Brown Planthopper Attack Research Articles

Ketahanan enam galur padi sawah (Oryza sativa L) terhadap wereng batang coklat (Nilaparvata lugens Stål) asal Patokbeusi, Subang

Dalam pelepasan varietas baru, selain diperlukan informasi mengenai karakter-karakter kualitatif maupun kuantitatif galur, juga perlu diperhatikan keunggulan lainnya, seperti ketahanan terhadap wereng batang cokelat (WBC) (Nilaparvata lugens, Stål) (Hemiptera: Delphacidae). Tujuan penelitian ini adalah untuk mengetahui ketahanan terhadap WBC pada 6 (enam) galur calon varietas yang dikembangkan oleh IPB University, yaitu TCIPB202101, TCIPB202102, TCIPB202103, TCIPB202104, TCIPB202105, dan TCIPB202106. Pengujian ketahanan terhadap WBC dilakukan dengan melakukan uji penapisan dan uji perkembangan populasi. Varietas Inpari 30 dan Ciherang digunakan sebagai kontrol. Hasil penelitian menunjukkan bahwa galur TCIPB202106 merupakan galur yang paling tahan terhadap serangan WBC, sementara yang paling rentan terhadap serangan WBC adalah galur TCIPB202103. Rata-rata jumlah nimfa pada galur TCIPB202106 tiga kali lebih rendah dibandingkan dengan Inpari 30 dan Ciherang. Hasil uji perkembangan populasi sejalan dengan hasil uji penapisan yang menunjukkan bahwa galur TCIPB202106 tergolong dalam kategori agak tahan WBC.

Rice brown planthopper monitoring and detection by spectral reflectance: a review

Brown planthopper (BPH) has been one of the main pests of rice worldwide. Monitoring is important factor for determining attacks and estimating their effects. The traditional monitoring approach is usually conducted through visual observation and field scouting, with limitations such as subjectivity and time consumption. Remote sensing is an alternative pest monitoring method that covers a larger area in a shorter time. This paper discusses a remote-sensing method that uses a spectral approach to detect BPH attacks. Literature was filtered and processed using the PRISMA method. According to the spectral sensor, studies were classified into multispectral and hyperspectral sensors. Based on this scale, there are four studies on the panicle, leaf, canopy, and field levels. The model used single-wave reflectance and spectral indices as predictors. Various algorithms were used in the studies: linear regression, Principal Component Analysis, and Machine Learning to estimate the severity class, BPH Population density, and yield loss. A combination of spectral reflectance with other parameters, such as weather, fertilizer application, and infestation time, was conducted to improve the performance of the detection model. This review provides state-of-the-art spectral reflectance usage for detecting BPH attacks and opportunities for future development.

Osa-miR162a Enhances the Resistance to the Brown Planthopper via α-Linolenic Acid Metabolism in Rice (Oryza sativa).

The brown planthopper (BPH) is the most serious pest causing yield losses in rice. MicroRNAs (miRNAs) are emerging as key modulators of plant-pest interactions. In the study, we found that osa-miR162a is induced in response to BPH attack in the seedling stage and tunes rice resistance to the BPH via the α-linolenic acid metabolism pathway as indicated by gas chromatography/liquid chromatography-mass spectrometry analysis. Overexpression of osa-miR162a inhibited the development and growth of the BPH and simultaneously reduced the release of 3-hexenal and 3-hexen-1-ol to block host recognition in the BPH. Moreover, knockdown of OsDCL1, which is targeted by osa-miR162a, inhibited α-linolenic acid metabolism to enhance the resistance to the BPH, which was similar to that in miR162a-overexpressing plants. Our study revealed a novel defense mechanism mediated by plant miRNAs developed during the long-term evolution of plant-host interaction, provided new ideas for the identification of rice resistance resources, and promoted a better understanding of pest control.

Infestation by the Piercing-Sucking Herbivore Nilaparvata lugens Systemically Triggers JA- and SA-Dependent Defense Responses in Rice.

It has been well documented that an infestation of the piercing-sucking herbivore, brown planthopper (BPH), Nilaparvata lugens, activates strong local defenses in rice. However, whether a BPH infestation elicits systemic responses in rice remains largely unknown. In this study, we investigated BPH-induced systemic defenses by detecting the change in expression levels of 12 JA- and/or SA-signaling-responsive marker genes in different rice tissues upon a BPH attack. We found that an infestation of gravid BPH females on rice leaf sheaths significantly increased the local transcript level of all 12 marker genes tested except OsVSP, whose expression was induced only weakly at a later stage of the BPH infestation. Moreover, an infestation of gravid BPH females also systemically up-regulated the transcription levels of three JA-signaling-responsive genes (OsJAZ8, OsJAMyb, and OsPR3), one SA-signaling-responsive gene (OsWRKY62), and two JA- and SA- signaling-responsive genes (OsPR1a and OsPR10a). Our results demonstrate that an infestation of gravid BPH females systemically activates JA- and SA-dependent defenses in rice, which may in turn influence the composition and structure of the community in the rice ecosystem.

Sakuranetin protects rice from brown planthopper attack by depleting its beneficial endosymbionts

Plants produce chemical defenses that poison insect herbivores or deter their feeding, but herbivores are also accompanied by microbial endosymbionts crucial for their nutrition, reproduction, and fitness. Hence, plant defenses could target a herbivore's beneficial endosymbionts, but this has not yet been demonstrated. Here, we studied flavonoids that are induced when rice is attacked by a phloem-feeding pest, the brown planthopper (BPH), which harbors beneficial yeast-like symbionts (YLS) essential for insect nutrition, such as by remedying deficiencies in sterols. BPH attack dramatically increased sakuranetin accumulations in leaf sheaths and phloem exudates. Sakuranetin is an antifungal phytoalexin derived from the antibacterial precursor, naringenin, via catalysis of naringenin-O-methyltransferase (NOMT). When added to artificial diets, sakuranetin decreased BPH survivorship, suggesting that it functions as an induced defense. Mutation of NOMT abolished sakuranetin accumulation and increased BPH oviposition and hatching rates. High-throughput amplicon sequencing revealed that BPH fed on sakuranetin-deficient nomt lines were enriched in YLS with only minor changes in the bacterial endosymbionts, compared to those feeding on sakuranetin-rich wild-type (WT) plants. In-vitro feeding of sakuranetin suggested that this flavonoid directly inhibited the growth of YLS. BPH feeding on nomt lines accumulated higher cholesterol levels, which might be attributed to increases in the supply of sterol precursors from the YLS, while nomt lines suffered more damage than WT plants did from BPH herbivory. BPH-elicited accumulation of sakuranetin requires intact jasmonate (JA) signaling. This study reveals that rice uses a JA-induced antifungal flavonoid phytoalexin in defense against BPH by inhibiting its beneficial endosymbionts.

Genetics, Mechanisms and Deployment of Brown Planthopper Resistance Genes in Rice

Among the rice insects, brown planthopper (BPH), (Nilaparvata lugens Stål) is a monophagous migratory phloem-sucking insect causing severe loss in Asiatic countries. High nitrogen and willful insecticide application coupled with an increase in temperature have created havoc by this pest during the last few years in certain parts of India, Indonesia, China, Japan, Taiwan, Vietnam, and the Philippines. Though chemical control measures are advocated to mitigate this insect, yet, the incorporation of host-plant resistance factor is the preferred approach to manage this insect attack owing to the high cost of chemical control and adverse effects on the environment. To date, more than 40 major resistance genes and 22 minor genes or quantitative trait loci (QTLs) are identified. Cloning of 11 BPH resistance genes has been completed to date. Majority of the cloned genes produced coiled-coil nucleotide-binding and leucine-rich repeat protein for the defense response in the host plant. Salicylic acid, jasmonic acid, ethylene, mitogen-activated protein kinases, Ca2+, OsRac1, and other signaling molecules play a definite role in the defense response. Signal transduction may lead to sieve tube sealing, production of metabolites, and induction of proteinase inhibitor for defense response against BPH attack. Plants have intrinsic mechanisms for recognition of damage-associated and herbivore-associated molecular patterns and elicitors for host defense response. This review provides an update on the sources of resistance, identification of resistance genes, gene maps, (QTL) detection, cloning, insights into the molecular mechanisms of resistance, and deployment of resistance genes for durable and broad-spectrum resistance in the cultivars against BPH.

Low-level cadmium exposure influences rice resistance to herbivores by priming jasmonate signaling

The heavy metal, cadmium (Cd), has become a new threat to rice production in paddy fields. Cd is absorbed by rice roots and translocated to shoots, where it accumulates in different tissues. Rice is also commonly attacked by insect herbivores, but the effects of low-level Cd exposure on the performance of rice pests and the underlying mechanisms remain unexplored. We investigated brown planthopper (BPH) performance on Cd-exposed rice in the laboratory and field. Low-level Cd exposure did not significantly affect rice growth but decreased hatching rate and extended hatching duration of BPH eggs. No direct toxic effect of low Cd exposure on BPH eggs were found in in vitro developmental rate assays. By transcriptome analysis, a total of 747 rice genes were differentially expressed in Cd-exposed plants under BPH attack. Interestingly, BPH-elicited jasmonate (JA) and phenylpropanoid pathway genes were up-regulated by Cd exposure. Consistently, the levels of JAs and JA-mediated phenylpropanoid derivatives were also increased. Furthermore, Cd exposure did not affect BPH performance on mutant plants impaired in JA biosynthesis ( aoc-2 ) and signaling ( myc2–5 ), suggesting that JA is required to influence BPH performance under Cd exposure. In the field, herbivore populations were reduced on Cd-treated plants compared with control plants. This study revealed that low-level Cd exposure primes JA-mediated defense responses in rice and thereby affects herbivore performance. • Low-level Cd exposure enhanced rice resistance to BPH in the laboratory and field. • BPH-elicited JA and phenylpropanoid levels were primed by low-level Cd exposure. • JA signaling is required for enhanced BPH resistance under Cd exposure.

Application of Vermicompost with Different Feeding Material for Inducing Rice Plant Resistance against Brown Planthopper (Nilaparvata lugens Stål.) Attack

Brown planthopper (BPH) is a major pest in rice plants and has become a global pest. This pest causes hopperburn in rice plants. This research aimed to know the effect of vermicompost from different feeding materials on rice plant damage by brown planthopper attack. This research was carried out in November 2019–March 2020 at the Sistandu integrated farming system, Serang City, Banten. The experiment method used in this research was a factorial Randomized Block Design (RBD) consisting of two factors with three replications. The first factor was vermicompost (P) 5 levels, while the second factor was rice varieties (V) with two groups so that there were ten treatments. Data were analyzed with ANOVA, then followed by 5% DMRT. The results showed that the application of vermicompost with different feeding materials gave non-significant results to the growth of rice plants in the vegetative phase and fecundity of the BPH. However, it significantly affected the intensity of rice plant damage in the generative phase, the offspring population of BPH, and the BPH feeding rate. While the use of two varieties of rice does not have a distinct effect on all parameters. There is no interaction effect between two factors, both vermicompost feeding material treatment and rice plant variety, to all the parameters that have been studied.

The jasmonic acid-amino acid conjugates JA-Val and JA-Leu are involved in rice resistance to herbivores.

The phytohormone jasmonic acid (JA) plays a core role in plant defence against herbivores. When attacked by herbivores, JA and its bioactive derivatives are accumulated at the damage site, and subsequently perceived by the jasmonate co-receptors COI1 and JAZ proteins. The (+)-7-iso-jasmonoyl-L-isoleucine (JA-Ile) is known to be the main active JA derivative controlling vascular plant responses to herbivores as well as other JA-regulated processes. However, whether other endogenous JA-amino acid conjugates (JA-AAs) are involved in herbivore-induced defence responses remain unknown. Here, we investigated the role of herbivore-elicited JA-AAs in the crop plant rice. The levels of five JA-AAs were significantly increased under the armyworm, leaf folder and brown planthopper attack. Of the elicited JA derivatives, JA-Ile, JA-Val and JA-Leu could serve as ligands to promote the interaction between rice COI1 and JAZs, inducing OsJAZ4 degradation in vivo. JA-Val or JA-Leu treatment increased the expression of JA- and defence-related pathway genes but not JA-Ile levels, suggesting that these JA-AAs may directly function in JA signalling. Furthermore, the application of JA-Val or JA-Leu resulted in JA-mediated plant growth inhibition, while enhancing plant resistance to herbivore attack. This study uncovers that JA-Val and JA-Leu also play a role in rice defence against herbivores.

Menguji Tingkat Serangan Wereng Batang Coklat Nilaparvata lugens Stal (Hemiptera: Delphacidae) pada Varietas Padi Asal Pasaman di Rumah Kaca

Brown planthopper (BPH) is a major pest on rice plants that can cause hopperburn and crop failure. The study aimed to determine the level of BPH attack on several local rice varieties in the Pasaman Regency. This research was conducted in a greenhouse, Faculty of Agriculture, Universitas Andalas, using a completely randomized design (CRD), with five treatments and five replications. The treatments were four different rice varieties from Pasaman and control (Siganteng, Pulau Batu, Mundam Kuning, Mundam Putih, IR 42). BPH was infested when the rice was five days after sowing. Observation parameters were the percentage and the intensity of the attacks. Observations were done until 15 days after infestation; after the IR 42 variety died 90%. The results showed that the attack rate of BPH on rice varieties from Pasaman was moderate. The lowest percentage of attack occurred in the Mundam Putih variety (94%), while the intensity of the attack was not significantly different from other varieties.

Molecular dissection of rice phytohormone signaling involved in resistance to a piercing-sucking herbivore.

Phytohormone, particularly jasmonate (JA) and salicylate (SA) signaling, plays a central role in plant responses to herbivore and pathogen attack. Generally, SA mediates resistance responses against biotrophic pathogens and phloem-feeding insects, while JA mediates responses against necrotrophic pathogens and chewing insects. The phytohormonal responses mediating rice resistance to a piercing-sucking herbivore, the brown planthopper (BPH), remains unknown. Here, we combined transcriptome analysis, hormone measurements, genetic analysis and a field study to address this issue. Infestation by BPH adult females resulted in significant transcriptional reprograming. The upregulated genes were enriched in the JA signaling pathway. Consistently, the concentrations of JAs, but not SA, were dramatically increased in response to BPH attack. Two JA-deficient lines (AOC and MYC2 knockout) and two SA-deficient lines (nahG overexpression and NPR1 knockout) were constructed. BPH performed better on JA-deficient lines than on wild-type (WT) plants, but similarly on SA-deficient and WT plants. During BPH attack, the accumulation of defensive secondary metabolites was attenuated in JA-deficient lines compared with WT plants. Moreover, MYC2 mutants were more susceptible to planthoppers than WT plants in nature. This study reveals that JA signaling functions in rice defense against BPH.

Battling against Brown Planthopper in Rice: Genomic Selection in Backcross Breeding to Produce Resistant Cultivars - A Review

Brown Planthopper (BPH), Nilaparvata lugens Stål, imposes a significant threat to the rice cultivation in Sri Lanka, generating 5–10% of annual yield losses. Rice farmers mainly adopt chemical methods to control the BPH attacks. The intensive use of insecticides is a crucial trigger for the development of resistance and hence continuous BPH outbreaks. Thus, the chemical methods of control do not provide a permanent solution to the BPH. The most recommended strategy of resolving the BPH crisis in rice is the development of resistant cultivars. Most of the Sri Lankan rice germplasm has already been screened for BPH resistance; however, reliable molecular breeding strategies must be implemented to acieve this target. Development of BPH resistant cultivars relies on utilizing appropriate genomic selection protocols in breeding schemes such as marker-assisted backcrossing. Therefore, a literature survey was carried out to evaluate BPH control methods and to emphasize the employment of backcross breeding with the genomic selection approach as a precise tool to develop BPH resistant rice varieties. The genetic basis of BPH resistance has been unravelled for many rice cultivars however, further screening is required to identify locally available resistant sources. The polymorphic markers for the foreground and background selection must be developed for the introgression of the BPH resistant genes and recovery of the recurrent parent genome. The validation of the markers developed in the international breeding and genetics programmes for the local germplasm is also an essential step prior to the genomic selection of BPH resistant rice varieties.

Brown Planthoppers Infestations and Insecticides Use Pattern in Java, Indonesia

In Brown Planthopper (BPH) has caused losses of rice production in Java due to excessive use of pesticides. This research aims to determine the relationship between crop damages caused by BPH and insecticides use schemes. The pesticide use schemes by farmers were observed in 15 districts on Java which were reported for having severe BPH attacks i.e. Banyuwangi, Jember, Blitar, Kediri, Lamongan, Tuban, Bojonegoro, Pati, Demak, Pekalongan, Tegal, Klaten, Sukoharjo and Indramayu, Subang. Most of the sample plots in 15 districts were in the category of damage levels 2 and 3. Most of districts having rice plantations were affected by BPH with insecticides. Rice plants that have the highest level of damage are those with over-pesticide application. There is a significant influence between insecticide use schemes and BPH attack rates in the field. BPH attacks increase in line with the increased use of pesticides, in terms of application frequency, the various types of pesticides, and the number of sprayed mixture pesticides. Many farmers use pesticides that are prohibited for rice cultivation, such as the Pyrethroid and Organophosphate groups. However, the incidence of BPH attacks stilloccur even though there are differences in the pesticide status of legality

An R2R3 MYB transcription factor confers brown planthopper resistance by regulating the phenylalanine ammonia-lyase pathway in rice

Brown planthopper (BPH) is one of the most destructive insects affecting rice (Oryza sativa L.) production. Phenylalanine ammonia-lyase (PAL) is a key enzyme involved in plant defense against pathogens, but the role of PAL in insect resistance is still poorly understood. Here we show that expression of the majority of PALs in rice is significantly induced by BPH feeding. Knockdown of OsPALs significantly reduces BPH resistance, whereas overexpression of OsPAL8 in a susceptible rice cultivar significantly enhances its BPH resistance. We found that OsPALs mediate resistance to BPH by regulating the biosynthesis and accumulation of salicylic acid and lignin. Furthermore, we show that expression of OsPAL6 and OsPAL8 in response to BPH attack is directly up-regulated by OsMYB30, an R2R3 MYB transcription factor. Taken together, our results demonstrate that the phenylpropanoid pathway plays an important role in BPH resistance response, and provide valuable targets for genetic improvement of BPH resistance in rice.

Global metabolite profiles of rice brown planthopper-resistant traits reveal potential secondary metabolites for both constitutive and inducible defenses.

Brown planthopper (BPH) is a phloem feeding insect that causes annual disease outbreaks, called hopper burn in many countries throughout Asia, resulting in severe damage to rice production. Currently, mechanistic understanding of BPH resistance in rice plant is limited, which has caused slow progression on developing effective rice varieties as well as effective farming practices against BPH infestation. To reveal rice metabolic responses during 8days of BPH attack, this study examined polar metabolome extracts of BPH-susceptible (KD) and its BPH-resistant isogenic line (IL308) rice leaves. Ultra high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QToF-MS) was combined with multi-block PCA to analyze potential metabolites in response to BPH attack. This multivariate statistical model revealed different metabolic response patterns between the BPH-susceptible and BPH-resistant varieties during BPH infestation. The metabolite responses of the resistant IL308 variety occurred on Day 1, which was significantly earlier than those of the susceptible KD variety which showed an induced response by Days 4 and 8. BPH infestation caused metabolic perturbations in purine, phenylpropanoid, flavonoid, and terpenoid pathways. While found in both susceptible and resistant rice varieties, schaftoside (1.8 fold), iso-schaftoside (1.7 fold), rhoifolin (3.4 fold) and apigenin 6-C-α-L-arabinoside-8-C-β-L-arabinoside levels (1.6 fold) were significantly increased in the resistant variety by Day 1 post-infestation. 20-hydroxyecdysone acetate (2.5 fold) and dicaffeoylquinic acid (4.7 fold) levels were considerably higher in the resistant rice variety than those in the susceptible variety, both before and after infestation, suggesting that these secondary metabolites play important roles in inducible and constitutive defenses against the BPH infestation. These potential secondary metabolites will be useful as metabolite markers and/or bioactive compounds for effective and durable approaches to address the BPH problem.

OsMKK3, a Stress-Responsive Protein Kinase, Positively Regulates Rice Resistance to Nilaparvata lugens via Phytohormone Dynamics.

Plants undergo several but very precise molecular, physiological, and biochemical modulations in response to biotic stresses. Mitogen-activated protein kinase (MAPK) cascades orchestrate multiple cellular processes including plant growth and development as well as plant responses against abiotic and biotic stresses. However, the role of MAPK kinases (MAPKKs/MKKs/MEKs) in the regulation of plant resistance to herbivores has not been extensively investigated. Here, we cloned a rice MKK gene, OsMKK3, and investigated its function. It was observed that mechanical wounding, infestation of brown planthopper (BPH) Nilaparvata lugens, and treatment with methyl jasmonate (MeJA) or salicylic acid (SA) could induce the expression of OsMKK3. The over-expression of OsMKK3 (oe-MKK3) increased levels of jasmonic acid (JA), jasmonoyl-L-isoleucine (JA-Ile), and abscisic acid (ABA), and decreased SA levels in rice after BPH attack. Additionally, the preference for feeding and oviposition, the hatching rate of BPH eggs, and BPH nymph survival rate were significantly compromised due to over-expression of OsMKK3. Besides, oe-MKK3 also augmented chlorophyll content but impaired plant growth. We confirm that MKK3 plays a pivotal role in the signaling pathway. It is proposed that OsMKK3 mediated positive regulation of rice resistance to BPH by means of herbivory-induced phytohormone dynamics.

Identification and analysis of brown planthopper-responsive microRNAs in resistant and susceptible rice plants

The brown planthopper (BPH) is the most devastating insect pest of rice. The rice gene BPH15 confers resistance to BPH. MicroRNAs (miRNAs) regulate a spectrum of development and defense response processes in plants. In this study, we analyzed six miRNA profiles of a BPH15 introgression line (P15) and a susceptible recipient line (PC) at three time points (0 h, 6 h and 48 h) after BPH attack, and identified 464 known miRNAs and 183 potential novel miRNAs. Before the BPH feeding, we identified 23 miRNAs differentially expressed in P15 and PC. We speculated that the resistant plant is in a priming state by the regulation of miRNAs. After the BPH feeding, 104 miRNAs were found to be expressed differentially in P15 (68 in P15-6/P15-0, 36 in P15-48/P15-0), and 80 miRNAs were found expressed differentially in PC (32 in PC-6/PC-0, 48 in PC-48/PC-0), which illustrated that miRNA expression is activated upon attack. These miRNAs regulate different pathways that contribute to the basal defense and specific resistance of rice to the BPH. Our study provides additional data for scientists to further explore the mechanism of plant defense against insect attack and to find a way for efficient insect control.

Expression Analysis of Genes Related to Rice Resistance Against Brown Planthopper, Nilaparvata lugens

Brown planthopper (BPH) is an insect species that feeds on the vascular system of rice plants. To examine the defence mechanism of rice plants against BPH, the pathogenesis-related genes (PR1a, PR2, PR3, PR4, PR6, PR9, PR10a, PR13, PR15 and PRpha), signaling molecule synthesis genes (AOS, AXR, ACO and LOX), antioxidant-related genes (CAT, TRX, GST and SOD) and lignin biosynthesis-related genes (CHS, CHI and C4H) were investigated in a resistant rice variety. AOS, PR6, PR9 and PR15 genes showed significantly increased relative expression levels at 24.38-, 19.17-, 14.71-, and 12.74-fold compared to the control. Moderate increased relative expression levels of lignin biosynthesis-related gene (C4H), pathogenesis-related genes (PR4, PR10a and PRpha), and antioxidant-related gene (GST) were found, while CHI, LOX, SOD, TRX1 and AXR showed decreased relative expression levels. It was thus clearly shown that wound-induced response genes were activated in rice plants after BPH attacks through AOS activation. Jasmonic acid signaling molecule may activate PR6, PR15, GST and CAT subsequently increasing their expression for H2O2 detoxification. PR6 were expressed at the highest relative level among the PR genes. These genes therefore have also a considerable synergistic role with the other genes against BPH by interfered their digestion tract system.

Molecular Characterization of Rice OsLCB2a1 Gene and Functional Analysis of its Role in Insect Resistance.

In plants, sphingolipids, such as long-chain bases (LCBs), act as bioactive molecules in stress responses. Until now, it is still not clear if these lipids are involved in biotic stress responses to herbivore. Herein we report that a rice LCB gene, OsLCB2a1 encoding a subunit of serine palmitoyltransferase (SPT), a key enzyme responsible for the de novo biosynthesis of sphingolipids, plays a critical role in plant defense response to the brown planthopper (BPH) attack and that its up-regulation protects plants from herbivore infestation. Transcripts of OsLCB2a1 gene in rice seedlings were increased at 4 h, but decreased at 8–24 h after BPH attack. Sphingolipid measurement profiling revealed that overexpression of OsLCB2a1 in Arabidopsis thaliana increased trihydroxylated LCB phytosphingosine (t18:0) and phytoceramide by 1.7 and 1.3-fold, respectively, compared with that of wild type (WT) plants. Transgenic Arabidopsis plants also showed higher callose and wax deposition in leaves than that of WT. Overexpression of OsLCB2a1 gene in A. thaliana reduced the population size of green peach aphid (Myzus persicae). Moreover, the electrical penetration graph (EPG) results indicated that the aphids encounter resistance factors while reaching for the phloem on the transgenic plants. The defense response genes related to salicylic acid signaling pathway, remained uplgulated in the OsLCB2a1-overexpressing transgenic plants. Our data highlight the key functions of OsLCB2a1 in biotic stress response in plants.

Map-based Cloning and Characterization of the BPH18 Gene from Wild Rice Conferring Resistance to Brown Planthopper (BPH) Insect Pest.

Brown planthopper (BPH) is a phloem sap-sucking insect pest of rice which causes severe yield loss. We cloned the BPH18 gene from the BPH-resistant introgression line derived from the wild rice species Oryza australiensis. Map-based cloning and complementation test revealed that the BPH18 encodes CC-NBS-NBS-LRR protein. BPH18 has two NBS domains, unlike the typical NBS-LRR proteins. The BPH18 promoter::GUS transgenic plants exhibited strong GUS expression in the vascular bundles of the leaf sheath, especially in phloem cells where the BPH attacks. The BPH18 proteins were widely localized to the endo-membranes in a cell, including the endoplasmic reticulum, Golgi apparatus, trans-Golgi network, and prevacuolar compartments, suggesting that BPH18 may recognize the BPH invasion at endo-membranes in phloem cells. Whole genome sequencing of the near-isogenic lines (NILs), NIL-BPH18 and NIL-BPH26, revealed that BPH18 located at the same locus of BPH26. However, these two genes have remarkable sequence differences and the independent NILs showed differential BPH resistance with different expression patterns of plant defense-related genes, indicating that BPH18 and BPH26 are functionally different alleles. These findings would facilitate elucidation of the molecular mechanism of BPH resistance and the identified novel alleles to fast track breeding BPH resistant rice cultivars.