Differential profiling of selected defence‐related genes induced on challenge with Alternaria brassicicola in resistant white mustard and their comparative expression pattern in susceptible India mustard

The lack of availability of sources of resistance against Alternaria brassicicola within the family Brassicaceae has made oilseed mustard plants a target for one of the most damaging and widespread fungal diseases, Alternaria black spot. Of the other non‐host‐resistant/tolerant plants, Sinapis alba, white mustard, is considered to be the most important apart from Arabidopsis. To understand the defence response of S. alba upon incompatible interaction with this pathogen, a functional genomic approach using cDNA amplified fragment length polymorphism was performed. The highly reproducible bands, found to be either more amplified or uniquely present in infected S. alba plants compared with non‐infected plants, were further subjected to comparative reverse Northern analysis in the incompatible white mustard (S. alba) and compatible India mustard (Brassica juncea L.) plants. The suppression of 46% of the genes in the compatible background indicates the possibility of effective and specific recognition of Alternaria in S. alba. Analysis of the 118 genes up‐regulated specifically in infected S. alba compared with B. juncea showed that 98 genes have similarity to proteins such as receptor‐like protein kinase genes, genes involved with calcium‐mediated signalling and salicylic acid‐dependent genes as well as other genes of known function in Arabidopsis. The apparent expression profile data were further confirmed for selected genes by quantitative real‐time polymerase chain reaction analysis. Classification of these genes on the basis of their induction pattern in Arabidopsis indicates that the expression profile of several of these genes was distinct in S. alba compared with B. juncea.     

Genome-wide identification and characterization of Chitinase gene family in Brassica juncea and Camelina sativa in response to Alternaria brassicae

Chitinases belong to the group of Pathogenesis-related (PR) proteins that provides protection against fungal pathogens. This study presents the, genome-wide identification and characterization of chitinase gene family in two important oilseed crops B. juncea and C. sativa belonging to family Brassicaceae. We have identified 47 and 79 chitinase genes in the genomes of B. juncea and C. sativa, respectively. Phylogenetic analysis of chitinases in both the species revealed four distinct sub-groups, representing different classes of chitinases (I-V). Microscopic and biochemical study reveals the role of reactive oxygen species (ROS) scavenging enzymes in disease resistance of B. juncea and C. sativa. Furthermore, qRT-PCR analysis showed that expression of chitinases in both B. juncea and C. sativa was significantly induced after Alternaria brassicae infection. However, the fold change in chitinase gene expression was considerably higher in C. sativa compared to B. juncea, which further proves their role in C. sativa disease resistance to A. brassicae. This study provides comprehensive analysis on chitinase gene family in B. juncea and C. sativa and in future may serve as a potential candidate for improving disease resistance in B. juncea through transgenic approach.     

Stable,fertile somatic hybrids between <Emphasis Type="Italic">Sinapis alba</Emphasis> and <Emphasis Type="Italic">Brassica juncea</Emphasis> show resistance to <Emphasis Type="Italic">Alternaria brassicae</Emphasis> and heat stress

Wild relatives of Brassica are a rich reservoir of genes that are invaluable for the improvement of cultivated species. Sinapis alba is a close relative of crop Brassicas that possesses several desirable traits such as tolerance to Alternaria black spot disease, heat stress, insect pests and nematodes. This study is aimed at developing and characterizing hybrids between Brassica juncea and S. alba with the ultimate goal of transferring genes for tolerance to Alternaria brassicae and heat stress, the traits that are lacking in cultivated Brassica. We generated three hybrids between B. juncea and S. alba through protoplast fusion. The hybridity was confirmed through cytology and molecular markers. While two of the hybrids were symmetric, the third one was asymmetric and had greater resemblance to B. juncea. Hybrids showed some characteristic features of the parents and were fully male and female fertile and also set seeds upon back crossing with the parent species. In vitro leaf assay and field inoculation studies revealed that the hybrids are highly resistant to A. brassicae. Besides, hybrids set seeds at temperature of >?38 °C when parents failed to produce seeds indicating that hybrids possess heat tolerance. These stable hybrids provide a reliable genetic resource for transfer of genes from S. alba into cultivated Brassica species.     

Fatal attraction: search for a dead-end trap crop for the pollen beetle (Meligethes aeneus)

In sustainable pest management, orientation of insect pests can be manipulated by utilizing the relative attractiveness of different host plants. Plants attractive for oviposition but not offering a suitable resource for the development of larvae are called dead-end trap crops. In this study, the number of eggs and larvae and larval survival of Meligethes aeneus (Fab.) in the buds of Brassica napus L., B. rapa L., B. nigra L., B. juncea L., Eruca sativa Mill., Raphanus sativus Pers. and Sinapis alba L. were compared in 2011 and 2012. Overall infestation rate of buds varied from 0 to 71 %; the least attractive plants were S. alba and E. sativa. Egg clutch size per bud was greater on B. nigra and lower on S. alba and E. sativa than on B. napus. Dead larvae were found only in E. sativa and R. sativus buds. Over the two study years, 19 % of larvae on E. sativa and 35 % on R. sativus were dead. In conclusion, M. aeneus preferred to oviposit on Brassica species rather than on cruciferous plants from the other genera. In addition, R. sativus has the features of dead-end trap crop because 35 % of the larvae failed to survive.     

Molecular Characterization of an Oomycete-Responsive PR-5 Protein Gene from <Emphasis Type="Italic">Zingiber zerumbet</Emphasis>

The tropical spice crop ginger (Zingiber officinale Roscoe) is highly susceptible to soft rot disease caused by the necrotrophic oomycete Pythium aphanidermatum (Edson) Fitzp. However, Zingiber zerumbet (L.) Smith, a wild relative of ginger, is resistant to P. aphanidermatum and has been proposed as a potential donor for soft rot resistance to Z. officinale. We identified a member of the pathogenesis-related protein group 5 (PR-5) gene family in Z. zerumbet that is expressed constitutively but upregulated in response to infection by P. aphanidermatum. Expression of this gene was upregulated as early as 1.5 h post inoculation (hpi) with the pathogen, peaked at 6 hpi, declined by 9 hpi, and again peaked at 15 hpi before declining at 48 hpi. A cDNA of this PR-5 gene, designated as ZzPR5, encodes a 226-amino-acid predicted protein with a calculated pI of 5.05. The N terminus of this protein contains a 22-amino-acid signal peptide, suggesting that the protein may show apoplastic accumulation like other acidic PR-5 proteins. Phylogenetic analysis revealed high similarity between ZzPR5 and PR-5 proteins reported from other plant species, especially from other Zingiberales. Molecular modeling of ZzPR5 protein revealed an acidic surface cleft, a feature characteristic of glycoside hydrolases and antifungal PR-5 proteins. In molecular docking studies, a linear polymeric molecule of (1,3)-β-d-glucan, a major constituent of the oomycete cell wall, fitted favorably into the surface cleft of ZzPR5 and interacted with acidic amino acids known to be involved in glucan hydrolysis, suggesting a potential antioomycete activity for ZzPR5 protein. Elucidation of the molecular mechanism of ZzPR5 may provide important insight toward engineering soft rot resistance into the obligatory asexual ginger.     

The relative attractiveness of Brassica napus,B. rapa,B. juncea and Sinapis alba to pollen beetles

It is often suggested that weeds from the same family as the crop plant may increase insect pest damages by providing shelter and additional oviposition opportunities. We compared the relative attractiveness of Brassica rapa L., B. juncea L., Sinapis alba L. and B. napus L. (Capparales: Brassicaceae) to the pollen beetle and its hymenopteran parasitoids in field conditions. Our results revealed that none of the investigated plants increased the pest abundance on B. napus plants. On the contrary, B. juncea and S. alba lured beetles away from B. napus during its damage-susceptible stage. The parasitism rate of pollen beetle larvae was the highest on B. juncea plants, indicating that cruciferous weeds could improve the natural control of the pollen beetle by providing additional hosts for parasitoids. Therefore, close relatives of oilseed rape might be used to trap pollen beetle adults, but also to support populations of natural enemies that could decrease the number of beetles.     

Green peach aphid [Myzus persicae (Sulzer) (Hemiptera: Aphididae)] control using Brassicaceae ethyl ester oil sprays

Control of green peach aphid (Myzus persicae), a globally important pest, using plant‐derived oils is a promising alternative to conventional insecticides. Although various plant‐derived oils are potentially useful for insect control, dose–response studies and efficacy comparisons among oils have not been widely reported. Our objective was to compare M. persicae control by plant‐derived oils, focusing on oils derived from Brassicaceae species that exhibit rotational and environmental quality benefits. We thus applied sprays of emulsified ethyl esters from the seed oils of yellow mustard (Sinapis alba), oriental mustard (Brassica juncea) and rapeseed (Brassica napus) to M. persicae in a laboratory bioassay. A dose–response relationship was modelled for the S. alba spray yielding LD₅₀/LD₉₅ values of 18.2 ± 0.87/128.1 ± 5.10 μg ester per cm² (P < 0.0001). Ethyl esters of oils from all three species and soybean (Glycine max) ethyl ester were compared to determine the efficacy of Brassicaceae oils relative to the dominant plant‐oil spray currently available. All ethyl esters were equally efficacious despite measured differences in fatty acid profiles among the oils. Oils derived from mustards B. juncea and S. alba are potentially useful feedstocks for the production of insecticidal sprays, and testing on additional insects is warranted.     

Systemic Resistance to Powdery Mildew in Brassica napus (AACC) and Raphanus alboglabra (RRCC) by Trichoderma harzianum TH12

Trichoderma harzianum TH12 is a microbial pesticide for certain rapeseed diseases. The mechanism of systemic resistance induced by TH12 or its cell-free culture filtrate (CF) in Brassica napus (AACC) and Raphanus alboglabra (RRCC) to powdery mildew disease caused by ascomycete Erysiphe cruciferarum was investigated. In this study, we conducted the first large-scale global study on the cellular and molecular aspects of B. napus and R. alboglabra infected with E. cruciferarum. The histological study showed the resistance of R. alboglabra to powdery mildew disease. The growth of fungal colonies was not observed on R. alboglabra leaves at 1, 2, 4, 6, 8, and 10 days post-inoculation (dpi), whereas this was clearly observed on B. napus leaves after 6 dpi. In addition, the gene expression of six plant defense-related genes, namely, PR-1, PR-2 (a marker for SA signaling), PR-3, PDF 1.2 (a marker for JA/ET signaling), CHI620, and CHI570, for both genotypes were analyzed in the leaves of B. napus and R. alboglabra after treatment with TH12 or CF and compared with the non-treated ones. The qRT-PCR results showed that the PR-1 and PR-2 expression levels increased in E. cruciferarum-infected leaves, but decreased in the TH12-treated leaves compared with leaves treated with CF. The expression levels of PR-3 and PDF1.2 decreased in plants infected by E. cruciferarum. However, expression levels increased when the leaves were treated with TH12. For the first time, we disclosed the nature of gene expression in B. napus and R. alboglabra to explore the resistance pathways in the leaves of both genotypes infected and non-infected by powdery mildew and inoculated or non-inoculated with elicitor factors. Results suggested that R. alboglabra exhibited resistance to powdery mildew disease, and the application of T. harzianum and its CF are a useful tool to facilitate new protection methods for resist or susceptible plants.     

Glucosinolate profile and oviposition behavior in relation to the susceptibilities of Brassicaceae to the cabbage seedpod weevil

Understanding how host‐plant characteristics affect behavioral and physiological responses of insect herbivores is of considerable importance in the development of resistant crop germplasm. Feeding, oviposition preference, larval development, and oviposition behavior of the cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham) (= Ceutorhynchus assimilis Payk.) (Coleoptera: Curculionidae), were investigated on eight Brassicaceae species that differed in their glucosinolate profiles. The least preferred host plants for feeding and oviposition were the Sinapis alba L. lines while the Brassica carinata L. line was most preferred. Larval development occurred most rapidly on Brassica rapa L. and slowest on S. alba. Larval weight was highest on B. napus L. and lowest on S. alba. Total glucosinolate levels did not influence C. obstrictus larval growth or development; however high levels of specific glucosinolates such as p‐hydroxybenzyl and 3‐butenyl glucosinolate were associated with increased developmental time or reduced weight. The time required for oviposition behavioral events was measured on different host‐plant species: B. rapa, B. napus, B. napus×S. alba, B. tournefortii Gouan., B. juncea (L.) Czern, B. carinata, B. nigra (L.) Koch., and S. alba. The early steps in the sequence were completed faster on more susceptible host plants (B. carinata, B. napus, and B. rapa) than on relatively resistant ones (B. tournefortii and B. juncea). Females explored pods of B. nigra and S. alba, but oviposition occurred only rarely on these species. There was no significant difference in the location on the pod on which oviposition occurred among the different plant species. Mean eggs laid per female weevil were highest on the B. napus×S. alba hybrid and lowest on B. nigra and S. alba.     

Particle size distribution of the major Alternaria alternata allergen,Alt a 1, derived from airborne spores and subspore fragments

Fungal fragments are abundant immunoreactive bioaerosols that may outnumber the concentrations of intact spores in the air. To investigate the importance of Alternaria fragments as sources of allergens compared to Alternaria spores, we determined the levels of Alternaria spores and Alt a 1 (the major allergen in Alternaria alternata spores) collected on filters within three fractions of particulate matter (PM) of different aerodynamic diameter: (1) PM_>10, (diameter>10 μm); (2) PM_2.5-10 (2.5–10μm); (3) PM_2.5 (0.12–2.5 μm). The airborne particles were collected using a three stage high-volume ChemVol cascade impactor during the Alternaria sporulation season in Poznań, Poland (30 d between 6 July and 22 September 2016). The quantification of Alt a 1 was performed using the enzyme-linked immunosorbent assay. High concentrations of Alt a 1 were recorded during warm and dry d characterized by high sunshine duration, lack of clouds and high dew point values. Atmospheric concentrations of Alternaria spores correlated significantly (r = 0.930, p < 0.001) with Alt a 1 levels. The highest Alt a 1 was recorded in PM_2.5-10 (66.8 % of total Alt a 1), while the lowest in PM_2.5 (<1.0 %). Significantly more Alt a 1 per spore (>30 %) was observed in PM_2.5-10 than in PM_>10. This Alt a 1 excess may be derived from sources other than spores, e.g. hyphal fragments. Overall, in outdoor air the major source of Alt a 1 are intact Alternaria spores, but the impact of other fungal fragments (hyphal parts, broken spores, conidiophores) cannot be neglected, as they may increase the total atmospheric Alt a 1 concentration.     

Pathogenic Variability within Indian Alternaria brassicae Isolates Using Seed,Cotyledon and Leaf of Brassica Species

Thirty Alternaria brassicae (Berk.) Sacc. isolates from diverse geographical locations of India were studied for pathogenic variability on seed, cotyledon and true leaves of Brassica species. Seed germination was reduced maximum by isolate BAB‐39 in Brassica juncea cultivar Varuna (22.1%), Brassica rapa var. Toria cultivar PT‐303 (12%), Brassica carinata cultivar Kiran (12%), Brassica napus cultivar GSL‐1 (11%) and tolerant source of B. juncea genotype PHR‐2 (7%), although least by isolate BAB‐49. Maximum lesion size on leaf was recorded in B. juncea cultivar Rohini (11.2, 16.5 and 16.8 mm) with isolates BAB‐09 (Pantnagar), BAB‐19 (Bharatpur) and BAB‐39 (Kangra), respectively, and categorized as highly virulent, while minimum lesion size of 3.2, 3.7 and 3.8 mm was observed with isolates BAB‐47 (Tonk), BAB 49 (Jobner) and BAB 04 (Kamroop), respectively, considered the weak isolates. On B. alba, BAB‐09, BAB‐19 and BAB‐39 isolates caused maximum lesion size of 3.7, 3.8 and 3.9 mm, respectively, even though it showed maximum tolerance. In both seed and cotyledon inoculation method, the per cent Alternaria blight severity above 80% was observed with isolate of BAB‐39 (91.5%), BAB‐19 (89.0%), BAB‐09 (85.5%) and least in isolate BAB‐49 (34.0%). Brassica seed, cotyledon and leaf showed the similar positive response for categorizing A. brassicae isolates as virulent and avirulent. This information could be used to the development and assessment of resistant brassica germplasm, especially with A. brassicae populations exhibiting increased virulence.     

Transgenic Brassica juncea Plants Expressing MsrA1, a Synthetic Cationic Antimicrobial Peptide,Exhibit Resistance to Fungal Phytopathogens

Cationic antimicrobial peptides (CAPs) have shown potential against broad spectrum of phytopathogens. Synthetic versions with desirable properties have been modeled on these natural peptides. MsrA1 is a synthetic chimera of cecropin A and melittin CAPs with antimicrobial properties. We generated transgenic Brassica juncea plants expressing the msrA1 gene aimed at conferring fungal resistance. Five independent transgenic lines were evaluated for resistance to Alternaria brassicae and Sclerotinia sclerotiorum, two of the most devastating pathogens of B. juncea crops. In vitro assays showed inhibition by MsrA1 of Alternaria hyphae growth by 44–62 %. As assessed by the number and size of lesions and time taken for complete leaf necrosis, the Alternaria infection was delayed and restricted in the transgenic plants with the protection varying from 69 to 85 % in different transgenic lines. In case of S. sclerotiorum infection, the lesions were more severe and spread profusely in untransformed control compared with transgenic plants. The sclerotia formed in the stem of untransformed control plants were significantly more in number and larger in size than those present in the transgenic plants where disease protection of 56–71.5 % was obtained. We discuss the potential of engineering broad spectrum biotic stress tolerance by transgenic expression of CAPs in crop plants.     

Valuable New Resistances Ensure Improved Management of Sclerotinia Stem Rot (Sclerotinia sclerotiorum) in Horticultural and Oilseed Brassica Species

Field resistances against Sclerotinia rot (SR) (Sclerotinia sclerotiorum) were determined in 52 Chinese genotypes of Brassica oleracea var. capitata, 14 Indian Brassica juncea genotypes carrying wild weedy Brassicaceae introgression(s) and four carrying B‐genome introgression, 22 Australian commercial Brassica napus varieties, and 12 B. napus and B. juncea genotypes of known resistance. All plants were individually inoculated by securing an agar disc from a culture of S. sclerotiorum growing on a glucose‐rich medium to the stem above the second internode with Parafilm tape. Mean stem lesion length across tested genotypes ranged from <1 to >68 mm. While there was considerable diversity within the germplasm sets from each country, overall, 65% of the B. oleracea var. capitata genotypes from China showed the highest levels of stem resistance, a level comparable with the highest resistance ever recorded for oilseed B. napus or B. juncea from China or Australia. One Indian B. juncea line carrying weedy introgression displayed a significant level of both stem and leaf resistance. However, the vast majority of commercial Australian oilseed B. napus varieties fell within the most susceptible 40% of genotypes tested for stem disease. There was no correlation between expressions of stem versus leaf resistance, suggesting their independent inheritance. A few Chinese B. oleracea var. capitata genotypes that expressed combined extremely high‐level stem (≤1 mm length) and leaf (≤0.5 mean number of infections/plant) resistance will be particularly significant for developing new SR‐resistant horticultural and oilseed Brassica varieties.     

Differentially Expressed Proteins and Associated Histological and Disease Progression Changes in Cotyledon Tissue of a Resistant and Susceptible Genotype of Brassica napus Infected with Sclerotinia sclerotiorum

Sclerotinia rot caused by Sclerotinia sclerotiorum is one of the most serious diseases of oilseed rape. To understand the resistance mechanisms in the Brassica napus to S. sclerotiorum, comparative disease progression, histological and proteomic studies were conducted of two B. napus genotypes (resistant cv. Charlton, susceptible cv. RQ001-02M2). At 72 and 96 h post inoculation (hpi), lesion size on cotyledons was significantly (P≤0.001) smaller in the resistant Charlton. Anatomical investigations revealed impeded fungal growth (at 24 hpi and onwards) and hyphal disintegration only on resistant Charlton. Temporal changes (12, 24, 48 and 72 hpi) in protein profile showed certain enzymes up-regulated only in resistant Charlton, such as those related to primary metabolic pathways, antioxidant defence, ethylene biosynthesis, pathogenesis related proteins, protein synthesis and protein folding, play a role in mediating defence responses against S. sclerotiorum. Similarly a eukaryotic translation initiation factor 5A enzyme with increased abundance in susceptible RQ001-02M2 and decreased levels in resistant Charlton has a role in increased susceptibility to this pathogen. This is the first time that the expression of these enzymes has been shown to be associated with mediating the defence response against S. sclerotinia in cotyledon tissue of a resistant cultivar of B. napus at a proteomics level. This study not only provides important new insights into the resistance mechanisms within B. napus against S. sclerotiorum, but opens the way for novel engineering of new B. napus varieties that over-express these key enzymes as a strategy to enhance resistance and better manage this devastating pathogen.     

Studies on the relationship between three species of Coleoptera and certain species of annual Mustard and Rape

Experiments with annual mustards have confirmed American work which demonstrated that Sinapis alba L. and Brassica nigra Koch were less susceptible than Brassica juncea Coss. to infestation by larvae of the cabbage seed weevil (Ceuthorbyncbus assimilis Payk.). The stem damage by cabbage stem weevil (C. quadridens Panz.) was less severe, and fewer stems were infested, on the variety of S. alba grown in the experiments, than on the other species. All the types of plant under observation were damaged by blossom beetles (Meligethes aeneus F.). Whilst it may be possible to select or breed a variety a variety of B. juncea less susceptible to damage by the two weevils, it seems that the problem of blossom beetle damage is unlikely to be overcome by such methods.

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Zusammenfassung In den Jahren 1958/59 wurden Beobachtungen durchgeführt über den Schaden an den Blütenknospen verschiedener Senf- und Rapsarten durch Rapsglanzkäfer (Meligethes aeneus F.), über den Schotenbefall durch Larven des Kohlschotenrüßlers (Ceutborbynchus assimilis Payk.) und über Befall und Schaden an den Stengeln durch die Larven des Gefleckten Kohltriebrüßlers (C. quadridens Panz.). In Feldversuchen wuchsen in mehrfacher Wiederholung folgende Pflanzenarten: Brassica juncea Coss var. Trowse und verwandte Arten, Sinapis alba L., B. nigra Koch und B. campestris oleifera var. annua Metz (Arlo turniprape).Es wurde festgestellt, daß S. alba und B. nigra gegen den Befall mit Kohlschotenrüßlerlarven weniger anfällig sind als B. juncea und daß S. alba auch sehr viel weniger Stengelbefall mit Larven des Kohlschotenrüßlers erleidet als die anderen Arten. Alle geprüften Arten werden durch Rapsglanzkäfer geschädigt, doch mag die Schwere ihres Schadens durch die geringe Größe der Versuchsparzellen und die infolgedessen hohe Populationsdichte der Käfer pro Fläche und Pflanze übermässig vergrößert worden sein.Es wird angeregt, eine geeignete Sorte von B. juncea mit niedriger Anfälligkeit gegenüber den beiden Käfern zu züchten oder zu selektieren. Es scheint jedoch, daß die lange Blütezeit von B. juncea und S. alba diese Arten besonders anfällig für Befall mit Rapsglanzkäfern macht, und daß es unwahrscheinlich ist, daß Pflanzenzucht oder-selektion weniger anfällige Sorten hervorbringen können, die für die Handelsgewürzsamen-Anbauer wirtschaftlich annehmbar sind.

     

Co-inoculation of Urea and DAP Tolerant <Emphasis Type="Italic">Sinorhizobium meliloti</Emphasis> and <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> as Integrated Approach for Growth Enhancement of <Emphasis Type="Italic">Brassica juncea</Emphasis>

Two plant growth promoting rhizobacteria––Sinorhizobium meliloti RMP1 and Pseudomonas aeruginosa GRC₂ were studied for integrated nutrient management to obtain improved yield of Brassica juncea. Low concentrations of urea and diammonium phosphate (DAP) stimulated the growth of both S. meliloti RMP1 and P. aeruginosa GRC₂. 1 M of urea and 0.35 M of DAP was found lethal for RMP1, while 1.3 M and 0.37 M concentrations of urea and DAP proved to be toxic for GRC₂. Lc₅₀ was observed as 0.49 M of urea and 0.15 M of DAP for RMP1, and 0.66 M urea and 0.18 M of DAP for GRC₂. Urea and DAP adaptive variants of RMP1 and GRC₂ was isolated. Adaptive bacterial variants had better growth rates at sub-lethal (Lc₅₀) concentrations of urea and DAP as compared to non-adaptive variants. They also retained plant growth promoting attributes similar to non adaptive variants. GRC₂ and RMP1 did not affect the growth of each other and were chemotactically active for DAP, urea as well as root exudates of B. juncea. Both the isolates colonized well in the rhizosphere of B. juncea, as their populations were recorded ≈5 log₁₀ cfu g⁻¹ after 120 days. Interestingly, the colonization ability was found even better when both strains were co-inoculated, as their population was recorded in the range of ≈6 log₁₀ cfu g⁻¹ after 120 days. In field trials, application of RMP1 and GRC₂ resulted in significant increase in biomass and yield of B. juncea as compared to control. However, yield was better with application of half dose and full dose of recommended fertilizers. Interestingly, the biomass as well as yield improved further when both isolates were applied together along with half dose of recommended fertilizers.     

Goldfish (Carassius auratus L.) possess natural antibodies with trypanocidal activity towards Trypanosoma carassii in vitro

Natural infection of cyprinids, such as carp, with the extracellular protozoan parasite Trypanosoma carassii can attain up to 100% prevalence and cause significant host morbidity and mortality, particularly in aquaculture settings. Host recovery from T. carassii infection has been shown to be antibody (Immunoglobulin M; IgM)-mediated, conferring long-term immunity in recovered animals upon challenge. To assess the role of IgM in parasite clearance in the goldfish, IgM was purified by PEG-6000 precipitation from goldfish serum collected at 0 (naïve), 21 (peak parasitaemia) and 42 (recovery phase; immune) days post infection (dpi) and used for in vitro assays. Purified IgM from 0, 21, and 42 dpi serum showed dose- and time-dependent trypanocidal activity in vitro. Incubation of T. carassii with 0 dpi IgM showed the greatest reduction in trypanosome numbers after 24 h, followed by 42 dpi IgM, and finally by 21 dpi IgM. The trypanocidal activity of the PEG-purified IgM was abrogated by pre-absorption with parasites in vitro and was affected by temperature. Furthermore, studies using 0 dpi IgM purified using gel permeation chromatography showed increased trypanocidal activity, with complete elimination of parasites after 12 h when incubated with 200 μg of 0 dpi IgM, or by 24 h when incubated with 80 μg or 100 μg of 0 dpi IgM. Lastly, in vivo passive transfer experiments demonstrated that while immune serum or purified IgM from 42 dpi serum conferred protection against a challenge, neither 0 dpi serum or 0 dpi purified IgM conferred protection against challenge with T. carassii.     

The role of glucosinolates and their hydrolysis products in oviposition and host-plant finding by cabbage webworm, Hellula undalis

The cabbage webworm, Hellula undalis (Fabricius) (Lepidoptera: Pyralidae), a tropical pest on crucifers (Brassicaceae), differentiated among host-plant species for oviposition in laboratory and field tests. White mustard, Sinapis alba (L.) var. Selinda, was the preferred host-plant, followed by Brassica juncea (L.) Czern. et. Coss var. Canadian brown mustard, and pak-choi, Brassica campestris L. ssp. chinensis var. Joi Choi, Black Behi and Bai Tsai. Glucosinolates (GS), secondary plant compounds characteristic to the Cruciferae plant family, and their breakdown products were analyzed by using HPLC and GC-MS-techniques. Species differed in GS composition and concentration. Content of GS was highest in S. alba with progressively lower contents detected in B. juncea and B. chinensis. The aromatic GS, 4-hydroxybenzyl-GS and benzyl-GS, were detected in S. alba. In B. juncea the alkenyl GS, allyl-GS, dominated, whereas in varieties of B. chinensis indolyl and alkenyl GS predominated. Oviposition of H. undalis females on the non-host-plant Vigna unguiculata ssp. sesquipedalis (L.) Fruwirth was stimulated by application of GS extracts from the crucifer species; the extract from S. alba was preferred, followed by extracts from B. juncea and B. chinensis. Hydrolysis of GS in the plant extract from B. chinensis causes loss of the oviposition stimulatory effect of the extract. Application of the GS, allyl-GS, and benzyl-GS also stimulated oviposition by H. undalis. Significantly more eggs were laid on leaves treated with the aromatic GS, benzyl-GS, than with the alkenyl GS, allyl-GS. Host-plant odor attracted H. undalis females but not males, in behavioral assays conducted in a Y-tube olfactometer. Low concentrations of the GS hydrolysis product, allyl-isothiocyanate, induced anemotaxis of females, but a high concentration of allyl-isothiocyanate was repellent. Oviposition by H. undalis females was not stimulated by host-plant volatiles. Females laid eggs on inserted traps and the walls of the Y-tube regardless of presence or absence of host-plant odor. The relevance of these results in the context of crucifer-insect interactions is discussed.     

The role of glucosinolates and their hydrolysis products in oviposition and host-plant finding by cabbage webworm, Hellula undalis

The cabbage webworm, Hellula undalis (Fabricius) (Lepidoptera: Pyralidae), a tropical pest on crucifers (Brassicaceae), differentiated among host‐plant species for oviposition in laboratory and field tests. White mustard, Sinapis alba (L.) var. Selinda, was the preferred host‐plant, followed by Brassica juncea (L.) Czern. et. Coss var. Canadian brown mustard, and pak‐choi, Brassica campestris L. ssp. chinensis var. Joi Choi, Black Behi and Bai Tsai. Glucosinolates (GS), secondary plant compounds characteristic to the Cruciferae plant family, and their breakdown products were analyzed by using HPLC and GC‐MS‐techniques. Species differed in GS composition and concentration. Content of GS was highest in S. alba with progressively lower contents detected in B. juncea and B. chinensis. The aromatic GS, 4‐hydroxybenzyl‐GS and benzyl‐GS, were detected in S. alba. In B. juncea the alkenyl GS, allyl‐GS, dominated, whereas in varieties of B. chinensis indolyl and alkenyl GS predominated. Oviposition of H. undalis females on the non‐host‐plant Vigna unguiculata ssp. sesquipedalis (L.) Fruwirth was stimulated by application of GS extracts from the crucifer species; the extract from S. alba was preferred, followed by extracts from B. juncea and B. chinensis. Hydrolysis of GS in the plant extract from B. chinensis causes loss of the oviposition stimulatory effect of the extract. Application of the GS, allyl‐GS, and benzyl‐GS also stimulated oviposition by H. undalis. Significantly more eggs were laid on leaves treated with the aromatic GS, benzyl‐GS, than with the alkenyl GS, allyl‐GS. Host‐plant odor attracted H. undalis females but not males, in behavioral assays conducted in a Y‐tube olfactometer. Low concentrations of the GS hydrolysis product, allyl‐isothiocyanate, induced anemotaxis of females, but a high concentration of allyl‐isothiocyanate was repellent. Oviposition by H. undalis females was not stimulated by host‐plant volatiles. Females laid eggs on inserted traps and the walls of the Y‐tube regardless of presence or absence of host‐plant odor. The relevance of these results in the context of crucifer‐insect interactions is discussed.