Hybrid Breeding Programs Research Articles

Little heterosis found in diploid hybrid potato: The genetic underpinnings of a new hybrid crop.

Hybrid potato breeding has become a novel alternative to conventional potato breeding allowing breeders to overcome intractable barriers (e.g. tetrasomic inheritance, masked deleterious alleles, obligate clonal propagation) with the benefit of seed-based propagule, flexible population design, and the potential of hybrid vigor. Until now, however, no formal inquiry has adequately examined the relevant genetic components for complex traits in hybrid potato populations. In this present study, we use a 2-step multivariate modeling approach to estimate the variance components to assess the magnitude of the general and specific combining abilities in diploid hybrid potato. Specific combining ability effects were identified for all yield components studied here warranting evidence of nonadditive genetic effects in hybrid potato yield. However, the estimated general combining ability effects were on average 2 times larger than their respective specific combining ability quantile across all yield phenotypes. Tuber number general combining abilities and specific combining abilities were found to be highly correlated with total yield’s genetic components. Tuber volume was shown to have the largest proportion of additive and nonadditive genetic variation suggesting under-selection of this phenotype in this population. The prominence of additive effects found for all traits presents evidence that the mid-parent value alone is useful for hybrid potato evaluation. Heterotic vigor stands to be useful in bolstering simpler traits but this will be dependent on target phenotypes and market requirements. This study represents the first diallel analysis of its kind in diploid potato using material derived from a commercial hybrid breeding program.

Estimation of combining ability and heterosis for yield and its component traits for identification of promising red rice (Oryza sativa L.) hybrids developed from new WA-based CMS lines and red kernel breeding lines

Combining ability analysis and heterosis enables plant breeders in anticipating improvement in productivity through hybridization and selection. In this study, line × tester mating design was used to develop 42 red rice hybrids by utilizing newly developed six WA-based CMS lines and seven testers selected from red kernel breeding lines at Zonal Agricultural Research Station, V.C. Farm, Mandya during kharif, 2018. The phenotypic performance of hybrids along with parents and checks were evaluated for grain yield and yield contributing traits. Analysis of variance revealed that variance due to the line × tester was significant for almost all the characters studied. Combining ability analysis revealed the predominance of non-additive gene action for most of the characters studied. On the basis of gca effects, CMS 2 among the lines and MO-21 among testers were identified as good general combiners for most of the traits studied. High sca effects were observed in the crosses, viz., CMS-1 × ME-19, CMS-2 × IET-14757 and CMS-4 × MSN-98 and they were also found to be the best combinations for grain yield and its component traits. The crosses CMS 5 × MSN-10-3, CMS 2 × ME-19 and CMS 5 × IET-14757 exhibited high mean grain yield and high standard heterosis over the standard commercial check KRH-4. These hybrids further need to be evaluated in multi-location trails for commercial exploitation of heterosis in red rice hybrid breeding program. Keywords: Hybrid rice, CMS, Combining ability, Heterosis, GCA, SCA &nbsp

Prediction of wheat quality parameters combining Raman, fluorescence, and near‐infrared spectroscopy (NIRS)

AbstractBackground and ObjectivesA high amount of the world wheat production is used for bread making. Due to its simplicity, wheat samples are traded based on protein content, although this is only an indirect measurement of baking quality. As direct bread quality traits like loaf volume, water absorption, and dough properties are cumbersome to measure along wheat supply chains and in wheat breeding programs, this study aims to predict directly dough properties and baking behavior by combining complementary information from near‐infrared, Raman, and fluorescence spectroscopy. Several proven data preprocessing and regression algorithms were evaluated, including partial least‐squares regression (PLSR) and genetic algorithm (GA).FindingsA highly diverse sample set of 415 wheat samples from a wheat hybrid breeding program was analyzed as whole grain, whole grain flour, and extracted flour. The best predictive models yielded a 10‐fold cross‐validated coefficient of determination R2 of .973, .873, .774, .835, .369, .447, .311, .512, .536, .723, and .715 for protein content, wet gluten, loaf volume, water uptake, elongation resistance to extension, extensibility, ratio number, extensograph energy, maltose number, plant height, and grain yield, respectively.ConclusionThe prediction accuracies are well suited for screening purposes in wheat breeding and allow better quality assessment compared to protein content along wheat supply chains.Significance and NoveltyIn this study, complementary spectroscopic techniques are combined for the first time to achieve higher prediction accuracy for a wide range of wheat quality parameters. In addition, Raman and fluorescence spectroscopy were used to predict quality data from a large sample set.

Evaluation of Germplasm and Development of Markers for Resistance to Plasmodiophora brassicae in Radish (Raphanussativus L.)

The rapid spread of clubroot disease caused by Plasmodiophora brassicae threatens radish (Raphanus sativus) production in China because some cultivation types lack clubroot-resistant (CR) genes. However, few molecular markers for clubroot resistance have been developed and used in hybrid breeding programs. In this study, 27 immune and 6 highly resistant accessions were identified among 95 radish inbred lines. The genes Rsa10003637 and Rsa10025569/Rsa10025571 were respectively identified from an XYB36-2 reference genome as the homologs of Crr1 and CRa from Brassica rapa by means of homology and synteny analysis. The association between the degree of clubroot resistance and the genotype of these CR genes suggested that Rsa10025569-H3 can be used as a clubroot-resistant haplotype. The sequence identity of Rsa10025569 in clubroot-resistant lines (CR-60 and CR-88) and clubroot-susceptible lines (CR-10 and CR-35) was 92.47%, and there was a 699 bp insertion at the end of the fourth exon in the clubroot-susceptible line. Association analysis of a BC1F1 population derived from the cross CR-88 (resistance) × CR-10 (susceptible) revealed an apparent correlation between polymorphisms at the Rsa10025569 locus and degree of clubroot resistance. On the basis of the results, molecular marker-assisted selection was used to transfer disease resistance genes to susceptible varieties and a new CR germplasm of Xinlimei was obtained.

The hybrid lethality of interspecific F1 hybrids of Nicotiana: a clue to understanding hybrid inviability-a major obstacle to wide hybridization and introgression breeding of plants.

Reproductive isolation poses a major obstacle to wide hybridization and introgression breeding of plants. Hybrid inviability in the postzygotic isolation barrier inevitably reduces hybrid fitness, consequently causing hindrances in the establishment of novel genotypes from the hybrids among genetically divergent parents. The idea that the plant immune system is involved in the hybrid problem is applicable to the intra- and/or interspecific hybrids of many different taxa. The lethality characteristics and expression profile of genes associated with the hypersensitive response of the hybrids, along with the suppression of causative genes, support the deleterious epistatic interaction of parental NB-LRR protein genes, resulting in aberrant hyper-immunity reactions in the hybrid. Moreover, the cellular, physiological, and biochemical reactions observed in hybrid cells also corroborate this hypothesis. However, the difference in genetic backgrounds of the respective hybrids may contribute to variations in lethality phenotypes among the parental species combinations. The mixed state in parental components of the chaperone complex (HSP90-SGT1-RAR1) in the hybrid may also affect the hybrid inviability. This review article discusses the facts and hypothesis regarding hybrid inviability, alongside the findings of studies on the hybrid lethality of interspecific hybrids of the genus Nicotiana. A possible solution for averting the hybrid problem has also been scrutinized with the aim of improving the wide hybridization and introgression breeding program in plants.

Combining Ability Analysis of Fruit Yield and Quality Traits in Tomato (Solanum lycopersicum L.)

Combining ability analysis is essentially required to isolate exceptional resource material for heterosis breeding programme. In this experiment combining ability of important agronomic and quality traits were estimated in 6 tomato parents and 30 crosses between them, in order to identify better parents with high combining ability and new recombinants with high yield and superior quality. The comparative heterosis analysis was also done using a commercially demanding variety Abhinav, as a standard check. The results indicated the involvement of both additive and non additive genetic effects in the expression of traits under study, however, preponderance of non-additive gene action was observed. The parents AVTO-2 and NTL-50 were the best performer for comprehensive parameters including yield and the cross combination AVTO-2 x JTL-08-15 was the best high-yielding combiner. The information and the genetic material generated in this study can be used in the future tomato hybrid breeding programme to develop new superior varieties

Unveiling combining ability and heterotic grouping of newly developed winter maize (Zea mays) inbreds

Pooled analysis of the test-crosses evaluation of 61 newly developed maize (Zea mays L.) inbred lines usingtwo inbred testers namely BML-6 and BML-7 during rabi 2016-17 and 2017-18 at ICAR-IIMR Regional Centre,Begusarai revealed significant variation among genotypes, general combining ability (GCA) and specific combiningability (SCA) effects for all the traits. Out of 61 inbred lines, 29 exhibited significant positive GCA effect for grainyield with maximum GCA effect value of 25.64. Inbred lines, viz. IMLSB-1299-5, IMLSB-406-2, IMLSB-334B-2,IMLSB-814-2 and IMLSB-285-1 were identified as the best general combiners on the basis of GCA effects whichcan be utilized to a greater extent in hybrid breeding programme. Out of 29 inbred lines with significant positive GCAeffects, 12 and 17 lines also showed significant positive SCA effects with tester, BML-7 and BML-6 respectively, thuswere classified into two heterotic groups ‘A’ and ‘B’, respectively. Out of 122 test-crosses, 14 exhibited significantand positive heterosis for yield over three national checks. The information generated on the heterotic grouping willhelp in further streamlining the available germplasm into heterotic pools and thereby augmenting the national hybridbreeding programme.

Organelle genome assembly uncovers the dynamic genome reorganization and cytoplasmic male sterility associated genes in tomato

To identify cytoplasmic male sterility (CMS)-associated genes in tomato, we determined the genome sequences of mitochondria and chloroplasts in three CMS tomato lines derived from independent asymmetric cell fusions, their nuclear and cytoplasmic donors, and male fertile weedy cultivated tomato and wild relatives. The structures of the CMS mitochondrial genomes were highly divergent from those of the nuclear and cytoplasmic donors, and genes of the donors were mixed up in these genomes. On the other hand, the structures of CMS chloroplast genomes were moderately conserved across the donors, but CMS chloroplast genes were unexpectedly likely derived from the nuclear donors. Comparative analysis of the structures and contents of organelle genes and transcriptome analysis identified three genes that were uniquely present in the CMS lines, but not in the donor or fertile lines. RNA-sequencing analysis indicated that these three genes transcriptionally expressed in anther, and identified different RNA editing levels in one gene, orf265, that was partially similar to ATP synthase subunit 8, between fertile and sterile lines. The orf265 was a highly potential candidate for CMS-associated gene. This study suggests that organelle reorganization mechanisms after cell fusion events differ between mitochondria and chloroplasts, and provides insight into the development of new F1 hybrid breeding programs employing the CMS system in tomato.

Evaluation of growth and yield traits in rice genotypes using multivariate analysis

Rice (Oryza sativa L.) is the first staple crop in terms of production and area of cultivation in Nepal. The amount of genetic variability is important factor in identifying suitable genotypes in rice breeding programs. This study was conducted in Khumaltar, Lalitpur, Nepal during rainy seasons of 2018 and 2019. Forty rice genotypes were planted in Alpha Lattice Design with two replications to determine the genetic diversity among them. The rice genotypes were grouped into 7 clusters based on growth and yield traits. The traits sucnamely plant height, panicle length, number of tillers/plant and grain yield were found highly significant (p < 0.01). Rice genotypes NR 10676-B-1-3-3-3 produced the highest yield (5.65 t/ha), followed by NR10410-89-3-2-1-1 (5.54 t/ha). The highest distance between cluster centroids (83.51) was found in the cluster 2 (Bange Masino, Hansa raj, Indrabeli, NR 11178-B-B-6-1, NR 11368-B-B-17, Pokhreli Jethobudho, Pokhreli Masino), and cluster 4 (IR73008-136-2-2-3, IR74052-95-3-2) indicating genetic dissimilarity among the genotypes which can be utilized in a hybrid breeding programme. Genotypes of cluster 2 had the highest grain yield (4.97 t/ha). The results of this study suggest that genotypes grouped in cluster 2 can be grown for higher grain production in mid-hills of Nepal.

Identification and Fine-Mapping of Quantitative Trait Loci Controlling Plant Height in Central European Winter Triticale (×Triticosecale Wittmack).

The quantitatively inherited trait plant height is routinely evaluated in triticale breeding programs as it substantially influences lodging and disease susceptibility, is a main contributor to biomass yield, and is required to improve hybrid seed production by fine-tuning plant height in the female and male parental pools in hybrid breeding programs. In this study, we evaluated a panel of 846 diverse Central European triticale genotypes to dissect the genetic architecture underlying plant height by genome-wide association mapping. This revealed three medium- to large-effect QTL on chromosomes 5A, 4B, and 5R. Genetic and physical fine-mapping of the putative QTL revealed that the QTL on chromosome 5R most likely corresponds to Ddw1 and that the QTL on chromosome 5A is likely to be Rht12. Furthermore, we observed a temporal trend in registered cultivars with a decreasing plant height during the past decades, accompanied by an increasing use of the height-reducing alleles at the identified QTL. In summary, our results shed new light on the genetic control of plant height in triticale and open new avenues for future improvement by breeding.

Genetic diversity and heterotic orientation of South Africa maize inbred lines towards tropical and temperate testers

An efficient hybrid breeding program defines and utilizes a few heterotic groups. Objectives of this study were to determine genetic diversity and alignment of South Africa maize inbred lines collection towards tropical and temperate testers. Forty-four maize inbred lines were genotyped with 56,110 single nucleotide polymorphism (SNP) markers. A total of 40 lines were crossed to two tropical and two temperate inbred line testers. Due to seed shortages, testcross hybrids containing 14 and 18 lines were used in 2014/2015 and 2015/2016 seasons, respectively. Genotypes and specific combining ability (SCA) effects of hybrids were significantly different (P < 0.05) for grain yield. There was a weak correlation between molecular genetic distances and both grain yield mean performance and SCA effects of hybrids, indicating that productivity of maize inbred lines could not be reliably determined based on molecular genetic distances. The SCA data classified these maize inbred lines into three heterotic groups with respect to both tropical and temperate testers. The study also indicated high level of diversity among the maize inbred lines, which was shown by both the dendogram and molecular genetic distances. The SNP marker data classified the inbred lines into 11 clusters that could be simplified into three major groups of normal maize endosperm and two groups of quality protein maize endosperm types. However, the SNP data indicated that maize lines were more aligned towards the tropical than temperate inbred testers. This information would be useful for simplifying heterotic classification of the lines with profound implications for breeding progress.

A nonS-locus F-box gene breaks self-incompatibility in diploid potatoes

Potato is the third most important staple food crop. To address challenges associated with global food security, a hybrid potato breeding system, aimed at converting potato from a tuber-propagated tetraploid crop into a seed-propagated diploid crop through crossing inbred lines, is under development. However, given that most diploid potatoes are self-incompatible, this represents a major obstacle which needs to be addressed in order to develop inbred lines. Here, we report on a self-compatible diploid potato, RH89-039-16 (RH), which can efficiently induce a mating transition from self-incompatibility to self-compatibility, when crossed to self-incompatible lines. We identify the S-locusinhibitor (Sli) gene in RH, capable of interacting with multiple allelic variants of the pistil-specific S-ribonucleases (S-RNases). Further, Sli gene functions like a general S-RNase inhibitor, to impart SC to RH and other self-incompatible potatoes. Discovery of Sli now offers a path forward for the diploid hybrid breeding program.

New PCR-specific markers for pollen fertility restoration QRfp-4R in rye (Secale cereale L.) with Pampa sterilizing cytoplasm

Pampa cytoplasmic male sterility phenomenon is used extensively in the rye hybrid breeding programs. It relies on sterilizing action of the cytoplasm resulting in non-viable pollen of female lines. The sterilizing effect is problematic for reversion, and efficient restores are needed. The most promising QTL is located on chromosome 4R, but other chromosomes may also code the trait. Advanced recombinant inbred lines formed bi-parental mapping population genotyped with DArTseq markers. Genetic mapping allowed the seven linkage groups to construct with numerous markers and represent all rye chromosomes. Single marker analysis and composite interval mapping were conducted to identify markers linked to the pollen fertility. Association mapping was used to detect additional markers associated with the trait. A highly significant QTL (QRfp-4R) that explained 42.3% of the phenotypic variation was mapped to the distal part of the long arm of the 4R chromosome. The markers localized in the QRfp-4R region achieve R2 association values up to 0.59. The homology of the 43 marker sequences to the loci responsible for fertility restoration in other species and transcription termination factor (mTERF) linked to Rf genes was established. Ten markers were successfully converted into PCR-specific conditions, and their segregation pattern was identical to that of unconverted DArTs.

The magic of genomics in creating hybrid potato

The magic of genomics in creating hybrid potato

Cultivation and characterization of primordial germ cells from blue layer hybrids (Araucana crossbreeds) and generation of germline chimeric chickens

The chicken (Gallus gallus) is one of the most common and widespread domestic species, with an estimated total population of 25 billion birds worldwide. The vast majority of chickens in agriculture originate from hybrid breeding programs and is concentrated on few commercially used high performance lines, whereas numerous local and indigenous breeds are at risk to become extinct. To preserve the genomic resources of rare and endangered chicken breeds innovative methods are necessary. Here, we established a solid workflow for the derivation and biobanking of chicken primordial germ cells (PGCs) from blue layer hybrids. To achieve this, embryos of a cross of heterozygous blue egg layers were sampled to obtain blood derived and gonadal male as well as female PGCs of different genotypes (homozygous, heterozygous and nullizygous blue-allele bearing). The total efficiency of established PGC lines was 45% (47/104) within an average of 49 days until they reached sufficient numbers of cells for cryopreservation. The stem-cell character of the cultivated PGCs was confirmed by SSEA-1 immunostaining, and RT-PCR amplification of the pluripotency- and PGC-specific genes cPOUV, cNANOG, cDAZL and CVH. The Sleeping Beauty transposon system allowed to generate a stable integration of a Venus fluorophore reporter into the chicken genome. Finally, we demonstrated that, after re-transfer into chicken embryos, Venus-positive PGCs migrated and colonized the forming gonads. Semen samples of 13 raised cell chimeric roosters were analyzed by flow cytometry for the efficiency of germline colonization by the transferred PGCs carrying the Venus reporter and their proper differentiation into vital spermatids. Thus, we provide a proof-of-concept study for the potential use of PGCs for the cryobanking of rare breeds or rare alleles.

Pearl Millet Blast Pathogen Virulence Study and Identification of Resistance Donors on Virulent Isolate

Pearl Millet leaf Blast caused by Pyricularia grisea [teleomorph: Magnaporthe grisea], is spreading at an alarming rate in the major Pearl millet growing geographies of India effecting grain yield and green fodder yield. Blast isolates collected from Jaipur, Alwar and Toopran regions of India and virulence study conducted to identify the most virulent isolate among the three isolates. Artificial screening for Blast conducted on a raised bed method utilising uniform Blast Nursery (UBN) method. Eleven Pearl Millet genotypes (ICMB01333, ICMB03444, ICMB03555, ICMB06111, ICMB95444, ICMB11666, ICMB14333, ICMB14666, ICMB97111, ICMR12888 and ICMR06444) were screened with three blast isolates utilising artificial screening method. Among the eleven genotypes, ten genotypes were showing susceptible to Jaipur isolate indicating that the Jaipur isolate having highest virulence among the three isolates. To identify Blast resistant donors for Jaipur isolate, a set of 93 genotypes containing of 45 maintainer lines and 48 restorer lines were screened under both UBN and field conditions (Jaipur, Rajasthan). Among all the lines evaluated, five lines are showing resistant reaction for Jaipur isolate with disease score less than 1.9. ICMR06444 from restorer background and IC414K14B5, IC594K16B5, RBB037 and IC6912K18B from maintainer background are identified as resistant lines. Identified lines can be utilised in pearl millet hybrid breeding programme.

Back to the future: implications of genetic complexity for the structure of hybrid breeding programs.

Commercial hybrid breeding operations can be described as decentralized networks of smaller, more or less isolated breeding programs. There is further a tendency for the disproportionate use of successful inbred lines for generating the next generation of recombinants, which has led to a series of significant bottlenecks, particularly in the history of the North American and European maize germplasm. Both the decentralization and the disproportionate contribution of inbred lines reduce effective population size and constrain the accessible genetic space. Under these conditions, long-term response to selection is not expected to be optimal under the classical infinitesimal model of quantitative genetics. In this study, we therefore aim to propose a rationale for the success of large breeding operations in the context of genetic complexity arising from the structure and properties of interactive genetic networks. For this, we use simulations based on the NK model of genetic architecture. We indeed found that constraining genetic space through program decentralization and disproportionate contribution of parental inbred lines, is required to expose additive genetic variation and thus facilitate heritable genetic gains under high levels of genetic complexity. These results introduce new insights into why the historically grown structure of hybrid breeding programs was successful in improving the yield potential of hybrid crops over the last century. We also hope that a renewed appreciation for “why things worked” in the past can guide the adoption of novel technologies and the design of future breeding strategies for navigating biological complexity.

Genome-Wide Association and Prediction of Male and Female Floral Hybrid Potential Traits in Elite Spring Bread Wheat Genotypes.

Hybrid wheat breeding is one of the most promising technologies for further sustainable yield increases. However, the cleistogamous nature of wheat displays a major bottleneck for a successful hybrid breeding program. Thus, an optimized breeding strategy by developing appropriate parental lines with favorable floral trait combinations is the best way to enhance the outcrossing ability. This study, therefore, aimed to dissect the genetic basis of various floral traits using genome-wide association study (GWAS) and to assess the potential of genome-wide prediction (GP) for anther extrusion (AE), visual anther extrusion (VAE), pollen mass (PM), pollen shedding (PSH), pollen viability (PV), anther length (AL), openness of the flower (OPF), duration of floret opening (DFO) and stigma length. To this end, we employed 196 ICARDA spring bread wheat lines evaluated for three years and genotyped with 10,477 polymorphic SNP. In total, 70 significant markers were identified associated to the various assessed traits at FDR ≤ 0.05 contributing a minor to large proportion of the phenotypic variance (8–26.9%), affecting the traits either positively or negatively. GWAS revealed multi-marker-based associations among AE, VAE, PM, OPF and DFO, most likely linked markers, suggesting a potential genomic region controlling the genetic association of these complex traits. Of these markers, Kukri_rep_c103359_233 and wsnp_Ex_rep_c107911_91350930 deserve particular attention. The consistently significant markers with large effect could be useful for marker-assisted selection. Genomic selection revealed medium to high prediction accuracy ranging between 52% and 92% for the assessed traits with the least and maximum value observed for stigma length and visual anther extrusion, respectively. This indicates the feasibility to implement genomic selection to predict the performance of hybrid floral traits with high reliability.

PARENTAL SELECTIONS IN SORGHUM (SORGHUM BICOLOR L.) ON THE BASIS OF HETEROSIS AND COMBINING ABILITY IN ASSOCIATION WITH SSR DIVERSITY IN SUB-TROPICAL PLAINS OF UTTARAKHAND, INDIA

Selection of genetically diverse and complementary parents for important key traits is most difficult task in any hybrid breeding programme. The objective of this study was to estimate heterosis and relative combining abilities with associated SSR diversity for identification of unique sorghum genotypes. A total of forty crosses and thirteen parental lines including five cytoplasmic male sterile (CMS) lines and eight pollinator lines with two standard check varieties were phenotyped using six agro-morphological traits and genetic diversity was estimated by using five polymorphic SSR markers. Sorghum genotypes were crossed with CMS lines using a line × tester mating design and 40 hybrids, 13 parents and two check varieties were field-evaluated using alpha lattice design with three replications. General combining ability (GCA), specific combining ability (SCA) and heterosis for grain yield and other associated attributes were determined. SSR diversity estimates were ranged from 0.54 to 0.90. Among CMS lines, 11A2 and MR750A2 and among pollinators, UPC2 and M35-1 were reported as best general combiners. A2 cytoplasm was found to be more efficient to produce more heterotic combination with experimental lines. Cross, 11A2 x UPC2 gave best results of heterosis for most of the characters. MR750 A2 x UPC2, 11A2 x UPC2, ICSA467 x UPC2, ICSA467 x CS3541, ICSA 467 x RS29, ICSA 467 x M35-1 and 11A2 x M35-1 revealed significant and positive values of heterosis, SCA and GCA. However, no direct correlation was detected with heterosis and molecular diversity for most of the characters. These results may be used for the exploitation of hybrid vigor in sorghum breeding programmes

An assessment of genetic diversity and combining ability of elite castor genotypes suitable for rainfed conditions

A study was conducted to assess the diversity of 72 castor genotypes used as male lines in the hybrid breeding programme in India using multivariate analysis in addition to morphological characterization using DUS (Distinctiveness, Uniformity and Stability) testing guidelines of castor. Fifteen agronomical and three morphological traits were measured in 72 genotypes in field studies conducted for two years. The multivariate data set was subjected to genetic divergence analysis using Mahalonobis’ D2 static and clustered into nine subgroups following Tocher’s method in addition to Principal Component Analysis (PCA). The genotypes from Clusters 1 and 5 and Clusters 2 and 5 are genetically diverse with 556.9 and 469.7 units while cluster 7 genotypes with higher mean seed yield are potential candidates as varieties after multilocation testing. In PCA, the first two canonical variants were significant and accounted for 68 per cent of the inter accession variability. Grouping of castor genotypes was also done based on four grouping characteristics of DUS guidelines like stem color, bloom, capsule spines and maturity. Combining ability analysis indicated that DCS-96, DCS-94, DCS-104, DCS-97 were good general combiners for seed yield while M-568 x DCS-96 yielded 21 per cent standard heterosis over the best check DCH-177.