Heterologous expression of Nilaparvata lugens (Stål) voltage-gated sodium channels in Sf9 cells for electrophysiological and pyrethroid modulation studies.

Capsaicin preferentially inhibits slow-inactivation sodium currents in insects.

Molecular characterization of DSC1 orthologs in invertebrate species

BackgroundThe insect gustatory system plays a central role in the regulation of multiple physiological behaviors and the co-evolution between insects and their hosts. The gustatory receptors (Gr) are important to allow insects to sense their environment. It is critical to the selection of foods, mates and oviposition sites of insects. In this study, the Gr family genes of the brown planthopper (BPH) Nilaparvata lugens Stål (Hemiptera: Delphacidae) were identified and analyzed, and their potential relationship to the fecundity of BPH was explored by RNA interference (RNAi).ResultsWe identified 32 putative Gr genes by analyzing transcriptome and genome data from BPH. Most of these Gr proteins have the typical structure of seven transmembrane domains. The BPH Gr genes (NlGrs) were expressed in virtually all tissues and stages, whilst higher transcript accumulations were found in adult stages and in the midguts of females. Based on the phylogenic analysis, we classified NlGrs into five potential categories, including 2 sugar receptors, 2 Gr43a-like receptors, 7 CO2 receptors, 5 bitter receptors and 13 NlGrs with unknown functions. Moreover, we found that 10 NlGrs have at least two alternative splicing variants, and obtained alternative splicing isoforms of 5 NlGrs. Finally, RNAi of 29 NlGrs showed that 27 of them are related to the transcript levels of two fecundity related genes vitellogenin and vitellogenin receptor.ConclusionsWe found 32 Gr genes in BPH, among which at least 27 are required for normal expression of fecundity markers of this insect pest. These findings provide the basis for the functional study of Grs and the exploration of potential genes involved in the monophagous character of BPH.

Piriformospora indica is an endophytic fungus that can promote the growth and confer resistance against diverse stresses in host plants by root colonization. However, the effects of P. indica colonization on improving plant resistance to insect pests are still less explored. The brown planthopper (BPH) Nilaparvata lugens is a serious monophagous pest that causes extensive damage to rice plants. Here, we aimed to evaluate the effects of P. indica colonization on rice resistance against BPH. The colonization of P. indica in rice roots resisted damage from BPH. Age-stage, two-sex life table analyses showed that feeding on P. indica-colonized rice plants affected BPH's female adult longevity, oviposition period, fecundity, population parameters and population size. BPH female adults feeding on P. indica-colonized plants excreted less honeydew. P. indica colonization remarkably increased the duration of np, N2, and N3 waveform, as well as the occurrences of N1 and N2, and decreased the duration of N4-b for BPH on rice plants. Meanwhile, the weight of BPH on the colonized plants was significantly lower than the control. In addition, the feeding and oviposition preferences of BPH to P. indica-colonized plants were reduced. qRT-RCR analyses revealed that P. indica colonization induced the expressions of jasmonic acid (JA)- and salicylic acid (SA)-related genes in rice plants. P. indica colonization can reduce BPH performance on rice plants with potential inhibitory effects on population growth. Collectively, these results support the potential for endophytically colonized P. indica as an effective strategy to improve insect resistance of crops. © 2024 Society of Chemical Industry.

The depressant scorpion neurotoxin LqqIT2 selectively modulates the insect voltage-gated sodium channel

Distinct functional properties of sodium channel variants are associated with usage of alternative exons in Nilaparvata lugens

Delta-paluIT1 and delta-paluIT2 are toxins purified from the venom of the spider Paracoelotes luctuosus. Similar in sequence to mu-agatoxins from Agelenopsis aperta, their pharmacological target is the voltage-gated insect sodium channel, of which they alter the inactivation properties in a way similar to alpha-scorpion toxins, but they bind on site 4 in a way similar to beta-scorpion toxins. We determined the solution structure of the two toxins by use of two-dimensional nuclear magnetic resonance (NMR) techniques followed by distance geometry and molecular dynamics. The structures of delta-paluIT1 and delta-paluIT2 belong to the inhibitory cystine knot structural family, i.e. a compact disulfide-bonded core from which four loops emerge. Delta-paluIT1 and delta-paluIT2 contain respectively two- and three-stranded anti-parallel beta-sheets as unique secondary structure. We compare the structure and the electrostatic anisotropy of those peptides to other sodium and calcium channel toxins, analyze the topological juxtaposition of key functional residues, and conclude that the recognition of insect voltage-gated sodium channels by these toxins involves the beta-sheet, in addition to loops I and IV. Besides the position of culprit residues on the molecular surface, difference in dipolar moment orientation is another determinant of receptor binding and biological activity differences. We also demonstrate by electrophysiological experiments on the cloned insect voltage-gated sodium channel, para, heterologuously co-expressed with the tipE subunit in Xenopus laevis oocytes, that delta-paluIT1 and delta-paluIT2 procure an increase of Na+ current. delta-PaluIT1-OH seems to have less effect when the same concentrations are used.

SummaryVoltage-gated sodium (NaV) channels, initially characterized in excitable cells, have been shown to be aberrantly expressed in non-excitable cancer tissues and cells from epithelial origins such as in breast, lung, prostate, colon, and cervix, whereas they are not expressed in cognate non-cancer tissues. Their activity was demonstrated to promote aggressive and invasive potencies of cancer cells, both in vitro and in vivo, whereas their deregulated expression in cancer tissues has been associated with metastatic progression and cancer-related death. This review proposes NaV channels as pharmacological targets for anticancer treatments providing opportunities for repurposing existing NaV-inhibitors or developing new pharmacological and nutritional interventions.

Structure–activity relationships for the action of 11 pyrethroid insecticides on rat Nav1.8 sodium channels expressed in Xenopus oocytes

Mutations in NlInR1 affect normal growth and lifespan in the brown planthopper Nilaparvata lugens

The brown planthopper (BPH) Nilaparvata lugens (Stål) (Homoptera: Delphacidae) is considered a threat to rice (Oryza sativa ssp.) crop in many parts of the world including India. Among the BPH-resistance (R) genes so far reported in rice, most of them are ineffective against BPH biotype 4 predominant in the Indian sub-continent. In this study, we show the introgression line RPBio4918-230S was identified as BPH resistant after five years of rigorous screening at seedling stage and two years at tillering and reproductive stages. The inheritance of resistance indicated that two recessive genes are involved at seedling and reproductive stages. The allelic relation with known genes using linked reported markers suggested that the genes present in RPBio4918-230S are different. We report here the genetics of the two newly introgressed BPH resistance genes from O. nivara in the background of Swarna which are effective at all the important growth stages. The genes have been tentatively named as bph39(t) and bph40(t). The honeydew area (feeding rate) and days to wilt parameters observed at 30 days after sowing in BC1F3 indicated that newly introgressed genes have both antibiosis and tolerance mechanisms for resistance. The BPH resistance genes identified in this study would facilitate the breeding of broad spectrum and durable resistance in rice against BPH biotype 4.

Abstract. Puspito AN, Tigara MRN, Putra SID, Rozzita N, Ubaidillah M. 2023. Molecular screening of local Indonesian rice to identified resistant varieties against brown planthopper (Nilaparvata lugens) attacks. Biodiversitas 24: 5503-5512. Brown planthopper (Nilaparvata lugens Stal) is a significant pest in rice (Oryza sativa L.), resulting in a yield loss of around 20-80%. Environmentally friendly control involves looking for potential resistance in local Indonesian rice, because it’s naturally resistant to pests and diseases and has several tolerant mechanisms for dealing with stress. However, the resistance potential of local rice has not been widely studied, so it is necessary to carry out screening to identify the resistance possessed by local Indonesian rice and continue with molecular analysis to validate the presence of brown planthopper resistance genes. This study aimed to determine the possible resistance level of 24 Indonesian local rice varieties to brown planthopper pests. The research was conducted at the Agrotechnology Laboratory, Faculty of Agriculture, University of Jember. In June-November 2022. This research included screening using the third instar nymph brown planthopper, preference testing to analyze the preference level for each local rice variety and molecular analysis using six BPH markers (RM 247, RM 6869, RM 19291, g12140-2, RM 3331, and RM 5479) with the MAS technique. The results showed that in the preference test, Lahoten, Fatuk Masin, and Sukamandi had a higher preference value than other local Indonesian rice. In the screening, the average local rice with very resistant criteria is Leukat Medan, while those with moderately vulnerable criteria are Sukamandi. In the molecular analysis of local Indonesian rice, the Aek Sibundong variety had the most resistance, while the Kapuas and Sukamandi varieties had the least resistance.

Author index vol. 19 (1983)

Abundance of brown plant hopper (BPH) Nilaparvatalugens (Stål) (Delphacidae: Homoptera) is modulated by prevalent weather conditions of rice growing seasons and locations. Categorization of BPH adults caught in light traps (nos/week/trap) into low, moderate and high and formulation of criteria accounting weather variables [maximum/ minimum/ mean temperature (ÚC), morning/evening/mean relative humidity (%), rainfall (mm) and sunshine hours (h/day) and wind speed (km/h)] during kharif of2011-16 for four locations viz., Ludhiana (Punjab), Chinsurah (West Bengal), Raipur (Chhattisgarh) and Aduthurai (Tamil Nadu) with associated rules for weather based BPH prediction. Validation of BPH predictions for kharif 2017 indicated 96, 87, 73 and 61% accuracies in respect of Aduthurai (TN), Raipur (CG), Ludhiana (PB) and Chinsurah (WB). Future weather based predictions of BPH based on climatic projections of representative concentration pathway (RCP) 4.5 for 2020, 2050 and 2080 indicated absence of high population at Chinsurah (WB) during all time periods of 2020-2080. Progressively reducing BPH abundance from past (2011) to all future periods was noticed at Aduthurai (TN). ‘High’ BPH from 2020 and beyond over 2011 and 2016 at Raipur (CG) and reducing ‘high’ but increasing ‘moderate’ category between 2020-2050 but the reverse in 2080 at Ludhiana (PB) were predicted indicating requirement of continued monitoring strategies put in place at these locations. The observed spatial variability of climate change influence on BPH implied a need for zonation mapping of rice insects including BPH for India.

Potent Actions of the Pyrethroid Insecticides Cismethrin and Cypermethrin on Rat Tetrodotoxin-Resistant Peripheral Nerve (SNS/PN3) Sodium Channels Expressed in Xenopus Oocytes