Borer Resistance Research Articles

Unraveling the proteomic changes involved in the resistance response of Cajanus platycarpus to herbivory by Helicoverpa armigera.

The pigeonpea wild relative Cajanus platycarpus is resistant to Helicoverpa armigera, one of the major pests responsible for yield losses in Cajanus cajan. Deciphering the molecular mechanism underlying host plant resistance is pertinent to identify proteins that aid in the mitigation of the insect pest. The present study adopted comparative proteomics as a tool to interpret the resistance mechanism(s) in C. platycarpus vis-à-vis C. cajan during continued herbivory (up to 96 h). Over-representation analysis of the differentially expressed proteins implicated a multi-dimensional resistance response accomplished by both physical and chemical barriers in C. platycarpus. While the chemical basis for resistance was depicted by the upregulation of proteins playing a rate limiting role in the phenylpropanoid pathway, the physical basis was provided by the regulation of proteins involved in microtubule assembly and synthesis of lignins. Upregulation of proteins in the polyamine pathway indicated the role of metabolite conjugates to be negatively affecting herbivore growth. Reallocation of resources and diversion of metabolic flux to support the production of secondary metabolites could be the probable approach in the wild relative against herbivory. Our study provided deeper insights into the pod borer resistance mechanism in C. platycarpus for utility in crop improvement. KEY POINTS: • Pod borer resistance in Cajanus platycarpus is multi-dimensional. • Pod borer resistance has been arbitrated to cell wall rigidity and secondary metabolites. • Phenylpropanoid pathway derivatives apparently shaped the plant chemical defense against pod borer.

Convergent molecular evolution among ash species resistant to the emerald ash borer.

Recent studies show that molecular convergence plays an unexpectedly common role in the evolution of convergent phenotypes. We exploited this phenomenon to find candidate loci underlying resistance to the emerald ash borer (EAB; Agrilus planipennis), the USA’s most costly invasive forest insect to date, within the pan-genome of ash trees (the genus Fraxinus). We show that EAB-resistant taxa occur within three independent phylogenetic lineages. In genomes from these resistant lineages, we detect 53 genes with evidence of convergent amino acid evolution. Gene tree reconstruction indicates that for 48 of these candidates, the convergent amino acids are more likely to have arisen via independent evolution than by another process, such as hybridisation or incomplete lineage sorting. Seven of the candidate genes have putative roles connected to the phenylpropanoid biosynthesis pathway and 17 relate to herbivore recognition, defence signalling or programmed cell death. Evidence for loss-of-function mutations among these candidates is more frequent in susceptible species, than in resistant ones. Our results on evolutionary relationships, variability in resistance, and candidate genes for defence response within the ash genus could inform breeding for EAB resistance, facilitating ecological restoration in areas this beetle has invaded.

Screening and characterization of molecular markers for sugarcane (Saccharum officinarum L.) resistance to shoot borer pest

Sugarcane (Saccharum officinarum L.) is one of the main crops in Indonesia and is known as a sugar-producing plant. Sugar belongs to one of the 9 essential culinary ingredients in Indonesia. With the high demand for sugar the government in 2017 imported 109,147 tons of sugar or equivalent to IDR 823.8 billion to fulfill the demand. Efforts to increase sugarcane productivity are often constrained by complex pests that attack sugarcane shoots. One way to overcome it is to breed plant varieties that are resistant and of good quality. The purposes of the present study were to screen sugarcane shoot borer resistance gene using the molecular marker SacMPI-Like 3, to determine the phylogenetic relationship between MPI in sugarcane with other species in the family Andropogenae, and to determine the most effective molecular markers for detecting MPI. The primer was designed by using Primer3 Plus. DNA samples of 22 sugarcane varieties derived from the Genetics and Breeding Laboratory, Biology Faculty of Gadjah Mada University were PCR-amplified using 3 selected primer designs. Results showed that all of the 22 samples of sugarcane DNA contained SacMPI-Like 3 ranged from 500 to 600 bp. Some of the samples were sequenced to obtain the arrangement of nucleotide bases for comparison with samples from the NCBI GeneBank. The phylogenetic tree analysis showed that 3 large clusters were formed depended on the presence of MPI. The first cluster consisted of SacMPI1_PS_58, SacMPI1_PS_951, SacMPI2_PS_384, SacMPI2_PS_951, SacMPI3_PS_851, SacMPI3_PS_951, CA282462.1_SHC (Saccharum officinarum L.), XR002447315.1_ SB, XR002447314.1_SB (Sorghum bicolor), XR003227569.1 PH, XR003227568.1_PH (Panicum hallii) EU972719.1_ZM, NM001158424.2_ZM, EU960955.1_ZM, and EU951995.1_ZM (Zea mays). The second cluster consisted of XM024458314.1_BD (Brachypodium distachyon), CT827984.1_OZ, and XM026021872.1_OZ (Oryza sativa).

Genetic parameters and selection of sugarcane for borer resistance in the advanced selection stage

Abstract This study aimed to investigate genetic parameters and selection strategies for sugarcane resistance to borer and determine the effects of selection for borer resistance on yield traits. The infestation index by borer (IIB) and yield traits were assessed over 3 years in 35 sugarcane clones planted in four locations in southeastern Brazil. There was no genotype × environment (year or location) interaction for borer resistance. Consequently, selection may be performed at only one location and year or by the mean of clones in several locations and/or years. The borer population affected the genotypic variance for borer resistance but when genotypic variance was significant, heritability was elevated and suitable genetic gain was achieved. Selection for borer resistance reduced the genetic gains for tons of cane per hectare, theoretical recoverable sugar, and tons of sugar per hectare; however, satisfactory selection gains for both borer resistance and yield were achieved using selection index.

Evaluation of morpho-molecular diversity and pod borer resistance in country bean

Evaluation of morpho-molecular diversity and pod borer resistance in country bean

Evaluation of Susceptibility of Some Sorghum (Sorghum bicolor L. Moench) to Stem Borers in Far North Region of Cameroon: A Case of Off Season Local Varieties

Introduction: Among cereals, Sorghum is the most consumed as food in the Far North of Cameroon. Muskuwari, which is an off season sorghum, plays a key role in the regulation of its availability. On the other hand, stem borers (Sesamia cretica Lederer) constitute a major constraint, compromise its yield and reduce cereal supply. Despite this fact, ecological control measures to reduce losses are still little known.
 Objective: The present research aimed at evaluating the susceptibility of ten local varieties of Muskuwari against Lepidoptera stem borers in natural conditions.
 Place and Duration of Study: The study was conducted during the 2012 and 2013 agricultural campaign at Ngassa, a locality of Maroua.
 Methodology: Experimentation was carried out in a Completely Randomized Block design with tree replications. Ten local varieties were then under natural infestations. Degrees of infestation were estimated by visual observation and destructive methods. Each year, Seed losses in term of percentage of total harvest loosed, were estimated from 30 ears per variety randomly selected from infested and uninfected plants.
 Results: The results showed a large variation in agronomic performance depending on the parameters considered. Mandouéri, Bourgouri, Tchangalari and Soukatari with infestation rates ranging from 4% to 11% and seed losses ranging from 0.96% to 23.42% are more tolerant or less susceptible than other varieties while Safra’s varieties are always the most susceptible to stem borers with over to 40% seed loss.
 Conclusion: The study showed there are resistant or tolerant varieties of Muskuwari able to cope with the attacks of stem borers not exploited to mitigate damages. Degree of infestation, seed loss, number of caterpillars and gallery length per plant are suitable parameters for varietal screening of stem borer resistance. Since varietal resistance is an ecological and easily adoptable option, investigations that could lead to Muskuwari varietal improvement could boost cereal supplly in the Far North Region of Cameroon.

Efficiency of Index-Based Selection Methods for Stem Borer Resistance in Maize (Zea mays L.)

Breeders need a simple and reliable index that could be used to make selection quickly in a breeding program. A study was conducted at the International Institute of Tropical Agriculture, Nigeria, to compare efficiency of four selection indices in selecting the best genotypes in a population improvement program involving a yellow-grained (DMR ESR-Y) and white-grained (DMR ESR-W) maize (Zea mays L.) population under artificial stem borer infestation. Rank summation index (RSI), Base index (BSI), Multiplicative index (MI), and Optimum index that uses heritability as weight (OI) were compared using grain yield, plant aspect, ear aspect, stalk breakage, and tolerance to stem borer as selection criteria. The selection criteria had moderate to high narrow-sense heritability. Each of the traits had a significant correlation with all selection indices, except MI in DMR ESR-Y. The BSI had the highest selection differential (23.32%) followed by OI (21.45%) in the white maize population. It also had the highest (29.11%) followed by RSI (20.99%) in the yellow maize population. The BSI also had strongest correlation with RSI in the white (−0.95**) and the yellow maize population (−0.90**). Percentage similarity was highest between BSI and RSI in the white (82.6%) and yellow maize populations (72.3%). This suggested that both BSI and RSI are good selection indices that could be used in improvement programs for stem borer resistance in maize.

Inheritance of resistance traits to African stem borer in grain sorghum

The African stem borer (Busseola fusca [Fuller]) is an important insect pest of cereals, mainly maize, sorghum and millets. The pest causes up to 80% reduction in grain yield, depending on the pest population in the field, cultivar and the management practices employed. This reduction in yield translates into food insecurity, especially in semi-arid lands (ASALs) where sorghum is cultivated by small holder farmers. This study investigated the inheritance of resistance traits to the African stem borers in grain sorghum in Kenya. The experimental material consisted of seventeen sorghum lines with varying levels of resistance to the African stem borer. The mating design employed was North Calorina Design 2, where 15 sorghum lines were used as females on two males. The crosses were evaluated in two seasons at University of Embu farm in 2011/2012 short and long seasons replicated twice. Artificial infestation with African stem borer neonates was done 30 days after planting using a camel brush. Data collected included stem borer damage and agro-morphological traits. Genetic analyses were performed using a line x tester method using Genstat statistical software. It was found that both additive and non-additive gene effects were important in conditioning resistance traits to the African stem borer. This implies that expression of high leaf glossiness, plant vigour and bloom waxiness in F1 hybrids is conditioned by additive genes and these traits can be used as morphological markers to select for resistance to the borer in sorghum. ICSB 464 x ICSB 473 was the best combiner for stem borer resistance and grain yield. Parents ICSA 464, ICSB 464 and ICSB 474, were among the good combiners for resistance to the stem borer. These parents can be utilised in developing superior sorghum hybrids resistant to the insect pest.Key words: Gene action, heritability, Sorghum bicolor

Evolution of Asian Corn Borer Resistance to Bt Toxins Used Singly or in Pairs.

Transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt) have revolutionized pest control, but the benefits of this approach have been reduced by the evolution of resistance in pests. The widely adopted ’pyramid strategy’ for delaying resistance entails transgenic crops producing two or more distinct toxins that kill the same pest. The limited experimental evidence supporting this strategy comes primarily from a model system under ideal conditions. Here we tested the pyramid strategy under nearly worst-case conditions, including some cross-resistance between the toxins in the pyramid. In a laboratory selection experiment with an artificial diet, we used Bt toxins Cry1Ab, Cry1F, and Cry1Ie singly or in pairs against Ostrinia furnacalis, one of the most destructive pests of corn in Asia. Under the conditions evaluated, pairs of toxins did not consistently delay the evolution of resistance relative to single toxins.

Genetic parameters and selection of sugarcane in early selection stages for resistance to sugarcane borer Diatraea saccharalis

Abstract A T1 (sugarcane population originating from true seeds) and T2 (first sugarcane clonal stage) population were used to estimate genetic parameters and compare selection strategies for Diatraea saccharalis (Lepidoptera: Crambidae) resistance in sugarcane. In the T1 stage, heritability at the family mean level (h²=0.77) was higher than individual genotype heritability (h²=0.16), and the additive genetic effect was more important for sugarcane borer resistance than non-additive effects. In addition, there was high genotypic variance among and within full-sib families. In the T2 population, genotypic variance was high, and heritability at the clone mean level was moderate (h²=0.61). We can conclude that family experiments enable selection of more promising families and parents for borer resistance. However, due to high genotypic variance within families, family selection at the T1 stage must be followed by clone selection at the T2 stage.

Gene action conditioning resistance traits to spotted stem borer, Chilo partellus, in grain sorghum

Understanding the mode of gene action conditioning traits of interest in sorghum is important for effective and efficient plant breeding programs. The objective of this study was to establish the nature of gene action for components that contribute to resistance to spotted stem borer, Chilo partellus, in grain sorghum. The experimental material consisted of seventeen sorghum lines with varying levels of resistance to C. partellus. Genetic analyses were performed using a line x tester method using Genstat statistical software. There was significant variation among the F1 for C. partellus resistance and grain yield. The general combining ability (GCA) for deadheart damage was significant (P ≤ 0.01) implying that this trait was governed by an additive type of gene action. Specific combining ability (SCA) for exit holes and stem tunneling were significant (P ≤ 0.01) suggesting that these characters were conditioned by both additive and non-additive types of gene action. Lines ICSA 472, ICSA 464, ICSB 474 contributed high levels of resistance to hybrids while IESV 93042 SH, IS 21879 and IESV 91131 DL were good sources of genes for high grain yield. This observation implied that grain yield and stem borer resistance traits should be considered in development of C. partellus resistant sorghum since a resistant line doesn’t necessarily yield high and vice versa. Generally, results of this study indicated that it would be possible to breed for high C. partellus resistance from this set of germplasm for cultivation by farmers in areas where the insect pest causes epidemics.

Variability in Morpho-biochemical Traits Associated with Pod Borer (Helicoverpa armigera) Resistance in Pigeonpea Pods

Pigeonpea contributes to food and nutrition security among poor households in urban and rural areas. Globally it is characterized by stagnant and unstable yield due to its susceptibility to various stresses including the pod borer (Helicoverpa armigera) which causes substantial damage to the crop and may result in absolute economic yield loss. The existing cultivated pigeonpea are susceptible to pod borer with only a few genotypes reported to be tolerant based on pod and seed damage. Limited information is available on morphological and biochemical traits associated with pod borer resistance among the existing genotypes. This study was therefore carried out to identify diversified sources of resistance against pod borer damage. The study was set up to assess traits that may contribute to pod borer resistance among 12 selected elite pigeonpea genotypes in three replicates and means were separated based on LSD test using Genstat software. The field study was carried out in Kerio Valley during the long rains of April-September of 2017. The genotypes varied significantly for all the parameters measured at P≤0.05 with a mean of 608.33 g/100 g (crude protein), 175.61 mg/100 g (total phenol), 19.85 mg/100 g (total flavonoid), 0.448 mm (trichome length), 210.6 / 4 mm2(trichome density) and 0.353 mm(depth of locules). Significant negative correlation was also observed between total phenol, total flavonoid, depth of locules, trichome length and trichome density with pod damage. However, a positive correlation was recorded between crude proteins with pod damage. These results reveal that, host plant resistance is an association of several morphological and biochemical traits. Therefore, these genotypes with elevated levels can be selected and utilized in breeding towards improving resistance to pod borer in pigeonpea.

Assessment of phenotypic and genetic variation against pod borer among a subset of elite pigeonpea (Cajanus cajan) genotypes in Kenya

Molecular marker information supported by quality morphological data facilitates the choice of suitable parents for applied breeding. The main aim of this study was to assess genetic diversity among 55 cultivated yield elite pigeonpea lines using 21 simple sequence repeat (SSR) markers that are well distributed across the genome. Among the 55 pigeonpea genotypes, 16 medium duration were selected and evaluated in the field for response to pod borer resistance in varied agro-ecological zones of Kenya during long rains of April-October cropping season Twenty one primer pairs detected 80 alleles with a mean of 3.9 alleles per locus and polymorphism information content (PIC) ranging from 0.09 to 0.75 averaging to 0.39 suggesting a low genetic diversity. However, marker CcM1820 revealed the highest number of alleles (9) with a PIC value of 0.75. The genotype response to pod borer attack was significant (P<=0.05) with three genotypes (ICEAPs 01541, 01154-2 and 00902) revealing tolerance to pod borer. The markers based on Neighbor Joining, grouped the 55 genotypes into three main clusters based on parentage selection. Most genotypes developed from ICEAP 00068 as the maternal parent were grouped in Cluster I while cluster II comprised of improved genotypes and cluster III comprised genotypes developed from ICPL 87091 as maternal parent. The resistant genotypes identified in the field experiment were grouped in cluster I except ICEAP 00902 which grouped in cluster II. Future studies should focus on broadening genetic base by including more landraces and wild relatives to maximize selection and improve breeding work.

Improved method of screening maize germplasm for resistance against Chilo partellus (Swinhoe)

Thirty diverse maize genotypes were evaluated by infesting them artificially by stem borer, Chilo partellus under field conditions during Kharif, 2014 at ICAR-Indian Institute of Maize Research, Pusa Campus, New Delhi and observed for their reaction. The stem borer infestation was measured in terms of leaf injury rating (LIR), dead hearts and stem tunneling. The damage by C. partellus revealed significant differences among the genotypes in respect of all the three traits measured. The leaf injury rating ranged from 2.16 in PFSR51016/1 to 8.74 in HKI 1352. The genotype WNZPBTL2 recorded minimum (14.03 per cent) dead hearts while the genotypes HKI 1378 recorded maximum (55.94 per cent) dead hearts. The larval feeding inside the stem resulted in minimum stem tunneling in WNZPBTL2 and maximum in Basi local i.e. 13.75 and 44.75 per cent respectively. The correlations among damage parameters revealed significant positive association of leaf injury with dead hearts and stem tunneling. Thus these traits proved to be visual indicators of stem borer resistance. A selection index was constructed Division of Entomology, Indian Agricultural Research Institute, New Delhi 110012 India based on LIR and percent stem tunneling for selecting the best genotypes in the test population. The selection index led to the identification of WNZPBTL2 and PFSR 51016/1 as the resistance sources for C. partellus.

Foreign cry1Ac gene integration and endogenous borer stress-related genes synergistically improve insect resistance in sugarcane

BackgroundSugarcane (Saccharum spp. hybrids) is considered the most globally important sugar-producing crop and raw material for biofuel. Insect attack is a major issue in sugarcane cultivation, resulting in yield losses and sucrose content reductions. Stem borer (Diatraea saccharalis F.) causes serious yield losses in sugarcane worldwide. However, insect-resistant germplasms for sugarcane are not available in any collections all over the world, and the molecular mechanism of insect resistance has not been elucidated. In this study, cry1Ac transgenic sugarcane lines were obtained and the biological characteristics and transgene dosage effect were investigated and a global exploration of gene expression by transcriptome analysis was performed.ResultsThe transgene copies of foreign cry1Ac were variable and random. The correlation between the cry1Ac protein and cry1Ac gene copies differed between the transgenic lines from FN15 and ROC22. The medium copy lines from FN15 showed a significant linear relationship, while ROC22 showed no definite dosage effect. The transgenic lines with medium copies of cry1Ac showed an elite phenotype. Transcriptome analysis by RNA sequencing indicated that up/down regulated differentially expressed genes were abundant among the cry1Ac sugarcane lines and the receptor variety. Foreign cry1Ac gene and endogenous borer stress-related genes may have a synergistic effect. Three lines, namely, A1, A5, and A6, were selected for their excellent stem borer resistance and phenotypic traits and are expected to be used directly as cultivars or crossing parents for sugarcane borer resistance breeding.ConclusionsCry1Ac gene integration dramatically improved sugarcane insect resistance. The elite transgenic offspring contained medium transgene copies. Foreign cry1Ac gene integration and endogenous borer stress-related genes may have a synergistic effect on sugarcane insect resistance improvement.

Evaluation of Resistance in Brinjal (Solanum melongena L.) against Brinjal Shoot and Fruit Borer (Leucinodes orbonalis Guen.) Infestation: A Review

Brinjal or eggplant (Solanum melongena L.) is widely grown vegetable in South and South-East Asian countries. There are various factors that limits the production of brinjal among which brinjal shoot and fruit borer (Leucinodes orbonalis Guen) is the most common one which occurs during the time at all the phases of the crop development. The damage caused by shoot and fruit borer (Leucinodes orbonalis L.) in brinjal begins immediately after transplantation of crop and growers will have to harvest an immature crop. The life cycle of BSFB completes in 19-28 days. It is estimated by various specialists that increase in the number of shoots per plant will lower the attack rate of the pest. Round shape fruits are more susceptible compared to long bodied fruits. It is also examined that total sugar contents increase the attack while total phenol contents produce resistance to pest. The information of nature and relative extent of gene exploit (additive and non-additive) is of key importance in scheming appropriate and well-organized breeding plan for enhancement of resistance and crop yield. Physical and chemical features, for example, plant structure, fruit form, spines of leaves, branches, petioles, calyx of fruits, fruit skin thickness and shoot thickness, synthetic traits, for example, ash, crude fibre, silica, sugars, mineral ingredients, total phenol contents of fruit and shoot of brinjal are examined to be included towards the shoot and fruit borer resistance in brinjal.Int. J. Appl. Sci. Biotechnol. Vol 6(3): 199-206

English

Lepidopteran borers are the most devastating field pests of maize in West and Central Africa. In view of the rapidly changing climate which favours an upsurge of more destructive biotypes of insect pests, diverse sources of resistance from different genetic backgrounds need to be harnessed for crop improvement purposes. Forty tropical maize inbreds comprising adapted and exotic lines from International Institute of Tropical Agriculture (IITA) and International Maize and Wheat Improvement Centre (CIMMYT) maize breeding programs were evaluated for resistance to two species of stem borers- Sesamia calamistis and Eldana saccharina at Ibadan and Ikenne, Nigeria, under artificial infested and non-infested conditions in 2015 and 2016 cropping seasons. The experiment was laid out in a randomized complete block design in three replicates. Data were collected on agronomic traits and stem borer damage parameters. On average, the CML lines had relatively higher grain yield despite the high level of stem tunneling, stalk breakage and cob damage, with the exception of CML 67 (0.19 ton/ha) and CML 71 (0.06 tons/ha). BD 74-395 had the highest yield (1.45 t/ha) among the BDs, despite its high stalk breakage and cob damage. Among IITA lines, KU1414SR/SR, 1368 and 9030STR were the highest yielding with grain yields of 1.71, 1.39 and 1.19 t/ha, respectively. Moderate to high heritability was observed among the stem borer damage parameters. Negative genetic gain was observed in stem tunneling. Mean square of lines was significant for all the traits studied. The top-performing inbreds were similarly grouped using the rank summation index and principal component analysis. The exotic lines had good adaptability and showed potential as sources of stem borer resistance, and could therefore be explored in breeding programs for resistance to Eldana and Sesamia. Key words: Eldana saccharina, maize inbreds, resistance, Sesamia calamistis, tropics. &nbsp

Fine analysis of a genomic region involved in resistance to Mediterranean corn borer

BackgroundSesamia nonagrioides Lefebvere (Mediterranean corn borer, MCB) is the main pest of maize in the Mediterranean area. QTL for MCB stalk tunneling and grain yield under high MCB infestation had been located at bin 8.03–8.05 (4–21 cM and 10–30 cM respectively) in a previous analysis of the EP42 x EP39 RILs mapping population. The objective of the present work was to study with higher resolution those QTL, and validating and estimating with higher precision their locations and effects. To achieve this objective, we developed a set of 38 heterogeneous inbred families (HIFs) which were near-homozygous in the genome, except in the region under study. The HIFs were evaluated in multiple environments under artificial infestation with MCB and genotyped with SNPs.ResultsThe QTL for grain yield under high infestation was confirmed with higher precision and improved reliability at 112.6–116.9 Mb. On the contrary, the location of the QTL for stalk tunneling was not validated probably due to the fixation of some genomic regions during the development of the HIFs. Our study confirmed that the co-localization of the QTL for stalk tunneling and grain yield in the previous study was due to linked genes, not to pleiotropic effects. So, the QTL for grain yield can be used for improving grain yield without undesirable effect on stalk tunneling.ConclusionsThe HIF analysis is useful for validating QTL and for conducting deeper studies in traits related to corn borer resistance.

Evaluating less-used timber species for marine construction

Naturally durable species of timber are used as an alternative to preservative-treated timber for marine structures, but many species have not been evaluated for their potential for use in this environment. BS EN 275 evaluates marine borer resistance and specifies a 5-year test period: too long a period for screening tests to be economically viable. Furthermore, the test does not evaluate abrasion resistance. Novel fast-track screening methods were used in this study to evaluate the marine borer and abrasion resistance of 18 less-used timber species. Comparative resistance was assessed by comparing the feeding rates of marine borers and abrasion resistance observed in candidate species against greenheart and ekki, which were used as benchmark species. A number of less-used species, originating from South America and West Africa, performed better than the benchmark species in laboratory tests and over an 18-month exposure period in the sea. A number of species also performed comparatively well in abrasion trials although resistance to abrasion does not necessarily correlate with resistance to attack by marine borers.

Expression of Cry2Aa, a Bacillus thuringiensis insecticidal protein in transgenic pigeon pea confers resistance to gram pod borer, Helicoverpa armigera

Pigeon pea is an important legume infested by a plethora of insect pests amongst which gram pod borer Helicoverpa armigera is very prominent. Imparting resistance to this insect herbivore is of global importance in attaining food security. Expression of insecticidal crystal proteins (ICP) in diverse crops has led to increased resistance to several pests. We report in this paper, expression of Cry2Aa in transgenic pigeon pea and its effectiveness towards H. armigera by employing Agrobacterium-mediated in planta transformation approach. Approximately 0.8% of T1 generation plants were identified as putative transformants based on screening in the presence of 70 ppm kanamycin as the selection agent. Promising events were further recognized in advanced generations based on integration, expression and bioefficacy of the transgenes. Seven T3 lines (11.8% of the selected T1 events) were categorized as superior as these events demonstrated 80–100% mortality of the challenged larvae and improved ability to prevent damage caused by the larvae. The selected transgenic plants accumulated Cry2Aa in the range of 25–80 µg/g FW. The transgenic events developed in the study can be used in pigeon pea improvement programmes for pod borer resistance.