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Potato has about 100 related wild Solanum species growing naturally in the Americas. Solanum jamesii (jam), native to the southwest USA and Mexico, has many valuable traits for breeding, but making hybrids is extremely difficult. We investigated the approach of using the bridge species Solanum verrucosum (ver). A survey of all ver populations in the US Potato Genebank identified the best females. The standard bridge crossing technique using emasculation of ver and “mentor” double pollination after first pollinating with jam was very inefficient for most ver because: 1) emasculation depressed seedset in ver females, 2) despite very careful emasculation many accidental ver selfs resulted, and 3) mentor pollination produced many unwanted hybrids with the mentor pollen parent. We therefore produced populations of ver by backcrossing five generations into tuberosum cytoplasm. The BC5 lines are very vigorous in growth and flowering, but having very low male fertility and complete self-incompatibility they can be mass crossed with jam pollen without emasculation. Even with no mentor pollen, most pistils of verBC5 pollinated with jam produce a small fruit with an average of less than one normal seed. Resulting seedlings were confirmed ver-jam hybrids by DNA markers.

It is of critical importance for our understanding of speciation process to determine the forms of reproductive isolation and their relative importance in species divergence. Oryza nivara and O. rufipogon are direct ancestors of Asian cultivated rice and a progenitor-daughter species pair. Investigating the reproductive isolation between them provides insights into plant speciation and helps understanding of the rice domestication. Here, we quantitatively measured the major components of reproductive isolation between the two species based on common garden and crossing experiments for three pairs of sympatric populations in Nepal, Cambodia and Laos. We revealed significant differences in the flowering times between species pairs, with O. nivara flowering much earlier than O. rufipogon. A very weak reduction in seed set but no reduction in F1 viability and fertility were detected for the crosses between species relative to those within species. Moreover, we detected asymmetrical compatibility between species and found that emasculation significantly decreased pollination success in O. nivara but not in O. rufipogon. Our study demonstrates that the divergence between O. nivara and O. rufipogon is maintained almost entirely by the difference in flowering times and suggests that differential flowering times contribute to both habitat preferences and reproductive isolation between species.

The potato crop has much exotic related germplasm, so optimizing the techniques for obtaining hybrid seeds from interspecific crosses is of interest to potato researchers and breeders, especially when the cross of interest is very difficult and few hybrid seeds are expected per pollination. A model plant of Solanum verrucosum (a particularly useful wild bridge species) was selected to have very uniform and robust flower and seed production in natural crosses as a backdrop for detecting effects of different emasculation techniques. For three uniform buds in single inflorescences, one was pollinated naturally (N) after no emasculation, one was emasculated by gently opening the corolla and plucking out only the immature anthers (A) with a tweezer, and one had total (T) removal of the sepals, corolla and anthers with a tweezers. Pollen of a highly fertile diploid tuberosum male was applied uniformly to all three buds within an inflorescence one day later. No pistil abortion occurred, excluding that as a limiting factor for getting hybrid seed. But both average fruit weight and average seeds per fruit were highly significantly reduced by emasculation in the pattern T

Owing to their superior agronomic performance, the hybrids of vegetable crops are currently applied extensively. However, effective hybrid production requires a laborious manual emasculation to ensure the purity of hybrid seeds in tomato because of the lack of an effective male sterility system. Here, we created two types of tomato nuclear male-sterile lines with different screening markers in a clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system. Co-knockouts of male sterile 10(35) (Ms10(35)) and glutathione S-transferase (GSTAA) created a male-sterile line marked by a green hypocotyl. The Ms10(35) biallelic mutation was introduced into the woolly tomato background, resulting in the linkage of male sterility and a non-woolly phenotype. Two types of male-sterile lines were easily selected at the seedling stage by hypocotyl color or trichome density and further showed high seed purity during hybrid seed production. Our work established the procedure for a rapid transfer of the male-sterile phenotype to the parents of hybrids without extra-modification by the CRISPR/Cas9 system that can be practically applied to hybrid seed production in tomato. This method will be the basis and example for sterile parent creation of multiple crops for hybrid production with the CRISPR/Cas9 system. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11032-021-01215-2.

Differences in floral morphology are often hypothesized to stem from selection by different pollinators. Thus, the presence of multiple floral color morphs within a species might indicate visitation by different pollinator species. To test this prediction, we examined Ipomoea aquatica Forssk., a morning glory species with a “white” morph (all-white flowers) and a “purple” morph (white corolla lobes with purple corolla tubes). We studied this species in Nong Khai, Thailand, where some populations are monomorphic for a single color and others are polymorphic. We compared (a) animal visitation rates to each morph; (b) visitor and pollinator community composition at each morph; and (c) the female reproduction of each morph. Visitation rates were obtained from camcorder footage and used to analyze community composition. Female reproduction was assessed from a pollination experiment with five treatments (open, open emasculation, hand-cross, hand-self, and closed). We found that the main pollinators (bees and butterflies) visited both morphs, and that overall insect community composition to the two floral colors did not differ significantly. Moreover, we found that I. aquatica is capable of spontaneous autogamy but still benefits from pollinators, as flowers in the closed treatment set significantly fewer seeds than flowers in the open and hand cross-pollinated treatments. When comparing female reproduction between morphs, we did not find significant differences for either fruit set or seed set. These findings suggest that floral visitors interact with the two morphs similarly, and that the high-reproductive success experienced by both colors may help maintain the polymorphism in nature.

Baby corn has become a popular dietary choice worldwide. Here, we evaluated the potential of different male sterility systems as a tool to save cost for manual detasseling in baby corn. 24 hybrids having fertile (N-) and different sterile (T-, C- and S-) cytoplasms were analyzed for pollen sterility and various baby corn traits under three dates of sowing. ANOVA revealed significant genetic variation for number of baby corn ears, baby corn yield, length and width of baby corn ears, fodder weight and silking time. Cytoplasm and date of sowing caused significant variation for majority of baby corn characters. All the T-cytoplasm based hybrids showed no exertion of anthers and complete sterility except in one combination. C-cytoplasm based hybrids showed no to partial anther exertion and complete sterility to partial fertility of pollen. The S-type cytoplasm was quite unstable and showed partial to complete anther exertion and pollen fertility. Across hybrids and sowing time, T-cytoplasm had the highest number of baby corn ears per plot (61.83) and baby corn weight (2659.61 kg/ha) than C-cytoplasm (58.61, 2460.17 kg/ha), N-cytoplasm (57.39, 2323.08 kg/ha) and S-cytoplasm (56.83, 2301.89 kg/ha). The highest baby corn ear -length (8.82 cm), -diameter (1.48 cm), and fodder weight (35.07 t/ha) were recorded in T-cytoplasm. Late sowing had positive effects on baby corn over early planting. This information provides great significance for the utilization of male sterility in baby corn breeding. This is the first report on effects of different male sterility systems as a potential genetic emasculation mechanism in baby corn cultivation.

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.

The aim of this study was to determine the effect of selected factors on rye (Secale cereale L.) haploid embryo production by the wide crossing method. The study was performed on fifteen winter rye genotypes. This is the first time for rye when besides the genotype, on the enlargement of ovaries and haploid embryo production, such factors as: type of auxin analogues 2,4-dichlorophenoxyacetic acid (2,4-D), 3,6-dichloro-2-methoxybenzoic acid (dicamba) and 4-amino-3,5,6-trichloropyridine-2-carboxylic acid (picloram), and the time between florets emasculation and pollination were investigated. All factors had a significant impact on rye ovary enlargement, however the haploid embryo formation depended only on rye genotype, not on kind of auxin and days between emasculation to pollination. In total, twenty one haploid embryos were formed by six genotypes of fifteen tested. On average, 13.86% (after 2,4-D treatment) to 20.05% (after dicamba treatment) enlarged ovaries per emasculated florets were obtained. Most of the ovaries enlarged when florets were pollinated 4 and 6 days after emasculation. Most of the haploid embryos formed when florets were pollinated 6 days after emasculation. The obtained haploid embryos did not germinate.

Cynara cardunculus L., member of the Asteraceae family, includes three botanical varieties, fully-inter-fertile: scolymus (globe artichoke), altilis (cultivated cardoon) and sylvestris (wild cardoon).The artichoke production is traditionally carried out through vegetative propagation using offshoots or suckers. However, several new seed propagated cultivars have been developed in recent years, which showed high yield and ruled out phytosanitary problems inherent to vegetative propagation. In this context, hybrid seeds production, which exploits the heterosis phenomenon producing high performance plants, is of global interest. Manual emasculation is extremely difficult; therefore, it is essential to have a male-sterility system to achieve an efficient hybrids production. In Cynara genus, genic male sterility was found only in globe artichoke but the genetic bases of this phenomenon is poorly explored. The objective of this work was to elucidate the genetic male sterility in Cynara cardunculus L. combining SRAP technology and a BSA approach and to identify molecular markers associated to ms genes, feasible to be applied for MAS in breeding programs of the species. Segregation of the male sterility in our F2 population fit to a monogenic segregation model (3:1), revealing that only one gene (ms) is responsible, in homozygous recessive stage, to determine male sterile plants. Three SRAP markers linked to the ms gene were found. The nearest marker (SRAP 7-10.1774) was estimated to be 0.5 cM from the ms gene whereas the others (SRAP 4-9.332 and SRAP 4-9.700) were linked at 4.3 cM and 13.9 cM, respectively.

A robust literature ties emasculation to a range of compensatory behaviors. The present study shifts focus away from the effects of masculinity threat toward an understanding of young adult men’s experiences of emasculation in their own words. Drawing on 42 in-depth interviews with undergraduate men attending a selective U.S. university, we examine the behaviors, situations, and narratives—both experienced and hypothetical—that privileged young men perceive as threatening. We use these data not only to contribute to the empirical literature on masculinity threat, but also as a novel approach for theorizing about the meaning and structure of masculinity more broadly. This is an important task given recent social and economic changes that may have altered contemporary definitions of masculinity. Emasculation accounts provide unique analytical leverage for revealing men’s often unspoken understandings of acceptable masculine behavior. We find that, while many interviewees superficially espoused egalitarian and anti-homophobic beliefs, their emasculation narratives implicitly call for the subordination of women and other men. These performances consequently obscure and maintain traditional, hegemonic power relations. We discuss the implications of our finding for scholars, practitioners, and individual men who desire a more equitable gender structure.

To explore the feasibility of intra specific hybridisation between Robinia pseudoacacia (common diploid) and other Robinia varieties, tetraploid R. pseudoacacia, R. pseudoacacia var. decaisneana (Carr.) Voss., R. pseudoacacia Frisia, and R. pseudoacacia “Idaho” were collected as male parents, and hybridisation trials were conducted over a period of three consecutive years. The average seedling emergence rates of the five hybridised combinations were ~2.3,2.0, 3.3, 1.3, and 0 % per year, respectively. To ensure maximum seedling emergence rates, we found that the best pollinating times were the blooming days. To investigate the causes of low crossability, we also examined pollen-tube growth and fruit setting rates. The results indicated that the causes of low crossability were abnormal pollen-tube growth, failed development of fertilised ovule, and poor seed germination. Low fruit-setting rates caused by emasculation may also lead to low crossability.

Production of doubled haploid (DH) cereals is becoming increasingly important in crop breeding programs, but the methods currently applied still remain inefficient. In this study, we present the procedure for obtaining haploid and DH oat plants by pollination with maize. Thirty-three oat genotypes were used in the experiments. Oat plants (14,543 florets) were pollinated with maize pollen 2 days after emasculation and treated with auxin analogues: 2,4-dichlorophenoxyacetic acid (2,4-D) or 3,6-dichloro-2-methoxybenzoic acid (dicamba), at a concentration of 100 mg dm−3. These auxins had no significant influence on the number of haploid embryos developed, but they significantly affected their germination ability, and thus haploid and DH plant production. After application of 2,4-D, 5.06 % of haploid embryos developed per emasculated florets, 1.37 % of haploid plants and 0.54 % of DH lines, whereas after dicamba treatment, 4.3 % of haploid embryos, 0.64 % of haploid plants and 0.25 % of DH lines. Haploid embryos were obtained from all genotypes tested, however, their frequency differed between individual genotypes. The highest number of embryos per emasculated florets (9.0 %) was obtained from the DC09040 genotype after dicamba treatment, and from STH123 × Skorpion (8.9 %) after 2,4-D treatment. The genotype did not significantly affect the development of haploid plants, nevertheless the highest number of DH lines was obtained from the Arab × Typhon genotype. There were 52 DH lines acquired from 28 genotypes, which produced a total of 5227 seeds. The number of seeds varied between the DH lines from 2 to 595. Seeds of all the DH lines produced fertile next generation. DH lines are currently included in breeding programs.

Background Two crossing techniques for hybridization of chickpea have been reported and include pollination after emasculation and pollination without emasculation. Success of crossing with emasculation varied from 5 to 17%; while the success rate varied from 20 to 50% by pollination without emasculation. The important reason for the low success rate of the two procedures could be lack of detailed information on the flowering stages chosen for crossing together with the environment where plants grow. Results We describe a comprehensive method for chickpea crossing where two genotypes, ICCV96029 as female and PI503023 as male parent were used. Leaf shape and seed size were used as morphological markers to select hybrids. For crossing, incision was made along the central line of the keel petal for the removal of anthers and to expose the stigma for placement of pollen from donor parent on its surface. After pollination, style was inserted back gently inside the keel petal and covered by wing petals and standard petals to make a natural sac which prevents drying of internal organs. Alternatively, if the conditions are favorable there is no need to protect the pollinated flower and therefore petal removal method for cross-pollination can be used. Our method showed around 78% crossing success rate which is much higher than the previous results. Conclusions We have shown that the crossing by keel petal incision or petal removal is an effective approach which significantly increases the crossing success rate. Furthermore, our detailed method shows that the flowering stage, selection of parents and temperature play crucial roles in crossing success.

Emasculation—males becoming effectively sterile by self-removing their genitals—has long been considered a peculiar evolutionary phenomenon with unknown function, taxonomically restricted to few spiders and flies. In spiders, emasculation results in half or full eunuchs when males sever one or both sperm transferring organs, palps. Three types of emasculation, pre-maturation, mating, and post-mating are known in spiders, all having evolved multiple times. Males practicing pre-maturation emasculation sever one of their palps while still immature, then engage in strict monogyny via genital plugging and spontaneous death. Emasculation during mating also results in genital plugs, but half eunuchs have another chance to mate. So far, the behavior of those males that become eunuchs post-mating by self-removing disfigured palps has not been investigated empirically. We test the mechanism and adaptive significance of post-mating emasculation in coin spiders (Herennia multipuncta) and use phylogenetic reconstruction to understand its evolutionary history. Our laboratory assays corroborate three hypotheses related to mate monopolization: (1) The plugging hypothesis—predicting genital plugs to prevent female remating; (2) The better-fighter hypothesis—predicting enhanced eunuch aggressiveness toward rivals; and (3) The gloves-off hypothesis—predicting increased eunuch endurance. The support for these hypotheses in spiders practicing emasculation during and after mating reinforces recent phylogenetic interpretations of these two emasculation types being evolutionarily linked in the family Nephilidae. We weigh the evidence in support of three different, but equally parsimonious scenarios of nephilid emasculation evolution. We conclude that emasculation is an adaptive, sexually selected trait that calls for further comparative and experimental research.

Two possible intergeneric putative hybrids between Cancrinia maximowiczii and an interspecific hybrid (Chrysanthemum naktongense × Chrysanthemum ×morifolium ‘Aifen’) were produced without emasculation. The putative hybrids could be identified by ITS sequences and morphological characteristics. The distinct trait of the putative hybrids presented itself by 7–13 white tubular florets bursting out in the outer capitula. Results of flow cytometry analysis and chromosome counting did not support the nature of the putative hybrids. It was found that the ploidy levels of the putative hybrids and parents are diploid, hexaploid and diploid respectively. Whether the paternal parent is a donor of the genome or not, need to be analyzed further by GISH. We propose that C. maximowiczii may be transferred to the subtribe Artemisiinae based on ITS phylogenetic analysis, although the position of the species and the genus Cancrinia could not be confirmed here.

Tagetes patula L. is an annual plant belonging to the Asteraceae family. Currently, commercial F1 cultivars are produced through the use of artificial emasculation which is a very laborious procedure, particularly in view of the composite capitulum structure. To date, no male sterile line is available in this species, but the isolation of such material would provide a valuable tool for the establishment of an efficient cross-pollination system for the production of F1 hybrids. In this study, we report the characterization of a novel pollen abortion mutant of Tagetes patula which was isolated from 1,796 heat shock induced cutting seedlings. Histological and cytological observation demonstrated that the abnormal development of the microspores during the binucleate pollen stage led to pollen abortion, and this was correlated to premature tapetum degeneration. Cross hybridization experiments indicated that a recessive nuclear gene was responsible for the trait. This novel male sterile mutant of Tagetes patula appears to be an applicable material for improving the breeding efficiency of the species and may be used to significantly improve ornamental traits in F1 generations.

Quantitative trait locus (QTL) analyses have greatly enhanced our understanding of complex traits in rice (Oryza sativa). In parallel, the development of introgression lines has provided a powerful tool for elucidation of complicated genetic networks and identification of QTL. We recently developed a biotron breeding system that allows rapid indoor cultivation of rice plants. The system, however, has two relatively weak points in its application to marker-assisted breeding in rice: first, variation in generation times among cultivars; second, the low number of seeds produced by crosses. To compensate for these weaknesses, we propose utilizing cytoplasmic male sterility (CMS) and restorer (Rf) lines with a cv. Nipponbare genetic background. Through use of the Nipponbare genetic background, rice generation times of 2 months can be achieved regardless of any differences in the genetic background of the donor rice plant. This CMS–Rf system confers a high yield of hybrid seeds, avoids the need for emasculation and precludes accidental crosses. Our results demonstrate that this new methodology can markedly accelerate many different aspects of rice research, especially in functional genomics. The combination of biotron breeding system, early flowering habit and CMS will be of great value for screening candidate genes associated with QTL and for introducing useful QTL into elite cultivars.

Mode of reproduction and presence of reproductive barriers were studied in two closely related members of the genus Cyanus: the C. triumfetti (diploid 2n = 22) and C. montanus (tetraploid 2n = 44) groups. Based on results from isolation and emasculation experiments, taxa of these groups can be considered allogamous with a low selfing rate (0.07 %–0.21 % of achenes developed after selfing). Taxa of the C. triumfetti group hybridize easily and produce viable progeny. Differences in the percentage of well-developed achenes per capitulum obtained from interspecific crosses between members of the C. triumfetti group suggested different levels of reproductive isolation. The percentage of well-developed achenes of most homoploid crosses was 3.47 %–8.87 %. Higher percentages of well-developed achenes were obtained from crosses between Eastern Carpathian C. pinnatifidus and Alpine C. triumfetti s. str. (18.36 % ; 26.56 %) and between geographically close taxa in Central Europe (C. dominii, C. strictus and ‘intermediate morphotype’; 12.75 % –17.60 %), which indicate their overall close relatedness. Crossing geographically remote C. strictus and C. triumfetti s. str. yielded no or only few (0.99 %) well-developed achenes, indicating an increased degree of incompatibility in allopatry. The success of heteroploid crosses between plants belonging to different groups was reduced (2.96 %) and suggested reproductive incompatibilities between ploidy levels. The progeny of heteroploid crosses comprised 63 % of triploids of presumable hybrid origin on tetraploid as well as diploid maternal plants. Another 15.22 % of progeny had the maternal cytotype, probably resulting from selfing. Low viability of heteroploid hybrids supports the existence of post-zygotic mechanisms.

Intergeneric hybridizations were produced between Elachanthemum intricatum (Franch.) Ling et Ling and Opisthopappus taihangensis (Y. Ling) C. Shih without emasculation. About 12 and 16 % seed settings were obtained in reciprocal hybridizations. 17 seedlings germinated from 183 seeds from Elachanthemum intricatum (Franch.) Ling et Ling as female parent and 13 seedlings germinated from 109 seeds of Opisthopappus taihangensis (Y. Ling) C. Shih as female parent. 14 and 8 plants survived to maturity respectively. Only one progeny from Elachanthemum intricatum (Franch.) Ling et Ling in these hybridizations was found to be a true hybrid from the morphological characteristics and sequences of nrDNA ITS. The leaves of this new hybrid show some conspicuous intermediate features. The new hybrid has 5–8 mini ray female florets in the outer row of capitula. It is perennial just like its paternal parent (Opisthopappus) in contrast to its biennial maternal parent (Elachanthemum).

Acacia mangium is a major plantation species for the pulp and paper industry in south-east Asia and there are a number of active breeding programs. The species is predominantly outcrossing, but with a demonstrated capacity to set selfed seed where outcross pollen is limited, with consequent inbreeding depression in the progeny. Current controlled pollination methods therefore include a time-consuming emasculation step. We used microsatellite genotyping of seedlings to determine the consequences of outcross pollination with and without emasculation. Only 1 of 3 mother trees set a small amount (5%) of selfed seed. Using whole inflorescences from the male parent as the pollen applicator rather than sieved pollen reduced outcross contamination rates from 19.1 to 8.7% and substantially increased worker productivity. Application of sugar solution to the female flowers immediately prior to pollination increased yield of sound seeds per spike. Additional improvements to the pollination protocols are discussed.

Controlled pollination (CP) is a labour-intensive, but useful procedure applied in tree improvement programmes. However, the high costs involved and relatively low seed yields often obtained has, in most cases, necessitated the use of lower quality, open pollinated seed. The aim of the present study was to compare control-pollination methods for combinations among small-flowered eucalypt species. By making crosses within and among Eucalyptus grandis, E. smithii and E. macarthurii, we compared effectiveness, in terms of seed production and level of genetic contamination, of three CP techniques, namely emasculation of bagged flowers and subsequent pollination of receptive stigmas (Conventional method), emasculation and immediate pollination of stigmas with induced receptivity followed by bagging (One Stop Pollination), and pollination of cut styles without emasculation and bagging (Artificially Induced Protogyny). One tree of each species was used as the female in these crosses. Although Artificially Induced Protogyny using ripe and semi-ripe buds produced the highest seeds/flower pollinated in the majority of crosses carried out in this study, the technique, when performed on green buds, resulted in the highest capsule abortion. Molecular analysis using microsatellite markers also revealed that progeny from the Artificially Induced Protogyny method, when using green and semi-ripe buds, were highly contaminated by self- and external pollen. Of the three CP-techniques tested, One Stop Pollination had the lowest genetic contamination. However, this technique also had one of the lowest seed yields, while the Conventional method was intermediate in performance.

Hot water treatment was applied to Tartary buckwheat (var. ‘Hokkai T8’) for emasculation. Apical clusters of flower buds were soaked in a constant temperature water bath (42–44°C) in the afternoon and then the flowers which opened in the next morning were used for the investigation of self-fertilization and the artificial pollination. Hand pollination was carried out by rubbing the anthers taken from the male parent (var. ‘Hokkai T10’) to the stigma of the flowers treated by hot water. The seed set by self-fertilization was almost 0% when treated at 42°C for 8 min or more, at 43°C for 5 min or more and at 44°C for 3 min or more. With artificial pollination, the best performance was obtained when treated at 44°C for 3 min, in which the seed set was 55.1% and the matured seed was obtained 37.7% of the hand-pollinated flowers. Nine out of 26 progeny seedlings emerged and the cotyledonal color of them were all reddish green, probably indicating the hybrid of ‘Hokkai T8’ and ‘Hokkai T10’. The hybridization was reconfirmed by the segregation in F2. The hot water treatment at 44°C for 3 min was available to other seven varieties. From 24.5% to 100% of the hand-pollinated flowers set mature seeds though only one self-fertilized seed remained without artificial pollinations. This hot water treatment must be practically useful in hybridization breeding of Tartary buckwheat.

The versatility of the breeding system in the hybridogenous hexaploid, Hieracium rubrum, was demonstrated in emasculation and crossing experiments. The flow-cytometric ploidy analysis of 1095 seedlings amongst its' progeny enabled the determination and quantification of the reproductive pathway (apospory, haploid parthenogenesis, cross-fertilization of both reduced and unreduced female gametes) responsible for each progeny class. The progeny profiles were stable between two successive years. The percentage of hybrids arisen from crosses with tetraploid sexual H. pilosella was 7.9%. The rate of trihaploids generated by H. rubrum when crossed to H. pilosella was 3.95%, similar to that of pentaploid (n + n) and octoploid (2n + n) hybrids (3.95% and 3.39%). Unreduced pollen from H. pilosella contributed to hybridization much less frequently (0.56% of all progeny), than unreduced eggs of H. rubrum. The increased frequency of trihaploids formed by crossed compared to emasculated plants suggests an interaction between the presence of pollen and the autonomous development of meiotic embryo sacs. Although the environmental conditions (garden compared to unheated glasshouse) influenced the progeny following the emasculation, no corresponding response to environment was detected amongst the autonomously derived progeny following pollination with H. pilosella. However, there was an influence of pollen parent on progeny which varied under the different environmental treatments. The importance of residual sexuality in reproduction of apomicts is evident. The non-maternal progeny was generated with highly variable frequency especially in the glasshouse, with some capitula reaching up to 50%. Having an autonomous endosperm development, Hieracium subgen. Pilosella is almost unique among other aposporous genera, in which such variable reproduction mode is connected with pseudogamy.

The embryo rescue technique was successfully used to raise hybrids between Trifolium alexandrinum and T. constantinopolitanum. As a result of its narrow genetic base, genetic improvement in Egyptian clover (syn. Berseem; T. alexandrinum), an important fodder crop in tropical and subtropical countries, is hampered, thereby making it imperative to introduce alien genes from related species. In a conventional interspecific hybridization program, hybrids could not be raised due to post-fertilization barriers. Of the several combinations tried, pollination 2 days after emasculation was found to be the best. Globular embryos were observed 5-7 days after pollination (DAP), followed by heart-shaped embryos 10-12 DAP. Embryos excised at the heart-shaped stage responded well to EC3 culture medium. Of 612 crosses, 33 healthy embryos could be excised and cultured on EC3 medium. The plumule emerged 8-12 days following inoculation. The embryo-rescued plants were hardened, inoculated with Rhizobium and transferred to the field. The hybrids showed intermediate morphological features with reduced pollen fertility (55-65%) and a chromosomal complement of 2n = 16. Biochemical characterization using isozymes confirmed hybridity.

The occurrence of breast cancer in men is rare in comparison to women. Public knowledge that men can get breast cancer and of male breast self-examination are lacking. Research in the course and treatment of breast cancer in men is needed. Men generally present in more advanced stages of breast cancer than women, and have a poorer prognosis. In this article, the epidemiology, common symptoms, diagnostic methods, and current treatment of breast cancer in men are described. Gender differences in presentation and course of illness are discussed. Additionally, the psychological implications of breast cancer for male gender roles and masculine identity are explored. Directions for further investigation are given. Treatment providers are encouraged to educate themselves and their male patients on breast cancer in men and male breast examination techniques so that this disease may be identified earlier in its course and survival rates improved.

Data and findings concerning the development of an effective male sterility system (as already applied in the practice of producing tomato hybrid seed) through the use of the positional sterility (ps 2) gene are reported. Undesirable selfing and the necessity of emasculation are discussed as the two main disadvantages that limit the use of ps 2-sterile seed parents in tomato hybrid seed production. The following specific characteristics in the performance of ps 2-lines were evaluated: 1) the percentage of selfing in the ps 2-lines varies within and between the years of growing, being forever lowest during the period of hybrid seed production; 2) the percentage of selfed seeds when using a ps 2-line as seed parent in producing hybrid seed is significantly lower than the percentage of selfing, observed on this same line; 3) the ps 2-gene expressivity varies depending on the genotype. This enables the breeding of ps 2-lines exhibiting very low percentage of selfing; 4) stamen emasculation at anthesis (as applied in ps 2-lines) is significantly easier and more rapid than emasculation in floral buds. The easy maintenance of the sterile lines – by artificial selfing it is possible to produce 100% ps 2 progeny – and the high yield of hybrid seed obtained are discussed as important advantages in using this type of sterility in tomato hybrid seed production.

Controlled pollinations and observations of pollen tube growth, pollen fertility and cytological data were studied in 11 species ofMelastomataceae growing in “cerrado” in SE Brazil. Seven species produced apomictic fruits with viable seeds. Four species were not apomictic, with two self-incompatible (gametophytic SI) and two self-compatible, one showing spontaneous self-pollination. The apomictic species had lower pollen fertility than sexual ones — although in some cases differences were not significant — showing that low pollen fertility may be a useful indicator of apomixis if analysed using careful sampling supplemented by emasculation experiments. The apomictic species also showed meiotic irregularities, probably related to hybridization, polyploidy and the cause of low pollen fertility. Apomixis in this group probably is more associated with taxonomy and phylogeny than habitat or habit, since 85% of the apomictic species reported in the literature belong to the tribeMiconieae and occur in a wide range of vegetation types and have diverse habits. This suggests the existence of very extensive apomictic complexes comparable to those reported in mainly temperate genera ofAsteraceae andRosaceae.

It has been hypothesized that females of some dioecious species maintain stamens that produce sterile pollen as a means of attracting pollinators to promote greater seed set. However, this hypothesis has rarely been tested. This paper examines the role of pollinators in the maintenance of sterile stamens in the cryptically dioecious species, Thalictrum pubescens. Wind was found to contribute to pollination; branches of female T. pubescens enclosed in cheesecloth to exclude insects but not wind were still able to set seed. Therefore, females may not need the stamens for pollination. In 1994, insects were found to discriminate against emasculated female flowers, but this discrimination did not lead to a significant difference in either the amount of pollen received or seed set. In 1995, emasculation was combined with the addition of pollen to determine if emasculated females were pollen limited. No significant effect of pollen addition or emasculation was found. Emasculated branches in the pollen-addition treatment appeared to have slightly lower seed set than non-emasculated branches that received pollen, indicating that the slight reduction in seed set was caused by emasculation rather than pollen limitation. Since stamens do not appear to be maintained as pollinator attractants, other explanations, such as genetic constraints, must be investigated.

The effects of pollen storage and detached-tiller culture on polyhaploid production of hexaploid wheat were examined using maize and pearl millet crosses. Pollen storage at ultra-low temperature did not affect polyhaploid production frequency in pearl millet crosses, but greatly reduced frequency in maize crosses. Stored pearl millet pollen can be used as an alternative medium for wheat polyhaploid production when fresh pollen is not available. Detaching wheat tillers with spikes at crossing time and culturing them in a solution containing sucrose, sulfurous acid and 2,4- dichlorophenoxyacetic acid (2,4-D) resulted in no distinct reduction of polyhaploid production frequency in crosses with both maize and pearl millet. Hot-water emasculation after detaching wheat tillers was successful for these wide crosses. Detached-tiller culture makes it possible to collect the spikes from wheat plants growing in distant sites and handle them for wide crosses in a laboratory. These techniques avoid having to synchronize flowering times of both parents and result in considerable savings in terms of labor and space required for handling parent plants.

Hagerup's (1950) observations of rain pollination inNarthecium ossifragum are commonly admitted. Nevertheless,Daumann (1970) stated that pollen and stigmas suffer considerable damage from rain impact. Experimental pollinations and pollen observations were conducted at a single site in the Upper Ardennes, Belgium, during three years. Rain water had a deleterious effect on both fruit and seed set and on pollen germination. Fruit and seed set differed among years mainly due to rainy weather. Fruit set also varied among experimental treatments. Pollination trials showed thatNarthecium ossifragum is self-compatible and autofertile. Emasculation had a deleterious effect and caging had no effect on fertility.

Sesbania sesban was amiable to controlled cross pollination when the emasculation and pollination operations were performed in the morning. A medium of 10% sucrose solution was found to be optimal for in vitro germination of the pollen grains. The pollen is quite tolerant of orthodox storage conditions enabling controlled crosses to be performed among accessions that flower in differing seasons of the year.

Results from creation and comparative test of the new hybrid tomato cultivars are presented: Jar and Dar — semi-determinate suitable for early production in plastic hothouses and in the field; Viki, Asja and Lorin — indeterminate suitable for middle-early field production. Jar and Dar excel the standard in earliness and fruit size. Seed production of Dar, Viki and Asja is realized on a male sterile base (ps-2) and genetic morphological marker (ah) that makes easier the flower emasculation, increases the hybrid seeds purity and precipitates their realization the whole year because of exclusion of the necessity of carrying out a ground test. Above mentioned tomato cultivars are recognized for a spread in all regions of Bulgaria.

The aim of our research is the elaboration of a simple method of tomato hybrid seed production at the development of hybrids F1 (common and parthenocarpic) on the basis of functional male sterility for ecological conditions of Belarus. The results of study of tomato flowering biology are discussed. The optimal term for pollination without emasculation of functional male sterile forms Z-313 and B-3-1-8 is the 3-6-th days and parthenocarpic functional male sterile forms B-2-2, B-2-5, B-2-6, ą-3, ą-4, Z-1-3 — the 2-4-th days after the phase of yellow-green bud. Forms with short pistil (C-9464, C-3-1, ą-2) may be used in hybrid seed production after the removal of filaments directly before pollination. The existence of a marker gene (potato leaf) gives a good possibility to reject non-hybrid seedlings.

New haploid-wild species hybrids (H-S) with desirable tuber type and 2n gamete production have been identified. They provide the opportunity for the production of inexpensive, 4x hybrid TPS from 2x×2x crosses. A proposed system to utilize plants producing either 2n eggs or 2n pollen is described. One H-S hybrid (female parent) would be selected for male fertility, self-incompatibility, high frequency of 2n eggs and no 2n pollen; an unrelated H-S (male parent) for male fertility and high 2n pollen production. In addition both parents would be selected for profuse flowering, attractiveness to bumblebees and other desirable characteristics. The male and female parents would be planted in alternate hills with bumblebees doing the pollinations. The elimination of emasculation, pollen collection, and hand pollination could reduce 4x hybrid TPS costs by more than 50 percent.

The effects of different pollination techniques, with and without emasculation and delayed pollination, were investigated to find the conditions for maximum seed set after self-pollination and intraspecific and interspecific crosses of Brassica oleracea var. acephala. The results indicated that the pollination conditions achieving maximum seed set vary with the type of pollination. After controlled self-pollination, the best seed set occurs in bud 3 to bud 10. For the intraspecific cross, the youngest flower and the oldest bud produced the largest number of developed ovules but bud pollination was productive to bud 8. The yields from these two pollination types were best when the female parent was not emasculated. In the interspecific cross with B. campestris cv. Marco the best results came from the youngest flowers and the oldest buds subjected to the standard practice of pollinating directly after emasculation. Possible reasons for these effects are discussed.

The current position regarding reports in the literature on interspecific hybridization in the pulses is confused. Two major reasons can he advanced in explanation. The first is that frequently conspecific wild and cultivated forms have received different binomials and crosses between such are frequently regarded as interspecific hybrids. The second arises from mistaken interpretation of results of attempted interspecific hybridization when progeny strongly resembling the maternal parent are produced. It is suggested that these progeny might have been produced by failures in emasculation or rare accidental apomixis. All cultigens of the generaArachis, Cajanus, Cicer, Phaseolus andPisum are able to some extent to produce viable true interspecific hybrids as are the Asiatic forms ofVigna. True interspecific hybrids have not been produced withVicia faba nor withVigna unguiculata the cowpea.

The effect of GA4+7 (GA) on fruit and seed set of ‘Sonia’ roses unpollinated and pollinated with ‘Ilona’, was studied. GA at 0, 10, 50, 250 or 1250 ppm in water with 25% iso-propyl alcohol was applied 0, 7 or 14 days after emasculation. In general, GA improved fruit and seed set, and induced heavier, earlier ripening fruits. In the unpollinated and pollinated categories fruit weight and the number of achenes per fruit in comparable treatments were about the same. In the unpollinated category all achenes were parthenocarpic. In the pollinated category, 10 and 50 ppm GA after 14 days more than doubled the number of achenes per pollinated flower. Achenes with or without an embryo are a probable condition for fruit set. Effects of GA are discussed.

Various aspects of pollen longevity, in vitro germination of pollen and controlled pollination in Coffea arabica were investigated. High pollen viability could be maintained for more than two years, much longer than previously reported, by storing it under vacuum at 18°C. The most satisfactory method of in vitro germination of pollen was the hanging drop in a Van Tieghem cell, with a 10°, sucrose solution. For artificial cross-pollination it is necessary to carry out emasculation and bagging at the latest one day before anthesis. The stigmas of unpollinated flowers remained receptive for at least nine days.

Unidirectional intergeneric crosses using octoploid and hexaploid Fragaria species as a female parent and diploid and tetraploid Potentilla species as a male parent were performed, producing in toto 1345 fruits with an estimated 46089 seeds. The germinating seeds obtained by using P. anserina mostly perished at the cotyledon stage, a few developing into matroclinous octoploid seedlings. The seeds obtained by using P. fruiticosa produced two types of seedlings: matroclinous octoploids and genuine intergeneric hybrids. It is considered that the matroclinous octoploids resulted from contamination during the emasculation process. A great majority of the hybrid seedlings were slow in growth and development and perished before reaching the flowering stage. No haploids have been recovered. Possible reasons for absence of haploid genotypes in the progenies of these intergeneric crosses are considered. Among the seedlings of F. x ananassa cv. Tioga x P. fruiticosa, a seedling of an unusual phenotype was noticed, which upon chromosome determination, proved to be 2n=9x=63. This genotype displayed complete male and female sterility. The implication of the sterility of this seedling for bridging of the two genera is discussed.

1. A project has been initiated to explore the possibilities of selection for higher levels of sucrose storage in the wild species S. spontaneum, using a representative sample of parental clones under conditions of natural crossing. 2. The aim of the programme is the development of superior clones to represent the wild species in conventional breeding programmes, which involve repeated backcrossing to S. officinarum. 3. An analysis of the first generation following the intercrossing of 21 parental types without emasculation, has demonstrated extensive genetic variability within and between progeny groups for fibre, sucrose, reducing sugars and yield grade. 4. Fibre and sucrose percent fresh weight are characters of high repeatability (0.4-0.6), and show little evidence of non-additive genetic effects. Individual plant performance for these characters can therefore be taken as a satisfactory basis for selection in this material. 5. The average degree of self-fertilization occurring under conditions of natural crossing has been estimated to be 0.69±.13, based on analyses of the quantitative genetic data for fibre and sucrose percent fresh weight. 6. The within-family genetic variance observed is of the order of five times that expected if the parental clones were homozygous. Much of the genetic variability induced within-families is therefore due to self-fertilization of heterozygous parental material, though the exact proportion cannot be deduced from the present data. 7. The initial response to selection for increased sucrose percent fresh weight is predicted to be of the order of 50% of the population mean. Comparable responses in subsequent cycles of the programme appear to be possible, provided an adequate degree of outcrossing can be achieved by controlled pollination techniques. 8. The genetic correlations between sucrose and other characters of importance are favourable to the objectives of the breeder, or else of a low order. There is no general relationship between the somatic chromosome number of the parental clones and the mean sucrose level of their progeny.

Some factors are mentioned which have an influence on the fraction of triploids in polyploid beet varieties, viz. 1. the initial proportion of the parents (2n and 4n) 2. the way of harvesting of the seeds: from one of the parents or from both 3. male sterility 4. differential selection between the two types of pollen (n and 2n) 5. differential incompatibility and vitality 6. arrangement of the plants. THE FRACTION OF TRIPLOIDS IN POLYPLOID BEET VARIETIES Triploid beets cannot be reproduced as such. They have to be produced by crossing diploid × tetraploid plants. The cross probably introduces a heterosis effect, to which the triploids may in part owe their reputation. Unlike the procedure followed in maize, emasculation is impracticable. Therefore other means are needed to obtain a maximum fraction of triploids in the offspring. In order to arrive at an evaluation of the various breeding methods used, one can consider a simple model which is gradually extended with complicating factors. Let us assume a group of plants practising random mating, i.e. mating without preference with respect to the characters in discussion. Let us further assume the population to show no differential fertility or vitality, i.e. no differential selection at gametic or zygotic level. Then the assemblages of male and female gametes will each consist of two types: n and 2n, in relative frequencies directly proportional to the frequencies of the parental types: 2n and 4n. If we call these relative frequencies p and q (o ~< p ~< 1, p + q = 1) random cornbination of the gametes will give the following result: ? n n 2n 3n d' 2n 3n 4n

In crossing, emasculation can be applied or not. In both cases some variations are possible. Which method can best be applied depends among other things on the inflorescences of the varieties to be combined. With the cultivated varieties the mean percentage of successful crossings varies from 30 to 40. Success is dependent mainly on Phaseolus dumosus is a botanical form from Central America. Flowering only starts under rather high temperatures in short days. In the Netherlands this species does not produce any seed. Dumosus can readily be propagated asexually. The cross Ph. vulgaris × Ph. dumosus produces satisfactory results, the percentage of successful crossings varying from 0–38.

The practical utilization of heterosis in crop plants has been greatly facilitated during the past 15 years by the use of cytoplasmic male|sterility for low-cost, large-scale emasculation of the seed parents of hybrids. The method is now being used in commercial production of hybrid onions, sugar beets, field corn, grain sorghum, and petunias. Its use is contemplated for hybrid sweet corn, pop corn, red table beets, fodder beets, fodder sorghum, pearl millet, carrots, and garden peppers.

A high concentration of gibberellic acid (GA3, 2%) was found to act as a gametocide for the common onion, Allium cepa L., when sprayed in the beginning of the bolting process. This technique is suggested as a possible substitute for hand emasculation, since it would greatly facilitate interspecific and intervarietal crosses, recurrent backcrosses and the selection of good B lines.

Self-incompatibility (SI) is but one of the outerossing mechanisms extant in flowering plants that lead to a high level of heterozygosity in a population and to a genetical architecture based on homeostasis and hybrid vigor. But in contrast to other such systems, SI rigidly impedes self-pollination, which is desirable in breeding schemes for the rapid fixation of inherited characteristics as well as the testing of progeny and the derivation of inbred lines. SI may also be a barrier between plants of similar S (incompatibility) alleles, preventing exchange between them of desirable genes. Finally, SI may act as a unilateral barrier to crosses between self-incompatible and self-fertile individuals or species. In these respects, SI constitutes a nuisance and a problem to the plant breeder. Occasionally, SI may be an aid to the plant breeder. Self-incompatible plants may be crosspollinated with emasculation. Two self-incompatible varieties may be interplanted and permitted to cross through natural vectors. Yet, it is doubtful if these occasional advantages outweigh the inconveniences of incompatiblity. As an element of the breeding system, the type of incompatibility must be taken into account in the breeding of a crop planit. The type of SI may influence the crossing procedures used, the manner of selection of parents, and even the breeding goals. In some cases, the incompatibility may be avoided or bred out of a variety. In most crops, knowledge of the incompatibility system will spur breeding progress. The incompatibility system in the sweet potato (Ipomoea batatas Poir) has not yet been worked out in detail. Nevertheless, in widely scattered places in the biological literature, some of the facts concerning SI in

In nature, Solanum khasianumClarke (syn. S. variumDunal) is a self pollinated plant. However, artificial cross pollination is feasible when pollination is done around the time of anthesis, which is between 09.30 and 10.00. Due to prevalence of heterostyly bud selection has to be highly specific.

IN a previous communication1 I reported that emasculation of Glechoma hederacea flower buds resulted in a reduction in corolla size similar to that found in naturally occurring female flowers, and I suggested that the anthers produced a hormone causing enlargement of the corolla. An attempt to replace this by the application of β-indolylacetic acid to emasculated buds was ineffective—low concentrations having no effect and high concentrations (500 and 1,000 p.p.m.) causing inhibition of corolla growth.