Differential gene expression in gall midge susceptible rice genotypes revealed by suppressive subtraction hybridization (SSH) cDNA libraries and microarray analysis

Comparative Population Biology and Related Gene Expression in the Beta-Cypermethrin-Resistant Strains of Bactrocera dorsalis (Hendel)

Diptera and Lepidoptera species have the highest levels of insecticide resistance, and the mechanism of drug resistance has been studied in detoxification metabolism genes such as P450, GST, EST, and ABC. Since Bactrocera dorsalis are resistant to a variety of chemicals, the pattern and mechanism of resistance in Bactrocera dorsalis have been investigated from a variety of aspects such as detoxification metabolism genes, detoxification enzymes, intestinal symbiotic bacteria, and synergists in the world. In this study, 51 species and 149 detoxification metabolism genes were annotated in the Suppression Subtractive Hybridization (SSH) library, and 12 candidate genes related to beta-cypermethrin resistance were screened and quantitatively expressed in this library. Two genes were found to be upregulated in the egg stage, three genes in the larval stage, one gene in the pupal stage, and five genes in the adult stage, and four genes were found to be upregulated in the midgut and the malacca ducts in the midgut. The expression of cyp6g1, cyp6a22, GST-Epsilon9, and Trypsin-4 genes was upregulated in resistant strains, with the most obvious upregulation occurring in the midgut and the Malpighian tubules. These results provide new insights into the study of pesticide resistance in quarantine insects.

Genome assembly and transcriptomic analysis to elucidate the ability of Nasonovia ribisnigri to break host plant resistance

Aphid genomic resources enable the study of complex life history traits and provide information on vector biology, host adaption and speciation. The currant-lettuce aphid (Nasonovia ribisnigri (Hemiptera: Aphididae) (Mosley)) is a cosmopolitan pest of outdoor lettuce (Lactuca sativa (Asterales: Asteraceae) (Linnaeus)). Until recently, the use of resistant cultivars was an effective method for managing N. ribisnigri. A resistant cultivar containing a single gene (Nr-locus), introduced in the 1980s, conferred complete resistance to feeding. Overreliance of this Nr-locus in lettuce resulted in N. ribisnigri's ability to break resistance mechanism, with first reports during 2003. Our work attempts to understand which candidate gene(s) are associated with this resistance-breaking mechanism. We present two de novo draft assembles for N. ribisnigri genomes, corresponding to both avirulent (Nr-locus susceptible) and virulent (Nr-locus resistant) biotypes. Changes in gene expression of the two N. ribisnigri biotypes were investigated using transcriptomic analyses of RNA-sequencing (RNA-seq) data to understand the potential mechanisms of resistance to the Nr-locus in lettuce. The draft genome assemblies were 94.2% and 91.4% complete for the avirulent and virulent biotypes, respectively. Out of the 18,872 differentially expressed genes, a single gene/locus was identified in N. ribisnigri that was shared between two resistant-breaking biotypes. This locus was further explored and validated in Real-Time Quantitative Reverse Transcription PCR (qRT-PCR) experiments and has predicted localisations in both the cytoplasm and nucleus. This is the first study to provide evidence that a single gene/locus is likely responsible for the ability of N. ribisnigri to overcome the Nr-locus resistance in the lettuce host.

Tissue-specific gene expression shows a cynipid wasp repurposes oak host gene networks to create a complex and novel parasite-specific organ

Every organism on Earth depends on interactions with other organisms to survive. In each of these interactions, an organism must utilize the limited toolbox of genes and proteins it possesses to successfully manipulate or cooperate with another species, but it can also co-opt the genome machinery of its partner to expand its available tools. Insect-induced plant galls are an extreme example of this, wherein an insect hijacks the plant's genome to direct the initiation and development of galls consisting of plant tissue. However, previous transcriptomic studies have not evaluated individual tissues within a gall to determine the full extent to which a galling insect manipulates its host plant. Here we demonstrate that the cynipid wasp Dryocosmus quercuspalustris creates a complex parasite-specific organ from red oak tissue via massive changes in host gene expression. Our results show that the gall wasp is not merely modifying oak leaf tissue but creating extensive changes in gene expression between galled and ungalled tissue (differential expression in 28% of genes) and distinct gall tissue types (20% of genes). The outer gall tissue shows increases in various plant defence systems, which is consistent with its predicted functional role of protecting the wasp larva. The inner larval capsule shows suppression of large parts of the plant innate immune system and evidence for the wasp utilizing the plant's RNA interference mechanisms, which may be a potential mechanism for the wasp's control on gall growth.

Molecular and Histologic Adaptation of Horned Gall Induced by the Aphid Schlechtendalia chinensis (Pemphigidae)

Chinese galls are the result of hyperplasia in host plants induced by aphids. The metabolism and gene expression of these galls are modified to accommodate the aphids. Here, we highlight the molecular and histologic features of horned galls according to transcriptome and anatomical structures. In primary pathways, genes were found to be unevenly shifted and selectively expressed in the galls and leaves near the galls (LNG). Pathways for amino acid synthesis and degradation were also unevenly shifted, favoring enhanced accumulation of essential amino acids in galls for aphids. Although galls enhanced the biosynthesis of glucose, which is directly available to aphids, glucose content in the gall tissues was lower due to the feeding of aphids. Pathways of gall growth were up-regulated to provide enough space for aphids. In addition, the horned gall has specialized branched schizogenous ducts and expanded xylem in the stalk, which provide a broader feeding surface for aphids and improve the efficiency of transportation and nutrient exchange. Notably, the gene expression in the LNG showed a similar pattern to that of the galls, but on a smaller scale. We suppose the aphids manipulate galls to their advantage, and galls lessen competition by functioning as a medium between the aphids and their host plants.

Genetic analysis and fine mapping of the gall midge resistance gene Gm5 in rice (Oryza sativa L.)

The rice gall midge resistance gene, Gm5, confers remarkable antibiosis and is located in the same region on chromosome 12 in three different rice varieties. Fine mapping narrowed this region to a 49-kb segment and identified two candidate genes showing remarkable response to GM infestation. The Asian rice gall midge (GM; Orseolia oryzae; Diptera: Cecidomyiidae) invades rice shoots and forms galls, adversely affecting plant growth and yield production. Thus, the development of resistant varieties through the identification, mapping, and application of GM resistance genes is considered the most efficient strategy for managing this insect. Here, a GM resistance survey of F₂ populations derived from intercrosses between resistant rice varieties 'ARC5984,' '570011,' and 'ARC5833' indicated that the resistance gene Gm5 was located on the same chromosomal region in the three varieties. For the initial mapping, three independent F₂ mapping populations were developed for the three resistant varieties, and the Gm5 gene was consistently mapped to the same chromosomal region near marker 12M22.6. Fine mapping, which was conducted using the BC₁F₂ and BC₂F₂ populations derived from the 9311/ARC5984 cross, narrowed the Gm5 gene region to a 49-kb segment flanked by the markers Z57 and Z64. In the final mapped region, we detected 10 candidate genes, of which six were analyzed for their relative expression. Consequently, two of these genes, Os12g36830 and Os12g36880, showed significantly higher expression in GM-resistant plants than in GM-susceptible plants at 24 and 72 h after GM infestation. Finally, the PCR amplification of markers 12M22.5 and 12M22.6 yielded clear single bands, and these markers were effectively applied for the marker-assisted selection (MAS) of the Gm5 gene. With the developed MAS markers, the fine mapping of this resistance gene will facilitate its map-based cloning and incorporation into insect-resistant rice varieties through breeding.

Cytokinins Are Abundant and Widespread Among Insect Species

Cytokinins (CKs) are a class of compounds that have long been thought to be exclusively plant growth regulators. Interestingly, some species of phytopathogenic bacteria and fungi have been shown to, and gall-inducing insects have been hypothesized to, produce CKs and use them to manipulate their host plants. We used high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-MS/MS) to examine concentrations of a wide range of CKs in 17 species of phytophagous insects, including gall- and non-gall-inducing species from all six orders of Insecta that contain species known to induce galls: Thysanoptera, Hemiptera, Lepidoptera, Coleoptera, Diptera, and Hymenoptera. We found CKs in all six orders of insects, and they were not associated exclusively with gall-inducing species. We detected 24 different CK analytes, varying in their chemical structure and biological activity. Isoprenoid precursor nucleotide and riboside forms of trans-zeatin (tZ) and isopentenyladenine (iP) were most abundant and widespread across the surveyed insect species. Notably, the observed concentrations of CKs often markedly exceeded those reported in plants suggesting that insects are synthesizing CKs rather than obtaining them from the host plant via tissue consumption, compound sequestration, and bioaccumulation. These findings support insect-derived CKs as means for gall-inducing insects to manipulate their host plant to facilitate cell proliferation, and for both gall- and non-gall-inducing insects to modify nutrient flux and plant defenses during herbivory. Furthermore, wide distribution of CKs across phytophagous insects, including non-gall-inducing species, suggests that insect-borne CKs could be involved in manipulation of source-sink mechanisms of nutrient allocation to sustain the feeding site and altering plant defensive responses, rather than solely gall induction. Given the absence of any evidence for genes in the de novo CK biosynthesis pathway in insects, we postulate that the tRNA-ipt pathway is responsible for CK production. However, the unusually high concentrations of CKs in insects, and the tendency toward dominance of their CK profiles by tZ and iP suggest that the tRNA-ipt pathway functions differently and substantially more efficiently in insects than in plants.

Genomics of the Asian rice gall midge and its interactions with rice

Understanding virulence and manipulative strategies of gall formers will reveal new facets of plant defense and insect counter defense. Among the gall midges, the Asian rice gall midge (AGM) has emerged as a model for studies on plant-insect interactions. Data from several genomics, transcriptomics and metabolomics studies have revealed diverse strategies adopted by AGM to successfully invade the host while overcoming its defense. Adaptive skills of AGM transcend from its genomic and transcriptomic make-up. Information arising from studies on genetics, mitochondrial genome and miRNAs, amongst other parameters, highlights AGM's capacity to maneuver the host defense, reorient host metabolome and redirect its morphogenesis.

Metabolic and transcriptomic changes induced in host during hypersensitive response mediated resistance in rice against the Asian rice gall midge

BACKGROUND

An incompatible interaction between rice (Oryza sativa) and the Asian rice gall midge (AGM, Orseolia oryzae Wood-Mason), that is usually manifested through a hypersensitive response (HR), represents an intricate relationship between the resistant host and its avirulent pest. We investigated changes in the transcriptome and metabolome of the host (indica rice variety: RP2068-18-3-5, RP), showing HR when attacked by an avirulent gall midge biotype (GMB1), to deduce molecular and biochemical bases of such a complex interaction. Till now, such an integrated analysis of host transcriptome and metabolome has not been reported for any rice-insect interaction.

RESULTS

Transcript and metabolic profiling data revealed more than 7000 differentially expressed genes and 80 differentially accumulated metabolites, respectively, in the resistant host. Microarray data revealed deregulation of carbon (C) and nitrogen (N) metabolism causing a C/N shift; up-regulation of tetrapyrrole synthesis and down-regulation of chlorophyll synthesis and photosynthesis. Integrated results revealed that genes involved in lipid peroxidation (LPO) were up-regulated and a marker metabolite for LPO (azelaic acid) accumulated during HR. This coincided with a greater accumulation of GABA (neurotransmitter and an insect antifeedant) at the feeding site. Validation of microarray results by semi-quantitative RT-PCR revealed temporal variation in gene expression profiles.

CONCLUSIONS

The study revealed extensive reprogramming of the transcriptome and metabolome of RP upon GMB1 infestation leading to an HR that was induced by the generation and release of reactive oxygen species i.e. singlet oxygen and resulted in LPO-mediated cell death. RP thus used HR as a means to limit nutrient supply to the feeding maggots and simultaneously accumulated GABA, strategies that could have led to maggot mortality. The integrated results of transcript and metabolic profiling, for the first time, provided insights into an HR+ type of resistance in rice against gall midge.

Insect Gallers and Their Plant Hosts: From Omics Data to Systems Biology

Gall-inducing insects are capable of exerting a high level of control over their hosts' cellular machinery to the extent that the plant's development, metabolism, chemistry, and physiology are all altered in favour of the insect. Many gallers are devastating pests in global agriculture and the limited understanding of their relationship with their hosts prevents the development of robust management strategies. Omics technologies are proving to be important tools in elucidating the mechanisms involved in the interaction as they facilitate analysis of plant hosts and insect effectors for which little or no prior knowledge exists. In this review, we examine the mechanisms behind insect gall development using evidence from omics-level approaches. The secretion of effector proteins and induced phytohormonal imbalances are highlighted as likely mechanisms involved in gall development. However, understanding how these components function within the system is far from complete and a number of questions need to be answered before this information can be used in the development of strategies to engineer or breed plants with enhanced resistance.

Rice-gall midge interactions: Battle for survival

Gall midges are insects specialized in maneuvering plant growth, metabolic and defense pathways for their benefit. The Asian rice gall midge and rice share such an intimate relationship that there is a constant battle for survival by either partner. Diverse responses by the rice host against the midge include necrotic hypersensitive resistance reaction, non-hypersensitive resistance reaction and gall-forming compatible interaction. Genetic studies have revealed that major R (resistance) genes confer resistance to gall midge in rice. Eleven gall midge R genes have been characterized so far in different rice varieties in India. In addition, no single R gene confers resistance against all the seven biotypes of the Asian rice gall midge, and none of the biotypes is virulent against all the resistance genes. Further, the interaction of the plant resistance gene with the insect avirulence gene is on a gene-for-gene basis. Our recent investigations involving suppressive subtraction hybridization cDNA libraries, microarray analyses, gene expression assays and metabolic profiling have revealed several molecular mechanisms, metabolite markers and pathways that are induced, down-regulated or altered in the rice host during incompatible or compatible interactions with the pest. This is also true for some of the pathways studied in the gall midge. Next generation sequencing technology, gene expression studies and conventional screening of gall midge cDNA libraries highlighted molecular approaches adopted by the insect to feed, survive and reproduce. This constant struggle by the midge to overcome the host defenses and the host to resist the pest has provided us with an opportunity to observe this battle for survival at the molecular level.

The transcriptional landscape of insect galls: psyllid (Hemiptera) gall formation in Hawaiian Metrosideros polymorpha (Myrtaceae)

BACKGROUND

Recent studies show that galling Hymenoptera and Diptera are able to synthesize the plant hormone indole-3-acetic acid (auxin) from tryptophan and that plant response to insect-produced auxin is implicated in gall formation. We examined the leaf transcriptome of galled and ungalled leaves of individuals of the Hawaiian endemic plant Metrosideros polymorpha (Myrtaceae) subject to infestation by psyllid (Hemiptera) gall-makers in the genus Trioza (Triozidae).

RESULTS

Transcript libraries were sequenced using Illumina technology and the reads assembled de novo into contigs. Functional identification of contigs followed a two-step procedure, first identifying contigs by comparison to the completely sequenced genome of the related Eucalyptus, followed by identifying the equivalent Arabidopsis gene using a pre-computed mapping between Eucalyptus and Arabidopsis genes. This allowed us to use the rich functional annotation of the Arabidopsis genome to assess the transcriptional landscape of galling in Metrosideros. Comparing galled and ungalled leaves, we find a highly significant enrichment of expressed genes with a gene ontology (GO) annotation to auxin response in the former. One gene consistently expressed in all galled trees examined but not detected in any libraries from ungalled leaves was the Metrosideros version of SMALL AUXIN UPREGULATED (SAUR) 67 which appears to be a marker for leaf-galling in Metrosideros.

CONCLUSIONS

We conclude that an auxin response is involved in galling by Metrosideros psyllids. The possibility should therefore be considered that psyllids (like other insects examined) are able to synthesize auxin.

Comprehensive meta-analysis, co-expression, and miRNA nested network analysis identifies gene candidates in citrus against Huanglongbing disease

BACKGROUND

Huanglongbing (HLB), the most devastating disease of citrus, is associated with infection by Candidatus Liberibacter asiaticus (CaLas) and is vectored by the Asian citrus psyllid (ACP). Recently, the molecular basis of citrus-HLB interactions has been examined using transcriptome analyses, and these analyses have identified many probe sets and pathways modulated by CaLas infection among different citrus cultivars. However, lack of consistency among reported findings indicates that an integrative approach is needed. This study was designed to identify the candidate probe sets in citrus-HLB interactions using meta-analysis and gene co-expression network modelling.

RESULTS

Twenty-two publically available transcriptome studies on citrus-HLB interactions, comprising 18 susceptible (S) datasets and four resistant (R) datasets, were investigated using Limma and RankProd methods of meta-analysis. A combined list of 7,412 differentially expressed probe sets was generated using a Teradata in-house Structured Query Language (SQL) script. We identified the 65 most common probe sets modulated in HLB disease among different tissues from the S and R datasets. Gene ontology analysis of these probe sets suggested that carbohydrate metabolism, nutrient transport, and biotic stress were the core pathways that were modulated in citrus by CaLas infection and HLB development. We also identified R-specific probe sets, which encoded leucine-rich repeat proteins, chitinase, constitutive disease resistance (CDR), miraculins, and lectins. Weighted gene co-expression network analysis (WGCNA) was conducted on 3,499 probe sets, and 21 modules with major hub probe sets were identified. Further, a miRNA nested network was created to examine gene regulation of the 3,499 target probe sets. Results suggest that csi-miR167 and csi-miR396 could affect ion transporters and defence response pathways, respectively.

CONCLUSION

Most of the potential candidate hub probe sets were co-expressed with gibberellin pathway (GA)-related probe sets, implying the role of GA signalling in HLB resistance. Our findings contribute to the integration of existing citrus-HLB transcriptome data that will help to elucidate the holistic picture of the citrus-HLB interaction. The citrus probe sets identified in this analysis signify a robust set of HLB-responsive candidates that are useful for further validation.

The Transcriptome and Terpene Profile of Eucalyptus grandis Reveals Mechanisms of Defense Against the Insect Pest, Leptocybe invasa

Plants have evolved complex defenses that allow them to protect themselves against pests and pathogens. However, there is relatively little information regarding the Eucalyptus defensome. Leptocybe invasa is one of the most damaging pests in global Eucalyptus forestry, and essentially nothing is known regarding the molecular mechanisms governing the interaction between the pest and host. The aim of the study was to investigate changes in the transcriptional landscape and terpene profile of a resistant and susceptible Eucalyptus genotype in an effort to improve our understanding of this interaction. We used RNA-seqencing to investigate transcriptional changes following L. invasa oviposition. Expression levels were validated using real-time quantitative PCR. Terpene profiles were investigated using gas chromatography coupled to mass spectometry on uninfested and oviposited leaves. We found 698 and 1,115 significantly differentially expressed genes from the resistant and susceptible interactions, respectively. Gene Ontology enrichment and Mapman analyses identified putative defense mechanisms including cell wall reinforcement, protease inhibitors, cell cycle suppression and regulatory hormone signaling pathways. There were significant differences in the mono- and sesquiterpene profiles between genotypes and between control and infested material. A model of the interaction between Eucalyptus and L. invasa was proposed from the transcriptomic and chemical data.

Insect effectors and gene-for-gene interactions with host plants

Within the context of the four-phase model of plant immunity, gene-for-gene interactions have gained new relevance. Genes conferring resistance to the Asian rice gall midge (Orseolia oryzae) and the small brown planthopper (Nilaparvata lugens) have been cloned in rice (Oryza sativa). Mutations in insect avirulence genes that defeat plant resistance have been identified and cloned. Results are consistent with both the gene-for-gene hypothesis and the new model of plant immunity. Insect resistance genes encode proteins with nucleotide binding sites and leucine-rich repeats. Insects use effectors that elicit effector-triggered immunity. At least seven-percent of Hessian fly genes are effector encoding.

The imbalance of redox homeostasis in arthropod-induced plant galls: Mechanisms of stress generation and dissipation

BACKGROUND

Galls have specialized tissues for the protection and nutrition of the inducers, and these tissues have been studied from the developmental and histochemical perspectives. Recently, the role of oxidative stress in galls has been tested histochemically through detection of H2O2 in gall tissues.

SCOPE OF REVIEW

Developmental processes and cytological events are revisited from the perspective of the redox-potential balance in both the apoplast and symplast, especially concerning the accumulation of reactive oxygen species (ROS).

MAJOR CONCLUSIONS

The redox potential is imbalanced differently in the apoplast and symplast at gall sites, with the apoplast having lower antioxidant-buffering capacity than the symplast. The strategies to recover redox-potential homeostasis involve the dissipation of ROS by scavenging molecules, such as phenolics, flavonoid derivatives, tocopherol, and enzyme systems.

GENERAL SIGNIFICANCE

Insect galls are good models to test developmental hypotheses. Although the exact mechanisms of gall induction and development have not been elucidated at the biochemical and biophysical levels, modulation of the redox potential is involved in the crucial steps of gall initiation and establishment. This article is part of a Special Issue entitled Redox regulation of differentiation and de-differentiation.

Gas chromatography mass spectrometry based metabolic profiling reveals biomarkers involved in rice-gall midge interactions

The Asian rice gall midge (Orseolia oryzae Wood-Mason) is a serious pest of rice that causes huge loss in yield. While feeding inside the susceptible host, maggots secrete substances that facilitate the formation of a hollow tube-like structure called gall and prevent panicle formation. The present investigation was carried out to get an account of biochemical changes occurring in the rice plant upon gall midge feeding. Metabolic profiling of host tissues from three rice varieties, namely, TN1, Kavya, and RP2068, exposed to gall midge biotype 1 (GMB1), was carried out using gas chromatography mass spectrometry (GC-MS). TN1 and GMB1 represented compatible interaction, while Kavya and GMB1 as well as RP2068 and GMB1 represented incompatible interactions. The current study identified several metabolites that could be grouped as resistance, susceptibility, infestation, and host features based on their relative abundance. These may be regarded as biomarkers for insect-plant interaction in general and rice-gall midge interaction in particular.

Quantitative trait loci identification, fine mapping and gene expression profiling for ovicidal response to whitebacked planthopper (Sogatella furcifera Horvath) in rice (Oryza sativa L.)

BACKGROUND

The whitebacked planthopper (WBPH), Sogatella furcifera Horváth, is a serious rice pest in Asia. Ovicidal resistance is a natural rice defense mechanism against WBPH and is characterized by the formation of watery lesions (WLs) and increased egg mortality (EM) at the WBPH oviposition sites.

RESULTS

This study aimed to understand the genetic and molecular basis of rice ovicidal resistance to WBPH by combining genetic and genomic analyses. First, the ovicidal trait in doubled haploid rice lines derived from a WBPH-resistant cultivar (CJ06) and a WBPH-susceptible cultivar (TN1) were phenotyped based on the necrotic symptoms of the leaf sheaths and EM. Using a constructed molecular linkage map, 19 quantitative trait loci (QTLs) associated with WLs and EM were identified on eight chromosomes. Of them, qWL6 was determined to be a major QTL for WL. Based on chromosome segment substitution lines and a residual heterozygous population, a high-resolution linkage analysis further defined the qWL6 locus to a 122-kb region on chromosome 6, which was annotated to encode 20 candidate genes. We then conducted an Affymetrix microarray analysis to determine the transcript abundance in the CJ06 and TN1 plants. Upon WBPH infestation, 432 genes in CJ06 and 257 genes in TN1 were significantly up-regulated, while 802 genes in CJ06 and 398 genes in TN1 were significantly down-regulated. This suggests that remarkable global changes in gene expression contribute to the ovicidal resistance of rice. Notably, four genes in the 122-kb region of the qWL6 locus were differentially regulated between CJ06 and TN1 in response to the WBPH infestation, suggesting they may be candidate resistance genes.

CONCLUSIONS

The information obtained from the fine mapping of qWL6 and the microarray analyses will facilitate the isolation of this important resistance gene and its use in breeding WBPH-resistant rice.

Suppressive subtraction hybridization reveals that rice gall midge attack elicits plant-pathogen-like responses in rice

The Asian rice gall midge, Orseolia oryzae (Diptera: Cecidomyiidae), is the third most destructive insect pest of rice (Oryza sativa L.). Till date, 11 gall midge resistance gene loci have been characterized in different rice varieties. To elucidate molecular basis of incompatible (hypersensitive response plus [HR+] type) and compatible rice-gall midge interactions, two suppressive subtraction hybridization cDNA libraries were constructed. These were enriched for differentially expressed transcripts after gall midge infestation in two rice varieties (resistant Suraksha and susceptible TN1). In total, 2784 ESTs were generated and sequenced from the two libraries, of which 1536 were from the resistant Suraksha and 1248 were from the susceptible TN1. Majority (80%) of the ESTs was non-redundant sequences with known functions and was classified into three principal gene ontology (GO) categories and 12 groups. Upregulation of NBS-LRR, Cytochrome P450, heat shock proteins, phenylalanine ammonia lyase and OsPR10α genes from the Suraksha library, as revealed by real-time PCR, indicated that R gene mediated, salicylic acid related defense pathway is likely to be involved in gall midge resistance. Present study suggested that resistance in Suraksha against gall midge is similar in nature to the resistance observed in plants against pathogens. However, in TN1, genes related to primary metabolism and redox were induced abundantly. Results suggested that genes encoding translationally controlled tumor protein and NAC domain proteins are likely to be involved in the gall midge susceptibility.