf chlorosis, root rotting and necrosis, as the disease progressed, the whole plant gradually wilted and died. To recover the causal agent, symptomatic roots were excised, surface sterilized in 75% alcohol for 1.5 min, rinsed in sterilized water three times, dried, and placed on PARP selective medium (Jeffers and Martin 1986), and incubated at 20°C in dark. After 5 days, total of 26 Pythium-like isolates were obtained, and one representative isolate Py21-6 (available from the Institute of Plant Protection, Fujian Academy of Agricultural Sciences) was selected for further identification. Colonies of Py21-6 on PARP plate were white with dense, cottony, aerial, and transparent mycelia. Sporangia were terminal or intercalary, non-papillate, spherical, pyriform or ovoid, measuring 21.7 ± 2.8 × 19.3 ± 2.3 μm (n = 30). Zoospores were saucer-like, released out of sporangium after maturation, and dispersed quickly by swimming. Oogonia were spherical, terminal or occasionally intercalary. Oospores were globose, smooth and aplerotic. The dimensions of zoospores, oogonia, and oospores were 6.8 ± 0.7 μm, 21.6 ± 2.2 μm and 18.2 ± 2.7 μm (n = 30), respectively. Antheridia were bell-shaped or irregular, terminal, monoclinous, and usually one per oogonium. According to the morphological characteristics the isolate was initially identified as Pythium spp. (Van der Plaats-Niterink 1981, Yong et al. 2016). For further identification, DNA extracted from Py21-6, the cytochrome c oxidase subunit I (COI) gene and internal transcribed spacer (ITS) region were amplified and sequenced with primers FM55/FM52R (Long et al. 2012) and ITS1 /ITS4 (White et al. 1990), respectively. BLAST analysis of 680-bp COI (OM688194) and 728-bp ITS (OM663703) sequences revealed 99.86% and 99.99% similarity to Pythium vexans in GenBank (HQ708995 [COI], GU133572 [ITS]). Therefore, the pathogen was identified as P. vexans. In order to fulfill Koch's postulates, isolate Py21-6 was grown on Martin's liquid medium (Martin 1992) for 72 h to produce a spore suspensions of 106 oospores/ml, and the pathogenicity test was conducted by root-dip method. Three groups of 2-year-old Sanqi (15 plants per group) with root soaked for 20 min in oospore suspension were used for pathogenicity, and the other three groups (15 plants per group) with root dipped in sterilized water as control. All treated plants were replanted in (15-cm-diameter) pots (2 plants/pot) filled with mixture of sterilized soil: vermiculite: pearlite (2:1:1, v/v), maintained in greenhouse under 60% black shade cloth at 20 to 26°C with 80% relative humidity, and watered once every three days. After 21days, all inoculated plants showed the same symptoms observed on the original diseased plants in the field, whereas, the control plants remained symptomless. The same pathogen was successfully re-isolated from the inoculated plants, and identical to those of the originals based on morphological and sequence data. To our knowledge, this is the first report of P. vexans causing root rot on Sanqi in China (Farr and Rossman 2022). Root rot is one of the destructive diseases in Sanqi production, identification of the pathogen will be useful to develop effective field management strategies to control this disease.

Effect of zinc application on yield, nutrients uptake and biochemical properties of rice under Inceptisols

A field experiment was conducted in a randomized block design at Regional Agricultural Research Station, Karjat during kharif 2016-2019 to study the effect of zinc on soil fertility, yield, nutrients uptake and biochemical properties of rice under Inceptisols. Results revealed that the grain (50.65 q ha-1) and straw (56.74 q ha-1) yield of rice was significantly improved with application of zinc in the form of zinc sulphate @ 15 kg ha-1 at the time of transplanting through soil application (T7) which was better than foliar spray and root dipping methods. Significantly highest values of DTPA-extractable Zn (0.45 mg kg-1) and SO4-S (32.40 kg ha-1) were registered in the treatment T8. The zinc supplied plots led to significant enhancement in total N (93.38 kg ha-1), P (15.55 kg ha-1), K (96.80 kg ha-1) and S (35.54 kg ha-1) uptake in the treatment T7 and Zn (183.40 g ha-1) in the treatment T8. The treatment T7 showed higher hulling (74.28%), milling (63.32%), gel consistency (81mm), alkali spreading value (4.0) as well as the head rice recovery (57.80%), protein (8.96%) and amylose (24.40%) content which was acceptable.Overall, Zn-fertilization assumes great significance in improving soil properties, productivity and quality of rice.

Development of optimized Verticillium longisporum inoculation techniques for canola (Brassica napus)

Verticillium stripe, caused by Verticillium longisporum, is an emerging soilborne disease of canola (Brassica napus) in Canada. Improved inoculation protocols will facilitate study of Verticillium stripe and its management. Two inoculation techniques, a root-dip method at two inoculum concentrations and a grain inoculation method at four inoculum concentrations, were compared under greenhouse conditions with the canola cultivars ‘45H31’, ‘CS2000’ and ‘Westar’. Symptoms of Verticillium stripe appeared at early growth stages following root dip inoculation, resulting in seedling mortalities of up to 19.7%, 39.5% and 33.3% for ‘CS2000’, ‘45H31’ and ‘Westar’, respectively, at 35 days post-inoculation. Plants inoculated by the root-dip method incurred much greater mortality at the high versus low inoculum concentration. In the surviving adult plants, ‘45H31’ was moderately resistant while ‘CS2000’ was more susceptible to V. longisporum. The grain inoculation method did not cause early-stage mortality, although Verticillium stripe severity at the adult stage was significantly different between control and high inoculum concentrations for all cultivars. In addition, plant dry weight and height decreased as inoculum concentration increased. Inoculation of 1-week-old, 2-week-old and 3-week-old seedlings of ‘CS2000’ and ‘Westar’ was also compared by the root-dip method. The impact of host age at inoculation on disease development was not significant, although higher disease severity was observed at later inoculation in ‘CS2000’. The application of grain inoculum may be more suitable for large-scale screening or studies conducted under field conditions.

Identification and Characterization of Fusarium Species Associated With Amaranth (Amaranthus Species) Wilt Disease in the Semi-deciduous and Guinea Savannah Agro-ecological Zones of Ghana

Fusarium wilt is a major constraint in amaranth production in Africa; the disease can lead to total crop failure. However, few studies have identified Fusarium species associated with amaranth diseases in Ghana. The study was conducted to identify Fusarium species causing wilt in amaranth in the Semi-deciduous and Guinea Savannah
 Agro-ecological zones of Ghana and determine variations in isolates. Using standard laboratory procedures, fungal pathogens were isolated and culture characteristics studied. Variations in virulence were determined using root dip method. Sequence analysis of the internal transcribed spacer region of isolates was carried out for species identfication. Based on morphological features complemented by sequence analysis; Fusarium equiseti, F. oxysporum, F. solani and F. proliferatum were identified. Fusarium equiseti was the dominant species appearing in 82% of isolates. All the isolates were pathogenic. Based on virulence level, 9% of the isolates were classified as very highly virulent whilst 56% were weakly virulent. Genetically, isolates clustered into four groups irrespective of origin. The work identified and classified Fusarium species causing amaranth wilt in Ghana.

First Report of Fusarium Wilt of Industrial Hemp (Cannabis sativa L.) Caused by Fusarium oxysporum in the Northeast China.

Industrial hemp (Cannabis sativa L.) is an ancient and economically important crop used in food, medicine, textile, and paper industries (Chandra et al. 2017). In July 2021, an estimated 30% of the industrial hemp plants showed wilted leaves and root rot in the greenhouse at the Modern Agriculture Demonstration Area Management Center, Harbin City, Heilongjiang Province, China. Initially, the diseased plants exhibited green and reversible wilting of lower canopy leaves. Upon progression the plants showed irreversible wilting. The epidermal tissue of root and rhizome showed slight cracks and the vascular bundle exhibited light brown discoloration, and then died. Six randomly selected disease plants were collected. Small fragments (5 mm) were cut from the infected roots, surface-sterilized with 70% ethanol for 30s and 1% sodium hypochlorite for 5 min and rinsed three times in sterile H2O. Then the small pieces were embedded on potato dextrose agar at 25℃ for 4 days and sub-cultured by hyphal tipping to isolate the fungus. A single-spore culture was obtained by monosporic isolation. The colonies were characterized by an abundant white cottony mycelium, which became gray or purple with age. The macroconidia were transparent, short to medium in length, straight to slightly curved, septate 0 to 4, 16.8 to 26.6 µm long × 3.5 to 4.1 µm wide. The apical cells were long and tapering to a point and the basal cells were notched. Microconidia were elliptic or kidney-shaped, and septate 0 to 4. The conidia were 4.2 to 11.3 µm long × 3.5 to 5.5 µm wide (n = 50). The morphological characteristics were very similar to those of Fusarium oxysporum (Leslie and Summerell 2006). For molecular identification, the internal transcribed spacer (ITS), translation elongation factor 1-α (TEF1) and RNA polymerase II beta subunit (RPB2) genes were amplified and sequenced with the primers ITS1/ITS4, EF-1/EF-2 (Uwaremwe et al. 2020), and 5f2/7c (O'Donnell et al. 2010). The 520 bp (ITS), 948 bp (TEF1), and 861 bp (RPB2) sequences were deposited in GenBank with acce. nos. MZ722998, OK180473 and OK180474, respectively. NCBI BLAST analysis showed 98 to 100% similarity with the sequences of F. oxysporum. Moreover, the sequences alignment similarity for the six isolates were 100%. Based on the morphological and molecular characteristics, the isolates were identified as F. oxysporum. For the pathogenicity test, 20 seedlings were inoculated 30 ml of a conidial suspension (106 conidia/ml) using the root dip method. Another set of 20 seedlings were inoculated with the same quantity of sterile distilled water as the controls. After inoculation, all seedlings were maintained in a greenhouse at 25°C ± 2, with a relative humidity of 60 to 70% and a 16 h light/8 h dark cycle. This test was repeated twice. The leaves of the inoculated seedlings gradually became yellow and exhibited wilting within 15 to 20 days, the epidermal tissue of root showed light brown discoloration. Eventually the plants were dead within 40 to 50 days after inoculation. The control seedlings did not show any wilt symptoms. F. oxysporum was re-isolated from the infected root tissues to fulfill the Koch's postulates. In addition to F. oxysporum, F. brachygibbosum, Pythium aphanidermatum, F. solani, and F. equiseti have also been reported to cause wilt symptoms of industrial hemp (Zamir et al. 2018). To our knowledge, this is the first report of Fusarium wilt on C. sativa caused by F. oxysporum in the Northeast China.

Characterization and Pathogenicity of Lasiodiplodia theobromae Causing Black Root Rot and Identification of Novel Sources of Resistance in Mulberry Collections.

Black root rot (BRR) caused by Lasiodiplodia theobromae is an alarming disease of mulberry that causes tremendous economic losses to sericulture farmers in India and China. Successful control of this disease can be attained by screening germplasm and identifying resistant sources. Seventy four diseased root samples were collected from farmer’s fields belonging to four major mulberry growing states of South India. Based on morpho-cultural and scanning electron microscopy studies, 57 fungal isolates were characterized and identified as L. theobromae. Phylogenetic analysis of concatenated internal transcribed spacer and β-tubulin sequences revealed variation of the representative 20 isolates of L. theobromae. Following the root dip method of inoculation, pathogenicity studies on susceptible mulberry genotypes (Victory-1 and Thailand male) recognized the virulent isolate MRR-142. Accordingly, MRR-142 isolate was used to evaluate resistance on a set of 45 diverse mulberry accessions. In the repeated experiments, the mulberry accession ME-0168 which is an Indonesian origin belonging to Morus latifolia was found to be highly resistant consistently against BRR. Eight accessions (G2, ME-0006, ME-0011, ME-0093, MI-0006, MI-0291, MI-0489, and MI-0501) were found to be resistant. These promising resistant resources may be exploited in mulberry breeding for developing BRR resistant varieties and to develop mapping populations which successively helps in the identification of molecular markers associated with BRR.

Screening and validation of three molecular markers for disease resistance in eggplant

Fusarium oxysporum Schlecht. f.sp. melongenae (FOM), Verticillium dahliae (Ve) and Ralstonia solanacearum are major limiting pathogens affecting eggplant cultivation and their yield in the world. Natural resistance genes are the most environmentally friendly method to control the disease. Thus, marker-assisted selection (MAS) is preferred as a tool for screening resistance genes (R-genes) in eggplant resistance breeding. In this study, markers that are specifically linked to major disease resistance genes conferring resistance to F. melongenae, V. dahliae and R. solanacearum were tested in a population containing breeding materials to validate the resistance. Resistant Solanum melongena accessions LS1934 and LS2436 and their reciprocal crosses were used as the resistance resource for this validation study. Moreover, classical resistance tests to FOM and Ve were performed with the root-dip inoculation method for classification of all the accessions based on their resistance/susceptibility responses. The SCAR<sub>426</sub>, CAPs_903 and SIVR844 markers were highly informative for the determination of resistance genes (Fomg, Ve and ERs1). Therefore, in areas with high susceptibility to diseases, a highly efficient combination of the relevant R-genes and their pyramiding into commercial eggplant varieties are proposed to be implemented as a pragmatic approach.

Bioefficacy evaluation of ferrocenyl chalcones against Meloidogyne incognita and Sclerotium rolfsii infestation in tomato

The present study reports, bioefficacy evaluation of effective compounds against Meloidogyne incognita and Sclerotium rolfsii in pot cultured tomato. The identified five most effective compounds, i.e. (2E)-1-(4-Methylphenyl)-3-ferrocenyl-prop-2-en-1-one (6g), (2E)-1-(4-Methoxyphenyl)-3-ferrocenyl-prop-2-en-1-one (6h), (2E)-1-(3-Bromophenyl)-3-ferrocenyl-prop-2-en-1-one (6j), (2E)-1-(2,4-Dichlorophenyl)-3-ferrocenyl-prop-2-en-1-one (6k) and (2E)-1-(3,5-Dichloro-2-hydroxyphenyl)-3-ferrocenyl-prop-2-en-1-one (6p) along with Carbofuran 3G as positive control were tested at 20, 40 and 80 ppm by soil drenching and root dipping methods. The study revealed that all plant growth parameters were positively influenced by these compounds. The presence of an electron releasing group positively influenced the efficacy, and the activity was highest in compounds 6g and 6h at 80 ppm. Based on in vitro results against S. rolfsii, (2E)-1-Ferrocenyl-3-(4-bromophenyl)-prop-2-en-1-one (3b), (2E)-1-Ferrocenyl-3-(2,6-dichlorophenyl)-prop-2-en-1-one (3o) and (2E)-1-(5-Chloro-2-hydroxyphenyl)-3-ferrocenyl-prop-2-en-1-one (6o) along with Tebuconazole 25.9% EC and Hexaconazole 5% SC as positive control were evaluated. The shoot length was found to be highest (24.50 cm) in plants treated with 3b followed by 3o and 6o at 1000 ppm. The percent disease incidence was significantly decreased as compared to control. The percent disease incidence was found to be minimum in plants treated with 3b at 1000 ppm. However, root dipping was not as effective as soil drenching. Therefore, ferrocenyl chalcone derivatives proved to be of great fungicidal and nematicidal potential opening new opportunities for expanding their effectiveness as new pest control agents.

Correlation and regression models of tomato yield in response to plant growth by different bacterial inoculants and inoculation methods

AbstractThe focus of this research is to evaluate the performance of Bacillus, Pseudomonas, Azotobacter, and Azospirillum for their plant growth abilities in vitro and in vivo. The best performing bacterial isolates from preliminary screening (in vitro) were able to produce indole acetic acid (IAA) and gibberellic acid (GA3) of 0.25–22.63 and 5.9–31.8 μg ml–1, respectively, eight best isolates were further tested for their efficacy in promoting crop growth and yield of tomato (Lycopersicon esculentum Mill.) by different application methods namely seed coating, soil application, and seedling root dip method. The factorial data analysis provided evidence that the interaction of bacterial isolates and different inoculation procedures together generated better yield in the greenhouse pot experiment. The findings suggest that the inoculation of Azospirillum strain ASP25 by seedling root dip method produced greater yields. Correlation and regression models hypothesize that all the variables are positively correlated with yield at P < .01 and growth variables like number of fruits per plant (r2 = .886), shoot length (r2 = .695), and root volume (r2 = .554) at P ≤ .0001 contribute to the yield parameter individually and by multiple regression model all the plant growth variables together increased fruit yield per plant by 89% (r2 = .899). These results demonstrate that a high yield is always linked to a healthy vegetative development. However, as technology in agriculture progresses, the proposed method points to the usage and development of computer applications to estimate crop output.

Green house evaluation of IAA and GA3 producing yeast isolates on growth tomato crop by root dip method

A green house experiment was conduct by use of IAA (MZL -8 and TCL -1) and GA3 (CAL – 1 and ACL- 3) producing yeast isolates on growth of tomato crop by root dip method with 8 treatments and 3 replication at Department of Agricultural Microbiology, GKVK, Bengaluru. The yeastisolate TCL -1 recorded maximum plant height, number of leaves per plant, number of branches per plant, root length, fresh shoot biomass, dry shoot biomass, fresh root biomass, dry root biomass, IAA and GA3 content, 44.73 cm, 80, 11.40, 14.70 cm, 24.00 g/plant, 11.75 g/plant, 7.98 g/plant, 3.91 g/plant, 1.205 μg/g of leaf and 0.550 μg/g of leaf respectively. The control (T1) recorded Lowest plant height, number of leaves per plant, number of branches per plant, root length, fresh shoot biomass, dry shoot biomass, fresh root biomass, dry root biomass, IAA and GA3 content, 22.20 cm, 55.70, 8.00,9.00 cm, 11.00 g/plant, 6.23 g/plant, 3.67 g/plant, 2.07 g/plant, 0.384 μg/g of leaf and 0.200 μg/g of leaf respectively at 50 DAT.

Genome-Wide Association Study Reveals Genomic Regions Associated with Fusarium Wilt Resistance in Common Bean.

Fusarium wilt (Fusarium oxysporum f. sp. phaseoli, Fop) is one of the main fungal soil diseases in common bean. The aim of the present study was to identify genomic regions associated with Fop resistance through genome-wide association studies (GWAS) in a Mesoamerican Diversity Panel (MDP) and to identify potential common bean sources of Fop’s resistance. The MDP was genotyped with BARCBean6K_3BeadChip and evaluated for Fop resistance with two different monosporic strains using the root-dip method. Disease severity rating (DSR) and the area under the disease progress curve (AUDPC), at 21 days after inoculation (DAI), were used for GWAS performed with FarmCPU model. The p-value of each SNP was determined by resampling method and Bonferroni test. For UFV01 strain, two significant single nucleotide polymorphisms (SNPs) were mapped on the Pv05 and Pv11 for AUDPC, and the same SNP (ss715648096) on Pv11 was associated with AUDPC and DSR. Another SNP, mapped on Pv03, showed significance for DSR. Regarding IAC18001 strain, significant SNPs on Pv03, Pv04, Pv05, Pv07 and on Pv01, Pv05, and Pv10 were observed. Putative candidate genes related to nucleotide-binding sites and carboxy-terminal leucine-rich repeats were identified. The markers may be important future tools for genomic selection to Fop disease resistance in beans.

Antinemic activity of ferrocenyl chalcones against Meloidogyne incognita infestation in tomato

A series of ferrocenyl chalcones using acetylferrocene with different aldehydes were synthesized and their in vitro evaluation against Meloidogyne incognita was reported. The present study was carried out in net house conditions, Division of Nematology, ICAR-IARI, during rabi 2018-19, the bioefficacy evaluation of most effective compounds, identified by in vitro results, along with Carbofuran 3G in pot cultured tomato is reported. The identified, five most effective compounds, (2E)-1-Ferrocenyl-3-(4-bromophenyl)-prop-2-en-1-one (3b), (2E)-1-Ferrocenyl-3-(4- methoxyphenyl)-prop-2-en-1-one (3f), (2E)-1-Ferrocenyl-3-(3,4,5-trimethoxyphenyl)-prop-2-en-1-one (3h), (2E)-1- Ferrocenyl-3-(4-nitrophenyl) prop-2-en-1-one (3m) and (2E)-1-Ferrocenyl-3-(2,6-dichlorophenyl)-prop-2-en-1-one (3o) were undertaken for pot experiment at different concentrations, viz. 20, 40 and 80 ppm and by soil drenching and root dipping methods. The study revealed that all plant growth parameters were positively influenced by these compounds. It was also observed that the presence of electron releasing group positively influences the efficacy and the activity was highest in compound 3f and 3h @ 80 ppm at 30 DAI and 60 DAI. The activity was higher in soil drenching compared to root dipping method.