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Rapeseed-mustard, the oleiferous Brassica species are important oilseed crops cultivated all over the globe. Mustard aphid Lipaphis erysimi (L.) Kaltenbach is a major threat to the cultivation of rapeseed-mustard. Wild mustard Rorippa indica (L.) Hiern shows tolerance to mustard aphids as a nonhost and hence is an important source for the bioprospecting of potential resistance genes and defense measures to manage mustard aphids sustainably. We performed mRNA sequencing of the R. indica plant uninfested and infested by the mustard aphids, harvested at 24 hours post-infestation. Following quality control, the high-quality reads were subjected to de novo assembly of the transcriptome. As there is no genomic information available for this potential wild plant, the raw reads will be useful for further bioinformatics analysis and the sequence information of the assembled transcripts will be helpful to design primers for the characterization of specific gene sequences. In this study, we also used the generated resource to comprehensively analyse the global profile of differential gene expression in R. indica in response to infestation by mustard aphids. The functional enrichment analysis of the differentially expressed genes reveals a significant immune response and suggests the possibility of chitin-induced defense signaling. [ABSTRACT FROM AUTHOR]

The study aimed to decipher the variation in constitutive plant biochemicals, and their influence on development, reproduction and survival of Lipaphis erysimi (Kaltenbach) (Aphididae: Hemiptera) on diverse Brassica juncea (L.) Czern & Coss. (Brassicales) cultivars. These studies revealed significant differences in total nymphal, reproductive and developmental periods, fecundity and offspring survival of L. erysimi on the test B. juncea cultivars. Toal developmental period was significantly longer, while fecundity and survival were lower on Pusa Mustard 27, NRCHB 101, RLC 3, RH 749, RH 725, DRMR 150-35, Pusa Mustard 26 and Pusa Mustard 25, except in a few cases. Further, total protein, antioxidants, tannins, phenols, FRAP, glucosinolates, photosynthetic pigments and different enzymes tested were significantly higher, and total sugars lower in Pusa Mustard 32, Pusa Mustard 30, NRCHB 101, RLC 3, DRMR 150-35, Pusa Mustard 26 and Pusa Mustard 27 as compared to other B. juncea cultivars, except in a few cases. Total sugars exhibited significant and positive association with survival of L. erysimi, while total protein, ferric ion reducing power, chlorophyll A, carotenoids, catalase, phenyl ammonia lyase and tyrosine ammonia lyase showed significant and negative correlation with survival of L. erysimi. Further, the biochemical constituents suggested 94.99, 95.88, 95.30, 97.06 and 84.75% variation in total nymphal, reproductive and total developmental periods, fecundity and survival of the L. erysimi on the test B. juncea cultivars, respectively. Overall, DRMR 150-35, RLC 3, NRCHB 101 and Pusa Mustard 26 have higher amounts of anti-nutritional defence compounds and antioxidative enzymes, distress the growth and survival of L. erysimi, and thus could be deployed in Brassica improvement programme. [ABSTRACT FROM AUTHOR]

Indian mustard, Brassica juncea holds distinction of being second most significant contributor to the production of edible oilseeds in India. This crop encounters nearly 50 distinct kinds of insect pests. Among the several pest species, Lipaphis erysimi (Kaltenbach), commonly known as the mustard aphid, is responsible for causing substantial yield losses. The behaviour, development, and reproduction of aphids can be impacted by the nutritional composition of different plant components. Genotypes, within and between different species of Brassica(s), encompass a range of diversity and, thus, exhibiting varying levels of resistance to mustard aphids. The biochemical composition of different plant parts in mustard, such as leaves, buds, and siliqua, can exert a range of effects on infestation by L. erysimi. Specific dietary components have the capacity to allure aphids and promote their population growth. On the other hand, additional elements such as glucosinolates or other defense compounds exhibit the capacity to deter aphids. Therefore, the study was planned to elucidate the intrinsic constitutive and aphid-induced biochemical defense mechanisms in B. juncea and examine the impact on L. erysimi. Among 30 genotypes, it was observed that TN 3, EC 61–9-2–2-2, NPJ 50, Rohini, IC 355399, RLC 3, and Kranti exhibited elevated levels of biochemical components, reduced preference by aphids, and a significant increase in aphid induced biochemical contents. The impact of these modifications on the behaviour and establishment of L. erysimi was also examined. Overall, the biochemical constituents identified in B. juncea and elaborated their effect on growth and development of L. erysimi are suggested to be effectively employed for breeding Indian mustard genotypes with in-built resistance to L. erysimi. [ABSTRACT FROM AUTHOR]

Lipaphis erysimi is a key pest of rapeseed-mustard in Indian subcontinent. Although chemical control is the basis of its management, the unsustainability of this approach has accelerated global research efforts to find alternate solutions. Host plant resistance is one among these. A set of introgression lines were developed using Brassica fruticulosa previously found to be resistant to L. erysimi. Rigorous screening over the years led to the identification of 3 introgression lines (I8, I79, and I82) for field resistance to aphids. We evaluated these introgression lines under field and laboratory conditions along with B. fruticulosa (resistant parent), B. juncea var. PBR-210 (susceptible parent) to elucidate the mechanism of resistance. Significantly a smaller number of aphids settled on circular leaf discs of B. fruticulosa, I8 and I82 compared to that on PBR-210 after 24 and 48 h of release. A similar trend was observed in free choice field experiment with significantly less aphid colonization on B. fruticulosa, I8, I79 and I82 compared to PBR-210 indicating lower aphid preference for these genotypes. Further, no choice experiments revealed significant negative effects of these genotypes on aphid demographic parameters (nymphal survival, development period, fecundity and longevity). Tolerance may not be a mechanism of resistance as aphid population failed to develop on these genotypes. Thus, resistance in these introgression lines may be attributed to a synergistic combination of antixenosis and antibiosis mechanisms. [ABSTRACT FROM AUTHOR]

We investigated the susceptibility of five cabbage varieties ('Oxylus', 'Super Cross', 'Vantar F1 Hybrid', 'Santa'F1 and 'Fortune') to aphids. Trials were set up in the Accra plains for two rainy seasons in 2017. The first trial examined aphid infestation and the second included weekly blanket spray of neem oil at 0.48 L/ha (60 ml/15 L water) during the second rainy season. Five systematically sampled cabbage leaves per plot were examined for the numbers of aphids and associated natural enemies (predators). Symptoms of aphid attack (incidence and severity of infestation) were also recorded. Lipaphis erysimi pseudobrassicae (Davis) and Myzus persicae (Sulzer) (Hemiptera: Aphididae) were the two aphid species observed and their numbers differed significantly between varieties in both seasons during the first but not the second trial. Few aphids settled on 'Oxylus', while more occurred on 'Fortune'. L. e. pseudobrassicae was the most abundant aphid on all the varieties. Aphid numbers were significantly decreased by neem application. Occurrence of natural enemies did not differ significantly between varieties, except for spiders during the major rainy season. There was no significant difference in aphid infestation between varieties during the first season as all of them completely succumbed to the infestation, while in the second season aphid incidence and severity of infestation was highest on 'Fortune', with 'Oxylus' being the least attacked by aphids. The crop yield was zero during the first season without protection for all the varieties. However, in the second season, lower yields (0.19–3.66 t/ha) was obtained with cabbage without protection, and much higher yields (14.8–21.1 t/ha) were obtained on neem-treated plots. [ABSTRACT FROM AUTHOR]

Efficacy of insecticides and biological control agents in an Integrated Pest Management (IPM) program requires a full understanding of both these factors and their interactions. With this in mind, a study was conducted to build an IPM strategy to control Myzus persicae (Homoptera: Aphididae) in field Mustard (Brassica compestris) crops using a combination of insecticides and biological control agents. Five different insecticides (methomyl, matrine, carbosulfan, thiamethoxam, and pymetrozine) were used to test the survival of Aphidius matricariae wasps under field and laboratory conditions. Under laboratory conditions five different concentrations (1%, 0.5%, 0.25%, 0.13% 0.06%) along with the control were made of each insecticide. Parasitoids exposed to Pymetrozine showed the highest percent emergence at 82.96%, 65.18%, 64.07%, 53.70% and 46.66% of from mummified aphids followed by thiamethoxam, carbosulfan, matrine and methomyl, whereas under field conditions none of these insecticides showed negative impacts on the emergence of A. matricariae wasps. In the presence of insecticides, no significant effect on emergence of A.matricariae wasps from mummified aphids was observed with pymetrozine showing 90.91% emergence of A. matricariae wasps, carbosulfan 81.25%, matrine 80.27%, thiamethoxam 77.29% and methomyl 75.49% emergence, respectively. In addition to observing the effect of insecticides on the emergence of A. matricariae, efficacy of these insecticides against populations of M. persicae was also studied. In order of efficacy, thiamethoxam > matrine > pymetrozine > carbosulfan > methomyl showing 91.37%, 89.61%, 72.46%, 56.6% and 54.35% reductions in aphid populations, respectively. The results of this study show that a biological control agent together with these insecticides can be used simultaneously as part of an IPM program to control M. persicae in field Mustard. [ABSTRACT FROM AUTHOR]

Fertilizers utilization does not only play an important role in increasing the crop yield, but also they may influence the plant nutritional quality, thereby it affects the ecological interactions between herbivores and their natural enemies. In a field study, the effect of nitrogen fertilization (0, 75, 150 and 225 kg N ha−1) on population of mustard aphid, Lipaphis erysimi Kalt. (Hemiptera: Aphididae) and predatory gall midge, Aphidoletes aphidimyza (Diptera: Cecidomyiidae), in canola (Brassica napus L.), as well as their interactive impact on the plant yield was investigated. The population of aphid and predator were positively affected by nitrogen fertilization; the maximum abundances of which were observed in plants with 150 and 225 kg N ha−1 applied. However, predator to prey ratio was lower in the highest N level in comparison with the moderate level. The maximum suppression of the aphid by the predator was also observed in the moderate N level. The interactive effect of nitrogen fertilizing and the predator presence positively influenced the canola grain yield. The lowest yield losses due to aphid infestation were observed in plants fertilized with 150 kg N ha−1 in the presence of the predator. In this fertilization level, the plants could compensate the aphid damage more than the other treatment levels; hence, they produced significantly more grain yield. These findings indicate that adequate plant nutrition can help plants compensate for aphid damage and also positively affect the predator efficiency, leading to an improvement in the canola yield. [ABSTRACT FROM AUTHOR]

Nematode resistance protein HSPRO2 of Arabidopsis thaliana has important roles in defence response to the bacterium (Pseudomonas syringae) and shows response against oxidative stress and salicylic acid. We have explored the gene encoding it from Rorippa indica (L.) Hiern, a wild relative of cultivated crucifers experimentally challenged with mustard aphid Lipaphis erysimi. The gene seems to be a strong candidate for aphid tolerance in cultivated mustards. Presently we are reporting the results of a time-course quantitative relative expression analysis of HSPRO2 of R. indica where we have observed ~ tenfold increase in its expression in R. indica at 12 hours post infestation with L. erysimi. We have also isolated the full-length gene (1314 bp) by both 5′ and 3′ RACE (Rapid Amplification of cDNA Ends). Genome walking experiment identified the promoter sequence. Expression, purification and characterisation of RiHSPRO2 showed that it encodes for a 437 amino acid peptide. The 66 kDa recombinant RiHSPRO2 protein was purified for studying its efficacy against L. erysimi in an artificial diet-based insect bioassay that revealed LC50 (Lethal Concentration 50) values of RiHSPRO2 significantly within limits against L. erysimi. The present study might have a significant implication in future towards aphid management program of Brassica juncea through the development of aphid-tolerant transgenic plants. [ABSTRACT FROM AUTHOR]

Insect damage leads to changes in biochemical profile of plants. Response of three Brassica juncea-fruticulosa introgression lines (already reported resistant to Lipaphis erysimi) in terms of changes in biochemical constituents after aphid infestation was studied along with B. fruticulosa (resistant parent), B. juncea var. PBR −210 (susceptible parent) and B. rapa ecotype brown sarson BSH-1 (susceptible check). These six genotypes were grown under aphid infested and uninfested conditions and were sampled at peak aphid infestation to analyze the biochemical changes caused by aphid feeding from top 10 cm central twig of plant. A significant reduction in glucosinolates content in aphid infested plants of three introgression lines (I8, I79 and I82) was observed while opposite was observed in B. fruticulosa, PBR-210 and BSH-1. Exactly opposite trend was observed for total phenols where aphid infestation resulted in significant increase in phenols content in the three introgression lines while a decrease was observed in B. fruticulosa, PBR-210 and BSH-1. A general trend of decline in flavonols, total sugars and free amino acids content was observed after aphid infestation in all the genotypes. Glucosinolates and total phenols served as biochemical bases of resistance in the three introgression lines since there was downregulation of glucosinolates and upregulation of total phenols as against opposite trend observed in BSH-1 and PBR-210. [ABSTRACT FROM AUTHOR]

Main conclusion : Transgenic mustard plants ( Brassica juncea ) expressing non-allergenic and biologically safe RiD peptide show higher tolerance against Lipaphis erysimi. Rorippa indica defensin (RiD) has previously been reported as a novel insecticidal protein derived from a wild crucifer Rorippa indica. RiD was found to have an effective insecticidal property against mustard aphid, Lipaphis erysimi. In the present study, RiD was highly upregulated in R. indica during aphid infestation initiating a defense system mediated by jasmonic acid (JA), but not by salicylic acid (SA)/abscisic acid (ABA). RiD has also been assessed for biosafety according to the FAO/WHO guideline (allergenicity of genetically modified foods; Food And Agriculture Organisation of the United Nations, Rome, Italy, 2001) and Codex Alimentarius Guideline (Guidelines for the design and implementation of national regulatory food safety assurance programme associated with the use of veterinary drugs in food producing animals. Codex Alimentarius Commission. GL, pp 71-2009, 2009). The purified protein was used to sensitize BALB/c mice and they showed normal histopathology of lung and no elevated IgE level in their sera. As the protein was found to be biologically safe and non-allergenic, it was used to develop transgenic Brassica juncea plants with enhanced aphid tolerance, which is one of the most important oilseed crops and is mostly affected by the devastating pest- L. erysimi. The transgene integration was monitored by Southern hybridization, and the positive B. juncea lines were further analyzed by Western blot, ELISA, immunohistolocalization assays and in planta insect bioassay. Transgenic plants expressing RiD conferred a higher level of tolerance against L. erysimi. All these results demonstrated that RiD is a novel, biologically safe, effective insecticidal agent and B. juncea plants expressing RiD are important components of integrated pest management. [ABSTRACT FROM AUTHOR]

Mustard aphid, Lipaphis erysimi (Kaltenbach) is a major constraint in increasing the yield of rapeseed-mustard crops in India. Resistance to mustard aphid infestation and its correlation to some physiological and biochemical traits in selected varieties of different Brassica species were studied. Yield and oil content losses of up to 29.4% and 2.84%, respectively, were observed due to aphid infestation. Eruca sativa var. T-27 and Brassica carinata var. DLSC-2 were less susceptible to aphid infestation and had minimal yield losses. Surface wax, total glucosinolate, and phenol contents were found to correlate negatively with the aphid infestation, whereas the opposite relationship was obtained for the sugar content. The study suggests that physical and chemical barriers potentially play an important role in resistance against aphid infestation. [ABSTRACT FROM AUTHOR]

Rorippa indica, a wild crucifer, has been previously reported as the first identified plant in the germplasm of Brassicaceae known to be tolerant towards the mustard aphid Lipaphis erysimi Kaltenbach. We herein report the full-length cloning, expression, purification and characterization of a novel R. indica defensin (RiD) and its efficacy against L. erysimi. Structural analysis through homology modeling of RiD showed longer α-helix and 3rd β-sheet as compared to Brassica juncea defensin (BjD). Recombinant RiD and BjD was purified for studying its efficacy against L. erysimi. In the artificial diet based insect bioassay, the LC value of RiD against L. erysimi was found to be 9.099 ± 0.621 µg/mL which is far lower than that of BjD (43.51 ± 0.526 µg/mL). This indicates the possibility of RiD having different interacting partner and having better efficacy against L. erysimi over BjD. In the transient localization studies, RiD signal peptide directed the RiD: yellow fluorescent protein (YFP) fusion protein to the apoplastic regions which indicates that it might play a very important role in inhibiting nutrient uptake by aphids which follow mainly extracellular route to pierce through the cells. Hence, the present study has a significant implication for the future pest management program of B. juncea through the development of aphid tolerant transgenic plants. [ABSTRACT FROM AUTHOR]