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Four molecular marker systems--RAPD (random amplified polymorphic DNA), ISSR (intersimple sequence repeat), SRAP (sequence-related amplified polymorphism), and SSR (simple sequence repeat)--were used to evaluate seed genetic purity of a hybrid cabbage cultivar 'Zaoxia 16'. Genetic relationships of the F1 hybrids and their parents were analyzed with 157 RAPD primers, 54 ISSR primers, 84 SRAP primer combinations, and 44 SSR primers. Three RAPD primers (NAURP2006, NAURP2020, and NAURP2031), two ISSR primers (NAUISR1058 and NAUISR1062), one SRAP primer combination (NAUSR04/NAURS05), and two SSR primers (NAUSSR1011 and NAUSSR1031), which produced male and female parent-specific markers simultaneously, were selected for testing the genetic purity of the F1 seeds. A total of 210 'Zaoxia 16' hybrid individuals were investigated with these eight selected primers. Of these, 12 appeared to be false hybrids. Nine of the 12 putative false hybrids, confirmed with all eight primers, exhibited similar banding patterns to the female parent, suggesting that they could be derived from selfing of the female parent. The results were in accordance with those from field evaluations. This study showed that RAPD, ISSR, SRAP, and SSR markers are highly efficient and reproducible for genetic purity testing of cabbage commercial hybrid seeds. [ABSTRACT FROM AUTHOR]

Accounts of twentieth-century agricultural industrialization in the United States and beyond often center the production and distribution of commercial F1 hybrid seeds as a pivotal development. The commercialization of hybrid corn seeds in the 1930s was initially heralded as a science-driven advance in agricultural productivity. However, since the 1970s "hybrid seeds" have been linked to many perceived perils attendant on industrialized agriculture, from the undermining of farmers' independence to the diminishment of crop genetic diversity to the consolidation of corporate control over the global food system. First grouped with the semidwarf varieties of the Green Revolution to emblematize capital- and chemical-intensive agriculture, hybrids are today often lumped together with genetically modified varieties for much the same reason. This essay revisits the scholarship that helped produce this understanding of hybrid seeds. It explores how and why the singular history of hybrid corn inflected understandings of crop breeding and seed production in general, contributing to lasting confusion about the promises and pitfalls of distinct approaches to crop development and the nature of hybrid seeds. [ABSTRACT FROM AUTHOR]

A number of studies have been conducted on hybridization between transgenic Brassica napus and B. rapa or backcross of F1 hybrid to their parents. However, trait changes must be analyzed to evaluate hybrid sustainability in nature. In the present study, B. rapa and transgenic (BrAGL20) B. napus were hybridized to verify the early flowering phenomenon of F1 hybrids, and F1 hybrid traits were analyzed to predict their impact on sustainability. Flowering of F1 hybrid has been induced slightly later than that of the transgenic B. napus, but flowering was available in the greenhouse without low temperature treatment to young plant, similar to the transgenic B. napus. It is because the BrAGL20 gene has been transferred from transgenic B. napus to F1 hybrid. The size of F1 hybrid seeds was intermediate between those of B. rapa and transgenic B. napus, and ~40% of F1 pollen exhibited abnormal size and morphology. The form of the F1 stomata was also intermediate between that of B. rapa and transgenic B. napus, and the number of stomata was close to the parental mean. Among various fatty acids, the content of erucic acid exhibited the greatest change, owing to the polymorphism of parental FATTY ACID ELONGASE 1 alleles. Furthermore, F2 hybrids could not be obtained. However, BC1 progeny were obtained by hand pollination of B. rapa with F1 hybrid pollen, with an outcrossing rate of 50%. [ABSTRACT FROM AUTHOR]

[Objectives]Based on the paternal genetic characteristics of cucumber mitochondria, the purpose of this paper is to study the feasibility of mitochondria genome simple sequence repeat(mtSSR)in hybrid seed purity identification of cucumber. [Methods]The specific markers were developed according to the mitochondrial genome sequence of cucumber. Markers were screened with different ecotypes of cucumber varieties, and then the purity of F1 hybrid seeds was detected with polymorphic primers. [Results]Four pairs of polymorphic primers were screened from 72 pairs of mtSSR markers in 30 cucumber varieties. The PCR amplification of mtSSR4 primer could distinguish two polymorphic fragments of 102 and 107 bp. Three polymorphic fragments of 196, 224 and 242 bp were obtained with mtSSR10 primer. Three polymorphic fragments of 226, 239 and 281 bp could be amplified by mtSSR29 primer. Besides, mtSSR44 primer could amplify two polymorphic fragments of 184 and 194 bp. Cucumber purity test of four F1 hybrids showed that the bands of F1 hybrids were consistent with the male parent respectively and the results tested in field. Contamination of F1 hybrid seeds caused by self-inbred and other unknown pollens can be detected. [Conclusions]The purity of cucumber F1 hybrids was accurately identified by mitochondrial genome sequence-specific SSR markers. It is suggested that mitochondrial genome SSR technique has application prospects to ensure production quality of cucumber seeds. [ABSTRACT FROM AUTHOR]

Seed storability has a significant impact on seed vitality and is a crucial genetic factor in maintaining seed value during storage. In this study, RNA sequencing was used to analyze the seed transcriptomes of two rice thermo-sensitive genic male sterile (TGMS) lines, S1146S (storage-tolerant) and SD26S (storage-susceptible), with 0 and 7 days of artificial accelerated aging treatment. In total, 2658 and 1523 differentially expressed genes (DEGs) were identified in S1146S and SD26S, respectively. Among these DEGs, 729 (G1) exhibited similar regulation patterns in both lines, while 1924 DEGs (G2) were specific to S1146S, 789 DEGs (G3) were specific to SD26S, and 5 DEGs (G4) were specific to contrary differential expression levels. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that "translation", "ribosome", "oxidative phosphorylation", "ATP-dependent activity", "intracellular protein transport", and "regulation of DNA-templated transcription" were significantly enriched during seed aging. Several genes, like Os01g0971400, Os01g0937200, Os03g0276500, Os05g0328632, and Os07g0214300, associated with seed storability were identified in G4. Core genes Os03g0100100 (OsPMEI12), Os03g0320900 (V2), Os02g0494000, Os02g0152800, and Os03g0710500 (OsBiP2) were identified in protein–protein interaction (PPI) networks. Seed vitality genes, MKKK62 (Os01g0699600), OsFbx352 (Os10g0127900), FSE6 (Os05g0540000), and RAmy3E (Os08g0473600), related to seed storability were identified. Overall, these results provide novel perspectives for studying the molecular response and related genes of different-storability rice TGMS lines under artificial aging conditions. They also provide new ideas for studying the storability of hybrid rice. [ABSTRACT FROM AUTHOR]

Background: Epigenetic regulation of gene dosage by genomic imprinting of some autosomal genes facilitates normal reproductive development in both mammals and flowering plants. While many imprinted genes have been identified and intensively studied in mammals, smaller numbers have been characterized in flowering plants, mostly in Arabidopsis thaliana. Identification of additional imprinted loci in flowering plants by genome-wide screening for parent-of-origin specific uniparental expression in seed tissues will facilitate our understanding of the origins and functions of imprinted genes in flowering plants., Results: cDNA-AFLP can detect allele-specific expression that is parent-of-origin dependent for expressed genes in which restriction site polymorphisms exist in the transcripts derived from each allele. Using a genome-wide cDNA-AFLP screen surveying allele-specific expression of 4500 transcript-derived fragments, we report the identification of 52 maternally expressed genes (MEGs) displaying parent-of-origin dependent expression patterns in Arabidopsis siliques containing F1 hybrid seeds (3, 4 and 5 days after pollination). We identified these MEGs by developing a bioinformatics tool (GenFrag) which can directly determine the identities of transcript-derived fragments from (i) their size and (ii) which selective nucleotides were added to the primers used to generate them. Hence, GenFrag facilitates increased throughput for genome-wide cDNA-AFLP fragment analyses. The 52 MEGs we identified were further filtered for high expression levels in the endosperm relative to the seed coat to identify the candidate genes most likely representing novel imprinted genes expressed in the endosperm of Arabidopsis thaliana. Expression in seed tissues of the three top-ranked candidate genes, ATCDC48, PDE120 and MS5-like, was confirmed by Laser-Capture Microdissection and qRT-PCR analysis. Maternal-specific expression of these genes in Arabidopsis thaliana F1 seeds was confirmed via allele-specific transcript analysis across a range of different accessions. Differentially methylated regions were identified adjacent to ATCDC48 and PDE120, which may represent candidate imprinting control regions. Finally, we demonstrate that expression levels of these three genes in vegetative tissues are MET1-dependent, while their uniparental maternal expression in the seed is not dependent on MET1., Conclusions: Using a cDNA-AFLP transcriptome profiling approach, we have identified three genes, ATCDC48, PDE120 and MS5-like which represent novel maternally expressed imprinted genes in the Arabidopsis thaliana seed. The extent of overlap between our cDNA-AFLP screen for maternally expressed imprinted genes, and other screens for imprinted and endosperm-expressed genes is discussed.

The possible persistence of genetically modified (GM) crop-to-wild hybrid seeds in the soil seed bank is a major concern in risk assessment and is closely related to seed characteristics such as dormancy. In the present study, we generated F3 hybrids via crosses between GM soybean accessions and wild soybean and evaluated the dormancy, overwintering ability and inheritance of foreign genes in different-coloured hybrid seeds (yellow, green, brown and black). The results revealed that the 5-enolpyruvylshikimate-3-phosphate synthase transgene may have no influence on crop wild hybrid seed dormancy and overwintering ability, and the dormancy of the hybrid seeds was closely related to seed coat colour. F3 hybrid seeds with light colours (yellow and green) were relatively nondormant, while seeds that were dark (brown and black) in colour were relatively dormant. Moreover, the hybrid seeds that were dark in colour had a much stronger overwintering ability than the lighter-coloured seeds, with 21.33 % of the black seeds and 33.33 % of the brown seeds remaining viable after 240 days of soil burial. In contrast, almost all the F3 yellow and green seeds were no longer viable during winter. Scanning electron microscopy revealed that the lighter-coloured seeds had a thin palisade layer and very few surface deposits, while the darker-coloured seeds had a thicker palisade layer and a large area of honeycomb-like surface deposits similar to those of wild soybean seeds. Thus, the physical dormancy and overwintering ability of the darker-coloured seeds may be related to the seed coat. Our results suggest that transgenes of GM soybean might disperse into wild populations and persist in seed banks. [ABSTRACT FROM AUTHOR]

Background: Faba bean is a crop of agro-ecological and socio-economic importance in Morocco. Thus, in a changing climatic context, it is important to develop varieties that are resilient to several abiotic constraints, such as synthetics. However, the reproductive system must be understood. Methods: We aimed to estimate faba beans outcrossing rate under natural Moroccan conditions, using two varieties, 'Reina Mora' and 'Zina' and two phenotypic markers, seed coat color and its size and shape, in two contrasted locations, Saïs and Gharb. Varieties were sown in six alternate rows with six seeds per row and three replicates per location. The experiment consisted in counting the number of purple seeds within 'Zina's beige offspring. Besides, seeds collected from 'Reina Mora' were counted and processed for differences in size and shape. In total, 859 seeds were measured, including their length, width, thickness, geometric diameter, area and sphericity, enabling to distinguish hybrids from parental seeds and self-seeds. Result: Results showed an average inter-crossing of 3.7% in Saïs and 7.22% in Gharb. A more reliable open-pollination could be achieved by introducing bees and bumblebees colonies as well as using varieties from same geographic gene pools. [ABSTRACT FROM AUTHOR]

Since the 1970s 'hybrid seeds' have been linked to many perceived perils of industrialized agriculture. This essay revisits the scholarship that helped produce a dominant critical assessment of hybrid seeds, situating its emergence in a series of events and interventions of the late twentieth century. It explores how the singular history of F1 hybrid corn inflected understandings of crop breeding and seed production in general, contributing to effective political mobilization against agroindustry as well as lasting confusion about the promises and pitfalls of distinct approaches to crop development and the nature of hybrid seeds. [ABSTRACT FROM AUTHOR]

This work was conducted on the use of the RE (radicle emergence) test to estimate the seedling emergence (SE) and quality (seedling shoot weight (SSW), seedling root weight (SRW) and seedling height (SH)) of twelve hybrid cucumber seed lots with high germination (>95%) at low temperature conditions, high salt conditions and a combination of the two. The percentages of RE, which is a 2 mm radicle protrusion at 25 °C in the dark, were counted between 18 h and 32 h. The seeds were sown in peat moss in trays and kept at 15 °C (low temperature stress), or salty water was applied as 100 mM NaCl at 25 °C (salt stress) for three days, and both were applied in a combined-stress environment. Seedling emergence and quality parameters were reduced by both stress environments and their combination. SE, SSW, SRW and SH values ranged between: 91–100%, 614–844 mg, 102–143 mg, 6.8–8.8 cm at low temperature; 90–98%, 598–904 mg, 101–154 mg, 6.5–7.8 cm at salt stress; and 76–92%, 464–608 mg, 97–133 mg, 5.8–6.9 cm at their combination. The RE values with great differences seen among the lots (20–28 h) were regressed with seedling emergence and quality values. RE 24 h had the highest R2 and significant values in all stress environments as R2 = 0.596–0.858, p < 0.05–0.001 at low temperature; R2 = 0.620–0.827, p < 0.05–0.001 with salt; and R2 = 0.686–0.842, p < 0.05–0.001 with combined stresses. We concluded that RE as a vigour test can be used successfully to estimate the seedling quality of highly germinating hybrid cucumber seed lots. Use of the RE test in hybrid cucumber seeds and its influence on high-quality seedling production were discussed. [ABSTRACT FROM AUTHOR]

Background: Most crop seeds are F1 hybrids. Seed providers and plant breeders must be confident that the seed supplied to growers is of known, and uniform, genetic makeup. This requires maintenance of pure genotypes of the parental lines and testing to ensure the genetic purity of the F1 seed. Traditionally, seed purity has been assessed with a grow-out test (GOT) in the field, a time consuming and costly venture. Early in the last decade, seed testing with molecular markers was introduced as a replacement for GOT, and Kompetitive allele specific PCR (KASP) markers were recognized as promising tools for genetic testing of seeds. However, the markers available at that time could be inaccurate and applicable to only a small number of accessions or varieties due to the limited genetic information and reference genomes available. Results: We identified 4,925,742 SNPs in 50 accessions of the Brasscia rapa core collection. From these, we identified 2,925 SNPs as accession-specific, considering properties of flanking region harboring accession-specific SNPs and genic region conservation among accessions by the Next Generation Sequencing (NGS) analysis. In total, 100 accession-specific markers were developed as accession-specific KASP markers. Based on the results of our validation experiments, the accession-specific markers successfully distinguised individuals from the mixed population including 50 target accessions from B. rapa core collection and the outgroup. Additionally, the marker set we developed here discriminated F1 hybrids and their parental lines with distinct clusters. Conclusions: This study provides efficient methods for developing KASP markers to distinguish individuals from the mixture comprised of breeding lines and germplasms from the resequencing data of Chinese cabbage (Brassica rapa spp. pekinensis). [ABSTRACT FROM AUTHOR]

Based on prior knowledge and with the support of new methodology, solid progress in the understanding of seed life has taken place over the few last years. This update reflects recent advances in three key traits of seed life (i.e., preharvest sprouting, genomic imprinting, and stored-mRNA). The first breakthrough refers to cloning of the mitogen-activated protein kinase-kinase 3 (MKK3) gene in barley and wheat. MKK3, in cooperation with ABA signaling, controls seed dormancy. This advance has been determinant in producing improved varieties that are resistant to preharvest sprouting. The second advance concerns to uniparental gene expression (i.e., imprinting). Genomic imprinting primarily occurs in the endosperm. Although great advances have taken place in the last decade, there is still a long way to go to complete the puzzle regarding the role of genomic imprinting in seed development. This trait is probably one of the most important epigenetic facets of developing endosperm. An example of imprinting regulation is polycomb repressive complex 2 (PRC2). The mechanism of PRC2 recruitment to target endosperm with specific genes is, at present, robustly studied. Further progress in the knowledge of recruitment of PRC2 epigenetic machinery is considered in this review. The third breakthrough referred to in this update involves stored mRNA. The role of the population of this mRNA in germination is far from known. Its relations to seed aging, processing bodies (P bodies), and RNA binding proteins (RBPs), and how the stored mRNA is targeted to monosomes, are aspects considered here. Perhaps this third trait is the one that will require greater experimental dedication in the future. In order to make progress, herein are included some questions that are needed to be answered. [ABSTRACT FROM AUTHOR]

This article presents ethnographic research with in situ seed savers and seed activists in London. Unpicking the knotty relations between kinship, place, and generation among seed savers and their seeds, this article focuses on how the intrinsic and extrinsic get woven through generations and how the situ or environment of an entity is (and is not) recognized in its identity and multispecies kin relations. I argue that thinking about seeds and the worlds in which they grow suggests that they are not only embedded in their environments, but also embody their environments. If seeds bring with them their worlds, then they are inherently malleable, so seed savers are concerned about how commercial seed breeding and ex situ conservation denatures seeds' embodied relationships with their environments and, with that, their inherent intergenerational malleability. [seed saving, multispecies kinship, generation, environment]. [ABSTRACT FROM AUTHOR]

Seeds are valuable sources of carbohydrates, lipids, proteins, fibers, minerals, and vitamins. They provide energy and nutrition to germinating seedlings, food to humans, feed to livestock, and feedstocks to industry. High‐throughput analyses of gene expression in crops has identified many candidate genes associated with seed dormancy, longevity, germination, and vigor. In this review, we cover the latest research focusing on such key seed traits. Transcriptome analyses of time courses of seed filling have identified sets of genes expressed at different stages of this process. The potential role of epigenetics (including seed–endosperm imprinted genes) in regulating seed development and chemistry is highlighted herein. We also discuss how advances in genomics and seed biology are facilitating the unravelling of associations between seed traits with gene bank accessions and gene sequences, including how functional research can accelerate the discovery of allelic variants. Such knowledge of functional effects relating to gene variants is necessary for more efficient and cost‐effective management of genetic resources or for redesigning crops with specific seed characteristics. For instance, gene bank curators may assess seed viability by monitoring changes in gene expression of biomarker genes in dry seed samples to decide germplasm regeneration and assess genetic integrity of collections by monitoring changes in diversity and allele frequencies between samples of same accession stored in gene banks. We highlight that resistance to preharvest sprouting can be enhanced through genomics‐assisted breeding in otherwise nondormant rice (Oryza sativa L.) and wheat (Triticum aestivum L.) cultivars, while pimt, another valuable marker for seed longevity, may be deployed to enhance seed vigor in crops. [ABSTRACT FROM AUTHOR]

Seed coat colour is an important quality trait, domestication trait and morphological marker, and is closely associated with flavonoid and anthocyanin metabolism pathways. The seed coat colour of adzuki bean, an important legume crop, influences the processing quality of its paste, the commodity and its nutritional quality. In this study, the genetic relationships of seed coat colour were analysed using 12 hybridized combinations of F2 individuals and four F3 families derived from hybridized combinations between the accessions of eight seed coat colours. The loci of the colour traits were analysed based on phenotypes and using the chi-square test. Ivory colour is recessive to red and is controlled by a single R locus. Black, black mottle on grey, black mottle on red, light brown, golden and brown are all dominant to red. The phenotypes of black mottle on red, light brown, golden and brown are all controlled by a single genetic locus. Black mottle on grey is controlled by two loci. Black is controlled with two loci, and the black locus shows dominant epistasis to another locus. A genetic model of these seed coat colours was predicted. Our results will be important for gene mapping and cloning of seed coat colour characters and for providing further insight into the regulatory network of seed coat colour. [ABSTRACT FROM AUTHOR]

Interspecific hybridization studies involving reciprocal crosses were carried out on three Stachytarpheta spp. to investigate the genetic relationship among the three spp. The interspecific cross of S. angustifolia x S. cayennensis produced an F1 hybrid that was vigorous, floriferous, and partly fertile, but the seed setting percentage was low (29.83 %) despite the fairly high pollen fertility (63.14 %). The F2 seeds recovered from this cross failed to germinate. Interspecific crosses of S. cayennensis x S. angustifolia and S. cayennensis x S. indica produced F1 seeds which did not germinate. The interspecific crosses of S. angustifolia x S. indica and S. indica x S. angustifolia failed, and no seed set was observed, but S. indica x S. cayennensis produced F1 seeds which failed to germinate. The results from the hybridization studies showed that postzygotic-isolating mechanism has set a strong reproductive barrier among the three studied Stachytarpheta spp. manifested as embryo abortion in S. angustifolia x S. indica and S. indica x S. angustifolia, F1 seed inviability in S. indica x S. cayennensis, S. cayennensis x S. angustifolia and S. cayennensis x S. indica, F2 seed breakdown in S. angustifolia x S. cayennensis. The current study concluded that S. angustifolia is more closely related to S. cayennensis than S. indica and the three species are reproductively isolated. [ABSTRACT FROM AUTHOR]

Hybrid vigour, or heterosis, has been of tremendous importance in agriculture for the improvement of both crops and livestock. Notwithstanding large efforts to study the phenomenon of heterosis in the last decades, the identification of common molecular mechanisms underlying hybrid vigour remain rare. Here, we conducted a systematic survey of the degree of heterosis in Arabidopsis thaliana hybrids. For this purpose, two overlapping Arabidopsis hybrid populations were generated by crossing a large collection of naturally occurring accessions to two common reference lines. In these Arabidopsis hybrid populations the range of heterosis for several developmental and yield related traits was examined, and the relationship between them was studied. The traits under study were projected leaf area at 17 days after sowing, flowering time, height of the main inflorescence, number of side branches from the main stem or from the rosette base, total seed yield, seed weight, seed size and the estimated number of seeds per plant. Predominantly positive heterosis was observed for leaf area and height of the main inflorescence, whereas mainly negative heterosis was observed for rosette branching. For the other traits both positive and negative heterosis was observed in roughly equal amounts. For flowering time and seed size only low levels of heterosis were detected. In general the observed heterosis levels were highly trait specific. Furthermore, no correlation was observed between heterosis levels and the genetic distance between the parental lines. Since all selected lines were a part of the Arabidopsis genome wide association (GWA) mapping panel, a genetic mapping approach was applied to identify possible regions harbouring genetic factors causal for heterosis, with separate calculations for additive and dominance effects. Our study showed that the genetic mechanisms underlying heterosis were highly trait specific in our hybrid populations and greatly depended on the genetic background, confirming the elusive character of heterosis. [ABSTRACT FROM AUTHOR]

Background: Multiplex PCR has been successfully applied in many areas since it was first reported in 1988; however, it suffers from poor universality. Results: A novel method called Universal Multiplex PCR (UM-PCR) was created, which simultaneously amplifies multiple target fragments from genomic DNA. The method has two steps. First, the universal adapter-F and universal adapter-R are connected to the forward primers and the reverse primers, respectively. Hairpin structures and cross dimers of five pairs of adapter-primers are detected. Second, UM-PCR amplification is implemented using a novel PCR procedure termed "Two Rounds Mode" (three and 28-32 cycles). The first round (the first three cycles) is named the "One by One Annealing Round". The second round (28-32 cycles) combines annealing with extension. In the first two cycles of the first round, primers only amplify the specific templates; there are no templates for the universal adapters. The templates of universal adapters begin to be synthesized from the second cycle of the first round, and universal adapters and primers commence full amplification from the third cycle of the first round. Conclusions: UM-PCR greatly improves the universality of multiplex PCR. UM-PCR could rapidly detect the genetic purity of maize seeds. In addition, it could be applied in other areas, such as analysis of polymorphisms, quantitative assays and identifications of species. [ABSTRACT FROM AUTHOR]

The species in the Japanese knotweed complex ( Fallopia japonica s.l. and its hybrids) are among the most invasive plants on earth. Their expansion and reproduction in the introduced range have been mostly due to vegetative reproduction, but observations of low seedling numbers and hybridization processes exist. Knowledge of factors affecting germination characteristics is essential if the risk of sexual reproduction is to be assessed, and its impact on the ability of the species to spread and adapt to different environments. This study aims to examine the germination success of Fallopia japonica s.l. seeds of different ages, quality, and storage conditions. Irrespective of age and even after natural overwintering in the soil, seeds germinated quite well (48-79%). Ungerminated seeds collected in autumn of 2008 were characterized by a low weight/length ratio ( W/ L), low nutrient concentrations, and a greenish tepal coloration. These differences may be due to alternative male taxa participating in the pollination process. Spring collected seeds were subject to strong predation by birds. In contrast to the high germination observed under laboratory conditions, seed germination or early establishment in the field was inhibited and only a few seedlings were observed. Although the factors that inhibit the establishment of mature seeds in the field remain unknown, there is a clear risk that sexual reproduction could gain importance in the future as a result of changing environmental conditions or genetic adaptation. Not only would this facilitate expansive dispersal by wind, but it might also increase the potential for further adaptation of the species complex. [ABSTRACT FROM AUTHOR]

The fatty acid composition in the seed oil was significantly modified following the introduction of transgenes. To further enhance the desirable characteristics of rapeseed oil, it would be beneficial to develop a new approach for the simultaneous silencing of two or more target genes. Our goals in the current study were to (1) increase oleic acid to more than 75%, (2) reduce polyunsaturated fatty acids (PUFA) to about 10% and erucic acid to zero, and (3) accomplish these changes in a single-transformation event. In a single transformation, two fragments amplified from the fatty acid Δ12-desaturase 2 ( BnaFAD2) and fatty acid elongase 1 ( BnaFAE1) genes of Brassica napus were linked together to form a fusion fragment. The fusion fragment was then used to assemble unique intron-spliced hairpin interfering constructs. In the transgenic plant FFRP4-4, the expression of BnaFAD2 and BnaFAE1 genes was completely inhibited. The composition of oleic acid in FFRP4-4 rose to 85%, PUFA dropped to 10% and erucic acid was undetectable. All hybrid F1 seeds obtained from the reciprocal crossing of FFRP4-4 and GX-parents (with different genetic backgrounds) contained more than 80% oleic acid, about 10% PUFA and very low, or undetectable, erucic acid. The results confirmed that the fusion fragment silencing construct can simultaneously and effectively silence the target genes on a consistent basis. The strategy provides a useful tool for detecting gene function and advancing genetic engineering techniques for the improvement of agricultural crops. [ABSTRACT FROM AUTHOR]

Full potential of any hybrid can be exploited by ensuring the supply of genetically pure seeds. Conventionally, hybrid seed purity assessment is done through grow out test (GOT) which is based on the morphological and floral characters of plants grown to maturity. Being land and labor intensive, time consuming and influenced by the environment, there is an immense need to replace GOT with a simple, rapid, unbiased and cost-effective DNA based assay for hybrid purity assessment. With this objective, the parental lines of three commercial safflower hybrids of India (NH-1, NH-15 and DSH-129) were screened using 74 safflower EST-SSR markers and five markers were found to be polymorphic. A PCR-based assay with these markers showed both alleles of the parental lines in pure hybrids proving the heterozygosity, while the off-types were identified by the presence of either of the parental alleles. This assay could accurately determine the genetic purity in a predetermined sample of hybrids constituted by deliberately mixing seeds of parental lines. This is the first report demonstrating the utility of EST-SSR markers for the assessment of genetic purity of hybrids in crop plants. [ABSTRACT FROM AUTHOR]

Fitness of hybrids between genetically modified (GM) crops and wild relatives influences the likelihood of ecological harm. We measured fitness components in spontaneous (non-GM) rapeseed ×  Brassica rapa hybrids in natural populations. The F1 hybrids yielded 46.9% seed output of B. rapa, were 16.9% as effective as males on B. rapa and exhibited increased self-pollination. Assuming 100% GM rapeseed cultivation, we conservatively predict < 7000 second-generation transgenic hybrids annually in the United Kingdom (i.e. ∼20% of F1 hybrids). Conversely, whilst reduced hybrid fitness improves feasibility of bio-containment, stage projection matrices suggests broad scope for some transgenes to offset this effect by enhancing fitness. [ABSTRACT FROM AUTHOR]

Apomixis is the process of asexual reproduction through seed, in the absence of meiosis and fertilization, generating clonal progeny of maternal origin. Major benefits to agriculture could result from harnessing apomixis in crop plants. Although >400 apomictic plant species are known, apomixis is rare among crop plants, and the transfer of apomixis to crop varieties by conventional breeding has been largely unsuccessful. Because apomictic and sexual pathways are closely related, de novo engineering of apomixis might be achieved in sexually reproducing crops. Early consideration of issues relating to biosafety and intellectual property (IP) management can facilitate the acceptance and deployment of apomixis technology in agriculture. [ABSTRACT FROM AUTHOR]

In the Sahel, pearl millet yields are affected by the proportion of hybrid phenotype plants resulting from genetic mixing between domesticated and wild forms. Man counteracts this mixing by applying a production method, the efficiency of which is quantified in this study. Under experimental conditions, cultivated and wild pearl millet were hybridised in order to obtain cultivated pearl millet seeds including a known proportion of F1 hybrids tagged by two different allozymes. These seeds were sown in the field and the cultivation was conducted following practices common in the Sahel. The evolution of the survival rate of plants and the frequency of hybrids were followed over several stages during the season: sowing, germinating, emergence, thinning, flowering and maturing of the seeds. Owing to plant mortality in the experiment, the average tendency was a hybrid frequency that decreased steadily in the first part of the growing season from 42% during germination, to 37% at emergence. It then fell to 17% after the thinning of the plantlets by the farmer. At the end of the cycle, after thinning, only 11% of mature plants were hybrids. Thus, under the combined pressures of natural and human selection, the frequency of hybrids in the field declined drastically. In interaction with natural pressure, the farmer's practices of selection of seeds, sowing in pockets and thinning have the combined effect of heavily selecting the cultivated genotype and limiting without completely preventing the introgression of wild pearl millet genes into the cultivated genome. [ABSTRACT FROM AUTHOR]

Heritability of seed imbibition rate(IMR)in maize (Zea mays L.) is not known. Imbibition rate could provide informationon grain moisture loss rate (GMLR), were there a relationship between IMR and GMLR. The purposes of this research were: (1) to measure IMR and GMLR of F1 and F2 hybrids to estimate their narrow-sense heritability, and (2) to determine the correlation between IMR and GMLR. Thirty-five commercial hybrids (F1 seed) and their F2 seed were evaluated for IMR and GMLR estimated after imbibition. Imbibition rate was measured in six consecutive, 30-minute periods. After the final imbibition period, seeds were evaluated for GMLR in four consecutive, 15-minute periods. Nar row-sense heritabilities, determined via parent-off spring regression, were relatively high for imbibition rate (h2n = 82%) and for grain moisture loss rate following imbibition (h2 n = 81%). Thus, both imbibition rate and grain moisture loss rate were genetically controlled traits and can be improved via cyclic selection. In both F1 and F2 seeds, the initial seed moisture did not affect imbibition rate. Regression analyses indicated that imbibition rate declined progressively over time; a significant curvilinear relationship across the six periods was detected. The GMLR was significant only in the first 30-minutes for the F1 seeds, whereas it was significant in all four periods for F2 seeds. Initial seed moisture did, generally but not consistently, affect GMLR in F1 seeds. In F1 seeds, over all mean IMR across six periods was significantly correlated with over all mean GMLR (r = 0.53**). For the F2 seeds, the correlation was higher (r = 0.80**). Over all GMLR can be predicted reliably from overall IMR of F2 seeds. [ABSTRACT FROM PUBLISHER]

Onion, Allium cepaL., is grown worldwide for its fleshy bulbs which are used as food and medicinal purposes. Based upon global review of the major vegetables, onion ranks second to tomato in area under cultivation. Isolation of male sterility in cv. ‘Italian Red’ onion led to the development of many hybrid cultivars for various geoecological regions. Although the development of onion hybrid culti-vars started in the early 1930s, popularity of onion hybrid varieties is still continuing. In fact, almost two-third of onion varieties in catalogues of major seed companies are listed under hybrid category. This review deals with the floral characteristics, male sterility, production of hybrid onion and method for onion seed production. [ABSTRACT FROM AUTHOR]

Rapidity of improvement of cowpea cultivars often depends on the level of success achieved in the introgression of desirable gene(s) into varieties that are susceptible to biotic and abiotic stresses. This research work aimed at generating hybrids that possess resistant gene(s) to brown blotch disease as well as maintaining its brown seed coat, early maturing and high yield potentials. A mapping population was developed using single seed descent method of breeding between susceptible (Ife brown) and resistant (IT-95K-193-12) cowpea varieties to brown blotch disease. Hybrid seeds generated were inoculated with Colletotrichum truncatum and evaluated. A total of 356 crosses were made in direct (Ife brown × IT-95K-193-12) and reciprocal (IT-95K-193-12 × Ife brown) crosses. Only 8.43% percentage successful crosses were obtained. Seed coat colour was controlled by at least two genes and brown blotch was governed by maternal effect. Some of the hybrids generated possessed resistant gene(s) to brown blotch disease especially when IT-95K-193-12 was used as female parent and most of the hybrids were high yielding and early maturing especially among hybrids that originated when Ife brown was used as female parent. [ABSTRACT FROM AUTHOR]

Jatropha curcas L. (2n = 2× = 22) is increasingly attracting attention in the biodiesel industry for its oil. However, the cultivation of J. curcas L. is faced with numerous challenges unlike the cultivation of Ricinus communis L. (2n = 2× = 20), a closely related species. The generation of an intergeneric hybrid between J. curcas L. and R. communis L. was investigated. Intergeneric hybrids were produced by hand crossing. Immature embryos were rescued, in vitro, from the hybrid seeds and cultured on an enriched Murashige and Skoog (MS) medium for a month. The plantlets produced were grown in sterile peat moss in plastic pots and covered with polyethylene for 30 days, after which they were transferred into cement potted soil. The hybridity and the genuineness of the hybrids were successfully confirmed using randomly amplified polymorphic DNA (RAPD) markers. The number of branches, stem diameter, and leaf size of the F1 hybrids were similar to those of J. curcas L. while the plant height was similar to that of R. communis L. Young hybrids were treated with various concentrations (0%, 0.3%, 0.4%, and 0.5%) of colchicine to induce polyploids. The calli (JR6) treated with 0.3% colchicine recorded the highest tetraploid cell percentage (38.89%). A high tetraploid cell percentage (>50%) is significant in overcoming the problem of sterility after hybridization. [ABSTRACT FROM AUTHOR]