Introgression of resistance to bacterial wilt and shoot and fruit borer in eggplant using three-way cross and insights into molecular marker functional validation

Bacterial wilt (Ralstonia solanacearum) and fruit borer (Leucinodes orbonalis) are major concerns in cultivation of eggplant in Jharkhand and even in the other parts of the country. Keeping their adverse impact on quality production, nine brinjal genotypes were evaluated for three consecutive crop seasons against bacterial wilt and shoot and fruit borer. Results revealed wide range of variations among genotypes for important morphological characters viz., colour of stem, leaf, petiole, mid-rib, prickleness (spinyness), fruit shape, colour and fruit yield. The genotypes, CB-27, CB-41 and CB-1 showed resistance showing the lowest bacterial wilt incidence ranging from 2.7 to 4.5 per cent and minimum mean infestation of shoot borer ranging from 2.92 to 3.97 per cent with significantly higher fruit yield. Resistance against wilt and shoot and fruit borer depicted a significant importance for the breeders as well as for the commercial growers of this crop. On the basis of these findings, the superior genotypes viz., CB-1 (egg shaped & purple fruit), CB-27 (oblong & purple fruit) and CB-41 (oblong & light green fruit) could be recommended for commercial cultivation in the state of Jharkhand and adjoining areas of the similar agro-climatic conditions.

Brinjal (Solanum melongena L.), an important solanaceous vegetable crop cultivated across tropical and subtropical regions, is severely constrained by the Brinjal Shoot and Fruit Borer (Leucinodes orbonalis), the most destructive pest of the crop, capable of causing yield losses exceeding 70%. The current study is focused on field screening of 28 segregating F2 progeny families derived from complex three-way cross hybrids to identify transgressive segregants with inherent tolerance to BSFB damage. Correlation analysis revealed that total fruit yield per plant exhibited a strong positive association with marketable yield, total number of fruits per plant, and average fruit weight. Marketable yield showed a highly significant negative correlation with per cent fruit infestation (PFI) (r=-0.593), highlighting the direct economic impact of BSFB injury. Extensive phenotypic variability was observed, with PFI ranging from 0 to 75 per cent. Based on PFI and percent shoot infestation values, the genotypes were classified into distinct resistance categories, and a selection index was constructed using PFI and marketable yield with equal weightage. This approach enabled the identification of 50 superior lines combining higher marketable yield with reduced pest damage. These findings demonstrate that integrating PFI with key yield components can accelerate the development of high-yielding, BSFB-resistant brinjal cultivars.

Brinjal shoot and fruit borer (Leucinodes orbonalis) is a major devastating brinjal pest that leads to substantial yield losses. Besides this, it also infests the other major vegetable crops such as tomato and okra. India has an excellent germplasm diversity of brinjal species that can be explored to manage this pest. This review article thoroughly discusses several eco-friendly and advanced approaches to managing the infestation of Leucinodes orbonalis (brinjal shoot and fruit borer). The collected information regarding pests has concluded that integrated pest management strategies effectively reduce yield losses in Brinjal. However, advanced approaches such as genetic engineering and utilization of molecular markers can also contribute to the screening and development of resistant cultivars, while this technique can also help to analyze the pesticidal resistance of plants.Graphical abstract

Eggplant (Solanum melongena L.), an economically important vegetable crop in many countries in Asia and Africa, often has insufficient levels of resistance to biotic and abiotic stresses. Genetic resources of eggplant have been assessed for resistance against its most serious diseases and pests (bacterial and fungal wilts, nematodes and shoot and fruit borer). Attempts at crossing eggplant with its wild relatives resulted in limited success due to sexual incompatibilities. However, the ability of eggplant to respond well in tissue culture, notably plant regeneration, has allowed the application of biotechnology, particularly the exploitation of somaclonal variation, haploidisation, somatic hybridisation and genetic transformation for gene transfer. Somaclonal variation has been used to obtain lines with increased resistance to salt and little leaf disease. Traits of resistance against bacterial and fungal wilts have successfully been introduced into the cultivated eggplant through somatic hybridisation. However, most somatic hybrids were sterile when the parental lines were distantly related. In contrast, the use of close relatives as fusion partners or highly asymmetric fusion resulted in the production of fertile hybrids with resistance traits and a morphology close to the cultivated eggplant, thus avoiding the series of backcrosses necessary for introgression of desired traits into eggplant. As far as molecular markers and genetic engineering are concerned, the information available for eggplant is very scanty. Two genetic linkage maps have been established by using RAPD and RFLP markers. In order to analyse the genetic relationships between eggplant and its relatives, some studies based on AFLP and ctDNA analyses have also been conducted. So far only resistance against insects, and parthenocarpic fruit development have successfully been developed in eggplant using Agrobacterium tumefasciens transformation. However, some work on genetic engineering of eggplant for other biotic and abiotic stresses has recently been initiated.

A field experiment was conducted during kharif, 2017 at the Experimental Farm of Department of Horticulture, School of Agricultural Sciences and Rural Development, Medziphema Campus, Nagaland University. Eighteen genotypes of brinjal were evaluated inthree replications using Randomized Block Design (RBD). Study on the genetic divergence was carried out to assess the variability, association, direct and indirect effects on yield in eighteen genotypes of eggplant (Solanummelongena L.). High PCV and GCV were recorded by the number of fruit per plant (79.71 and 77.47) followed by fruit yield per plant (67.23 and 65.49). High heritability per cent of mean was registered for yield per plant (94.88) followed by number of fruit per plant (94.47), fruit length (90.25) and number of branches per plant (90.20) with high genetic advance number of fruit per plant (155.12) followed by yield per plant (131.41), fruit weight(65.18) and fruit diameters (52.63). High heritability with high genetic advance indicated the presence of additive gene effect. The correlation studies revealed strong positive association of fruit yield with number of fruits per plant (0.885), fruit length (0.684), percent infestation of shoot and fruit borer (0.625), number of branches (0.559) at genotypic level and number of fruits per plant (0.877), fruit length (0.668), number of branches per plant (0.523), percent infestation of shoot and fruit borer (0.399) and number of leaves per plant (0.363) at phenotypic level. The result of path analysis indicated that maximum positive direct effect on yield per plant was exhibited by fresh weight (1.362) followed by number of branches per plant (0.728), LAI (0.625) and percent incidence of bacterial wilt (0.295).

The brinjal shoot and fruit borer, Leucinodes orbonalis is a destructive pest of Solanum melongena. The control of L. orbonalis with extensive application of synthetic chemical insecticides resulted in the development of resistance with known genetic heterogeneity among populations. Understanding the genetic diversity of their populations is important in developing strategies for their management. The present investigation was performed to characterize populations of L. orbonalis for their genetic diversity in the entire region of Tamil Nadu, South India using random amplified polymorphic DNA (RAPD) primers as a tool of the molecular marker. Among 60 random 10-mer primers, only ten primers generated reproducible and scorable banding profile. Among the ten different random primers, the primers namely OPG 7, OPG 8, OPS 2 and OPS 7 generated the highest genetic variation with over 80% genetic polymorphism. Phylogram analysis produced 18 clusters with eight major and ten minor clusters. Cluster analysis, statistical fitness, population structure and analysis of molecular variance confirmed the significant genetic variation among different populations. A trait specific marker obtained through RAPD was cloned, sequenced and used to develop a stable diagnostic SCAR marker for DNA fingerprinting to distinguish the populations. Amplification of this locus in the samples of 20 different populations indicated recognition of the trait for pesticide resistance in 12 populations. The results suggest that the biochemical nature of host plant varieties of this insect pest and variation in the application of different insecticides are essential contributing factors for the genotypic variations observed among populations of L. orbonalis.

Eggplant (brinjal) is commonly affected by fungal and bacterial wilt, as well as shoot and fruit borer infestations, leading to significant yield losses. This study aimed to investigate the production of brinjal grafts using wilt-resistant rootstock, specifically Turkey berry (Solanum torvum Sw.), and to evaluate the field performance of the grafted plants. The success of grafting largely depends on the quality and compatibility of the Turkey berry rootstock. To produce Turkey berry rootstock, seeds were soaked in water for 12, 24, and 36 hours before being sown in protrays filled with cocopeat and in raised beds during May and October. The highest germination rate was observed in seeds soaked for 36 hours and sown in protrays, followed closely by those sown in raised beds. Brinjal scions, 30-35 days old, were grafted onto 55-60-day-old Turkey berry rootstocks and placed in a polytunnel under a shade net. These grafted plants were then transplanted into the field alongside non-grafted plants (seedlings) to compare their performance. Results showed that grafted brinjal plants had significantly greater plant height (142.54 cm), more branches per plant (21.17), and a higher number of fruits per plant (135.31) compared to non-grafted plants. The fruit yield was also notably higher in grafted plants, with 9.11 kg per plant and 61.65 t/ha, compared to 4.82 kg per plant and 30.45 t/ha in non-grafted plants. Grafted brinjal plants exhibited an extended growing period, higher net income, and a benefit-cost ratio (BCR) of 2.36. No instances of wilt were observed in grafted plants, and they also had lower incidences of shoot borer (15.31%) and fruit borer (11.74%) infestations compared to non-grafted plants. This grafting technique has the potential to enhance brinjal yield and productivity, promoting organic farming by reducing the need for pesticides.

Farmer participatory field trials were conducted for assessing the effects of an Integrated Pest Management (IPM) technology for the management of major pests of tomato (Solanum lycopersicum L.). The experiment was conducted during March to October, 2016 and 2017 at three locations, viz. Kota Kwanu, Majhgaon Kwanu and Malot Kwanu in Chakrata block of district Dehradun, Uttarakhand, India on two popular, bacterial wilt resistant tomato hybrids, viz. Abhinav and Heamsohna. The various treatments were as follows: T1, seed treatment with Trichoderma + Pseudomonas @ 20 g/kg of seeds: T2, use of FYM @ 100 Q/ha fortified with Trichoderma + Pseudomonas; T3, planting of Abhinav and Heamsohna; T4, weekly hand picking and destruction of leaves, shoots and fruits infected by late blight; T5, staking of plants; T6, four applications of cymoxanil + mancozeb @ 2 g/l at 30, 45, 60- and 75 days after planting; and T7, application of chlorantraniliprole 18.5% SC @ 0.3 ml/l at 65-days. Incidence of diseases such as late blight and bacterial wilt, and pests such as fruit borer, Helicoverpa armigera was significantly high in the control plots. The severity of pest and diseases was comparatively more in 2017 than 2016 due to conducive climatic conditions. Maximum yield (410 q and 400 q/ha) was recorded during 2016 and 2017, respectively due to IPM practices combining all possible components as compared to other treatments or control. As a result of enhanced fruit yield, the gross (Rupees 615 000/ha and Rupees 800 000/ha) and net income (Rupees 428 180/ha and Rupees 610 375/ha) were realized during 2016 and 2017, respectively. The cost benefit ratio was also maximum due to combination of all IPM components (1:2.3 and 1:3.22) both during 2016 and 2017, respectively. The IPM strategies combining all possible components proved significantly superior not only in effective management of major diseases and pests but also helped in realizing higher productivity and thereby enhanced income of tomato growers in remote tribal regions of Dehradun, Uttarakhand.

CRISPR/Cas9-based evidence that overexpression of Gm-mGST1 mediates abamectin resistance in the oriental fruit moth, Grapholita molesta.

Glycine max cultivars Lee68, Nannong 1138-2, and Nannong 8831 were used as the female parents, and hybrid lines (F5) 4,111, 4,076 (N23674 × BB52), 3,060 (Lee68 × N23227), and 185 (Jackson × BB52) that selected for salt tolerance generation by generation from the cross combination of G. max and G. soja were used as the male parents, 11 (A–K) backcrosses or three-way crosses were designed and 213 single hybrids were harvested. The optimized soybean simple sequence repeat (SSR)–polymerase chain reaction (PCR) system was used to analyze the SSR polymorphism of above parental lines and get the parental co-dominant SSR markers for hybrid identification, and in which 30 true hybrids were gained. The true hybrids (G1, G3, G9, G12, G13, G16) of G cross combination were chosen as the representative for the salt tolerance test, and the results showed that, as exposed to salt stress, the seedlings of G9 line displayed higher salt tolerant coefficient, relative growth rate, and dry matter accumulation, when compared with their female parent Nannong 1138-2, and even performed equally strong salt tolerance as the male parent 3,060. It provides a feasible method of the combination of molecular SSR markers and simple physiological parameters to identify the true hybrids of G. max and G. soja, and to innovate the salt-tolerant soybean germplasms.

Brinjal (Solanum melongena L.) has great genetic wealth in its centre of origin, which is a foundation for crop improvement. So far, conventional breeding approaches were commonly used for improvement of yield, quality and resistance to insect pests and diseases, but the advent of biotechnological tools like embryo rescue, haploid induction, genetic transformation and molecular markers hastened the programmes in brinjal. The developments can be on understanding of evolutionary relationships, wide hybridization, genomic studies, gene editing, transgenics and doubled haploidy. The wealth of wild species can be used for introgression of resistance to Fusarium oxysporum from S. aethiopicum; Verticillium dahliae from S. linnaeanum, S. aethiopicum and S. incanum; draught from S. incanum; Verticillium wilt; and salt from Solanum sodomaeum. Male-sterile lines in cultivated S. melongena have been developed using the cytoplasm of S. aethiopicum, S. anguivi, S. kurzii, S. virginianum, S. violaceum and S. grandiflorum. Genetic transformation of Cre and Barnase gene for male sterility and Cry-1Ac gene for resistance to shoot and fruit borer are the other leads of improvement in brinjal. In the future, use of CRISPR/Cas for targeted modification of valuable traits can be exploited.

Brinjal (Solanum melongena L.), a crucial solanaceous vegetable crop, faces significant challenges from biotic stressors like pests and diseases, as well as abiotic stressors such as drought and salinity. Conventional breeding methods are limited in effectively addressing these complex traits. Nevertheless, advancements in molecular breeding, genetic engineering and tissue culture techniques have revolutionized brinjal improvement. Marker-assisted selection (MAS) has enabled the identification and incorporation of quantitative trait loci (QTLs) associated with resistance to bacterial wilt, shoot and fruit borer and enhanced yield attributes. Genetic engineering approaches, such as the development of Bt brinjal, have provided effective pest resistance while minimizing pesticide dependency. Tissue culture methods, including anther culture, have facilitated the rapid development of double haploid (DH) lines with improved fruit quality and tolerance to low temperatures. These biotechnological tools present promising solutions to mitigate stress factors while improving yield, quality and sustainability in brinjal cultivation. Future research should focus on integrating CRISPR/Cas9 gene editing with MAS to accelerate trait-specific improvements and utilize wild relatives for novel gene introgression.

Exploring resistance in eggplant and its relative species to bacterial wilt and fruit borer

The discovery of wide-compatibility varieties (WCVs) that are able to produce normal fertility hybrids when crossed both to indica and japonica rice has enabled the fertility barrier between indica and japonica subspecies to be broken and provided the possibility of developing inter-subspecific hybrids in rice breeding programs. However, a considerable variation in the fertility level of hybrids from the same WCV crossed to different varieties has often been observed. One hypothesis for this variable fertility is that additional genes are involved in hybrid fertility besides the wide-compatibility gene (WCG). To assess such a possibility, we performed a genome-wide analysis by assaying a large population from a three-way cross ‘02428’/‘Nanjing 11’//‘Balilla’ using a total of 171 RFLP probes detecting 191 polymorphic loci distributed throughout the entire rice linkage map. Our analysis recovered 3 loci conferring significant effects on hybrid fertility. The major locus on chromosome 6 coincided in chromosomal location with the previously identified S 5 locus, and the 2 minor loci that mapped to chromosomes 2 and 12, respectively, were apparently distinct from all previously reported hybrid sterility genes. Interaction between the indica and japonica alleles at each of the loci caused a reduction in hybrid fertility. The joint effect of the 2 minor loci could lead to partial sterility even in the presence of the WCG. The location of the S 5 locus on the molecular marker linkage map was determined to be approximately 1.0 cM from the RFLP locus R2349. This tight linkage will be useful for marker-aided transfer of the WCG in hybrid rice breeding and for map-based cloning.

Septoria tritici blotch (STB), caused by the ascomycete Mycosphaerella graminicola (anamorph Septoria tritici), was the most destructive disease of wheat in Indiana and adjacent states before deployment of the resistance gene Stb1 during the early 1970s. Since then, Stb1 has provided durable protection against STB in widely grown wheat cultivars. However, its chromosomal location and allelic relationships to most other STB genes are not known, so the molecular mapping of Stb1 is of great interest. Genetic analyses and molecular mapping were performed for two mapping populations. A total of 148 F1 plants (mapping population I) were derived from a three-way cross between the resistant line P881072-75-1 and the susceptible lines P881072-75-2 and Monon, and 106 F6 recombinant-inbred lines (mapping population II) were developed from a cross between the resistant line 72626E2-12-9-1 and the susceptible cultivar Arthur. Bulked-segregant analysis with random amplified polymorphic DNA (RAPD), amplified fragment length polymorphism (AFLP), and microsatellite or simple-sequence repeat (SSR) markers was conducted to identify those that were putatively linked to the Stb1 gene. Segregation analyses confirmed that a single dominant gene controls the resistance to M. graminicola in each mapping population. Two RAPD markers, G7(1200) and H19(520), were tightly linked to Stb1 in wheat line P881072-75-1 at distances of less than 0.68 cM and 1.4 cM, respectively. In mapping population II, the most closely linked marker was SSR Xbarc74, which was 2.8 cM proximal to Stb1 on chromosome 5BL. Microsatellite loci Xgwm335 and Xgwm213 also were proximal to Stb1 at distances of 7.4 cM and 8.3 cM, respectively. The flanking AFLP marker, EcoRI-AGC/ MseI-CTA-1, was 8.4 cM distal to Stb1. The two RAPD markers, G7(1200) and H19(520), and AFLP EcoRI-AGC/ MseI-CTA-1, were cloned and sequenced for conversion into sequence-characterized amplified region (SCAR) markers. Only RAPD allele H19(520) could be converted successfully, and none of the SCAR markers was diagnostic for the Stb1 locus. Analysis of SSR and the original RAPD primers on several 5BL deletion stocks positioned the Stb1 locus in the region delineated by chromosome breakpoints at fraction lengths 0.59 and 0.75. The molecular markers tightly linked to Stb1 could be useful for marker-assisted selection and for pyramiding of Stb1 with other genes for resistance to M. graminicola in wheat.