The NPGS Sudan sorghum germplasm collection reveals a novel cluster of R genes associated with rust resistant

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.

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.

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.

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.

Developing new pigmented rice varieties that meet consumers' preferences requires addressing resistance to brown planthopper (BPH), a highly destructive insect pest of rice. To effectively manage this pest, it is essential to explore BPH resistance genes from rice germplasms and incorporate them into elite varieties. The objective of this study was to identify the source of resistance among local and improved pigmented rice varieties in Indonesia against field BPH. Furthermore, the study aimed to characterize their genetic diversity using molecular markers associated with Bph genes and functional markers for these genes. Eighty-eight local varieties from the Indonesian Agricultural Gene Bank, collected across 18 provinces between 1971 and 2019, and four improved varieties, were evaluated using the standard seed box screening test method. Among these entries, 6 local accessions and 1 improved variety exhibited moderate resistance. Genetic analysis of these entries and three randomly selected susceptible entries using 12 SSR and InDel markers associated with Bph gene loci showed that the moderately resistant entries had higher allele numbers (11 to 13) compared to the susceptible entries (4 to 7). These markers could distinguish the resistant group from the susceptible ones in cluster analysis. Genotyping using functional markers further showed that the moderately resistant entries had 2 to 4 combinations of Bph genes. In contrast, the susceptible entries contained neither Bph genes nor only one gene. Local accessions with a 2 to 4 Bph gene combination can be donors of BPH resistance in improving pigmented rice varieties.

Abstract. Chaerani, Dadang A, Fatimah, Husin BA, Sutrisno, Yunus M. 2021. SRAP analysis of brown planthopper (Nilaparvata lugens) populations maintained on differential rice host varieties. Biodiversitas 22: 4266-4272. Brown planthopper (Nilaparvata lugens Stål) biotypes differ in virulence to rice varieties carrying different Bph resistance genes. These biotypes are reported can be genetically discriminated against using DNA markers. Four brown planthoppers (BPH) populations, which displayed two virulence phenotypes, have been produced by selection and adaptation on four differential host varieties. Sequence-related amplified polymorphism (SRAP) marker preferentially amplifies the coding regions in the genome and, thus, can discriminate the observed virulence variations among those populations. This study aimed to analyze the genetic variation of four developed BPH populations using SRAP markers. Genetic analysis of a total of 40 BPH females with 18 polymorphic primers revealed equal genetic diversity parameter values among populations (Na: 1.1 to 1.4, Ne: 1.2 to 1.3, I: 0.22 to 0.29, He: 0.14 to 0.18, and UHe: 0.15 to 0.19). Analysis of population structure by AMOVA indicated low genetic variation among populations (9%). Still, pairwise PhiPT population values between all pairs of the population revealed the presence of moderate genetic differentiations (PhiPT ranged from 0.57 to 0.133, P<0.01). Two partial clusters in plots of PCoA were corresponded to two virulence groups, indicating the ability of SRAP markers to discriminate virulence phenotype. Further selection and adaptation are expected can form four desired virulence patterns with complete genetic separation among the population before its application as resistance screening agents of rice lines.

Abstract. Listihani L, Ariati PEP, Yuniti IGAD, Selangga DGW. 2022. The brown planthopper (Nilaparvata lugens) attack and its genetic diversity on rice in Bali, Indonesia. Biodiversitas 23: 4696-4704. The brown planthopper (Nilaparvata lugens) is an important pest on rice crops in Indonesia. The genetic diversity of BPH isolates in western Indonesia has been extensively reported, whereas eastern Indonesia isolates have not been reported. This research aims to analyze genetic diversity and evaluate the BPH attack's intensity on Bali rice plants. The research method used was an observation of attack percentage, population dynamics, attack intensity, and genetic diversity of BPH in 9 districts in Bali (Badung, Gianyar, Klungkung, Bangli, Karangasem, Tabanan, Denpasar City, Buleleng, and Jembrana). Molecular identification was carried out on N. lugens DNA in the mtCOI fragment. BPH attacks of >50% were found in the districts of Gianyar, Bangli, Jembrana, and Badung. The BPH population was primarily found in Ciherang and IR-64 varieties of rice in the Badung Regency, with 43.67 BPH per rice hill. In general, rice varieties grown in all observation locations were susceptible to BPH, such as Ciherang, IR-64, Inpari 32, and Situbagendit. In the Ciherang and IR-64 varieties, the highest attack intensity average value reached 30%. The sequence of N. lugens isolate from Bali Jembrana showed the highest nucleotide and amino acid homology with N. lugens isolate FSD-034 from Pakistan (MK301229) biotype Y of 99.5 -99.74% and 100%, respectively. This study found N. lugens biotype Y in rice plants for the first time in Indonesia. This study reported that Rice varieties Situbagendit and Inpari 32, previously resistant to BPH, are reported as susceptible to BPH.

Investigation of the predation potential of different fish species on brown planthopper (Nilaparvata lugens (Stål)) in experimental rice-fish aquariums and tanks

Genetic dissection and identification of candidate genes for brown planthopper, Nilaparvata lugens (Delphacidae: Hemiptera) resistance in farmers’ varieties of rice in Odisha

Simple SummaryIn recent years, the atmospheric CO2 concentration was increasing continuously, which has led to the change in the photosynthesis and chemical composition of rice plants. The growth and development of brown planthopper (BPH) Nilaparvata lugens are further affected. Plants release volatile organic compounds (VOCs) to mediate intra- and inter-specific interactions with other organisms in the surrounding environment. Therefore, here we aim to explore the effect of rice VOCs on the host selection ability of BPH under elevated CO2. Among the identified thirty-six rice VOCs, the contents of heptadecane, linalool and limonene from rice plants were significantly decreased under elevated CO2. Moreover, we found that the VOCs of rice damaged by BPH were also changed. Undecane, hexadecane, nonanal and 2,6-diphenylphenol from BPH-damaged rice plants under elevated CO2 were all significantly higher than those from healthy rice plants, which might lead to enhancement of the host selection ability of BPH, eventually aggravating the damage caused by BPH. However, the role of these VOCs in host selection ability of BPH is not clear, and more experiments are needed to verify their function.It is predicted that plant volatile organic compounds (VOCs) are affected by the atmospheric CO2 levels rising globally, which further affects the interaction between plants and herbivorous insects, especially the host selection behavior of herbivorous insects. In this study, the effects of elevated CO2 on the host-selection behavior of the brown planthopper (BPH) Nilaparvata lugens, and the emission of VOCs from the healthy and BPH-damaged rice plants were studied simultaneously to make clear the population occurrence of BPH under global climate change. Compared with ambient CO2, elevated CO2 significantly increased the host selection percent of BPH for the healthy (CK) and BPH-damaged rice plants, and the host selection percent of BPH for the BPH-damaged rice plants was significantly higher than that for the healthy rice plants under elevated CO2, which might be regulated by the transcription levels of OBP1, OBP2 and CSP8 in BPH due to the upregulated transcriptional levels of these three genes of BPH under elevated CO2. In addition, we analyzed and quantified the emission of VOCs in rice plants grown under ambient CO2 and elevated CO2 by GS-MS. A total of 36 VOCs from rice plants were identified into eight categories, including alkanes, alkenes, alcohols, aldehydes, ketones, esters, phenols and aromatic hydrocarbons. Elevated CO2 significantly decreased the contents of heptadecane, linalool and limonene from rice plants compared with ambient CO2. Besides, the contents of linalool, phytol, decanal, 1-methyldecalin and 2,6-diphenylphenol from BPH-damaged rice plants under ambient CO2, and undecane, hexadecane, nonanal and 2,6-diphenylphenol from BPH-damaged rice plants under elevated CO2 were all significantly higher than those from healthy rice plants. The percentage composition of phenols was positively correlated with the host selection rate of BPH. Our study indicates that elevated CO2 is beneficial to promote the host selection ability of BPH for rice plants damaged by BPHs due to the changed plant VOCs.

Herbivore-induced defense responses are often specific, whereas plants could induce distinct defense responses corresponding to infestation by different herbivorous insects. Brown plant hopper (BPH) Nilaparvata lugens, a phloem-feeding insect, and rice leaf folder (LF) Cnaphalocrocis medinalis, a chewing insect, are both specialist herbivores on rice. To characterize the distinct resistance primed by prior damage to these two specialist herbivores, we challenged rice plants with two herbivores during vegetative growth of parent plants and assessed plant resistance in subsequent ratoons. Here, we show that LF and BPH induce different suites of defense responses in parent rice plants, LF induced higher level of JA accumulation and OsAOS, OsCOI1 transcripts, while BPH induced higher accumulation of SA and OsPAL1 transcripts. Moreover, an apparent loss of LF resistance was observed in OsAOS, OsCOI1 RNAi lines. Ratoon plants generated from parents receiving prior LF infestation exhibited higher jasmonic acid (JA) levels and elevated levels of transcripts of defense-related genes associated with JA signaling, while ratoon generated from parents receiving prior BPH infestation exhibited higher salicylic acid (SA) levels and elevated levels of transcripts of defense-related genes associated with SA signaling. Moreover, previous LF infestation obviously elevated ratoons resistance to LF, while previous infestation by BPH led to enhanced resistance in ratoons to BPH. Pre-priming of ratoons defense to LF was significantly reduced in OsAOS and OsCOI1 RNAi plant, but silencing OsAOS and OsCOI1 did not attenuate ratoons resistance to BPH. These results suggest that infestation of two specialist herbivores with different feeding styles in parent crop led to distinct defense responses in subsequent rations, and the acquired resistance to LF in ratoons is associated with priming of jasmonic acid-dependent defense responses.

The brown planthopper (Nilaparvata lugens) is a major pest in rice cultivation. Its population can be effectively managed through biological control using the entomopathogenic fungus Beauveria bassiana. This study aimed to evaluate the effectiveness of the entomopathogenic fungus B. bassiana in controlling N. lugens under greenhouse conditions. Applications of B. bassiana at various concentrations revealed that 10⁸ conidia/mL treatment was the most effective, achieving up to 90% mortality within 7 days post-application. This treatment also recorded the lowest LT₅₀ value of 6.736 days and the highest regression value of 0.52, indicating a rapid and effective reduction in pest population. The mortality rate exhibited an increasing trend up to day five, followed by a decline as target population diminished, with cumulative mortality reaching 90% by day seven. These findings demonstrate that a concentration of 10⁸ conidia/mL is the most optimal for biological control of N. lugens using B. bassiana, both in terms of mortality rate and speed of action. The results support the potential of B. bassiana as a promising biological control agent in sustainable pest management strategies for agricultural systems.

Simple SummaryThe brown planthopper, Nilaparvata lugens, a plant phloem-sucking Hemipteran insect, has become the most destructive pest for rice—the major food source for half of the world’s population. Nilaparvata lugens possess robust fecundity, enabling population densities to increase quickly in a favorable environment. Nilaparvata lugens has also been used as a model system for ecological studies and for developing effective pest management. To better understand the regulation mechanisms of insect reproduction and to provide insights to improve pest control, we searched N. lugens genome and transcriptome databases and identified an NADPH oxidase 5 gene, which was specifically expressed in ovaries of female adults and freshly laid eggs in rice leaf sheaths. Although homologous NADPH oxidase 5 genes have been identified in many insect species, their reproductive functions remain unknown. In this work, our findings initially reveal a functional role of the NADPH oxidase 5 gene in molting and oviposition in N. lugens. This novel finding improves our understanding of the reproductive strategies in insects and provides a potential molecular target for effective pest control of the rice planthopper.The brown planthopper Nilaparvata lugens is a typical monophagous insect herbivore that feeds exclusively on rice sap. This insect pest causes serious damage to rice crops throughout East Asian countries. Chemical control remains the first choice for managing N. lugens populations; however, the use of insecticides has given rise to planthopper resurgence and additional environmental risks. Nilaparvata lugens is a model insect of Hemiptera because its whole genome sequence has been elucidated and is susceptible to RNA interference. In this study, our findings revealed that a superoxide-generating gene, NADPH oxidase 5 (Nox5), is essential for molting and oviposition in a Hemipteran insect Nilaparvata lugens. Knockdown of Nox5 transcript levels by RNA interference in 2nd–5th-instar nymphs results in significantly lethal deficits in the molting transitions from nymph–nymph and nymph–adult. Nox5 knockdown leads to a reduction of hydrogen peroxide in female ovaries and failure of oviposition from the insect ovipositor into the rice leaf sheath. Here, we provide in vivo evidence demonstrating that Nox5 is a key enzyme for regulating molting and oviposition in this insect species.