Intergeneric Crosses Research Articles

Sugarcane cultivation and sugar industry in Japan

In Japan, sugarcane is grown only in the South-western Islands, at the southern most end of the Japanese Archipelago. Most of these islands are in the subtropics, natural and environmental conditions are fairly severe to sugarcane cultivation because of frequent typhoons, droughts in summer, low temperatures in winter and poor soil fertility. In recent years, sugarcane production has been sluggish due to the lack of labour caused by the aging of farmers, a delay of mechanization in cultivation and unfavorable weather conditions. However, since sugarcane is still a major crop and plays a key role that supports the livelihood of the region, the network of sugarcane technologists is continuing the united efforts to improve sugarcane production in the region. This paper reviews the outline of current situation of sugarcane production, sugar industry, general cultivation practices and sugarcane breeding outline in Japan, and also discusses about new approaches to breed new types of sugarcane, as a energy use and cattle feed through inter-specific and intergeneric cross.

Interspecific hybrids between cultural sunflower Helianthus annuus L. and Helianthus salicifolius L.: Morphological and biochemical characterization

SUMMARY The direct organogenesis method in immature F 1 hybrid embryos from sunflower used for the first time in a study, was successfully applied for production of new forms from the intergeneric cross Helianthus annuus L. (cv. Albena) × H. salicifolius. A considerable number of new sunflower lines were produced after self-pollination and individual selection. Agronomic traits such as oil content in seed, 1000 seed weight, plant height, leaf width, leaf length, number of leaves, length of petiole stems, internode length, head diameter, stem diameter, diameter of branch head, number of branches, length of branches, number of ray florets, seed width, seed length, and seed thickness were investigated. After characterization of the hybrid progenies according to the indices, the conclusion can be drawn that lines 107 R, 114 R and 120 R show 76.5% intermediate phenotype in comparison with the two parental forms. The positive change was 15.5% and the negative change was 21.5%. Some of the new restorer lines were successfully used in heterosis breeding of sunflower. RESUMEN El método de organogénesis directa, aplicado por la primera vez en este investigación de los embriones F 1 de híbrido de girasol no madurados, fue aplicado con éxito para engendrar nuevas formas de cruzamiento intergenérico de Helianthus annuus L. (cv. Albena) × H. salicifolius. Tras la autofecundación y selección individual, fue obtenido el significante número de nuevas líneas de girasol. Estas líneas fueron analizadas en cuanto a las características agronóicas, como son el contenido de aceite en la semilla, el peso de 1000 granos, altura de la planta, ancho de la hoja, longitud de la hoja, número de hojas, longitud del pecíolo, longitud del internodio, diámetro de cabeza, diámetro del tallo, diámetro de cabezas secundarias, número de ramos, longitud de ramos, número de flores lingüiformes, ancho de la semilla, longitud de la semilla y grosor de la semilla. Tras la caracterización de la descendencia híbrida, de acuerdo con estos índices, fue concluido que las líneas 107 R, 114 R y 120 R demuestran 76,5% de intermediaridad del fenotipo en relación con las formas parentales. El cambio positivo fue 15,5%, negativo 21,5%. Algunas de estas líneas restauradoras fueron utilizadas con éxito en la selección de girasol heterótica. RÉSUMÉ La méthode d’organogénèse directe utilisée pour la première fois dans cette tude des embryons de tournesol immatures F 1 a été appliquée avec succès dans la production de nouvelles formes à partir du croisement intergénérique Helianthus annuus L. (cv. Albena) × H. salicifolius . Après autofécondation et sélection individuelle, un grand nombre de nouvelles lignées de tournesol a été obtenu. Les caractéristiques agronomiques suivantes ont été analysées: contenu d’huile dans la graine, poids de 1000 graines, hauteur de la plante, largeur de la feuille, longueur de la feuille, nombre de feuilles, longueur des tiges de pétiole, longueur internodale, diamètre de la tête, diamètre de la tige, diamètre des têtes secondaires, nombre de ramifications, longueur des ramifications, nombre de fleurons ligurés, largeur de la graine, longueur de la graine et épaisseur de la graine. Après caractérisation de la progéniture hybride relativement à ces indices, on peut conclure que les lignées 107 R, 114 R et 120 R montrent 76,5% de phénotype intermédiaire en comparaison aux deux formes parentales. Le changement positif a été de 15,5% et le changement négatif de 21,5%. Certaines des nouvelles lignées restauratrices ont été utilisées avec succès dans la sélection hétérosis du tournesol.

Effect of 2,4-Dichlorophenoxyacetic Acid on the Efficiency of Wheat Haploid Production by the Hordeum bulbosum Method

Intergeneric crosses between Japanese wheat cultivars (Triticum aestivum L. cv. Nishikazekomugi and Zenkojikomugi) and a tetraploid wild barley, Hordeum bulbosum L. were used to examine the effect of 2,4-dichlorophenoxyacetic acid (2,4-D) on the formation of wheat haploid embryo and its development into plantlets. The detached wheat spikes with florets pollinated with H. bulbosum were cultured for 14 days in a sucrose and sulfurous acid solution to which 2,4-D was added at the concentrations of 0, 25, 50, 75, 100, 125, 150, and 175 mg L−1. The percentages of florets with seeds set and with embryos formed were increased by increasing the concentration of 2,4-D up to 100 mg L−1. Fourteen days after pollination, embryos (haploid) were isolated from the seed and cultured on agarose-solidified B5 medium. Embryo size tended to decrease as the concentration of 2,4-D increased, but the larger embryos tended to have higher ability to develop into haploid plants. The percentage of florets from which haploid plantlets were developed by embryo culture was slightly increased by the treatment of the spikes with 25-100 mg L−1 2,4-D, but significantly reduced by 125-175 mg L−1 2,4-D. It is suggested that treatment with 2,4-D at 25 100 mg L−1 would be effective for haploid wheat production by of H. bulbosum method.

DEVELOPMENT OF PRSV-P RESISTANT CARICA PAPAYA GENOTYPES BY INTROGRESSION OF GENES FROM WILD VASCONCELLA SPECIES

This paper reports successful collaboration between researchers in the Philippines and Australia since 1993 on a project funded by ACIAR. Three intergeneric crosses were done between C. papaya and Vasconcella spp. resistant to Papaya Ring쳰ot Virus (PRSV-P). Production of F1 plants required embryo rescue and regeneration after an embryogenic phase in vitro. Eleven F1 plants from a cross between C. papaya and V. quercifolia were selected as being PRSV-P resistant and having some fertility, and 4 of these had sufficient fertility to produce embryos when backcrossed to papayas. Cytogenetic studies on one of these intergeneric hybrids revealed variable chromosome counts, presence of univalents, laggards and meiotic aberrations and pollen fertility of 0.2 - 2.2%. Segregating populations of first and second backcross plants were evaluated for PRSV-P resistance, fertility and morphological characteristics including fruit shape, size and quality. All first backcross plants were micropropagated in vitro before glasshouse and field evaluation. Variable reactions to the two viral strains in the two countries were observed. One plant (clone 54) demonstrated a high level of tolerance against multiple inoculations of PRSV-P in the glasshouse and stood up against aphid transmitted PRSV-P in the field for 9 months in Australia, however showed little resistance to PRSV-P in the Philippines. Results indicate that 3 backcrosses may be sufficient to produce fruit that are similar to papaya and commercially acceptable.

Plantes chlorophylliennes de blé dur obtenues par culture de microspores isolées : importance des prétraitements

In Triticum turgidum subsp. durum (Desf.) Husn., the utilization of in vitro anther culture is hampered by the very high frequency of albinism of the regenerated plants reaching in most cases 100%. Only in vitro ovary culture or intergeneric crosses with maize produce gynogenetic green haploid and doubled haploid plants. This paper is concerned with another very interesting method of androgenetic doubled haploid plant production, the in vitro isolated microspore culture. It is shown that this method, associated with cold alone or cold plus mannitol pre-treatments, of the spikes kept within their sheath leaves, during different times, have significant positive effects, not only on embryo production, but also on chlorophyllian plant regeneration. All pre-treatments and control taken together, a total of 16 490 embryos was obtained from 17.4 × 10 6 microspores of two T. durum varieties, among which 9320 embryos were transferred to regeneration medium and developed 150 chlorophyllian plants. Thus a long-term (five weeks) 4 °C cold pre-treatment of the microspores could be promising for green regeneration in durum wheat. To cite this article: Z. Labbani et al., C. R. Biologies 328 (2005).

Hybridism in the Kunzea ericoides complex (Myrtaceae): an analysis of artificial crosses

Observations of wild plants and herbarium specimens suggest that hybridism is a feature of the Australasian Kunzea ericoides (Myrtaceae) complex. In this study 73 artificial cross combinations were attempted with New Zealand material of Leptospermum scoparium, five Kunzea species, two varieties and six informally recognised entities within the New Zealand K. ericoides complex. The results of these crosses are documented, and for five hybrids spanning the intergeneric, interspecific and intraspecific crosses attempted, we provide a more detailed assessment based on morphology, molecular (nrDNA and chloroplast) sequence variation, and genomic in situ hybridisation (GISH). This is the first time GISH has been used in the Myrtaceae. Hybrids were easily generated between the New Zealand members of the K. ericoides complex, but not between them and the Australian K. ericoides complex. We were unable to produce hybrids between the New Zealand K. ericoides complex and two more distantly related Australian species, K. baxteri and K. parvifolia. Intergeneric crosses between New Zealand plants of Leptospermum scoparium, Kunzea sinclairii and an informally recognised variant K. aff. ericoides (b) were successfully produced, but failed to flower. The molecular evidence and observations after GISH show that even when low levels of sequence divergence exist, genome differentiation, to different extents, can be observed. The results confirm some suspected New Zealand hybrid complexes. However, while hybrids were easily generated artificially, natural instances of hybridism appear to be largely confined to those habitats significantly disturbed since European settlement of both countries.

Intergeneric hybrids between cultivated sunflower (Helianthus annuus L) and Verbesina helianthoides (genus Verbesina): Morphological and biochemical aspects

The direct organogenesis method in immature F1 hybrid embryos from sunflower used for the first time in this study, was successfully applied for production of new forms from the intergeneric cross Helianthus annuus (cv. Albena) × Verbesina helianthoides (genus Verbesina). A large number of new sunflower lines were produced after self-pollination and individual selection. Agronomic traits such as oil content in seed, 1000-seed weight leaf width, leaf length, number of leaves, length of petiole, internode length, head diameter, stem diameter, diameter of branch head, number of branches, length of branches, number of ray florets, seed width, seed length and seed thickness were investigated. After characterization of the hybrid progenies according to the above indices, the conclusion can be drawn that lines 131 R, 138 R, 140 R, 143 R and 144 R show 76.5% intermediate phenotype in comparison with the two parental forms. Some of the new restorer lines were successfully used in heterosis breeding of sunflower. The positive change was 35.3% and the negative change was 11.8%. Line 140 R is of positive breeding importance because it exhibited an oil value exceeding the cultural and wild parents by 2.9 and 24.6%, respectively.

Origin of the Blue‐Aleurone Gene in Sebesta Blue Wheat Genetic Stocks and a Protocol for Its Use in Apomixis Screening

Tracing the pedigree of the blue aleurone locus in the Sebesta Blue wheat (Triticum aestivum L.) genetic stocks has proven difficult. There is limited information on the original intergeneric crosses that moved the blue-aleurone trait from Thinopyrum ponticum (Podp.) Z.W. Liu & R.-C. Wang into wheat. Blue Baart, an unregistered genetic stock developed at the University of California-Davis, was the direct parental source for the blue-aleurone trait in Sebesta Blue. Its wheat pedigree is unclear because of the introgressing, bulk population technique by which it was developed from the original intergeneric wheat × Thinopyrum cross. In situ probing with total genomic DNA in the spring and winter Sebesta Blue lines showed a 4EL Thinopyrum translocation and numerous unidentified chromosomal rearrangements in the two winter lines. A protocol is presented for use of the Sebesta Blue genetic stocks for apomixis studies.

Overcoming hybridization barriers between pea and some of its wild relatives

Pea would benefit from the plasticity and adaptability of its cross-incompatible relatives Pisum fulvum and Lathyrus sativus L., and we have tested reciprocal sexual crossings by manually cross-pollinating plants of genotypes of these three species. Studies of in situ germination of pollen grains on stigmata showed that pollen tubes were generally unable to germinate or could not reach the ovary. A few putative hybrid pods were nevertheless harvested, with one grain per pod germinated in vitro, then micropropagated for flow cytometry, isoenzyme, molecular (ribosomal ITS PCR-RFLP) and genomic in situ hybridization (GISH) studies. One such grain was recovered from an inter-generic cross of P. sativum x L. sativus and four from an inter-specific P. sativum x P. fulvumcross. A strong cross-incompatibility was shown between pea and grass pea, where the putative hybrid turned out to be pea. Conversely, with the interspecific, P. sativum x P. fulvum cross, flow cytometry and isoenzymes with leaf tissues strongly suggested hybridity, while molecular approaches and GISH confirmed the production of inter-specific hybrids, and without the need for a wild type P. sativum accession as a bridging cross.

Breeding barriers between the cultivated strawberry, Fragaria × ananassa, and related wild germplasm

Five-hundred interspecific and intergeneric crosses were performed among accessions of the wild strawberries Fragaria vesca(2x), Duchesnea indica (8x), Potentilla tucumanensis (2x) and 9 genotypes of the cultivated strawberry, Fragaria×ananassa (8x), following an incomplete diallele mating design. Crosses between D. indica and F.×ananassa produced many putative hybrids when D. indica was used as female but a few achenes and plants when used as male; therefore, pollen-pistil compatibility relations were analyzed by fluorescence microscopy in this direction of the cross. Of the genotypic combinations, 78.6% were incompatible at the stigma level and 17.2% at the first third of the style. Only 3.6% were pollen-pistil compatible and produced fruits with achenes (seven did not germinate or originated short-lived plants and nine produced normal plants). F.vesca×F.×ananassa crosses produced 35 hybrid achenes but only 14% germinated, yielding short-lived plants; histological analyses revealed that inviable seeds had less developed (or collapsed) endosperms and smaller embryos than control plump F. vesca seeds. P.tucumanensis was only used as male, with negative results. These species and genera are partially isolated by a complex system of pre- and post-zygotic barriers. Knowledge of their nature would allow the breeder to devise strategies to put the genetic variability available in the group into a useful form.

Sex ratios in mule duck embryos at various stages of incubation

Mule duck hatcheries have long reported varying degrees of unbalance in the sex ratio, with a preponderance of male mules at hatching. The aim of the present study was to assess the distributions of sex ratios at various stages of development in embryos originating from intra- and intergeneric crosses between parental lineages (Muscovy male×Muscovy female, Pekin male×Pekin female, Muscovy male×Pekin female or Mule, and Pekin male×Muscovy female or Hinny). In Experiment I, embryo sexing was performed on Days 1 and 5 of incubation (by multiplex PCR) and at hatching (by vent observation). The sex ratio was not significantly modified during the early stages of embryo development whatever the genetic origin ( P>0.05, Days 1 and Day 5) but our results in mule and hinny ducklings confirmed the preponderance of males among normally hatched ducklings originating from the intergeneric lineage (58.9 and 55.4% males in mules and hinnies, respectively; P<0.05 in both cases). Sex ratio (vent sexing) in second grade (cull) ducklings revealed that 68% of these ducklings were females ( P<0.05). In Experiment II, the distribution of sex ratio was also performed in mule duck eggs from 6 batches (400,000 eggs/batch) first examined for fertility (candling) on Day 18 of incubation. These results indicate that the percentage of males present in the population of normally hatched ducklings increases when fertility decreases. In addition, this experiment also revealed that 83.7–90.5% of viable male mule embryos develop up to hatching, compared to only 43.0–51.0% of female mule embryos. Given that a deviation in sex ratio during the first stages of incubation is unlikely (Experiment I), it is concluded that the skewed sex ratio of mule ducks at hatching is primarily due to increased late mortality in female mule embryos occurring between egg transfer and hatching. This mortality originated, at least in part, from the intergeneric origin of female mules, and was marked to a greater or lesser extent depending on the initial success of fertilization in a given batch, a possible indication that the initial quality of gametes may selectively exert its influence at the later stages of embryo development.

Intergeneric Hybridizaton between Schlumbergera Lem. and Hatiora Britt. &amp; Rose (Cactaceae)

Post-pollination barriers to intergeneric hybridization between Easter cactus [Hatiora gaertneri (Regel) Barthlott, H. rosea (Lagerheim) Barthlott, and H. ×graeseri Barthlott ex D. Hunt] and holiday cactus [Schlumbergera truncata (Haworth) Moran and S. ×buckleyi (Buckley) Tjaden] were determined and procedures were devised for circumventing these barriers. Examination of Hatiora and Schlumbergera pistils at 72 hours after intergeneric crosses indicated no abnormalities in pollen germination or pollen tube growth in the upper style. Pollen tubes of Hatiora were arrested in the lower half of Schlumbergera styles and failed to enter the ovary. Schlumbergera pollen tubes exhibited normal growth in Hatiora styles but most tubes lost directionality, burst, or failed to penetrate the micropyles after reaching the ovary. Three growth regulators (BA, GA3 and NAAm) were applied individually to ovaries of `Crimson Giant' Easter cactus after intergeneric crosses. GA3 and NAAm increased fruit set compared to the control (lanolin alone) or BA but none of the fruit harvested 160 days after pollination contained mature embryos. Four progeny were obtained when a short-styled S. ×buckleyi clone was crossed as a female parent with H. ×graeseri. Isozyme patterns and morphological characteristics confirmed that the four progeny were intergeneric hybrids. This is the first report of successful intergeneric hybridization between Hatiora and Schlumbergera. Chemical names used: N-(phenylmethyl)-1H-purine-6-amine [benzyladenine (BA)]; gibberellic acid (GA3); α-naphthaleneacetamide (NAAm).

Mentor effects in the genusHieracium S.STR. (Compositae, Lactuceae)

Self-incompatibility was demonstrated in the diploid taxaHieracium alpinum andH. umbellatum using isolation experiments. However, self-incompatibility was broken down in diploidH. alpinum under the influence of foreign pollen from another species of this genus (mentor effects) during a series of crossing experiments. Interestingly, failure of the SI system was also recorded in diploidH. alpinum in an intergeneric cross with the representative of the closely related genus ofPilosella. This is the first record of autogamy in the genusHieracium s.str. The possible evolutionary significance of this phenomenon is discussed.

High efficiency production and genomicin situ hybridization analysis ofBrassica aneuploids and homozygous plants

Interspecific and intergeneric hybridizations have been widely used in plant genetics and breeding to construct stocks for genetic analysis and to introduce into crops the desirable traits and genes from their relatives. The intergeneric crosses between Brassica juncea (L.) Czern. & Coss., B. carinata A. Braun and Orychophragmus violaceus (L.) O. E. Schulz were made and the plants produced were subjected to genomic in situ hybridization analysis. The mixoploids from the cross with B. juncea were divided into three groups. The partially fertile mixoploids in the first group (2n = 36-42) mainly contained the somatic cells and pollen mother cells (PMCs) with the 36 chromosomes of B. juncea and additional chromosomes of O. violaceus. The mixoploids (2n = 30-36) in the second and third groups were morphologically quite similar to the mother plants B. juncea and showed nearly normal fertility. The plants in the second group produced the majority of PMCs (2n = 36) with their chromosomes paired and segregated normally, but 1-4 pairs of the O.violaceus chromosomes were included in some PMCs. The plants in the third group produced only PMCs with the 36 B. juncea chromosomes, which were paired and segregated normally. The mixoploids (2n = 29-34) from the cross with B. carinata produced the majority of PMCs (2n = 34) with normal chromosome pairing and segregation, but some plants had some PMCs with 1-3 pairs of chromosomes from O. violaceus and other plants had only PMCs with the B. carinata chromosomes. The Brassica homozygous plants and aneuploids with complete or partial chromosome complements of Brassica parents and various numbers of O. violaceus chromosomes were derived from these progeny plants. The results in this study provided the molecular cytogenetic evidence for the separation of parental genomes which was previously proposed to occur in the hybridizations of these two genera.

Production of Intergeneric Hybrids between the C3-C4 Intermediate Species Diplotaxis tenuifolia (L.) DC. and Raphanus sativus L.

In intergeneric crossings between Diplotaxis tenuifolia (2n = 22, DtDt) and five cultivars of Raphanus sativus (2n = 18, RR), an intergeneric F1 hybrid was produced from the crossing of D. tenuifolia × R. sativus cv. ‘4-season leaf’ through ovary culture followed by embryo culture. The induced amphidiploid (2n = 40, DtDtRR) showed well-regulated meiotic features at PMCs and a high pollen fertility (75 %). Three BC1 hybrids with DtRR (2n = 29) or DtDtR (2n = 31) genome constitutions were obtained by the same embryo rescue procedure in the crossings of amphidiploid × R. sativus and D. tenuifolia × amphidiploid, respectively. In the successive backcrossings of two BC1 hybrids (DtRR, 2n = 29) to R. sativus, 102 BC2 hybrids were obtained by conventional pollination. In the reciprocal crossing of R. sativus × BC1 hybrids, 12 reciprocal BC2 hybrids were also produced without embryo rescue. The somatic chromosome number of 89 BC2 hybrids with D. tenuifolia cytoplasm and 12 reciprocal BC2 hybrids with R. sativus cytoplasm ranged from 2n = 18 to 2n = 23 that were estimated to carry 2n = 18 chromosomes of R. sativus and zero to five chromosomes of D. tenuifolia. Among them, 24.7 % of the BC2 hybrids and 41.6 % of the reciprocal BC2 hybrids were assumed to be monosomic addition lines (MALs, 2n = 19). The novel intergeneric hybrids obtained in this study could become useful materials for investigating the genetic effects on C3-C 4 intermediate traits at the genomic and chromosomal levels, as well as for estimating the performance of genetic improvement in Brassicaceae.

PRODUCTION OF APOMICT-LIKE SEEDLING THROUGH INTERGENERIC CROSS BETWEEN JAPANESE PEAR AND APPLE BY MEANS OF POLLEN IRRADIATION

Apomixis may provide a new possibility for pear genetics, breeding and propagation. In this experiment we tried to produce apomictic seedlings in Japanese pear through an intergeneric cross between Japanese pear and apple by means of pollen irradiation. The false hybrid can be efficiently selected in this intergeneric crossing. Because the true intergeneric hybrid potent genetic lethal system, only the false hybrid with the possibility of apomixis should survive in the crossing. Japanese pear (Pyrus pyrifolia Nakai) ‘Kousui’ and apple (Malus pumila Mill.) ‘Fuji’ were used for the intergeneric cross. The apple pollen was irradiated by gamma ray from 60Co and pollinated on the Japanese pear. A total of fourteen intergeneric seedlings at 10Gy/h (50 and 80Gy) and 20Gy/h (60 and 120Gy) developed from 155 seeds, and an individual at 80Gy (10Gy/h) and five individuals at 120Gy (20Gy/h) survived without exhibiting lethal symptoms. Plant type and morphological characters of five apomict-like seedlings at 120Gy were similar to those of Japanese pear. Their RAPD markers were only inherited from Japanese pear and their DNA contents estimated by FCM were also similar to those of Japanese pear. From the above results, we conclude that five apomict-like seedlings may be true apomicts in Japanese pear.

Inheritance of organelle DNA sequences in a citrus-poncirus intergeneric cross.

Many land plants deviate from the maternal pattern of organelle inheritance. In this study, heterologous mitochondrial and chloroplast probes were used to investigate the inheritance of organelle genomes in the progeny of an intergeneric cross. The seed parent was LB 1-18 (a hybrid of Citrus reticulata Blanco cv. Clementine x C. paradisi Macf. cv. Duncan) and the pollen parent was the cross-compatible species Poncirus trifoliata (L.) Raf. All 26 progeny examined exhibited maternal inheritance of plastid petA and petD loci. However, 17 of the 26 progeny exhibited an apparent biparental inheritance of mitochondrial atpA, cob, coxII, and coxIII restriction fragment length polymorphisms (RFLPs) and maternal inheritance of mitochondrial rrn26 and coxI RFLPs. The remaining nine progeny inherited only maternal mitochondrial DNA (mtDNA) configurations. Investigations of plant mitochondrial genome inheritance are complicated by the multipartite structure of this genome, nuclear gene control over mitochondrial genome organization, and transfer of mitochondrial sequences to the nucleus. In this study, paternal mtDNA configurations were not detected in purified mtDNA of progeny plants, but were present in progeny DNA preparations enriched for nuclear genome sequences. MtDNA sequences in the nuclear genome therefore produced an inheritance pattern that mimics biparental inheritance of mtDNA.

Varietal differences in photosynthetic characters and chlorophyll fluorescence induction kinetics parameters among intergeneric progeny derived fromOryza×Sorghum, its parents, and hybrid rice

A comparative study on the photosynthetic parameters among intergeneric progenies derived fromOryza sativa L.×Sorghum vulgare L., its maternal parent Gui 630 and commercial 3-line hybrid rice Shanyou 63 in pot experiment in greenhouse was conducted. The morphological and photosynthetic characters of canopy leaves and chlorophyll fluorescence kinetic parameters includingFv/Fm,Fv/F0, photochemical quenching coefficient and non-photochemical coefficient of canopy leaves of 3 varieties were measured. The results showed the progeny, Yanyou 1, derived from an intergeneric cross of rice and sorghum possesses better canopy spatial architecture with thicker, heavier and bigger canopy leaf than its maternal parent Gui 630. Higher photosynthetic rate due to higher chlorophyll content, higher primary energy transformation efficiency, potential of PSII and non-photochemical quenching coefficient (qE) were also measured in Yuanyou 1. These explain partly why the intergeneric progeny has higher biomass production, and better tolerance to adverse conditions and higher field yields even under stress conditions.

×Sinocalycalycanthus raulstonii (Calycanthaceae): A New Intergeneric Hybrid between Sinocalycanthus chinensis and Calycanthus floridus

A morphological comparison of Calycanthus L., Chimonanthus Lindl., and Sinocalycanthus W.C. Cheng and S.Y. Chang is presented. Intergeneric crosses between Sinocalycanthus chinensis (W.C. Cheng and S.Y. Chang) W.C. Cheng and S.Y. Chang and Calycanthus floridus L. produced hybrid progeny. Data are presented comparing the parents and the progeny. ×Sinocalycalycanthus raulstonii Lasseigne and Fantz is proposed as the name for these hybrids and is validated with a Latin diagnosis. The original cultivar is named `Hartlage Wine'.

INTERSPECIFIC AND INTERGENERIC FERTILIZATION BARRIERS IN BROMELIACEAE

Bromeliaceae are tropical ornamentals with a variety of colours and inflorescence shapes. To remain the interest of the public, breeders create new cultivars using interspecific and intergeneric hand-pollinations. In our breeding studies, 4 genera were used: Aechmea (2 species), Guzmania (3 species), Tillandsia (1 species) and Vriesea (3 species). In preparation of crossing experiments, two important flower characteristics were studied: pollen quality and stigma receptivity. Pollen germination of different flower stages was determined by an in vitro germination test. All species, except two of the Guzmania species, possessed viable pollen and germination was always highest at anthesis. Stigma receptivity was studied by pollinating flowers before, at and after anthesis. Pollen germination and pollentube growth on stigma were visualised with fluorescence microscopy (aniline blue staining). All species showed optimal stigma receptivity and ovule penetration at anthesis. Interspecific and intergeneric hand-pollinations were performed with pollen and stigma at anthesis stage. Pollen germination on stigma, pollentube growth in style and ovary and fertilization of ovules was evaluated using fluorescence microscopy. Five species were self-compatible, making emasculation necessary. Half of the interspecific and all of the intergeneric crosses were classified as incongruent because no ovules were fertilised (prefertilization barriers) or no seedlings developed (postfertilization barriers). Prefertilization barriers occurred in the style, mostly the lower part of the style. Only in crosses with the self-incompatible Aechmea species as mother or the extremely short-styled Tillandsia species as father, pollentube growth stopped in the upper part of the style. To understand more about these style barriers, the morphology of the pistil was studied. Styles of all species consisted of a hollow channel, covered with protein-rich cells. These ‘feeder’-cells also appeared on the placenta and the ovule funiculus. In this way, pollen tubes could be guided towards the micropyles. Further, Ca-oxalate and starch grains were observed in the style.