Comparison of crossability, RAPD, SDS-PAGE and morphological markers for revealing genetic relationships within and among Lens species

The phylogenetic relationships among (sub)-species in the genus Lens have been reviewed based on recent published reports. There was both a substantial level of agreement and disagreement between reports based on different analytical procedures and different plant germ plasms. Lens culinaris ssp. orientalis appeared as the wild progenitor of the cultivated lentils. A gene flow from L. odemensis and L. ervoides during lentil crop evolution was suggested. Morphological characters (quantitative and qualitative) showed a different taxonomic pattern in the genus Lens. The use of nuclear and biochemical markers (RFLPs, RAPDs, seed-protein electrophoresis) appeared to be the most consistent and reliable methods for determining genetic relationships. It is suggested that these techniques be used in combination for taxonomic analysis of the genus Lens.     

High crossability of wild barley (Hordeum spontaneum C. Koch) with bread wheat and the differential elimination of barley chromosomes in the hybrids

Four bread wheat (Triticum aestivum L.) cultivars, Aobakomugi, Chinese Spring, Norin 61 and Shinchunaga, were pollinated with five barley lines/cultivars consisting of three cultivated barley (Hordeum vulgare L.) lines, Betzes, Kinai 5 and OHL089, and two wild barley (Hordeum spontaneum C. Koch) lines, OUH602 and OUH324. Crossability, expressed as the percentage of embryo formation, varied from 0 to 55.4% among the cross combinations. The two wild barley lines generally had a higher crossability than the previously reported best pollinator, Betzes, and some Japanese wheat cultivars were better as the female parent than Chinese Spring. Ninety four hybrid plants were obtained from 250 embryos cultured, and their somatic chromosome numbers ranged from 21 to 36. Eighteen plants were mosaic in chromosome number. Twenty one-chromosome plants appeared most frequently (45.7%) followed by 28-chromosome plants (14.9%). C-banding analysis revealed that elimination of barley chromosomes was mainly responsible for the occurrence of aneuploid plants. In hypoploids derived from Betzes-crosses, chromosome 5 was preferentially eliminated as previously reported, while in hypoploids derived from OUH602-crosses, chromosome 4 was preferentially eliminated. The wild barley line OUH602 may be a useful parent for producing a new wheat-barley addition set because of its high crossability with wheat and a different pattern of chromosome elimination.     

Breeding system and crossability in JapaneseEpimedium (Berberidaceae)

A series of experimental pollinations involving six species ofEpimedium provided strong evidence for an outbreeding system and no internal (postmating, postpollination) barrier to hybridization in the taxa concerned. Self-pollinations of four species,E. diphyllum, E. trifoliatobinatum, E. grandiflorum andE. sempervirens indicated high self-incompatibility (at most 5.4%, usually 0% in capsule-set). Field experiments in a population revealed the occurrence of cross-pollination. On the other hand, interspecific cross-pollinations showed high crossability at any combination of species (33.3%–100% in capsule-set). Furthermore, the interspecific F₁s obtained germinated at a high rate (usually more than 20%) and three of them, which bloomed, are highly fertile (more than 68.6% in pollen viability). The results were discussed in connection with the isolating mechanisms between the species ofEpimedium.     

Karyotype analysis of regenerated plants from callus cultures of interspecific hybrids of cultivated barley (Hordeum vulgare L.)

Summary The karyotype of 82 regenerated plants from callus cultures of interspecific hybrids between cultivated barley (Hordeum vulgare L.) and seven polyploid wild barley species was examined by C-banding or Feulgen staining. The karyotypic changes observed in 46 plants included aneuploidy, double haploidy, amphidiploidy, deletions, inversions, extra C-bands, and extra euchromatic segments. Apparently, chromosome 5, 6, and 7 of H. vulgare were more frequently exposed to elimination or structural change than the other chromosomes of this species. Irradiation of calli seemed to enhance the occurrence of karyotypic variants.     

Intrachromosomal mapping of crossability genes in wheat (Triticum aestivum)

Summary Intrachromosomal mapping studies were used to locate the positions of the genes Kr1 and Kr2, which control the crossability of wheat with Hordeum bulbosum, on chromosomes 5B and 5A, respectively. The location of Kr1 was established using the telocentric mapping technique and found to be on the long arm of chromosome 5B, distal to the centromere with a mean recombination frequency of 44.8±3.28%. Kr2 was located on the long arm of chromosome 5A by linkage with the major gene markers Vrn1, controlling vernalization requirement, and q, controlling ear morphology. Kr2 is closely linked to Vrn1, with a mean recombination frequency of 4.8±4.66%, and is distal to q with a mean recombination frequency of 38.1±10.60%. The similar locations of Kr1 and Kr2 on homoeologous chromosomes suggest that these two loci are homoeoallelic. Significant correlations between Hordeum bulbosum and rye crossability confirmed that Kr1 and Kr2 control the crossability of wheat with both species.     

Intergeneric hybridization between Brassica napus and Sinapis pubescens,and the cytology and crossability of their progenies

The cytological possibility of gene transfer from Sinapis pubescens to Brassica napus was investigated. Intergeneric hybrids between Brassica napus (2n = 38) and Sinapis pubescens (2n = 18) were produced through ovary culture. The F₁ hybrids were dihaploid and the chromosome configurations were (0–1) _III + (2–11) _II + (5–24) _I . One F₂ plant with 38 chromosomes was obtained from open pollination of the F₁ hybrid. Thirty-one seeds were obtained from the backcross of the F₂ plant with B. napus. Five out of seven plants had 38 chromosomes, and the pollen stainability ranged from 0% to 81.4%. In the B₂ plants obtained from the backcross of B₁ plants with B. napus, 66.7% of the plants examined had 38 chromosomes. S. pubescens may become a gene source for the improvement of B. napus.     

Production and characterization of fertile somatic hybrids of eggplant (Solanum melongena L.) with Solanum aethiopicum L.

Summary In order to produce fertile somatic hybrids, mesophyll protoplasts from eggplant were electrofused with those from one of its close related species, Solanum aethiopicum L. Aculeatum group. On the basis of differences in the cultural behavior of the parental and hybrid protoplasts, 35 somatic hybrid plants were recovered from 85 selected calli. When taken to maturity either in the greenhouse or in the field, the hybrid plants were vigorous, all rapidly overtopping parental individuals. The putative hybrids were intermediate with respect to morphological traits, and all of their organs were larger, particularly the leaves and stems. DNA analysis of the hybrids using flow cytometry in combination with cytological analysis showed that 32 were tetraploids, 1 hexaploid and 2 mixoploids. The hybrid nature of the 35 selected plants was confirmed by a comparison of the isoenzyme patterns of isocitrate dehydrogenase (Idh), 6-phosphogluconate dehydrogenase (6-Pgd) and phosphoglucomutase (Pgm). Chloroplast DNA (ctDNA) restriction analysis using Bam HI revealed that among the 27 hybrid plants analyzed, 10 had S. aethiopicum patterns and the 17 remaining hybrids exhibited bands identical with those of eggplant without any changes. All of the somatic hybrid plants flowered. Both parental plants had 94% stainable pollen, while the hybrids varied widely in pollen viability ranging from 30% to 85%. The somatic hybrids showed high significant variation in fruit production. Nevertheless, there was a tendency for low fertility to be associated often with S. aethiopicum chloroplast type and/or with an abnormal ploidy level, while good fertility was mostly associated with the tetraploid level and eggplant chloroplasts. Interestingly, 2 tetraploid somatic hybrid clones were among the most productive, yielding up to 9 kg/plant. As far as the fertility of the F₁ sexual counterpart was concerned, only 2 fruits of 50 g were obtained. Hybrid fertility in relation to phylogenetic affinities of the fusion partners is discussed.     

Occurrence of 2n pollen and ps gene frequencies in cultivated groups and their related wild species in tuber-bearing Solanums

Summary The gene frequency for parallel spindles (ps) was estimated from the frequency of plants producing 2n pollen in three cultivated groups: 2x Phureja (phu), 2x Stenotomum (stn), and 4x Andigena (adg), as well as in four related wild taxa: 2x Solanum brevicaule (brc), 2x S. sparsipilum (spl), 4x S. gourlayi (grl) and 4x S. gourlayi-S. infundibuliforme hybrids (grl-ifd). Plants with more than 1% large pollen were considered as 2n pollen producers. Observations of meiosis in a sample of 2n pollen-producing plants indicated that parallel spindles is the mechanism of 2n pollen formation. The number of plants with 2n pollen among the total examined was 228 plants (15.5%) of 1,473 in 2x spl, 31 (26.7%) of 116 in 2x brc, 92 (17.4%) of 528 in 2x stn, 665 (22.1%) of 3,008 in 2x phu, 731 (51.4%) of 1,421 in 4x adg, 591 (41.2%) of 1,436 in 4x grl, and 36 (64.3%) out of 56 in 4x grl-ifd. The ps gene frequencies assuming Hardy-Weinberg equilibrium were: 0.393 for 2x spl, 0.462 for 2x brc, 0.417 for 2x stn, 0.470 for 2x phu, 0.847 for 4x adg, 0.801 for 4x grl, and 0.895 for 4x grl-ifd. Twenty-five adg clones were randomly selected from a large population and were crossed with 2x clone W5295.7, which produces 2n pollen by parallel spindles (ps). The 4x progenies from 4x×2x crosses were used to determine the genotypes at the ps locus by screening 10–20 plants in each family for 2n pollen. Based on chromosome segregation at the ps locus, 9, 14, 1, and 1 clones were nulliplex, simplex, simplex or duplex, and duplex, respectively. The frequency of the ps gene in the adg population was estimated to be 0.825 and 0.815 for chromosome and chromatid segregation, respectively. The high frequencies of 2n pollen and the ps gene in cultivated 2x and 4x groups, and in wild taxa closely related to them, provide evidence for sexual polyploidization in the tuber-bearing Solanums.Paper No. 3032 from the Laboratory of Genetics. Research supported by the College of Agriculture and Life Sciences; International Potato Center; USDA, SEA, CGRO 84-CRCR-1-1389; and Frito Lay, Inc.     

The effect of the crossability loci Kr1 and Kr2 on fertilization frequency in hexaploid wheat x maize crosses

Summary Dominant alleles of the Kr1 and Kr2 genes reduce the crossability of hexaploid wheat with many alien species, including rye and Hordeum bulbosum, with Kr1 having the greater effect. However, a cytological study of wheat ovaries fixed 48 h after pollination showed that the wheat genotypes Highbury (kr1, Kr2) and Chinese Spring (Hope 5B) (kr1, kr2) were crossable with Seneca 60 maize, fertilization occurring in 14.4 and 30.7% of embryo sacs respectively. The latter figure was similar to the 29.7% fertilization found in Chinese Spring (kr1, kr2). Most embryo sacs in which fertilization occurred contained an embryo but lacked an endosperm and where an endosperm was formed it was usually highly aberrant. All three wheat x maize combinations were karyotypically unstable and rapidly eliminated maize chromosomes to produce haploid wheat embryos.     

A cladistic analysis of interspecific relationships ofSaguinus

The dental and cranial morphologies of all species ofSaguinus, S. oedipus, S. geoffroyi, S. leucopus, S. nigricollis, S. fuscicollis, S. labiatus, S. mystax, S. imperator, S. bicolor, andS. midas are examined. The following hypotheses are developed by cladistic methodology, using only synapomorphic characters to assess the interspecific relationships ofSaguinus.Saguinus are divided into two main groups; one consists ofS. oedipus, S. geoffroyi, andS. leucopus, and the other includesS. inustus, S. nigricollis, S. fuscicollis, S. labiatus, S. mystax, S. imperator, S. bicolor, andS. midas. In the former group,S. oedipus is more closely related toS. geoffroyi than either is toS. leucopus. In the latter group,S. labiatus, S. mystax, andS. imperator are classified into one group, andS. bicolor andS. midas form one monophyletic group.     

Cytogenetic studies of the F1 hybrids of Capsicum annuum with C. chinense and C. baccatum

Summary Partially sterile interspecific hybrids were obtained between C. annuum var. cerasiformis and C. chinense var. mishme (H₁), and C. annuum var. cerasiformis and C. baccatum var. pendulum (H₂). Morphologically the F₁ hybrids were intermediate between the corresponding parents. Meiosis was irregular in the two F₁ hybrids. Cytological analysis of the two F₁ hybrids revealed that the genome of C. annuum differs from C. chinense by two translocations and some minor structural alterations and from C. baccatum by two translocations, a single inversion and some minor structural alterations. Isolation barriers such as hybrid inviability, weakness and hybrid breakdown in the H₁ hybrid and, inaddition, desynapsis in the H₂, were operative in these taxa. The differences between the present findings and those reported earlier on the two F₁hybrids were attributed to differences in the genetic architecture of the taxa employed in hybridization.     

Genomic relationships among diploid wild perennial species of the genus Glycine Willd. subgenus Glycine revealed by crossability,meiotic chromosome pairing and seed protein electrophoresis

Summary The nomenclature of species beased on classical taxonomy can be verified from cytogenetic, biochemical and molecular studies. The objective of the study presented here was to provide further information on genomic affinities among species of the genus Glycine Willd. based on crossability, meiotic chromosome pairing of F₁ hybrids and seed-protein profiles. Meiotic chromosome pairing data revealed no genomic similarity between G. microphylla (BB) and G. falcata (FF), nor between G. tomentella (2n = 38; EE) and G. microphylla (BB). Despite morphological similarity between G. cyrtoloba (CC) and G. curvata no F₁ hybrid was obtained, although 748 flowers were pollinated. The seed-protein banding patterns showed G. latrobeana to be closer to the A-genome species than to others. Based on these results we assign genome symbol A₃A₃ to G. latrobeana. Likewise, G. curvata was allotted the designation C₁C₁ because the seed-protein banding patterns of G. curvata and G. cyrtoloba are similar. The genome designations of Glycine species based on cytogenetic investigations may be further extended by results obtained from biochemical and molecular approaches.Research supported in part by the Illinois Agricultural Experiment Station and US Department of Agriculture Competitive Research Grant 88-37231-4100     

The influence of parental genotype on the chromosome behaviour of Hordeum vulgare X H. bulbosum diploid hybrids

Summary The PMCs of 74 diploid hybrids involving ten H. vulgare varieties and three H. bulbosum lines were analysed at metaphase I and chromosome number and chiasma frequency recorded. There were differences between parental combinations and between plants within those combinations for both chromosome and chiasma number. It is suggested that these characters are controlled by both parents and that differences between plants within families reflect the heterozygosity of the H. bulbosum parents. Chromosomally stable, high pairing lines have been identified for use in a backcrossing programme to introduce H. bulbosum characters to the H. vulgare germplasm.     

Expansion of the geographical distribution of an exotic ladybird beetle, Adalia bipunctata (Coleoptera: Coccinellidae), and its interspecific relationships with native ladybird beetles in Japan

The first record of the exotic ladybird beetle, Adalia bipunctata (Coleoptera; Coccinellidae), in Japan was in 1993 at Osaka Nanko Central Park. Since that time, studies on the life history and geographical distribution of A. bipunctata have been ongoing, and its establishment in the Osaka Nanko area has been confirmed. A. bipunctata is a predacious ladybird beetle and a member of a guild that overlaps in habitat and prey with that of native ladybird beetles such as Harmonia axyridis and Menochilas sexmaculatus. We investigated the distribution of A. bipunctata and its interspecific relationships with native predacious ladybird beetles. In some areas, A. bipunctata was dominant in interspecific relationships with native ladybird beetles. For the first 10 years after A. bipunctata was discovered, it occurred only in the Osaka Nanko area, but the present geographical distribution indicates that it has expanded its range. Though the population density of this species was highest at the area recorded first, and tended to decrease in inverse proportion to the distance from Osaka Nanko Central Park, a satellite occurrence was observed in a remote area. The numbers of aphid and tree species (leaf shelter for aestivation and over-wintering) utilized by A. bipunctata have recently increased. Such increases will cause the rate of distribution of A. bipunctata to accelerate. Interspecific competition between H. axyridis and A. bipunctata, which occurs earlier than H. axyridis, may be avoided by desynchronization of the occurrence seasons, and another common predacious ladybird beetle, Coccinella septempunctata, may escape interspecific competition by habitat segregation.     

Phylogenetic relationships in some diploid species of Triticineae: cytogenetic analysis of interspecific hybrids

Summary Ten diploid species from genera Triticum, Aegilops, Haynaldia and Secale were included in a diallel crossing program. Forty-one different interspecific hybrids were obtained. The number of associations between chromosome arms at metaphase I of meiosis in pollen mother cells from the hybrids was taken as an indication of the degree of homology between parental genomes. Genome relationships were defined and indicated a possible pattern of differentiation from a common ancestor. Breeding strategies based on this information are proposed.     

Monosomic and double monosomic substitutions of Hordeum bulbosum L. chromosomes into H. vulgare L.

Summary One of the aims of the interspecific crossing programme between Hordeum vulgare L. and H. bulbosum L. has been to introgress desirable genes into barley from the wild species. However, despite their close taxonomic relationship there have been few reports of achieving this objective using amphidiploid hybrids. In order to broaden the range of available hybrids, partially fertile triploids between H. vulgare (2n = 2x = 14) and H. bulbosum (2n = 4x = 28) were developed and crossed with H. vulgare as female parent. From 580 progeny which were screened, eight putative single monosomic chromosome substitution lines and one double monosomic substitution were identified by cytological analysis. These involved the substitution of H. vulgare chromosome 1 (two lines), 6 (four lines), 6L (one line), 7 (one line) and 1 + 4 (one line) by their respective H. bulbosum homoeologues. The H. bulbosum chromosome was frequently eliminated during plant development, but it was observed regularly in pollen mother cells of two lines. However, pairing between the H. bulbosum chromosome and its H. vulgare homoeologue was low. Several of the lines were more resistant than their H. vulgare parents to powdery mildew (Erysiphe graminis DC. f.sp. hordei Em. Marchai), net blotch (Drechslera teres Sacc.) and scald (Rhynchosporium secalis (Oudem.) Davis). Apart from their use in studying genome relationships, their value to plant breeders will depend on the ease of inducing translocations between the parental chromosomes.     

Genetic relationships betweenLupinus pilosus andL. palaestinus (Fabaceae)

Lupinus pilosus Murr. andL. palaestinus Boiss., are both East Mediterranean annuals, greatly resemble each other in morphology, and have the same chromosome number (2n = 42). Some fertile hybrids can be formed by artificial hybridization or under unusual habitat conditions. Isolation in nature between the species is, however, maintained by prevalent selfing, partial reproductive barriers and genic imbalance, together with differences in ecological requirements. It is suggested that this speciation pattern which includes little morphological and hardly any chromosomal divergence might have occurred in other cases of edaphic vicariants too.     

In vitro pollen germination of species and two interspecific hybrids from the genus Brassica

In vitro pollen germination of five species and two interspecific hybrids from the genus Brassica was tested in four media. Genetically fixed differences in the demands for optimal pollen germination among species were found. The experiments were designed to define optimal content of mineral salts, sugar, and PEG for every investigated species or hybrids. The differences found among species are discussed in relation to the evolutionary trend.     

Prospects for interspecific hybridization of Lupinus atlanticus Gladst. with L. cosentinii Guss.

Summary Successful crossing is reported between L. atlanticus Gladst. (2n = 38) and L. cosentinii Guss. (2n = 32), using lines of both species selected for crossability followed by selection of relatively fertile progenies. In one cross, 82E75, from a single F₂ segregating plant, 22 F₃ seeds were obtained. Some other less crossable combinations were completely sterile in the f₁ or F₂. Backcrossing to both parent species was successful, but some crosses gave relatively more seed by using F₂ plants for backcrossing rather than F₂'s. It is concluded that potential exists for introgression of useful genes in both directions.     

Genomic relationships between species of theElymus semicostatus group andElymus sensu lato (Poaceae)

Meiotic pairing behaviour in 19 interspecificElymus hybrids is reported and discussed. The hybrids were made between four species belonging to theE. semicostatus group of sect.Goulardia, viz.,E. semicostatus, E. abolinii, E. fedtschenkoi, andE. panormitanus (all 2n = 28), andElymus species of seven different sections, viz., sect.Clinelymiopsis:E. caucasicus (2n = 28); sect.Elymus:E. sibiricus (2n = 28); sect.Goulardia:E. caninus (2n = 28),E. trachycaulus (2n = 28), andE. tsukushiensis (2n = 42); sect.Hyalolepis:E. batalinii (2n = 42); sect.Hystrix:E. hystrix (2n = 28); sect.Macrolepis:E. canadensis (2n = 28); and sect.Turczaninovia:E. dahuricus (2n = 42). Chromosomal pairing at meiotic metaphase I indicated that the species of theE. semicostatus group are genomically closer to the tetraploidE. caucasicus and the hexaploid species, regardless of sectional origin, than to the other tetraploid species of sectionGoulardia. Highest meiotic pairing was found in hybrids involvingE. caucasicus, E. tsukushiensis, andE. dahuricus. The presence of pairing regulating genes inE. abolinii is suspected.