True Hybrids Research Articles

Application of SSR Markers for Purity Testing of Hybrid Wheat (Triticum aestivum L.)

Exploitation of the full potential of any hybrid requires the possessing of genetically high-purity seeds. In order to avoid reduction in yield caused by using low purity seeds, development of a simple, rapid, and accurate method for hybrid purity assessment is of great essence and significance. For the identification of true hybrids, SSR markers provides authentic information that will help to the further progress of any research programme. In this study, total of 40 wheat hybrids and 14 parental lines were taken for the hybrid purity analysis with 20 SSR markers. These markers were used to find out the codominant loci in the hybrid and single dominant loci in parents. Out of 20 SSR markers, only 8 markers viz., Xwmc617, Xwmc457, Xwmc48, Xgwm153, Xbarc61, Xgwm273, Xbarc268 and Xgwm274 showed the polymorphic dominant loci in the parents and co-dominant loci midway between these parents. Therefore these SSR markers were used to confirm the forty hybrids. The range of allele size produced by SSR marker on the parental lines were 120 bp to 300 bp. The highest allel size (300 bp) was produced by marker Xbarc 268 whereas, the minimum allel size (120 bp) was produced by marker Xgwm 273. All the fourty hybrids showed similar banding pattern as parental lines, this proved the purity of hybrids in all these cross combinations. The confirmation of hybrid purity indicated that a single polymorphic marker was sufficient for detection of contaminations of these hybrids from their parents.

Genetic diversity and identification of interspecific hybrids of Anacardium species using microsatellites

Study of genetic diversity and interspecific hybridizations plays an imperative role in the genetic improvement of crop plants. Microsatellite or simple sequence repeats (SSRs) markers have been the marker of choice for many genetic studies in perennial tree crops. In this study, genetic diversity of 23 cashew (Anacardium occidentale L.) germplasm accessions with unique traits was carried out using the cashew SSR (CSSR) markers. Besides, true hybridity of the interspecific hybrids of A. occidentale and A. microcarpum Ducke was investigated. Eight of the 21 CSSRs screened in 10 diverse accessions were polymorphic and used for genetic diversity analysis in 23 accessions. Major allele frequency ranged from 0.50 to 0.98; gene diversity ranged from 0.10 to 0.50, and polymorphism information content (PIC) ranged from 0.10 to 0.38 for the surveyed SSR loci. Dendrogram analysis of 23 accessions formed two main clusters with two sub-clusters in each. Clustering of the accessions had no relationship with the geographic region of collection. In tree hybridizations, early screening methods are becoming indispensable to ascertain the true hybridity of progenies to save the costs and resources. For the first time, three CSSR markers that detect the true hybridity of interspecific hybrids of cashew and its wild relative A. microcarpum were identified. Hybrid purity index of the progenies in interspecific crosses varied from 67 to 100%. These three CSSR markers capable of distinguishing the two Anacardium species could be useful in evolutionary studies involving these species and their natural hybrids in the wilds.

Development of Mapping Population and Validation of Molecular Markers Associated with MYMV Resistance in Mungbean

Background: Mungbean yellow mosaic virus disease is the most devastating disease on Mungbean production. The virus is transmitted by whitefly and can cause yield losses from 75 to 100 per cent. The development of mungbean cultivars resistant to both virus and its vector is considered as one of the most desirable means of managing the disease as it is environmentally safe and highly efficient. The selection of resistant genotypes in conventional methods is complex and time consuming. Hence, the use of molecular markers linked with resistance genes is powerful as it hastens the breeding programmes. The current study was aimed to develop mapping population and to validate molecular markers associated with Mungbean yellow mosaic virus (MYMV). Methods: The present investigation was carried out with 260 F2 individuals that were derived from crossing DGGV-2 and IPM 2-14 during Kharif-2017 at Main Agril Research Station, UAS, Dharwad. Hybrid seeds of this cross were harvested individually and sown during rabi 2017 along with the two parents, as checks for distinguishing the true hybrids. Hybridity of F1s was confirmed through molecular marker analysis and the true F1s were selfed to raise the F2 generation. Result: Of the 24 previously reported simple sequence repeat markers used for detecting the polymorphism, two markers viz., CEDG305 and CEDG115 were found to be polymorphic between DGGV-2 and IPM-2-14. Two hundred and sixty F2 plants segregated in the ratio of 3 S:1 R (202 susceptible: 58 resistant) as phenotypic and 1: 2 :1 as genotypic ratio implying that single recessive gene controlled resistance. Single marker analysis revealed that the molecular markers CEDG305 and CEDG115 were associated with MYMV resistance with a phenotypic variance of 24.5 and 10.3 per cent respectively.

Identification of useful recombinants from interspecific hybrids of Citrullus lanatus and C. colocynthis

Watermelon (Citrullus lanatus) is an important fruit crop in the arid region of western India. The modern watermelon cultivars share a narrow genetic base and are susceptible to various stresses. Thus, there is a need to expand its genetic base through distant hybridization by interspecific crossing with C. colocynthis. An attempt was made to develop interspecific hybrids between lanatus and colocynthis followed by hybridity testing of F1 through SSR markers and biochemical analysis of F2. Out of nine primers, eight primers could successfully show amplification in parents and hybrids out of which two markers could correctly discriminate the true hybrid. The morphological analysis demonstrated that F1 progeny resembles much with C. colocynthis for most of the characters. Biochemical analysis of pulp of selected F2 plants and parents indicated that in many F2 plants biochemicals were higher than parents which suggest that the blending of genes from both species made a favourable effect. Diterpene was only present in watermelon and not detected in C. colocynthis or any of the F2 plants. GC–MS based fatty acid profiling of nine identified fatty acids namely palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid was done. It can be concluded that the interspecific hybrids between water melon and C. colocynthis as also confirmed by molecular markers and superior F2 plants can be used in watermelon breeding program for enhancing vital phytochemicals.

In Support of Winge's Theory of "Hybridization Followed by Chromosome Doubling".

Polyploidy—or chromosome doubling—plays a significant role in plant speciation and evolution. Much of the existing evidence indicates that fusion of unreduced (or 2n) gametes is the major pathway responsible for polyploid formation. In the early 1900s, a theory was put forward that the mechanism of “hybridization followed by chromosome doubling” would enable the survival and development of the hybrid zygote by providing each chromosome with a homolog with which to pair. However, to date there is only scant empirical evidence supporting this theory. In our previous study, interspecific-interploid crosses between the tetraploid Hylocereus megalanthus, as the female parent, and the diploid H. undatus, as the male parent, yielded only allopentaploids, allohexaploids, and 5x-and 6x-aneuploids instead of the expected allotriploids. No viable hybrids were obtained from the reciprocal cross. Since H. undatus underwent normal meiosis with regular pairing in the pollen mother cells and only reduced pollen grains were observed, the allohexaploids obtained supported the concept of “chromosome doubling.” In this work, we report ploidy level, fruit morphology, and pollen viability and diameter in a group of putative hybrids obtained from an embryo rescue procedure following controlled H. megalanthus × H. undatus crosses, with the aim to elucidate, for the first time, the timing and developmental stage of the chromosome doubling. As in our previous report, no triploids were obtained, but tetraploids, pentaploids, hexaploids, and 5x- and 6x-aneuploids were found in the regenerated plants. The tetraploids exhibited the morphological features of the maternal parent and could not be considered true hybrids. Based on our previous studies, we can assume that the pentaploids were a result of a fertilization event between one unreduced (2n) female gamete from the tetraploid H. megalanthus and a normal (n) haploid male gamete from H. undatus. All the allohexaploids obtained from the embryo rescue technique where those that regenerated from fertilized ovules 10 days after pollination (at the pro-embryo stage), showing that the chromosome doubling event occurred at a very early development stage, i.e., at the zygote stage or shortly after zygote formation. These allohexaploids thus constitute empirical evidence of “hybridization followed by chromosome doubling.”

Production and characterization of intergeneric hybrids by crossing radish with turnip and with Chinese kale

Distant hybridization can enrich the genetic background and diversity of crops by combining different species, and integrate the favorable parental traits or create heterosis. In the present study, intergeneric hybridization was performed between radish and turnip and between radish and Chinese kale by hand emasculation followed by tissue culture of putative hybrid seeds. A total of three and one hybrids were obtained from the cross of ‘Long yellow turnip’ and ‘Golden turnip’ with radish, respectively, but no hybrids were obtained in their reverse cross, indicating that the same cross combination has a large difference in the reciprocal crosses, and that the hybrid has certain unidirectionality. The majority of the hybrids of radish and turnip showed male sterility, white petals, and intermediate performance in most morphological traits when compared to their parents. Four true hybrids were obtained by the cross ‘Thin neck round radish’ × ‘Yellow flower kale’, while no hybrids were obtained by reverse cross combination. The hybrids looked more like their Chinese kale parents in having inflated stems. All putative intergeneric hybrids were confirmed by agronomic characteristics, chromosome counting, molecular markers, and pollen viability. Three kinds of hybrids were confirmed as genuine hybrids possessing 19, 19, and 18 chromosomes in their corresponding somatic cells by cytological observation. In addition, three kinds of allotetraploids were produced with 38, 38, and 36 chromosomes when chromosome doubling was achieved. In comparison with the diploid hybrid, the pollen viabilities of allotetraploids were significantly improved and a small number of seeds were produced. The improvements of these amphihaploids as useful genetic resources and the potential of intergeneric hybridization to enlarge the gene pool for radish, turnip, and Chinese kale breeding are discussed.

Production of allohexaploid Brassica hybrid between tuber mustard (Brassica juncea L. var. crassicaulis Chen &Yang) and Chinese kale (Brassica oleracea var. alboglabra Bailey)

Brassica is a key agricultural genus, containing oilseed and vegetable crops, which includes three major genomes (A, B and C), distributed in diploid (genomes: AA, BB and CC) and allotetraploid species (genomes: AABB, AACC and BBCC). Interspecific hybridization between Brassica species is an important way to combine valuable characters from the different species. In the present study, distant hybridization between inbred lines of tuber mustard (Brassica juncea var. crassicaulis Chen &Yang; AABB) and Chinese kale (Brassica oleracea var. alboglabra Bailey; CC) was conducted and allotriploid interspecific hybrids were identified. The hybrid seed set was improved by gibberellin treatment of the stigmas prior to pollination. Eight hybrid seedlings were obtained by bud pollination and ovary culture, and all seedlings were confirmed to be true hybrids by phenotypic analysis, cytological observation (27 chromosomes) and the use of parent-specific randomly amplified polymorphic DNA (RAPD) molecular markers. After tissue culture and colchicine-induced chromosome-doubling treatment, allohexaploid hybrids (AABBCC) were isolated and identified from the eight hybrids. The chromosomes of five plants were completely doubled, with a doubling rate of 5.68 %, and the number of chimeric plants was 24, at a rate of 27.27 %, when roots were immersed in 0.1 % colchicine solution. In comparison with the allotriploid hybrid, the synthetic hexaploid hybrids showed unique phenotypes with normal anthers, well-developed pods, larger flowers and petals, thicker stems than either parent and other phenotype types intermediate between the two parents. In the present study, synthetic tri-genomic Brassica vegetable germplasm, combining the A, B and C genomes, was created for use in vegetable breeding, as well as for a basis for further investigation of the mechanisms of Brassica evolution and adaptation. The current study is of great significance for the use of these allohexaploid plants to explore the heterotic effects of distant hybridization and for genetic improvement.

Confirmation of an interspecific hybrid of Drimia based on mitotic, stomatal and ISSR marker analyses

An interspecific hybrid between Drimia govindappae (♀) (2n = 2x = 20) and D. coromandeliana (♂) (2n = 4x = 40) was generated by artificial hand pollination. Mitotic, stomatal and ISSR analyses confirmed that the F1 plant was intermediate between the parents and exhibited the hybrid nature. The F1 plant had 2n = 3x = 30 chromosomes in root-tip cells. Stomata were anomocyctic and the size 42.59 × 34.38 µm. The ISSR primer analysis revealed transmission of both male and female specific bands to F1 plants thereby confirming their true hybrid nature. Dendrograms based on the discriminative ISSR markers (ISSR834 and ISSR836) also showed the similarity of F1 plant profile to male and female parents.

A Novel Flexible Hybrid Battery-Supercapacitor Based on a Self-Assembled Vanadium-Graphene Hydrogel

Batteries and supercapacitors are considered as key technologies for portable and wearable electronics which require lightweight, highly efficient and often flexible energy storage systems. Batteries can store a high amount of specific energy but deliver electricity at rather low current densities due to their intrinsically low power-handling capabilities. In contrast, supercapacitors can provide high specific power with outstanding cyclic stability and efficiency but have a low energy content. Thus, a key challenge for the fabrication of wearable/portable power sources is to simultaneously increase the energy and power densities, along with high durability, rapid charging, and facile scalability.In this work, we introduce a novel hybrid energy storage system that employs an innovative self-assembled graphene hydrogel which encapsulates a (vanadium IV) redox species that can exist in more than two oxidation states. These vanadium-graphene hydrogels can be cut into slices and pressed on a carbon cloth to form a flexible thin-film electrode of around ~180 µm thickness and with a mass loading of 3.3 mg cm-3. To assemble the hybrid device, a cationic-exchange membrane is sandwiched between two identical hydrogel electrodes. During the initial charging of the device, the vanadium IV is oxidized to vanadium V at the positive electrode and reduced to vanadium (III) at the negative electrode. The high surface area of the graphene hydrogel matrix (> 1000 m2/g) enables the supercapacitor mechanism of the hybrid. The different oxidation state of the encapsulated vanadium electrolyte induces a cell potential (~0.9 V) which grants the battery mechanism to the hybrid device. The combination of both mechanisms results in an outstanding capacity of 225 mA/g and unique characteristics of this power source. The capacity is roughly 8 times higher than that of a comparable graphene hydrogel supercapacitor without vanadium content, but the charging time is only double demonstrating a fast charging ability. The device also shows a true hybrid behavior. When operated with high current densities, it works like a supercapacitor and loses only 5% of its capacitance over 1000 charge/discharge cycles. When operated with low current densities, it shows characteristics of a battery. Here, the capacity losses are rather 40% to 50% over 1000 cycles. However, these losses can be easily restored by simple electric measures and there is only a 7% capacity loss after 1000 cycles and a restoration cycle. Our investigations suggest that during self-discharge, capacitance losses are partially converted into capacity through vanadium redox reactions which mitigates the self discharge. Additionally, the self-discharge does not permanently damage the hybrid device. The reason for these outstanding features are related to the simple design. Both half-cells initially consist of the same vanadium graphene hydrogel. Although ion crossover lowers the efficiency and triggers self-discharge, a complete discharge of the device converts all species, including those that crossed over, back to their initial redox state and, thus, resets the device to its initial condition. The mechanical robustness and flexibility of the device are investigated at different bending conditions. The results show a capacity retention of 97% at a bending angle of 135°, indicating excellent integrity of electrode materials under mechanical stress. Our work demonstrates that the novel concept of utilizing a redox species which can exist in more than two redox states, along with a high surface area electrode, presents a facile, scalable and high-performance design for hybrid battery-supercapacitors while the fabrication is considerably simplified. Figure 1

Spectral photon sorting for large-scale Cherenkov and scintillation detectors

We describe here measurements with a new device, the "dichroicon," a Winston-style light concentrator built out of dichroic reflectors, which could allow large-scale neutrino detectors to sort photons by wavelength with small overall light loss. Photon sorting would benefit large-scale water or ice Cherenkov detectors such as Hyper-Kamiokande or ICECUBE by providing a measure of dispersion, which in turn could allow improved position reconstruction and timing. For scintillator detectors like JUNO, upgrades to SNO+ or KamLAND-ZEN, or to water-based liquid scintillator detectors like Theia, dichroicons would provide effective discrimination between Cherenkov and scintillation light, allowing them to operate as true hybrid detectors. We include measurements with a prototype dichroicon using first a Cherenkov source to show spectral photon sorting works as expected. We then present measurements of two different LAB-based liquid scintillator sources, and demonstrate discrimination between Cherenkov and scintillation light. On the benchtop we can identify Cherenkov light with better than 90% purity while maintaining a high collection efficiency for the scintillation light. First results from simulations of a large-scale detector are also presented.

Developing of transgenic glyphosate-tolerant Indica restorer line with commercial application potential

Hybrid rice breeding offers an important strategy to improve rice production, and therefore is crucial for ensuring worldwide food security. Purity of hybrids is a key factor in keeping the high production of hybrid rice. While another important thing is mechanical weeding of hybrid rice, which could greatly release labor from laborious work and cut the production cost. Both of these two problems could be partly resolved by developing glyphosate-tolerant restorer lines. In this study, a novel glyphosate-tolerant gene I.variabilis-EPSPS* was transferred into elite indica restorer line Minghui 86 (MH86) by Agrobacterium-mediated transformation. By Southern blot and inverse PCR analysis, 3 transgenic restorer lines (MY28, MY50, and MY51) with a single copy of I.variabilis-EPSPS* integrated into the intergenic regions were selected from 72 regenerated transgenic plants. The inheritance of I.variabilis-EPSPS* in the 3 transgenic restorer lines was proved to follow Mendelian inheritance by germinating test. In the following generations, according to Southern blot, Northern blot, 3’RACE, and Western blot, I.variabilis-EPSPS* were proved to stably inherit and express in the candidate transgenic restorer lines. At the same time, glyphosate tolerance assay was performed in the field, in which the candidate transgenic restorer lines kept normal agronomic traits under glyphosate treatments with a dosage as high as 8400 g/ha. Therefore, the candidate transgenic restorer lines were highly tolerant to glyphosate. The 3 candidate transgenic restorer lines were respectively hybridized with the male sterile line II-32A, and their hybrids were respectively named as MY28H, MY50H, and MY51H. According to Southern blot and Western blot analysis, I.variabilis-EPSPS* could stably inherit to F1 hybrids and express in these hybrids, which indicated that the true hybrids could be distinguished by I.variabilis-EPSPS*. In the field test, the transgenic hybrids with I.variabilis-EPSPS* could suffer 3360 g/ha glyphosate without the damage of agronomic traits, which indicated the application potential of these hybrids in direct seeding. Collectively, the transgenic glyphosate-tolerant restore lines developed in this study were highly tolerant to glyphosate, and they had potential to be used in commercial production of hybrid rice.

Assessment of genetic purity of two sunflower (Helianthus annuus L.) hybrids using sequence characterized amplified region (SCAR) markers

Random amplified polymorphic DNA (RAPD) technique is easier to identify true hybrids. However, it hasinherent disadvantage of less reproducibility and that can be overcome by conversion of RAPD markers into sequence characterized amplified region (SCAR) markers. In the present investigation, RAPD analysis was carried out with the two hybrids, KBSH 41 and KBSH 42 along with their parents, polymorphic markers were identified and those markers were converted into SCAR markers. These markers would be of immense potential during routine genetic purity assessment of the two sunflower hybrids.

Miniature inverted-repeat transposable elements (MITEs), derived insertional polymorphism as a tool of marker systems for molecular plant breeding.

Plant molecular breeding is expected to give significant gains in cultivar development through development and utilization of suitable molecular marker systems for genetic diversity analysis, rapid DNA fingerprinting, identification of true hybrids, trait mapping and marker-assisted selection. Transposable elements (TEs) are the most abundant component in a genome and being used as genetic markers in the plant molecular breeding. Here, we review on the high copious transposable element belonging to class-II DNA TEs called "miniature inverted-repeat transposable elements" (MITEs). MITEs are ubiquitous, short and non-autonomous DNA transposable elements which have a tendency to insert into genes and genic regions have paved a way for the development of functional DNA marker systems in plant genomes. This review summarises the characteristics of MITEs, principles and methodologies for development of MITEs based DNA markers, bioinformatics tools and resources for plant MITE discovery and their utilization in crop improvement.

Production, Identification and Characterization of Erianthus rockii × Narenga porphyrocoma Intergeneric Hybrids as a New Germplasm for Sugarcane Breeding and Genetic Research

As the wild relative genera of sugarcane, Narenga porphyrocoma and Erianthus rockii are becoming more potential germplasm sources due to valuable traits in sugarcane breeding. Many previous studies were performed to integrate the desirable characters from wild species into modern sugarcane cultivars. Until now, the lack of fertility in hybrids is still a thorny problem in most cases. In our present study, a rare hybrid between E. rockii (2n = 30) and N. porphyrocoma (2n = 30) had been developed for the first time. The molecular primers MSSCIR66, SMC720BS and SMC597CS were successfully applied to identify the putative F1 hybrids. Besides, the chromosome composition and transmission have also been reported to screen the true F1 hybrids via genomic in situ hybridization. From the breeding point of view, the implications of gene introgression from N. porphyrocoma and E. rockii are discussed.

Intra- and interspecific diversity analyses in the genus Eremurus in Iran using genotyping-by-sequencing reveal geographic population structure

Eremurus species, better known as ‘Foxtail Lily’ or ‘Desert Candle’, are important worldwide in landscaping and the cut-flower industry. One of the centers of highest diversity of the genus Eremurus is Iran, which has seven species. However, little is known about the genetic diversity within the genus Eremurus. With the advent of genotyping-by-sequencing (GBS), it is possible to develop and employ single nucleotide polymorphism (SNP) markers in a cost-efficient manner in any species, regardless of its ploidy level, genome size or availability of a reference genome. Population structure and phylogeographic analyses of the genus Eremurus in Iran using a minimum of 3002 SNP markers identified either at the genus level or at the species level from GBS data showed longitudinal geographic structuring at the country scale for the genus and for the species E. spectabilis and E. luteus, and at the regional scale for E. olgae. Our analyses furthermore showed a close genetic relatedness between E. olgae and E. stenophyllus to the extent that they should be considered subspecies within an E. olgae/stenophyllus species complex. Their close genetic relatedness may explain why crosses between these two (sub)species have been found in the wild and are exploited extensively as ornamentals. Last, current species identification, while robust, relies on flower morphology. A subset of seven SNPs with species-specific (private) alleles were selected that differentiate the seven Eremurus species. The markers will be especially useful for cultivar protection and in hybrid production, where true hybrids could be identified at the seedling stage.

Cut-style Pollination Can Effectively Overcome Prefertilization Barriers of Distant Hybridization in Loquat

Loquat [Eriobotrya japonica (E. japonica)], a small genus of the subtribe Malinae that consists of ≈30 species, is an evergreen rosaceous fruit tree that is native to southeastern China, and some wild species that possess novel, favorable traits have excellent breeding potential. For example, Eriobotrya bengalensis blooms in late spring and ripens in early autumn in Guizhou Province, China, which prevents cold injury in winter by breeding spring-flowering cultivars using the special characters. Therefore, in the present study, the pollination treatments of cut-style pollination were evaluated that may promote successful distant hybridization in Eriobotrya japonica ‘Dawuxing’ × Eriobotrya deflexa and E. japonica ‘Dawuxing’ × E. bengalensis. The results indicated that the impairment of the pollen tube growth in the upper third of the style after pollen germination is an important factor leading to the failure of distant hybridization between the species tested in E. japonica, and that cut-style pollination can effectively overcome prefertilization barriers of the distant hybridization combination. Furthermore, the results of allele-specific polymerase chain reaction (AS-PCR) showed that S-genotypes, in accordance with the S-RNase heredity to separate the rule completely in offspring, should be both parents' S-RNase, and that the random 50 seedlings of Eb-2 and Ed-2 are true hybrids.

Hybridity testing of tomato F1 progenies derived from parents with varying fruit quality and shelf life using single nucleotide polymorphism (SNPs)

The demand for tomato is increasing day by day mostly because of the increased per capita fresh fruit consumption. Nonetheless as a perishable fruit crop, it has relatively short life after ripening thus experiences remarkable post-harvest losses. The study was to select true F1 hybrids using SNPs for the development of inbred lines with long shelf life character through marker assisted backcrossing. Nine out of the one hundred and forty SNP markers failed, 93 were uninformative and 38 were polymorphic and spread across the 12 chromosomes. The major allele frequency, gene diversity, heterozygosity and Polymorphic Information Content (PIC) for each locus were calculated for SNP markers using Power Marker 3.5. The mean value of the major allele frequency was 0.673, ranging between 0.529 and 0.794. The average gene diversity and Heterozygosity values were 0.419 and 0.125 respectively. The PIC ranged from 0.273 (Sly11-Rx4) to 0.375 (Sly04-9) with a mean of 0.329. Of the 31 polymorphic SNPs, two SNPs (Sly04-9 and Sly07-2) exhibited the maximum PIC and a gene diversity value of 0.50. The markers Sly11-13 and Sly11-Rx4 were found to be the least informative with PIC and gene diversity values equaling 0.327 and major allele frequency of 0.794. The maximum heterozygosity was observed with SNP markers Sly03-8, Sly06-7, Sly08-1, Sly08-8, while the minimum heterozygosity was observed with SNPs marker Sly02-9, Sly06-1, Sly10-4, Sly10-5, Sly11-13, Sly11-Rx4, and Sly12-9.The SNPs tested for shelf life genes rin (Sly05-rin1 and Sly05-rin2) and nor (Sly10-nor) were monomorphic within the seven different plants (parentals). The SNP (Sly10-alc) tested for the alc gene was however, polymorphic within the seven lines. The result indicates that only one SNP (Sly10-alc) is a functional SNP to detect a long shelf life gene. Tomato genotypes CSIR/CRI-P002 and CSIR/CRI-ATS064 were however, polymorphic for alc. The other SNPs for rin and nor were not useful and new SNPs are needed to be redesigned. The molecular test revealed two superior F1 hybrids which were selected for evaluation as lines for improvement. The advantage is the reduction in cost, time, labor and field space requirement.

Isolation and Identification of Molecular Markers for Fingerprinting of Chilli Hybrids & its Parental Lines

Chilli (Capsicum annum) is the predominant sp., which is cultivated in both hot and sweet papers. The maintenance of the genetic purity of chilli plant is a matter of great concern for the breeders. For genetic purity analysis, between true hybrids and off-types, breeders find out morphological differences between them, but this technique is cannot be recognized easily and also costly, tedious to score, and environmentally sensitive. Alternatively, molecular markers based genetic purity analysis can be employed. The molecular marker-based technique was thus used to overcome the conventional method drawbacks. The main objective of the study is to identify informative molecular markers (ISSR and RAPD) capable of distinguishing Chilli hybrids and their parental lines and their utilization in seed purity assessment. Five parental lines of Chilli (i.eCH10, CH12, CH530, CH709, CH734) were used for the production of 3 hybrids. Total 30 ISSR and 8 RAPD primers were selected for the study of 5 parental lines, among them 2ISSR and 1 RAPD primers produced unique fingerprinting across the hybrids. The ISSR marker UBC815 amplified alleles specific to different parental lines(CH10 & CH12) for hybrids (ACH112), The ISSR marker UBC 827, amplified alleles specific to different parental lines(CH709 & CH12) for hybrids (ACH179). Likewise, RAPD primer B20 for hybrid ACH 753 and their parental lines(CH734 & CH530). Thus, the above study showed that the aid of molecular markers is more reliable, highly efficient, and reproducible for assessing fingerprinting of Chilli commercial hybrid seeds with more accuracy.

Contribution and Stability of Yield Components of Diploid Hybrid Potato

Recently, a hybrid breeding system was developed for diploid potato. We compared performance of diploid hybrids with commercially available tetraploid cultivars. Therefore, seedling tubers were produced from true hybrid seeds in field conditions. In the subsequent year, diploid hybrids grown from seedling tubers showed a yield potential comparable with commercial tetraploid cultivars: the highest yielding diploid hybrids showed a yield comparable with the lower yielding tetraploid cultivars. Yields of hybrids and commercial tetraploid cultivars were broken down into different yield components and the interactions with growing conditions were quantified. The stability of yield and other relevant traits in different growing conditions was similar between hybrids and commercial cultivars. The contribution of the different yield components to total yield over different environments was compared between diploid hybrids and tetraploid cultivars. In diploid hybrids as well as tetraploid cultivars, more tubers per stem resulted in the highest yield gain, while an increase in tuber size resulted in a relatively smaller increase of total yield.

Hybridization and hybrid detection through molecular markers in finger millet [Eleusine coracana (L.) Gaertn.

ABSTRACTSelection of an appropriate hybridization method and use of molecular markers to study genetic purity of hybrids are important factors in crop improvement. In this study, our objective was to analyze two emasculation methods in finger millet and to present a strategy for the assessment of the genetic purity of F1 hybrids using molecular markers. Two parental lines of finger millet, PR 202 and IE 2606, were used for reciprocal crossing. Emasculation was performed with hot-water and hand methods; their efficiencies were compared. The hand method produced ~50-120 seeds per panicle and the hot-water method yielded ~30-90 seeds per panicle. The crossing efficiency was checked using molecular markers. The hot-water method was more efficient (52–80%) compared with the hand-emasculation method (16–40%). Simple sequence repeat (SSR), random amplified polymorphic DNA (RAPD) and inter simple sequence repeat (ISSR) markers were used to analyze the genetic variation in the parental lines. Twelve out of 28 RAPD markers, 4 out of 20 ISSR markers and 21 out of 101 SSR markers showed polymorphism between parental lines. The genetic purity was 16–80% based on RAPD and SSR markers. This study suggested that molecular markers can be utilized to compare the efficiency of emasculation methods and are highly useful for the identification of true hybrid seedlings in the early stages of growth.