Eggplant Breeding Research Articles

Genetic diversity analysis of Eggplant Germplasm from Iran: assessments by morphological and SSR markers.

Eggplant is an important vegetable that has long been cultivated in different parts of Iran. The major objectives of the eggplant breeding program are to improve fruit quality, increase yield performance through heterosis breeding, and introduce abilities of pest and disease resistance from wild relatives. In order to select suitable parents for breeding purposes, with respect to the genetic and morphological diversity of eggplant cultivars, it is necessary to have sufficient knowledge of genetic diversity and classification of germplasms. This experiment was conducted in a randomized block design at the Seed and Plant Improvement Institute (SPII) in Karaj, Iran. Here, morphological diversity was assessed among a collection of eggplants which comprised four Iranian lines and 13 non-Iranian genotypes. For this purpose, 16 morphological traits were analyzed in the plants. Given the weakness of morphological analysis in providing precise characterizations of genetic divergence, a molecular study was also carried out by using five Simple Sequence Repeat (SSR) markers. In addition to the univariate analysis, the multi-descriptor variation was studied among the genotypes using two methods of multivariate analyses. The genotypes differed significantly in terms of the morphological traits. The multivariate analyses of morphological data indicated that eggplants from two different origins were clearly differentiated. Three main clusters were distinguished by a morphological UPGMA dendrogram in which non-Iranian genotypes, with the exception of 11,212, constituted cluster I and required the maximum number of days to flower, days to fruit set, and days to first harvest. Cluster II was identified with two Iranian lines BJ30, Y60, and one non-Iranian genotype (11,212) which showed the highest values of stem diameter, fruit diameter, fruit length, fruit length-to-width ratio, number of fruits per plant, and yield. Cluster III comprised two Iranian lines, D1 and D7, and showed the maximum plant height, number of internodes, number of nodes, number of leaves, number of stems, fruit weight, and fruits weight per plant. The highest and lowest intra-cluster genetic distances were observed in cluster I and cluster II, respectively. Based on SSR analysis, high levels of similarity were detected between several genotypes, namely, Y60 and 13,411; BJ30 and 1111; D7 and 13,521; 21,881 and 13,421. High levels of heterozygosity and polymorphism information content (PIC) were observed in this study. This not only indicated high levels of polymorphism and an equal distribution of the evaluated loci but also suggested that these genotypes can be considered for the development of diverse parental lines which are of interest in breeding programs.

Identification and Functional Analysis of MicroRNAs and Their Target Genes in Reverse Thermosensitive Genic Male Sterility of Eggplant

Thermosensitive genic male sterile (TGMS) lines are the core of two-line hybrid systems. MicroRNAs (miRNAs) play critical roles in plant growth and development. However, knowledge of regulation of anther development by miRNAs in TGMS eggplant (Solanum melongena) is largely unexplored. To investigate the mechanism underlying miRNA regulation of male sterility, we employed high-throughput small RNA sequencing in anther samples from the reverse TGMS line 05ms and the temperature-insensitive line S63 in eggplant, under high temperature and low temperature conditions. The 05ms line is sterile at low temperature and fertile at high temperature. A total of 166,273,427 raw reads were obtained, 143 known miRNAs from 42 miRNA families and 104 novel miRNAs were detected. Further, six differentially expressed miRNAs (DEMs) were identified, including three known (miR168b-3p, miR397–5p, and miR408) and three novel miRNAs (Novel_116, Novel_119, and Novel_97), which might be related to anther development. Moreover, the six DEMs were validated by quantitative real-time polymerase chain reaction and 892 target genes of which were predicted. Gene Ontology analysis of target genes revealed significant enrichment in the “copper ion binding,” “oxidation-reduction process,” and “oxidoreductase activity” terms. Kyoto Encyclopedia of Genes and Genomes analysis revealed that “plant hormone signal transduction” and “other glycan degradation” were enriched. In addition, we constructed regulatory networks comprising miRNAs, target genes, and important terms/pathways and found the miR397-5p was the most linked miRNA, down-regulated under low temperature. Our findings contribute to understanding of the roles of miRNA during anther development and provide the theoretical foundation for two-line hybrid breeding of eggplant.

Nutritional Value of Eggplant Cultivars and Association with Sequence Variation in Genes Coding for Major Phenolics.

Eggplant is a widely consumed vegetable, with significant nutritional value and high antioxidant content, mainly due to its phenolic constituents. Our goal was to determine the levels of carbohydrates, proteins, total phenolics, anthocyanins, flavonoids, chlorogenic acid, and the antioxidant capacity in thirteen eggplant cultivars cultivated in Greece and to identify sequence polymorphisms in key regulating genes of the phenylpropanoid pathway (C4H, HCT, HQT, C3H, F3H, ANS, MYB1), which might relate to the phytochemical content of those cultivars. The carbohydrates’ content differs among and within cultivars, while the rest of the phytochemicals differ only among cultivars. The cultivars ‘EMI’ and ’Lagkada’ scored higher than the rest in phenolics, anthocyanins, ascorbic acid, caffeoylquinic acid, and antioxidant capacity. Moreover, significant correlations were observed between various ingredients and the antioxidant capacity (FRAP and DPPH). Sequence analysis revealed several SNPs in C4H, HQT, F3H, ANS, and MYB1 among the cultivars studied. According to chi-square and logistic regression analyses, the missense mutation C4H4-108 correlates significantly with flavonoids, anthocyanins, and proteins; the synonymous mutation HQT-105 correlates with anthocyanins and ascorbic acid; the missense mutation HQT-438 correlates with flavonoids and chlorogenic acid, while the missense mutation ANS1-65 correlates with anthocyanins and sugars. These polymorphisms can be potentially utilized as molecular markers in eggplant breeding, while our data also contribute to the study of eggplant’s secondary metabolism and antioxidant properties.

Genome-wide identification and analysis of the TCP gene family in eggplant (Solanum melongena L.)

TCP (teosinte branched1/cincinnata/proliferating cell factor) is a group of plant-specific transcription factors that play important roles in plant growth and development. To date, there are no report about TCP transcription factors in eggplant (Solanum melongena L). In this study, twenty-nine eggplant TCP (SmTCP) family genes distributed on 11 chromosomes were identified from the genome database of eggplant using bioinformatics methods. The results showed that all members of the family contained sequences encoding TCP conserved domains with length of amino acids ranging from 201 to 538 and exon numbers of 1 or 2. Subcellular localization revealed that three SmTCP proteins (SmTCP02/03/21) were located in the cytoplasm and the other SmTCP proteins were located in the nucleus. The 29 TCP transcription factors were divided into ClassⅠ (PCF) and ClassⅡ (CIN and CYC/TB1) by phylogenetic tree and sequence analysis. Collinearity analysis showed that 17 pairs (21) of SmTCP genes had collinearity, and these collinearity genes belonged to segmental duplication. Analysis of gene expression patterns showed that all 29 members of SmTCP gene family were expressed in 15 tissues or organs, but the expression patterns were different. Among them, four gene (SmTCP18/19/20/25) of CIN subfamily were highly expressed in leaves at different growth stages. Analysis of cis-acting elements in the promoter region of SmTCP showed that there were four types of cis-acting elements, which were light response related cis-acting elements, growth and development related cis-acting elements, hormone response related cis-acting elements and stress related cis-acting elements. In summary, the molecular basis of SmTCP genes in eggplant and the influence of TCP gene on the growth and development of eggplant provided a theoretical basis for molecular breeding of eggplant.

Comparative Transcriptome Analysis Reveals Gene Expression Differences in Eggplant (Solanum melongena L.) Fruits with Different Brightness.

Fruit brightness is an important quality trait that affects the market value of eggplant. However, few studies have been conducted on eggplant brightness. In this study, we aimed to identify genes related to this trait in three varieties of eggplant with different fruit brightness between 14 and 22 days after pollination. Using RNA-Seq Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses, we found that wax- and cutin-related pathways and differentially expressed genes displayed significant differences among different development stages and varieties. Scanning electron microscopy revealed that the wax layer was thinner in ‘30-1’ and ‘QPCQ’ than in ‘22-1’. Gas chromatography-mass spectrometry analysis revealed that wax content was significantly lower in ‘30-1’ than in ‘22-1’, which indicated that wax may be an important factor determining fruit brightness. We further identified and analyzed the KCS gene family, which encodes the rate-limiting enzyme of FA elongation in wax synthesis. The results provide an insight into the molecular mechanisms of fruit brightness in eggplants and further eggplant breeding programs.

Characterization and QTL identification in eggplant introgression lines under two N fertilization levels

Lowering nitrogen inputs is a major goal for sustainable agriculture. In the present study, a set of 10 Solanum melongena introgression lines (ILs) developed using Solanumincanum as the exotic donor parent were grown under two nitrogen fertilization doses supplied with the irrigation system: 1) 8.25 mmol · L−1 NH4NO3, corresponding to the high nitrogen treatment (HN), and 2) no external nitrogen supply, corresponding to the low nitrogen treatment (LN). Twenty traits, including plant growth and yield parameters, fruit size and morphology, nitrogen and carbon content in leaf and fruit, and phenolics content in fruit, were evaluated. The aim was to select of potential materials for eggplant breeding under low N inputs, as well as to identify and locate putative QTLs associated with the traits evaluated. No significant differences were observed between the soil characteristics of the HN and LN treatments, except for nitrogen and iron content, which was slightly lower in the HN, probably as a consequence of higher nutrient removal from soil by plants in the latter group. Analysis of variance showed that lowering nitrogen inputs did not significantly affect the final yield, fruit morphology, size and phenolics content. Most agronomic traits were highly and positively correlated with each other under both treatments, as well as total phenolics with chlorogenic acid content. The assessment of the differences between each IL and the recipient parent resulted in the identification of 36 QTLs associated with most of the traits—12 were specific to the HN, 17 specific to the LN, and 7 were stable across treatments. The introgressed fragment of S. incanum generally had a negative effect on the trait, except for QTLs for fruit dry matter, for fruit length on chromosome 10 under the HN, and for fruit pedicel length on chromosome 9 under the LN. The increase over AN-S-26 of the allele of S. incanum for the QTLs detected ranged between −73.98% and 26.03% in HN and −73.67% and 34.43% in LN. These findings provide useful tools for the utilization of S. incanum in eggplant breeding under lower nitrogen fertilization.

Identifying Quantitative Trait Loci for Thousand Grain Weight in Eggplant by Genome Re-Sequencing Analysis.

Eggplant (Solanum melongena L.; 2n = 24) is one of the most important Solanaceae vegetables and is primarily cultivated in China (approximately 42% of world production) and India (approximately 39%). Thousand-grain weight (TGW) is an important trait that affects eggplant breeding cost and variety promotion. This trait is controlled by quantitative trait loci (QTLs); however, no quantitative trait loci (QTL) has been reported for TGW in eggplant so far, and its potential genetic basis remain unclear. In this study, two eggplant lines, 17C01 (P1, wild resource, small seed) and 17C02 (P2, cultivar, large seed), were crossed to develop F1, F2 (308 lines), BC1P1 (44 lines), and BC1P2 (44 lines) populations for quantitative trait association analysis. The TGWs of P1, P2 and F1 were determined as 3.00, 3.98 and 3.77 g, respectively. The PG-ADI (polygene-controlled additive-dominance-epistasis) genetic model was identified as the optimal model for TGW and the polygene heritability value in the F2 generation was as high as 80.87%. A high-quality genetic linkage bin map was constructed with resequencing analysis. The map contained 3,918 recombination bins on 12 chromosomes, and the total length was 1,384.62 cM. A major QTL (named as TGW9.1) located on chromosome 9 was identified to be strongly associated with eggplant TGW, with a phenotypic variance explanation of 20.51%. A total of 45 annotated genes were identified in the genetic region of TGW9.1. Based on the annotation of Eggplant genome V3 and orthologous genes in Arabidopsis thaliana, one candidate gene SMEL_009g329850 (SmGTS1, encoding a putative ubiquitin ligase) contains 4 SNPs and 2 Indels consecutive intron mutations in the flank of the same exon in P1. SmGTS1 displayed significantly higher expression in P1 and was selected as a potential candidate gene controlling TGW in eggplant. The present results contribute to shed light on the genetic basis of the traits exploitable in future eggplant marker-assisted selection (MAS) breeding.

Fruit Composition of Eggplant Lines with Introgressions from the Wild Relative S. incanum: Interest for Breeding and Safety for Consumption

The wild species Solanum incanum has been used as a donor parent for the development of a set of eggplant introgression lines (ILs), which are of interest for breeding for stress tolerances and relevant morpho-agronomic traits but could also be useful for breeding for fruit quality, due to the generally higher content in health-promoting compounds of S. incanum. The use of eggplant ILs with introgressions from S. incanum requires ensuring that glycoalkaloids levels are below safety limits. We evaluated 25 fruit composition traits, including proximate composition, sugars, acids, phenolics, glycoalkaloids, and minerals in a set of 16 eggplant ILs with S. incanum, both parents and the F1, grown under two environments (open field and screenhouse). The results demonstrated that the parents were significantly different regarding most fruit composition traits. Large variation was found among the 16 ILs for all traits analyzed and a strong influence of the environment accounted for the variation of 17 out of the 25 traits evaluated. Although the S. incanum parent produced fruits with high levels of glycoalkaloids, the 16 ILs showed mean values of total glycoalkaloids below the currently accepted safety limit for human consumption (200 mg kg−1 fresh weight). Overall, the ILs produced fruits that are safe for consumption, with nutritional and functional quality similar to the recipient parent. Furthermore, six putative QTLs were detected spread over chromosomes 3 for crude protein, 5 for malic and total acids, and 7 for chlorogenic acid and solamargine, and potential candidate genes were spotted for most of them, which provide new relevant information for eggplant breeding.

History of development and results of selection of Solanaceae crops in FSBSI FSVC

The article presents a brief history of the establishment of the Laboratory of Plant Breeding and Seed Production of Solanaceae Crops of FSBSI FSVC. The process of development of tomato, pepper, eggplant and physalis breeding is shown from the beginning of the establishment until the present time. Practical selection of Solanaceae crops in FSBSI FSVC is directly connected with the name of Academician VASKhNIL A.V. Alpatyev, who is the founder of scientific research on thermophilic crops. On the basis of conducted scientific researches the technique of creation of cold-resistant, early-ripening cultivars of tomato was developed, including influence of certain conditions on parental forms and hybrid material from its first generations to increase adaptability to new, not characteristic conditions of selected material. Subsequently, this technique was applied to the breeding of sweet pepper, eggplant and physalis. Interspecific hybridisation was used to enrich the gene pool of Solanaceous crops. As a result of distant hybridization, the following cultivars were created: the original tomato cultivar Severyanin with large parthenocarpic fruits on 1 and 2 racemes; an anadrous mutant for use in breeding; ultra-rapid, short-stage forms for obtaining heterosis effect; the cultivar Vkusny with increased content of dry matter in fruits. On the basis of interspecific hybrid of Ph. ixocarpa x Ph. angulata, the cultivars Dessert and Lakomka, characterized by high yield and resistance to diseases, high content of sugars, pectin and absence of bitterness, are created. Types of pepper Capsicum chinense, C. frutescens and C. annuum were used to create resistant forms to viral diseases. Involvement of wild eggplant species (Solanum aethiopicum, S. macrocarpon) to the breeding process allowed to obtain hybrid combinations with flavonoids content 1,3 times higher and phenolcarboxylic acids 1,6–1,7 times higher than in S. melongena.The development of theoretical bases ofSolanaceae crops breeding for resistance to biotic and abiotic stressors, as well as for high quality production, allowed to create a series of cosmopolitan cultivars, which at present are in demand, both in production and as a source material. The current scientific priorities are to use innovative biotechnology and molecular marking methods to accelerate the breeding process and improve selection efficiency.

Extensive transcriptome changes underlying the fruit skin colour intensity variation in purple eggplant

Fruit skin colour intensity is one of the most important economic traits of purple eggplant. A wide diversity for fruit skin colour intensity exists in purple eggplant and the accumulation of anthocyanins and chlorophylls of fruit skin mainly affected colour intensity. However, limited information is available contributing to the molecular mechanisms underlying fruit skin colour intensity variation in purple eggplant. In the present study, variation of two purple eggplant advanced lines EP26 and EP28, with different fruit skin colour intensity was investigated. Higher anthocyanin contents and lower chlorophyll contents were observed in EP26 with deeper fruit skin colour intensity at two developmental stages. Comparative transcriptome analysis of EP26 and EP28 identified a total of 2218 differential expressed genes (DEGs) at two developmental stages. Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that these DEGs were mainly involved in flavonoid biosynthesis and photosynthesis. In addition, a total of 131 transcription factors including MYB, bHLH, WRKY, and NAC exhibited dynamic changes, which might be responsible for the variation of fruit pigments accumulation between EP26 and EP28. Taken together, these results expand our knowledge of molecular mechanisms underlying fruit skin colour intensity variation in eggplant, which allowing for improvement of fruit coloration in eggplant breeding.

Evaluation of Advanced Backcrosses of Eggplant with Solanum elaeagnifolium Introgressions under Low N Conditions

Selection and breeding of eggplant (Solanum melongena) materials with good performance under low nitrogen (N) fertilization inputs is a major breeding objective to reduce environmental degradation, risks for human health, and production costs. Solanum elaeagnifolium, an eggplant wild relative, is a potential source of variation for introgression breeding in eggplant. We evaluated 24 plant, fruit, and composition traits in a set of genotyped advanced backcrosses (BC2 and BC3) of eggplant with S. elaeagnifolium introgressions under low N conditions. Significant differences were found between the two parents for most traits, and a wide phenotypic diversity was observed in the advanced backcrosses, with some individuals with a much higher yield, nitrogen use efficiency (NUE), and phenolics content than the S. melongena parent. In general, the lower the proportion of S. elaeagnifolium genome introgressed in the advanced backcrosses, the higher was the general phenotypic resemblance to S. melongena. Putative QTLs were detected for stem diameter (pd4), presence of prickles in stem (ps6), leaf (pl6) and fruit calyx (pc6), fruit width (fw7), chlorogenic acid content (cg5), total phenolic acid peaks area (ph6), chlorogenic acid peak area (ca1), and phenolic acids pattern (cp1). Our results reveal that introgression breeding of eggplant with S. elaeagnifolium has a great interest for eggplant breeding, particularly for adaptation to low N conditions. These materials can potentially contribute to the development of improved eggplant varieties for a more sustainable agriculture.

Genetic Diversity and Utilization of Cultivated Eggplant Germplasm in Varietal Improvement.

Eggplant is the fifth economically most important vegetable in the Solanaceae family after tomato, potato, chili, and tobacco. Apart from the well-cultivated brinjal or aubergine eggplant (Solanum melongena L.), two other underutilized eggplant species, the African eggplant (S. macrocarpon L.) and the scarlet eggplant (S. aethiopicum L.), were also cultivated with local importance where the leaves and fruits are used for food and medicinal purposes. The major objectives of the eggplant breeding program are to improve fruit quality, increase yield performance through heterosis breeding, and introduce pest and disease resistances from wild relatives. Europe and Asia hold a wide collection of germplasm resources with significant potential for genetic improvement. While cultivated eggplant is susceptible to several fungi and bacteria, many wild relatives offer potential resistance to these pathogens. In this paper, we review the genetic resources and diversity of cultivated eggplant and its wild relatives. As a point of departure, we examine the economic importance, domestication, taxonomy characterization, and relationships of the crop and its wild relatives. The importance of evaluating and safeguarding wild relatives is highlighted, as crop wild relatives are highly underrepresented. A key section in this study is an overview dedicated to genetic resources, resistance to biotic and abiotic stresses, pre-breeding, and breeding for sustainable eggplant production.

English

The scarlet eggplant (Solanum aethiopicum L.) is an African traditional vegetable grown for its edibles leaves and fruits, which can contribute to food security in Republic of Benin. However, very little information is available on the genetic variability of this vegetable for varietal improvement purposes. Sixty accessions of scarlet eggplants collected throughout 52 villages in Benin republic were characterized using 34 (10 qualitative and 24 quantitative) variables. The experiment was laid out using complete randomized block design with three replications on the experimental site of Massi. The Principal Component Analysis (PCA) analysis revealed 18 discriminating quantitative variables. A strong correlation was observed between plant height, number of fruits per plant, fruit diameter, fruit weight and number of seeds per fruit. A cluster phenogram divided the 60 accessions into three groups corresponding to Kumba (Cluster 1), Gilo (Cluster 2), and Shum groups (Cluster 3). These groups differed by the number of seeds per fruit, weight of fruits, diameter of fruits, number of fruits per plant, plants height at flowering stage, plants length, and plant width. Accessions Samibi, Ikangougou, Kannan and Yètchanmiyé with the highest fruit weight per plant can be used as parents in the framework of a scarlet eggplant breeding program in Republic of Benin. Key words: Benin, accessions, traits diversity, breeding program.

Doubled Haploids in Eggplant.

Simple SummaryThis review compiles the most relevant advances made in the production of doubled haploid plants in eggplant, the application of doubled haploid lines in breeding programs, and the future perspectives for the development of alternative technologies for doubled haploid generation in this species.Eggplant is a solanaceous crop cultivated worldwide for its edible fruit. Eggplant breeding programs are mainly aimed to the generation of F1 hybrids by crossing two highly homozygous, pure lines, which are traditionally obtained upon several self crossing generations, which is an expensive and time consuming process. Alternatively, fully homozygous, doubled haploid (DH) individuals can be induced from haploid cells of the germ line in a single generation. Several attempts have been made to develop protocols to produce eggplant DHs principally using anther culture and isolated microspore culture. Eggplant could be considered a moderately recalcitrant species in terms of ability for DH production. Anther culture stands nowadays as the most valuable technology to obtain eggplant DHs. However, the theoretical possibility of having plants regenerated from somatic tissues of the anther walls cannot be ruled out. For this reason, the use of isolated microspores is recommended when possible. This approach still has room for improvement, but it is largely genotype-dependent. In this review, we compile the most relevant advances made in DH production in eggplant, their application to breeding programs, and the future perspectives for the development of other, less genotype-dependent, DH technologies.

Phenotypic Characterization and Differential Gene Expression Analysis Reveal That Dwarf Mutant dwf Dwarfism Is Associated with Gibberellin in Eggplant

Dwarfism is a desirable trait in eggplant breeding, as it confers higher lodging resistance and allows simplified management and harvest. However, a few dwarf mutants have been reported, and the molecular mechanism underlying dwarfism in eggplant is completely unknown. Here, we report a dwarf mutant (dwf) isolated from an ethyl methyl sulfonate (EMS)-induced mutant library. The hypocotyl length, plant height, and length of internode cells of dwf were significantly decreased compared to those of the wild-type parent ‘14-345’ (WT). Differential gene expression analysis revealed that GA-related genes, including GA2ox and DELLA, were up-regulated whereas the gibberellin (GA3) content decreased in dwf. Moreover, exogenous GA3 treatment significantly increased the relative growth rate of dwf compared to WT, further indicating the important roles of GA in regulating the dwarf phenotype of dwf. Collectively, our findings shed light on GA-mediated dwarfism in dwf plants and offer a good germplasm that could be used for eggplant dwarfism breeding in the future.

Fruit shape morphometric analysis and QTL detection in a set of eggplant introgression lines

Eggplant fruit shape is an important quantitative agronomic trait. The use of introgression lines (ILs) for QTLs identification is a powerful tool for the elucidation of the genetic control of eggplant fruit shape. In the present study, a set of 16 eggplant ILs, each harboring a single marker-defined chromosomal segment from the wild eggplant relative S. incanum in the genetic background of S. melongena, was evaluated for fruit shape in two environments (open field and screenhouse). A detailed phenotyping of the fruits of the two parents, hybrid and ILs was performed using 32 morphological descriptors of the phenomics tool Tomato Analyzer. Several morphological differences were found between parents, and the hybrid displayed negative heterosis for many fruit shape traits, being more similar to the S. incanum parent. Significant differences for most fruit shape descriptors were found between ILs and the recipient parent. For many descriptors, the genotype factor had the highest contribution to the percentage of the sum of squares. Although the contributions of the environment and the G × E interaction were significant for almost all descriptors, their effects on fruit shape were relatively low. Hierarchical clustering revealed nine clusters of highly correlated traits and six ILs groups. A total of 41 stable QTLs spread over ten chromosomes were detected. Of these, twenty QTLs associated to Basic Measurement and Fruit Shape Index descriptors were syntenic to other previously reported in several intraspecific and interspecific eggplant populations, while twenty-one QTLs, including Blockiness, Homogeneity, Asymmetry and Internal Eccentricity, were new. In addition, mutations associated to genes belonging to SUN, OVATE and YABBY families described in tomato were reported in the QTLs genomic regions identified in eggplant. Eleven SUN and YABBY genes were proposed as potential candidate controlling fruit shape variations in eggplant. Our results provide novel and highly relevant insights on the genetics of fruit shape in eggplant and have important implications for eggplant breeding.

Inheritance of alloplasmic fertility restoration in eggplant (Solanum melongena L.)

Cytoplasmic male sterility (CMS) system has been exploited worldwide in field and vegetable crops. In eggplant, alloplasmic CMS lines were developed through interspecific hybridization between Solanum aethiopicum L. × S. melongena L., while the restorer (R) lines were isolated from the reciprocal cross. The knowledge about inheritance of Rf gene is must for its further use in breeding and molecular studies. Therefore, four sets of CMS (D-CMS 291A, D-CMS 99A, D-CMS 5A and D-CMS 72A) and restorer (R 2-1, R 3-4, R 6-2 and R 2596-2) lines were used to develop F1, F2 and backcross progenies, to understand the inheritance mechanism. Phenotyping of all the populations and test of goodness of fit revealed involvement of a single dominant gene (Rf) for fertility restoration. The visual scoring of flowers for male sterility and fertility was further validated with the tests on pollen stainability, germination and index. Among others, media containing 0.5% agar + 300 ppm calcium nitrate + 5% sucrose + 50 mg/l boric acid + 400 mg/l PEG 4000 furnished the best results for in vitro pollen germination. Differences between and within male sterile and restorer lines were observed for pistil and stamen length and girth, pollen stainability and germination. Stable expression of CGMS and restorer lines in all the generation progenies confirmed their utility in future eggplant breeding programs.

Uticaj genotipa i spoljašnje sredine na prinos plavog patlidžana

One of the goals in eggplant breeding (Solanum melongena L .) is higher yield, as well as adaptation to different environments. Our study included 20 different eggplant genotypes. The experiment was conducted at three different locations (Smederevska Palanka, Vranovo and Kusadak) using a randomized complete block design in three replications. The influence of two factors on yield per plant was examined: genotype and location. Two-factor ANOVA showed a significant influence of genotype, location as well as genotype x location interaction on yield per plant . After the analysis of 20 genotypes at three different locations, the recorded average yield per plant was 2 .47 kg. Significantly higher yields per plant than the general average were recorded for genotypes K13 (3 .02 kg), K20 (2 .99 kg), K21 (3 .44 kg), K34 (4 .35 kg), K39 (4 .28 kg). The hig-hest yield had the genotype K34 at the location Vranovo (4 .71 kg). At the locatio of Smederevska Palanka, genotype K39 had the highest average value, while genotype K1 (1 .09 kg) had the lowest yield below the general average. Genotype K39 had a significantly higher yield per plant above the average value at the Kusadak site. Based on the results of AMMI analysis, it can be concluded that there are significant differences between locations, genotypes as well as interactions (Table 3). Of the total sum of squares, 86 .10% refers to the effect of genotype, while the sum of squares of genotype × location is three times higher than the sum of squares of location (10 .25% compared to 3 .07%). The most stable location based on the AMMI stability coefficient (0 .92) was Smede-revska Palanka, while the least stable was Kusadak (2 .34). Genotypes K13, K39, K36, with a yield above the general average, had a low value of PC1, which indicates that they were less influenced by locations, ie. that they had good yield stability in all locations . Genotype K34 stood out as the most productive genotype. Genotypes K3, K7, K16, K19 and K38 were below the average yield value but proved to be stable . The strongest interaction (ASV) was observed in genotypes K1 (below average yield) and K21, K25 (above average yield), where the last two are closely adapted to the location Kusadak.

Molecular characterization of heat tolerance in eggplant (Solanum melongena) lines using SSR markers

High temperature is one of the most important environmental stresses causing heavy reduction in yield of eggplant (Solanum melongena L.) in India. Therefore, development of heat tolerant eggplant variety is an important breeding objective. The present investigation was conducted to assess genetic variation among 62 eggplant lines including heat tolerant and susceptible lines in order to identify novel heat tolerant lines in changing climate in India. We employed 15 simple sequence repeat (SSR) markers to study polymorphisms among eggplant lines obtained from eggplant breeding program. The observations were analyzed using Power Marker version 3.5. The range of amplified number of bands was from 2 to 3 in each of 15 markers. The allele frequency was ranged from 0.5 to 0.7931 with an average of 2.067 alleles per locus. Among the 15 polymorphic SSR markers, 67% markers had PIC value higher than 0.3 with heterozygosity of individual loci was ranged from 0.00 to 0.1667. The marker emf01C03 had higher number of allele (3) and the marker emd03C01 had maximum PIC value and gene diversity. The NJ dendrogram obtained by 15 SSR markers divides 62 lines into 7 clusters where the cluster VII comprised of most heat tolerant lines (DBL-21, Guhala Chatua Local). The amplification pattern of heat tolerant lines also differ which implies different genetic architecture of heat tolerant lines. The research work will be very useful to combine these diverse sources of genetic variability to develop heat tolerant variety (s) in eggplant.

Genetic parameters of drought tolerance for agromorphological traits in eggplant, wild relatives, and interspecific hybrids

AbstractCrop wild relatives (CWRs) have barely been used in eggplant (Solanum melongena) breeding. However, introgression breeding may help in coping with the challenges posed by climate change. During the rainy and dry seasons, we evaluated nine accessions of eggplant, nine accessions of seven related species (of which six are CWRs and one is a cultivated relative), and 12 interspecific hybrids. Drought tolerance scores, calculated as ratios of growing rates and ratios of mean values during the rainy and dry seasons, were obtained for vegetative growth and yield‐related traits. Considering the vegetative growth and yield‐related traits evaluated, the F1 hybrid progenies of eggplant with S. insanum MEL1 × INS2 and MEL4 × INS3, S. anguivi MEL6 × ANG1, and S. dasyphyllum MEL6 × DAS1, plus the S. sysimbriifolium accession SIS1, displayed drought tolerance. Small to large gaps were observed between phenotypic and genotypic CVs of drought tolerance scores, reflecting variable influence of environmental factors on drought tolerance of the traits evaluated. In addition, the narrow‐sense heritability was generally moderate, indicating that genes with dominance and/or epistasis effects may be involved in the expression of drought tolerance. High genotypic correlations for drought tolerance scores between pairs of traits such as branching index and leaf length, leaf petiole diameter and plant height, number of stamens per flower, and fruit pedicel length suggest that drought tolerance of these traits is controlled by genes that are in linkage disequilibrium and/or have pleiotropic effects. The results are relevant for the development of drought‐tolerant cultivars of eggplant.