Production Of Interspecific Hybrids Research Articles

Model experiment for practical application of inseminated sperm method for production of interspecific hybrids (Clarias gariepinus × Heterobranchus longifilis)

In this study, the inseminated sperm method (sperm injection into the ovarian lobe in externally fertilised fish species) combined with hormonal induction was conducted as a novel method to produce hybrid catfish by induced/tank spawning. In the treated group, four Clarias gariepinus ♀ were inseminated equally with Heterobranchus longifilis sperm in the ovaries at a dosage of 1 mL/fish and then introduced into four spawning cages together with four C. gariepinus ♂. Ovulation was induced by extracted carp pituitary (CPE) hormonal administration (♀; 5 mg CPE/BW kg). The hybridization rate was determined on the basis of morphological markers to distinguish between pure African catfish and hybrid in juvenile stage. A control experiment was also designed to determine this and to explore possible interactions between the two genotypes. In the control group, in vitro fertilisation (IVF) was used to produce pure progeny of C. gariepinus and the hybrid progeny between C. gariepinus ♀ × H. longifilis ♂. Exogenously fed larvae from each treatment were raised and compared after 28 days in four replications; the mixed group contained 50 C. gariepinus and 50 hybrids from IVF grown together, while every 100 larvae from each cage spawning pair were grown separately. The hybridisation rate determined based on morphological traits was 98.11 ± 1.59 (mean ± S.D.) for 28-day-old reared offspring. There were no significant differences (P > 0.05) in survival rate (%) between C. gariepinus (45.79 ± 6.82 %) and the hybrid (54.21 ± 6.82 %) in the control treatment; therefore, neither genotype had a negative effect on the other during the rearing period. From this result, we supposed that the hybridisation rate was also over 95 % at the moment of fertilisation. This approach could be an alternative method for producing hybrid catfish or other fish species without in vitro fertilisation.

Development of a low-density SNP genotyping panel by a novel technology mGPS and its application in germplasm identification of abalone

Abalones (genus Haliotis) are important shellfish in fisheries and aquaculture industries in China. Genetic interactions between abalone species are common in Chinese fisheries since their artificial breeding involves the production of interspecific hybrids of Pacific abalone (H. dicus hannai) and Green abalone (H. fulgens) as well as Pacific abalone (H. dicus hannai) and Xishi abalone (H. gigantea). To achieve better abalone breeding management and investigate the discrepancies between different abalone groups, this study developed and validated an SNP genotyping tool by the methods of genomic resequencing and Genotyping by Pinpoint Sequencing of multiplex PCR products (mGPS). We established a DNA fingerprint for five abalone groups through target SNPs located in 59 segments identified from 130 abalone resequencing datasets. Five distinct groups were successfully discriminated from 244 abalone individuals based on the group discrepancy analysis. The results indicated that the genetic distances between Pacific abalone, Green abalone, and H. fulgens ♀ × H. discus hannai ♂ and between Pacific abalone, Xishi abalone, and H. gigantea ♀ × H. discus hannai ♂ were relatively close. However, H. fulgens ♀ × H. discus hannai ♂ and H. gigantea ♀ × H. discus hannai ♂ had a closer genetic relationship with their original female parents Pacific abalone and Xishi abalone, respectively. In addition, a core set of two specific SNPs sourced from 59 segments was diagnostic in identifying the five abalone groups. Our results present a novel method with the advantages of high efficiency and low cost and thus have potential applications in genetic research. The identified genotyping panel developed based on this method is a valuable tool that can improve our understanding of the connectivity and difference between five abalone groups. Furthermore, the core SNP markers could contribute to future authentication and conservation of abalone germplasm resources.

Tissue Culture Techniques for the Production of Interspecific Hybrids in Poland: History and Achievements

Abstract Interspecific hybridization is a significant plant evolutionary process and, concomitantly, a frequently used method to broaden the genetic variability of species and genetically improve crops. However, in distant crosses, many prezygotic and postzygotic barriers are encountered that prevent free, uncontrolled gene flow between species. Therefore, various experimental methods exploiting tissue culture, such as in vitro fertilization, embryo rescue, and protoplast fusion, have been developed to raise hybrids that cannot be obtained naturally through conventional approaches. Professor Maciej Zenkteler of the Adam Mickiewicz University in Poznań pioneered the use of tissue culture in Poland to overcome barriers to sexual crossing. In the mid-1960s, he employed in vitro pollination in which pollen grains were directly applied onto the surface of exposed ovules as the primary method to bypass prezygotic barriers and in vitro culture of isolated ovules and developing embryos (embryo rescue) to overcome post-zygotic barriers. These approaches proved effective for species possessing numerous ovules and large placentas, such as representatives of the families Caryophyllaceae, Solanaceae, and Brassicaceae. Soon thereafter, these methods were extended to other Polish institutes and universities and applied for crop improvement, such as for the production of intergeneric hybrids between Salix and Populus species, resynthesis and broadening of the genetic variability of oilseed rape ( Brassica napus L.), and the generation of new interspecific hybrids of Allium . In the late 1970s, Professor Zenkteler was the first to undertake protoplast fusion. At that time, it appeared that no incompatibility could exist at the fusion level and that somatic hybridization would supersede the possibilities offered by sexual hybridization; however, the reality turned out to be slightly harsh. Nonetheless, successful regeneration of different interspecific hybrids of potato, tomato, or gentians has been achieved by Polish research groups thus far.

Characterisation of Eucalyptus rhizospheric communities using fatty acid methyl ester (FAME) profile analysis

Hybrid vigour is exploited in Eucalyptus forestry through the production of interspecific hybrids. Hybrids are deployed via cuttings that often suffer from poor rooting. Rhizospheric microorganisms have been associated with rooting enhancement, therefore knowledge of the diversity of microorganism communities, and their abundance and changes over time could be of value in commercial forestry. This knowledge could be applied when sourcing and formulating combinations of useful rhizospheric microorganisms for the treatment of Eucalyptus hybrid cutting genotypes, specifically to improve rooting in the nursery for the establishment of clonal forests. Fatty acid methyl ester (FAME) profiles were prepared for 3-month-old and 5-year-old soil samples collected from rhizospheres of Eucalyptus grandis × Eucalyptus nitens clones to characterise microbial diversity. Saturated, monounsaturated and polyunsaturated fatty acids were present in both soil age groups, although in different proportions. Proportions of saturated fatty acids in the younger samples were greater than in the older samples, while proportions of unsaturated fatty acids were fewer in the younger samples. Palmitic (C16:0) and stearic (C18:0) acids were the most prevalent. Both Shannon’s and Simpson’s indices confirmed that younger soils were more diverse. The greater proportion of polyunsaturated fatty acids in older samples, especially linoleic, α-linolenic and γ-linolenic acids, suggests increasing establishment of fungi.

Selection gains for the palm oil production from progenies of American oil palm with oil palm

Abstract The objective of this work was to estimate the genetic parameters, correlations, and selection gains for the oil production of interspecific hybrids progenies between American oil palm, of ‘Manicoré’ origin, and oil palm, of ‘La Mé’ origin. Thirty-nine progenies were evaluated from the sixth to the ninth year after planting, for the productivity of fresh fruit bunches (PROD_FFB), oil content in the bunch (OCB), and palm oil productivity (PROD_OP). The genetic parameters and gains from direct (GDS) and indirect (GIS) selection were estimated for PROD_OP. High values of heritability for the CVg/CVe ratio indicated favorable conditions for the selection. With the selection of 20% of the progenies (selection in both sexes), the following estimates were obtained: 11.15% GDS for PROD_OP, 9.1% GIS for OCB, and 8.1% GIS for PROD_FFB. The PROD_OP of the progenies was of 6,175, 6,057, and 5,995 kg ha-1 per year with GDS and GIS for OCB and PROD_FFB, respectively. The restricted selection of the LM2T male genitor offspring resulted in 5.1% estimated GSD and in a mean of 5,800 kg ha-1 per year for PROD_OP. Selection gains for PROD_OP can be achieved immediately through the selection restricted to oil palm male genitors, and, in the medium and long term, through the interspecific reciprocal recurrent selection between American oil palm and oil palm populations.

Production of interspecific hybrids between Japanese gentians and wild species of Gentiana.

Wide hybridization, which is a powerful tool to broaden genetic variation, has been used in breeding of many crops. However, in ornamental gentian few wide hybridizations have been reported. Interspecific hybridizations between two gentian cultivated species (Gentiana scabra and G. triflora) and 11 wild species, which were classified in five sections, were carried out using ovule culture. When G. scabra was used as a female parent, normal seedlings and hybrid plants were obtained from eight and five interspecific combinations, respectively. The yield of seedling produced from ovule culture depended on interspecific combinations, ranging from 0.3 to 427.7 normal seedling per flower. In the hybridization of G. triflora with five wild species, normal seedlings and plants were produced in five and four interspecific combinations, respectively. The yield of normal seedling ranging from 0.4 to 228.3 was different between not only interspecific combinations but also reciprocal crosses. Two cultivated species are classified in sect. Pneumonanthe, and successful production of hybrids was obtained from the hybridization with species classified in sections Pneumonanthe or Cruciata. The hybrid nature of the produced plants was confirmed by molecular marker and morphology. The production of interspecific hybrids opens a novel prospect in ornamental gentian breeding.

Developmental Stage and Shape of Embryo Determine the Efficacy of Embryo Rescue in Introgressing Orange/Yellow Color and Anthocyanin Genes of Brassica Species.

Vegetables in Brassica are some of the world’s most commonly cultivated plants and have a wide range of consumable plant organs. Improvement of this group of vegetables is limited at the species level due to limited genetic variability. Interspecies hybridization could be a powerful alternate tool for broadening the genetic variability of target traits. Embryo rescue technique is necessarily practiced in interspecies hybridization for protecting embryos from premature abortion. However, its success depends on the age of ovaries, shape of embryos, and the effect of female genotype. In this study, we carried out a wide range of interspecies crossing for introgressing target traits (orange/yellow color in cabbage and anthocyanin in Chinese cabbage) and optimizing the appropriate age of ovaries, the shape of embryo, and the suitable genotypes of such crosses. We observed that 15 DAP (days after pollination) was the best for embryo rescue in the diploid-diploid (Brassica rapa × B. oleracea) crosses, while 20 DAP was optimum for amphidiploid-diploid (B. napus/B. juncea × B. rapa) crosses. Cotyledonary shape of embryos and genotypes of amphidiploid species were the best for successful plant regeneration in interspecies crosses. We successfully selected plants with desired orange/yellow inner leaves for cabbage and higher anthocyanin in Chinese cabbage. The results of this study have the potential to be applied for the efficient production of interspecific hybrids and to develop Brassica vegetables with new traits, which could have potential for the enrichment of the human diet.

Quantitative trait loci (QTL) for salinity tolerance traits in interspecific hybrids of Eucalyptus

Soil salinity is one of the major limiting factors in productivity of plants. Cultivation of industrially important fast growing saline tolerant tree species is one of the options to reclaim the saline soils. Some of the Eucalyptus species are salt tolerant and production of interspecific hybrids of these species would enhance productivity in saline environments. In this study, phenotypic parameters for growth, physiology and mineral nutrition were estimated in Eucalyptus camaldulensis × E. tereticornis F1 hybrids to understand the mechanism of salinity tolerance and localize quantitative trait loci (QTL) involved in sodium chloride (NaCl) stress. Salt injury scoring and plasma membrane damage showed a significant difference between tolerant and susceptible individuals, which was correlated with the gas exchange measurements and Na+, K+ and K+/Na+ ratio. Under salinity, correlation of gas exchange measurements showed strong positive correlations between the traits, Anet, gs, Ci and E indicated the role of stomatal function. It was inferred that sequestration of NaCl by the salt tolerant individuals was through compartmentalization of Na+ and its detoxification by maintenance of K+/Na+ ratio. Totally, 33 QTL were identified under salinity and control conditions. Co-localization of QTL regulating Na+ and K+ transport substantiated their influence in salinity tolerance which could be due to the closely linked genes or by pleiotropic effect of same genes on these traits. Fine mapping with more molecular markers will locate the QTL precisely and validating with field trails could hasten the traditional methods for salinity breeding.

Comparing mating designs to restore seed production of interspecific hybrids betweenTrifolium repens(white clover) andTrifolium uniflorum

AbstractInterspecific hybrids betweenTrifolium uniflorumand cultivated white clover (Trifolium repens) have highly useful characteristics for temperate pastoral systems derived from both parent species. However, the early hybrids (F1and BC1) also have unacceptably poor seed production for commerce. This study analysed the basis for the poor seed production and investigated breeding strategies for overcoming the problem. The BC1F1generation produced lower‐than‐expected numbers of heads per plant and seeds per floret. Backcrossing of selected hybrids to white clover corrected these deficiencies and created new variation. Seed numbers were also returned to near target levels by recurrent selection within the BC1generation. Thus, it was possible to retain a theoretical average of 25% ofT. uniflorumgenome and still achieve high seed production per plant. The BC1F2and BC2F1generations produced high seed numbers per plant, along with reasonable variation. Both of these second‐generation hybrid forms have high reproductive potential and should be the focus for the selection of the desired combinations of agronomic and seed production traits.

SISTEMA DE PRODUÇÃO DE MUDAS EM HÍBRIDOS INTERESPECÍFICOS ENTRE CAIAUÉ E DENDÊ

O objetivo deste trabalho foi avaliar três sistemas de produção de mudas de híbridos interespecíficos (HIE) entre caiaué e dendê, diferença entre 12 progênies de irmãos germanos do cultivar BRS Manicoré e a interação entre esses dois fatores. Os sistemas de produção avaliados foram: (i) viveiro de dois estágios com sombreamento inicial (sistema convencional); (ii) viveiro de dois estágios sem sombreamento inicial e (iii) viveiro de um estágio sem sombreamento inicial. Foram avaliadas as variáveis altura da planta, número de folhas e diâmetro do coleto aos 106, 191 e 393 dias após a semeadura. Em todas as variáveis e épocas analisadas, os fatores genótipo e ambiente foram significativos e o fator inteiração genótipo x ambiente não foi significativo pelo teste F. O melhor desenvolvimento das mudas no viveiro ocorreu no sistema de produção de uma fase sem sombreamento inicial. O viveiro de duas fases com sombreamento inicial, que é atualmente o mais adotado, resultou em menor desenvolvimento das mudas.

Molecular identification of intergenus crosses involving catfish hybrids: risks for aquaculture production

ABSTRACT Monitoring of the interspecific hybrid production and trade is essential for the appropriate management of these animals in fish farms. The identification of catfish hybrids by morphological analysis is unreliable, particularly of juveniles and post-F1 individuals. Therefore, in the present study, we used five molecular markers (four nuclear genes and one mitochondrial gene) to detect hybrids in the trade of pimelodid juvenile fish from different stocks purchased of five seed producers in Brazil. Samples commercialized as pintado (pure species Pseudoplatystoma corruscans ) from three fish farms were genetically identified as hybrid cachapinta (♀ P. reticulatum x ♂ P. corruscans ). In the stocks purchased as cachandiá (hybrid between ♀ P. reticulatum x ♂ Leiarius marmoratus ) and cachapira (hybrid between ♀ P. reticulatum x ♂ Phractocephalus hemioliopterus ), we suggested the occurrence of intergenus crosses involving the hybrid cachapinta, which was used instead of the pure species P. reticulatum . The problems involving the hybrid cachapinta production were discussed in the present study, especially because these animals have caused genetic contamination and threatened the genetic integrity of natural and cultivated populations. In order to improve the surveillance of the production and provide criteria for the correct management of catfish hybrids, genetic markers has become an excellent alternative to the morphological identification, including juveniles or post-F1 generations.

Genetic and phenotypic diversity of natural American oil palm (Elaeis oleifera (H.B.K.) Cortés) accessions

Elaeis oleifera has become a valuable genetic resource for the production of interspecific hybrids of E. oleifera (H.B.K) Cortes × Elaeis guineensis Jacq. to address plant disease problems affecting oil palm cultivation. In this study, we evaluated the phenotypic and genetic diversity of accessions of E. oleifera from different countries in South America using morpho-agronomic traits and microsatellite markers (Simple Sequence Repeats, SSRs). Analyses of variance for yield and bunch components demonstrated statistically significant differences among countries and geographical regions for several of the traits evaluated. SSR marker analyses revealed high genetic diversity (HT = 0.797) and the presence of specific alleles by each country of origin from E. oleifera. The clustering topology obtained showed four distinguishable E. oleifera groups, which matched the geographical distribution of the accessions and thus exhibited a high genetic differentiation (GST = 0.512) and a low gene flow Nm = 0.238 among countries. The results enabled us to demonstrate that E. oleifera has a specific genetic structure and a phenotypic variability with different characteristics between origins, and the accessions from each country of origin contributed to the increase in total genetic diversity. A core collection was defined based on the accuracy of the classification of individuals with respect to their country of origin. The information reported in this study will be of great interest to oil palm researchers because new strategies for breeding programs can be developed based on these advances.

KARYOTYPE ALTERATIONS AFTER HYBRIDIZATION BETWEEN Pennisetum purpureum AND Pennisetum glaucum

ABSTRACTNapier grass and pearl millet are tropical forages from the genus Pennisetum. The variability in those species is explored in breeding programs of forages, as well as in the production of interspecific hybrids. Hybridization is a phenomenon that leads to intergenomic conflicts following the elimination of genomic sequences. In this sense, the present work aimed to study the genomic alterations occurring after interspecific hybridization of pearl millet and Napier grass with the use of cytogenetics and flow cytometry tools. These methods allowed the evaluation of chromosome morphometry, DNA content and genomic ratio in pearl millet, Napier grass and hybrids. It was observed that pearl millet and Napier grass have chromosomes with superposed size. The hybrid presents chromosomes that are smaller than expected, leading to karyotype alterations. Additionally, comparing the DNA content of parents and hybrids, loss of DNA content was demonstrated. Further, changes in the pearl millet and Napier grass genome ratio were also verified in the hybrid nucleus. Moreover, genomic rearrangements were shown to occur through karyotype alterations in the hybrid.

Interspecific hybridization between Brassica napus and Brassica rapa ssp. chinensis genotypes through embryo rescue and their evaluation for crossability

The genus Brassica contains several important crop species that are used for a variety of purposes. Brassica napus and Brassica rapa are the most important ones for their use as oilseed crops. In Brassica , interspecific hybridization is a potential and useful method for transferring valuable traits between species of commercial interest. For breeding Brassicas resistant to some diseases, i.e. clubroot, attempts of transferring resistant genes (CR) through interspecific hybridization have also been reported. The main step in the introgression process is the production of interspecific hybrids between the two species. However, the cross-incompatibility occurring in wide hybridization might hamper the possibility of obtaining hybrid progenies. For that reason, the crossability study is essential and may give an insight into the cross-compatibility relationship among the species, the direction of success of crossing, and the crossability barriers of some combinations, if any. In the present study, interspecific reciprocal crosses between B. napus and B. rapa ssp. chinensis genotypes were carried out in order to determine their crossability and to produce their F1 hybrids. Crossability was analyzed based on the pollen germination index (PGI) and the development of hybrid embryos in in vitro cultures. It was observed that the unilateral interspecific incompatibility occurred in crosses between B. napus × B. rapa ssp. chinensis. When B. napus cultivars were used as a maternal parent, pollen grains of B. rapa germinated well on the stigmas, while only a small number of pollen tubes could elongate near the ovules, resulting in a low development of hybrid embryos. Using the B. rapa ssp. chinensis as the pistillate parent in the crosses, it was found that the crossability was relatively higher than that in the case of the reciprocal cross. This resulted in a greater number of embryos obtained. Generally, it was concluded that the selection of parental components for hybridization is an important step for obtaining breeding success.

Evaluation of reproductive barriers contributes to the development of novel interspecific hybrids in the Kalanchoë genus.

BackgroundInterspecific hybridization is a useful tool in ornamental breeding to increase genetic variability and introduce new valuable traits into existing cultivars. The successful formation of interspecific hybrids is frequently limited by the presence of pre- and post-fertilization barriers. In the present study, we investigated the nature of hybridization barriers occurring in crosses between Kalanchoë species and evaluated possibilities of obtaining interspecific hybrids.ResultsThe qualitative and quantitative analyses of pollen tube growth in situ were performed following intra- and interspecific pollinations. They revealed occurrence of pre-fertilization barriers associated with inhibition of pollen germination on the stigma and abnormal growth of pollen tubes. Unilateral incongruity related to differences in pistil length was also observed. The pollen quality was identified as a strong factor influencing the number of pollen tubes germinating in the stigma. In relation to post-fertilization barriers, endosperm degeneration was a probable barrier hampering production of interspecific hybrids. Moreover, our results demonstrate the relation of genetic distance estimated by AFLP marker analysis of hybridization partners with cross-compatibility of Kalanchoë species. At the same time, differences in ploidy did not influence the success of interspecific crosses.ConclusionsOur study presents the first comprehensive analysis of hybridization barriers occurring within Kalanchoë genus. Reproductive barriers were detected on both, pre- and post-fertilization levels. This new knowledge will contribute to further understanding of reproductive isolation of Kalanchoë species and facilitate breeding of new cultivars. For the first time, interspecific hybrids between K. nyikae as maternal plant and K. blossfeldiana as well as K. blossfeldiana and K. marnieriana were generated.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-014-0394-0) contains supplementary material, which is available to authorized users.

Artificial Hybridization between U.S. Native Ruellia caroliniensis and Invasive Ruellia simplex: Crossability, Morphological Diagnosis, and Molecular Characterization

The potential for natural hybridization to occur between non-native, invasive species and closely related native species is of interest to biologists, conservationists, and land managers, particularly in regions such as the southeastern United States where numerous non-native species have become serious environmental pests. To explore this potential between the invasive plant species Ruellia simplex and the closely related, sympatric Ruellia caroliniensis, we conducted a study of reproductive crossability and hybrid viability. Results indicate that the production of interspecific hybrids is possible, but only in one direction (i.e., with R. caroliniensis as the maternal parent). Artificial hybrids were weak, slow-growing, and sterile. These data suggest that it is unlikely that R. caroliniensis × R. simplex hybrids could invade the gene pool of native R. caroliniensis. We also characterized hybrids at the molecular level by sequencing parents plus F1 progeny for the nuclear ribosomal internal transcribed spacer (ITS) + 5.8S region. All hybrid genotypes formed a strongly supported clade with the maternal parent, Ruellia caroliniensis. Within this clade, hybrid individuals were not differentiable from maternal genotypes. We then examined general plant morphology of hybrid individuals and the two parents. Unlike results from the molecular characterization, there was a strong signal of hybrid intermediacy from this morphological work. We conclude that morphology but not molecular sequence data (from nrITS) can be used to distinguish the two parents and their F1 hybrids.

Detection of SNP and validation of a SFP InDel (deletion) in inverted repeat region of the Prunus species chloroplast genome

In order to control tree size, disease, precocity and stress most Prunus varieties are cultivated as composite plants grafted onto desirable rootstocks that impart all the afore-mentioned traits. Several Prunus rootstock breeding programs have been focused on the production of interspecific hybrids. The pedigree of most of these rootstocks remains unknown due to the lack of parental information necessitating the application of DNA-based knowledge in breeding programs. The amplification and sequencing of the chloroplast inverted repeat B (IRB) region spanning 25,960bp from P. cerasifera (myrobalan plum) Ehrh., P. amygdalus (almond) and P. persica (peach) using the ASAP method revealed a single nucleotide polymorphisms (SNP) in the rps19-rpl2 IRB region in myrobalan when compared to almond and peach. In addition, a prominent and an easily identifiable single feature polymorphism (SFP-InDel (deletion)) of 18 nucleotides was discovered in reference to the peach chloroplast genome in the ycf1 gene in the IRB region. In this work, it has been developed a highly useful polymorphic molecular marker to characterize the maternal parent in interspecific hybrids of Prunus rootstocks as a first step toward developing pedigree information. The ycf1 SFP-InDel (deletion) has been successfully used in several 3-way hybrids generated in the stone fruit rootstock breeding program for the characterization of new interspecific plant material. This SFP is expected to be highly utile in characterizing the maternal lineage of Prunus hybrids in other breeding programs.

Review: Breeding spring canola (Brassica napusL.) by the use of exotic germplasm

Rahman, H. 2013. Review: Breeding spring canola ( Brassica napus L.) by the use of exotic germplasm. Can. J. Plant Sci. 93: 363–373. The need of broadening genetic diversity in spring canola (Brassica napus) breeding programs seems to be the general consensus among canola breeders and researchers. Diversity analysis by the use of molecular markers has identified several B. napus gene pools as well as allied Brassica species that are genetically distinct from spring canola B. napus; and these gene pools can be used for the improvement of this crop. Use of genetically diverse and un-adapted B. napus germplasm in the breeding of spring canola can be challenging, as introduction of several unwanted traits/alleles from exotic germplasm into spring canola occurs, and this would require repeated cycles of breeding for improvement. Similarly, use of allied species can be even more challenging due to the difficulties associated with interspecific hybrid production, sterility of hybrids, linkage drag, and the introduction of unwanted alleles. However, this can be compensated in the long-term perspective for the improvement of this crop. Some research efforts have been made in recent years to broaden allelic diversity in spring canola for the improvement of seed yield and other traits in open-pollinated and hybrid cultivars with promising results. Seed yield is a complex trait which is controlled by several gene loci with multiple alleles at these loci as well as interactions between loci and different alleles. This makes the identification of right allelic combinations an extremely challenging task. However, canola breeders have been able to make steady improvements in this crop in past decades based on the amount of allelic diversity present in existing breeding material. Introduction of favourable new alleles in breeding programs would allow breeders to create superior allelic combinations, enhancing the diversity in current breeding materials to further improve the crop. With the availability of the Brassica genome sequence, knowledge of sequence variation in specific genes and cost-effective high-throughput genotyping, it is expected that molecular plant breeding will play an important role in the breeding of canola cultivars. Discovery of favourable allele combinations in a short span of time is likely to be facilitated through the application of modern breeding tools.

Endogenous hormone profiles during early seed development of C. arietinum and C. anatolicum

Cicer anatolicum, a perennial species, has ascochyta blight resistance superior to that found in the cultivated chickpea. However, hybridization barriers during early stages of embryo development curtail access to this trait. Since hormones play an essential role in early embryo development, we have determined the hormone profiles of 4-, 8-, and 12-day old seeds from a Canadian chickpea (Cicer arietinum L.) cv. CDC Xena, from Indian cvs. Swetha and Bharati, and from a perennial accession of C. anatolicum (PI 383626). Indole-3-acetic acid content peaked on day 4 in CDC Xena, on day 8 in both Indian cultivars but only on day 12 in C. anatolicum. The cytokinins, isopentenyladenosine (iPA) and trans zeatin riboside (tZR) were predominant in CDC Xena and Swetha seeds on day 4, whereas cis zeatin riboside was the major component in Bharati. In C. anatolicum, iPA maxed out on day 4 and tZR on day 12. The bioactive gibberellin GA1 spiked on day 4 in CDC Xena and Bharati, on day 8 in Swetha but only on day 12 in C. anatolicum. Eight-day old seeds had the highest abscisic acid content in the cultivars but spiked on day 12 in the perennial species. The hormone profiles of the perennial species showed delayed spikes in all four hormone groups indicating that there is a mismatch in the hormone requirements of the different embryos. Improving synchronization of early seed hormone profiles of cultivated and perennial chickpea should improve interspecific hybrid production.

Production of interspecific hybrids between commercial cultivars of the eggplant (Solanum melongena L.) and its wild relative S. torvum

Interspecific hybrids between cultivars of eggplant (Solanum melongena L.) and its wild relative S. torvum, which has disease resistance and desirable traits for crop improvement, were obtained by cross-hybridization and embryo rescue. Twenty-one hybrid progenies were obtained and examined based on morphological traits, RAPD and ISSR markers. Five of them were confirmed to be true interspecific hybrids. Eighteen and 14 bands from 7 RAPD and 14 ISSR primers, respectively, were polymorphic and present in all five hybrid seedlings and their parents. The morphological characteristics of leaf margin, inflorescence type and spine positions of the five seedlings were intermediate to the parents. These interspecific hybrids had low pollen viability, probably due to abnormal meiosis.