Different regeneration potential of mesophyll protoplasts from cultivated and a wild species of tomato

Mesophyll protoplasts were isolated from leaves of three cultivars of Lycopersicon esculentum (L.) Mill., namely Hilda 72, Rutgers and Rentita, and from the wild tomato species Lycopersicon peruvianum (L.) Mill. Protoplasts from L. peruvianum divided and grew actively in a liquid medium according to Zapata et al. (1977), whereas protoplasts from the tomato cultivars Hilda 72 and Rutgers showed comparable rates for cell division only, when the content of major elements in this medium was reduced to one half of the original concentration and when mannitol as osmoticum was replaced by glucose. In Rentita protoplasts no cell division could be observed in about 15 different modifications of the five basic culture media tested. The morphogenetic potential of these tomato cells was assessed by comparing the root and shoot formation of protoplasts and of leaf explants. L. peruvianum exhibited the highest potential. Calli derived from protoplasts regenerated roots on Murastrige-Skoog agar containing 1 M benzylaminopurine (BAP) plus 10 M indole-3-acetic acid (IAA) and 0.1 M BAP plus 1 M IAA. Shoot formation occurred in the combinations of 10 M BAP with 0.1, 1.0, and 10 M IAA. Plantlets regenerated from the L. peruvianum calli could be grown in soil. No shoots or roots were regenerated from calli of Hilda 72 and Rutgers protoplasts in all combinations of BAP and IAA tested in the range from 0.1 M to 100 M, thus indicating the rather low morphogenetic potential of these protoplasts as compared to protoplasts from L. peruvianum leaves.Abbreviations BAP benzylaminopurine - IAA indole-acetic acid - TMV tobacco mosaic virus     

Introgression of the Haynaldia villosa genome into γ-ray-induced asymmetric somatic hybrids of wheat

To study the effect of -ray treatment on donor and derived somatic hybrids, we carried out -ray donor treatment experiments with a wide range of -ray dosages and asymmetric somatic hybridization between protoplasts of wheat (Triticum aestivum L. Jinan 177) and protoplasts of Haynaldia villosa Schur. treated with different dosages of -rays (40, 60 and 80 Gy, respectively). We first screened the putative hybrids by isozyme analysis, followed by characterization of nuclear and organellar genome composition of the hybrids. Genomic in situ hybridization on mitotic metaphases demonstrated that the donor chromosome elimination in the hybrids increased with increased -ray dosage. Intergenomic chromosome recombination/translocations were observed in the hybrids from different dosages of -rays. PCR amplification of 5S rDNA spacer sequences showed that only some of the regenerated hybrid clones inherited donor 5S rDNA sequences, suggesting that the donor DNA was also eliminated randomly. Restriction fragment length polymorphism analysis using mitochondrion (mt) and chloroplast (cp) gene-specific probes showed that the hybrid calli contained mt genomes of both parents and the cp genome of only one of the parents. Recombinations between parental mt as well as cp genes were found in the hybrid clones. Furthermore, development of the hybrid clones was dependent on the -ray dosage used for the donor treatment. Regenerated plants were only obtained from fusion combinations of low (40 Gy) and intermediate (60 Gy) dose irradiation. The possible role and significance of -rays on the introgression of small segments of donor chromosomes to the receptor is discussed.     

Comparative study ofTriticum aestivum andT. timopheevi genomes using C-banding technique

The somatic chromosomes ofTriticum timopheevi and those of two varieties ofT. aestivum, Chinese Spring and Bezostaya-1, have been identified by a Giemsa staining technique. The data suggest thatT. timopheevi and tetraploid wheats had a common ancestor from which their genomes differentiated due to chromosomal aberrations and the increase of heterochromatin in the chromosomes of theT. timopheevi G-genome. The differences between the chromosomes of the AB and AG genomes result in substitutions and large translocations between these chromosomes in interspecific hybrids.     

Non-reciprocal gonadal dysgenesis in hybrids of the chironomid midge Chironomus thummi

In male hybrids of the cross Chironomus thummi thummi (stock Hl) x Ch. th. piger (stock E) , but not the reciprocal cross, rudimentary testes develop at a growth temperature of 21 ° C. Within the dysgenic testes of these hybrids a number of abnormalities are observed which are restricted to the germ line. Approximately 60% of the hybrid males show allocyclic chromosome behaviour in spermatogonia and spermatocyte I nuclei. Within these nuclei two groups of four chromosomes are formed which differ from one another in their state of condensation. Each chromosome group consists of three long and one short chromosome. In cases where allocycly is very pronounced, the chromosomes of both groups disintegrate into numerous unequally sized fragments at meiotic prometaphase I, and gametes are not produced. In individuals, in which the allocycly is less pronounced or absent the nuclear divisions appear to be normal but chromosome and chromatid aberrations are frequent, and the number of viable sperm is reduced. In these males, the chiasma frequency is also decreased more than 12-fold in comparison with the reciprocal, unaffected piger x thummi hybrids.     

Transposition of mobile genetic elements in interspecific hybrids of Drosophila

In situ hybridization of labeled DNA of four mobile dispersed genetic elements (mdg), isolated from D. melanogaster and C. virilis genomes, with polytene chromosomes of the larvae of several Drosophila species has been carried out. The data show that the mdg elements exhibit a high degree of species specificity. The same conclusions are derived from filter hybridization using ³²P-labeled D. melanogaster and D. virilis DNA and cloned mdg sequences immobilized on nitrocellulose filters. We attempted to induce transpositions (jumping) of mdg elements specific for D. virilis chromosomes to the chromosomes of related species (e.g. D. littoralis Meigen) originally lacking the representatives of this family of repeats. For this purpose we produced hybrid stocks with synthetic karyotoypes characterized by different combinations of D. virilis homologous chromosomes and hybrid chromosomes. In one of such stocks we did find by in situ hybridization the insertion of a D. virilis mdg element into the fifth chromosome of D. littoralis Meigen. The transposition (jumping) took place in the only region where somatic pairing between the fifth chromosomes of D. virilis and D. littoralis occurs more or less regularly in the hybrids. Since crossing-over in hybrid chromosomes of males is excluded in such synthetic stocks, gene conversion may be responsible for this transposition. The possible bearing of the phenomenon observed on the problem of hybrid dysgenesis is discussed.     

Meiosis and fertility of F1 hybrids between hexaploid bread wheat and decaploid tall wheatgrass (Thinopyrum ponticum)

As the first step in the transfer of barely yellow dwarf virus resistance and salt tolerance from decaploid tall wheatgrass (Thinopyrum ponticum) into hexaploid bread wheat (Triticum aestivum L.), octoploid intergeneric hybrids (2n = 8x = 56) were synthesized by crossing the tall wheatgrass cultivar Alkar with wheat cvs. Fukuhokomugi (Fuko) and Chinese Spring. (Fuko x Alkar) F₁ hybrids were studied in detail. The F₁ hybrids were perennial and generally resembled the male wheatgrass parent with regard to morphological features and gliadin profile. Most hybrids were euploid with 56 chromosomes and showed high chromosome pairing. On an average, in 6 hybrids 83.6% of the complement showed chiasmatic association, some between wheat and wheatgrass chromosomes. Such a high homoeologous pairing would be obtained if Ph1, the major homoeologous pairing suppressor in wheat, was somehow inactivated. Some of the Fuko x Alkar hybrids had high pollen fertility (18.5–42.0% with a mean of 31.5%) and high seed fertility (3–29 seeds wtih a mean of 12.3 seeds per spike), offering excellent opportunities for their direct backcrossing onto the wheat parent.     

Betrachtungen zum Problem der Frostresistenzzüchtung von Tomaten

Zusammenfassung Zweijährige Selektion auf Frostresistenz bei einer Kreuzung der argentinischen Tomatensorte Platense mit der nordamerikanischen Pearl Harbour unter Freilandbedingungen erwies sich bei Überprüfung in der Kühlkammer im Vergleich zu frostempfindlichen Kultursorten als ergebnislos. Es wird daher der Schluß gezogen, daß auch bei Tomaten eine erfolgreiche Züchtung auf Frostresistenz nur durch Einkreuzung mit frostresistenten Wildarten möglich ist, die auch vorhanden sind. Unter den verfügbaren Wildarten wurde Frostresistenz beiL. peruvianum undL. hirsutum gefunden.     

A Cytogenetic Study of the Leaf Beetle Genus Cyrtonus (Coleoptera, Chrysomelidae)

The chromosomes of ten species of Cyrtonus and the genome sizes of six are surveyed. Among the total of 15 chromosomally studied species, 11 have 2n=28 chromosomes and a 13+Xy_p male meioformula, three have 2n=40 and 19+Xy_p and one 2n=46 and 22+Xy_p. All but one species with 28 chromosomes show only metacentric or submetacentric chromosomes, whereas the species with 40 and 46 chromosomes display some telocentrics or subtelocentrics, that are probably derived from the former by centric fissions. However, since the number of major chromosome arms is strikingly higher in these latter species (NF=70 and 78) than in the 28-chromosome species (mostly NF=56), other chromosomal rearrangements such as pericentric inversions or heterochromatin accretions could also be involved. The genome sizes display a narrow range, from 1C=0.6–1.22pg, and they are not significantly correlated with the chromosome numbers. Some possible factors implied in the rough chromosomal evolution of Cyrtonus are discussed in relation to a few other genera of the subfamily Chrysomelinae.     

A comparison of male and female recombination frequency in wheat using RFLP maps of homoeologous group 6 and 7 chromosomes

A novel approach was used to compare male and female recombination rates in wheat. Doubled haploid lines were developed from an F₁ using two distinct approaches: the anther-culture technique and the Hordeum bulbosum system, from which sets of lines were developed from male and female meioses, respectively. The genotype of the lines was established at RFLP and isozyme markers polymorphic on chromosomes of homoeologous groups 6 and 7, and male and female linkage maps were calculated using this information. The markers in one segment of chromosome 6B exhibited disturbed segregation frequencies in the anther-culture population. The male and female maps differed significantly in recombination frequency between some markers on two chromosomes, and these were consistent in direction within chromosomes and inconsistent in direction between chromosomes. In two of the four chromosomes studied the male map was much longer than the female map. These results suggest that significant differences may exist in male and female recombination frequencies in bread wheat which are specific to certain chromosomal segments but are inconsistent in direction between chromosomes. Other factors, such as environmental influences, may also be important in creating differences.     

Meiotic studies ofElymus nutans andE. jacquemontii (Poaceae,Triticeae) and their hybrids withPseudoroegneria spicata and seventeenElymus species

Hybridizations ofElymus nutans andE. jacquemontii were carried out with one species ofPseudoroegneria (S genome), and 20Elymus species, each containing either of the SH, SY, SYH, or SYW genomes. Chromosome configurations were analysed at metaphase I of the two target taxa and their interspecific hybrids. It is concluded that (i)E. nutans is an allohexaploid containing the SYH genomes, andE. jacquemontii is an allotetraploid having the SY genomes; (ii) the genomic affinity is associated with the geographic distance between the species studied; (iii) minor genomic structural rearrangements have occurred within the hexaploid taxon ofE. nutans.     

Further cytogenetic analyses of the Croatian triploid shallot “Ljutika” (Allium cepa var.viviparum, Alliaceae) and its comparison with the Indian triploid “Pran”

Feulgen and silver-stained karyotypes and meiosis of two triploid viviparous onion forms (Allium cepa var.viviparum), the Croatian Ljutika and the Indian Pran, were comparatively analyzed. The results of chromosome measurements show that Ljutika and Pran are karyologically not identical, although significant similarities were found in the morphology of their chromosomes. Five geographically distant clones of Ljutika showed good agreement in the number and gross morphology of the chromosomes and in the number and position of NORs and interphase nucleoli. Heterotrivalents were predominant in meiosis of Ljutika but a relatively high frequency of higher multivalents together with univalents and bivalents were also observed. The relationship between Ljutika and Pran and their possible origin are discussed.     

Electromyographic analysis of relaxed postures

Six male volunteers assumed either relaxed or unrelaxed postures, as defined by a Behavioral Relaxation Scale, in seven areas of the body. Electromyographic (EMG) levels in the muscle groups associated with each area were determined for both categories of postures. In all instances, the relaxed postures produced significantly lower EMG levels than the unrelaxed postures. This indicates that the Behavioral Relaxation Scale is a valid behavioral measure of relaxation. Also, it supports other studies which have shown that direct training in emitting relaxed postures is an effective means of achieving relaxation.This study was conducted in partial fulfillment of the M.A. degree by Jerry P. Maurer. Appreciation is expressed to Tz-Yi Jiang, Dr. Robert Lehr, and Jim Rice for their assistance.     

Population cytogenetics of the genus Caledia (Orthoptera: Acridinae)

The acridine grasshopper, Caledia captiva exists as two chromosomal races in south-east Queensland. One of these, the Moreton race inhabits the coastal region to the east of the Great Dividing Range. All chromosomes of the complement (2n=11II+XO/XX) have been involved in centromeric rearrangement, which transforms the acro- and telocentric chromosomes into submeta- and metacentric elements. The second, or Torresian race is widely distributed through southern Papua, Arnhem Land, Cape York Peninsula and down the east coast of Australia as far south as Brisbane. This race, which is characterised by a completely acro- and telocentric chromosome complement, approaches the Moreton race in south-east Queensland where the two races are separated by less than 1 km, along a front of at least 150 km. Evidence is presented to show that chromosome introgression is occurring across the contact zone and this takes place in one direction only, namely the Torresian chromosomes are infiltrating into the Moreton race but not reciprocally. Furthermore, the introgression of chromosomes across the zone is limited to certain members of the Torresian complement and even then these successful chromosomes show highly variable degrees of penetrance into the Moreton race. It is proposed that a tension zone exists between these two races which is maintained by the interaction of (a) ecological tolerance differences on either side of the zone and (b) by partial competitive exclusion due to the interracial differences in phenology. This case of parapatric association with limited hybridisation is unique in its clarity due to the marked differences in the appearance of the chromosome complements of these races which permits direct assessment of the behaviour of most members of the genome in hybrids and their derivatives.     

The genetic defect in the various types of human β-galactosidase deficiency

Summary Gene localization studies revealed the presence of two structural -galactosidase (GAL) loci on the human chromosomes 3 and 22 (de Wit et al., 1979). To determine the function of these genes, proliferating hybrid cell lines were isolated following fusion of fibroblasts from two different patients with a GAL deficiency and Chinese hamster cells. The hybrids were analyzed electrophoretically and immunologically.Fibroblasts from a patient with an adult type of GAL deficiency associated with a neuraminidase deficiency were used for the first fusion. No evidence for a structural GAL mutation was found in these hybrids. The absence of a structural GAL mutation is consistent with a primary defect in neuraminidase in this adult patient.Fibroblasts from a patient with the infantile type 1 G_M1-gangliosidosis were used for the second fusion. It is concluded that the human determinants present in the isolated hybrid lines occur in heteropolymeric man-Chinese hamster molecules. The heteropolymeric isoenzyme in (+3–22) hybrids is very labile and is sensitive to neuraminidase treatment. Therefore it is concluded that the infantile type 1 patient is mutated in the structural GAL gene on chromosome 3. Because this patient has a primary defect in G_M1-GAL, the GAL gene on chromosome 3 is apparently a G _M1-GAL gene. Interaction of the two GAL loci results in an additional band of GAL activity on electrophoresis. This suggests that the gene on chromosome 22 is also a structural G _M1-GAL gene.     

Unique sequences for two HLA-DRB1 genes expressed on distinct DRw6 haplotypes

We have used restriction fragment length polymorphism (RFLP) analysis and DNA sequencing to characterize two distinct DRB1 alleles expressed on DRw52 and DQw7-associated haplotypes but not readily defined by conventional DR serology. These two haplotypes, designated HLA-D HAG and PEV, react variably with DRw13(w6), DRw14(w6), and the more broad DR 3+6 antisera. Analysis of RFLP revealed that HLA-D HAG and PEV are associated with different DRw52 variants, and that HAG is indistinguishable from DRw18(3) haplotypes. Sequencing of the HAG and PEV DRB1 genes showed each to represent novel alleles. Nevertheless, these sequences show similarities with the other alleles of the DR5, w6, and w8 family. HAG (DRB1*1303) appears to have arisen either from two recombinational events involving at least three DRB1 sequences (DRB1*1101, DRB1*0803, DRB1*0401) or from a single recombinational event together with multiple point mutational events. PEV appears to represent a DRB1*1301-1302/DRB1*1101 recombinant allele, with recombination having occured in the region of bases 175 – 198. The results of this study suggest that the DRw52 family haplotypes is derived from a relatively restricted number of ancestral sequences, with diversity among DRB1 alleles within this family arising through gene conversion or recombination events.     

Different ζ globin gene deletions among Black Americans

Summary Four types of chromosomes with a deletion between the human embryonic and globin genes were identified among 2.8% of 321 Black Americans from Georgia. Two deletions of approximately 11 kb which differed by about 300 bp occurred on chromosomes with or without a polymorphic Xba I site 5 to the globin gene [(X⁺) or (X^-)]. The deletions are identifiable in Xba I digests of genomic DNA using an or a globin gene probe which yield fragments of 23 kb from (X⁺)–^* chromosomes or 27 kb from (X^–)–^* chromosomes. Digestion with other enzymes and probing with both and probes gave fragments typical of the two globin gene deletions previously identified in Polynesians. Among Black Americans, these globin gene deletions have been found in combination with globin gene deletions in trans but not in cis. Homozygotes have not been found. Hematologic data on carriers of the globin gene deletions in association with Hb AS, SS, and SC suggest that these deletions have no effect on the function of the adult globin genes.     

Study of the three-genome hybridLycopersicon esculentum Mill. —L. chilense Dun. —L. peruvianum var ‘humifusum’ Mill. and its use as a source for resistance

L. peruvianum var humifusum is reproductively the most isolated of the species of the genusLycopersicon. It can be crossed with the cultivated tomato usingL. chilense as an intermediary. After a series of backcrosses of the three-genome hybrid F₁ (L. esculentum ×L. chilense) ×L. peruvianum var humifusum withL. esculentum, accompanied by selection for resistance to some economically important diseases, several lines were established. One of these lines, Cm 180, which showed resistance toClavibacter michiganensis subsp.michiganensis, was subjected to genetic analysis. This resistance was found to be controlled by a single dominant gene (Cm) that was not allelic to the gene originating fromL. hirsutum f.glabratum. ThisCm gene was genetically mapped on chromosome 4. The germ plasm ofL. peruvianum var humifusum in combination withL. chilense was transferred intoL. esculentum. Different breeding lines possessing resistance to various diseases and pests could be developed from this material.     

Chromosome behavior and cell lineage in triploid and mosaic salivary glands of species hybrids in Sciara

Summary A study of the salivary glands of triploid hybrids between females of Sciara ocellaris and males of Sciara reynoldsi throws light on several problems concerning chromosome behavior, species relationships and embryonic development. The specimens studied possess two sets of ocellaris chromosomes and one set of reynoldsi chromosomes. Three types of conditions are represented; 2X3A; 3X3A; and a mosaic possessing cells of both kinds.Heterozygosity of chromosome band pattern in the hybrids shows that the ocellaris homologs are not true sisters and that the sperm probably united with a diploid fusion nucleus composed of two polar bodies and not with the oötid nucleus. This indicates strongly that in a previously described diploid hybrid mosaic some cells developed parthenogenetically from such a fusion nucleus, while others were biparental in origin. The evidence supports the view that the initial influences or reactions of the foreign reynoldsi sperm differ from those of the ocellaris sperm immediately after entry into the egg, but that then and later the differences are relatively slight, although numerous. This agrees with our earlier evidence from the hybrids in indicating that the two parental species are separated genetically, as well as in chromosome band pattern, by many small differences.Species-specific characteristics of chromosome behavior are described which retain their specificity in the hybrids.The 2X3A cells lack a reynoldsi X. The double ocellaris X in such cells (including those in the mosaic) exhibits the peculiar features manifest by the single X in ordinary diploid XO males in the pure species (and in many other Diptera). It is pale and diffuse in structural appearance, and throughout its entire length is uniformly much greater in diameter than it is in the 3X3A cells. The possible significance of this behavior is discussed in relation to problems of sex determination (e. g., Bridges' ratio theory) and those concerning time of gene action. The structural resemblance to the puffs and bulbs found in salivary gland chromosomes is striking and raises the question as to how far morphological characteristics of chromosomes can be used as criteria of gene activity. The double X in the 2X cells of the mosaic, surrounded by 3X cells, exhibits the same peculiarities as those in a pure 2X3A male-type specimen, indicating that we are dealing with intracellular, not intercellular phenomena.Conditions in the mosaic gland support the evidence from the diploid hybrids (some described here for the first time) in indicating that the salivary gland is formed by differentiation of cells which happen to lie in the proper region, regardless of their ancestry. The triploid mosaic specimen (and also a diploid mosaic) is presumed to be a female in which the normal male-producing type of chromosome elimination occurred in one or more mitotic divisions during cleavage or later.     

Meiotic analysis ofElymus caucasicus,E. longearistatus,and their interspecific hybrids with twenty-threeElymus species (Triticeae,Poaceae)

Interspecific hybridizations were carried out between the two tetraploidsElymus caucasicus andE. longearistatus, and 23 tetraploids and hexaploids ofElymus containing SH, SY, SYH, and SYW genomes and representing various geographical regions. Meiotic pairing was studied in the two target species and their hybrids. It is concluded from this study that (i) interspecific hybridization is fairly easy to perform although strong reproductive barriers exist between the species; (ii)Elymus caucasicus andE. longearistatus are allotetraploids, and share the diverged SY genomes; (iii) the divergence of SY genomes is correlated with the geographic distance between theElymus spp. studied.     

Flexibility on the karyotype evolution in bitterlings (Pisces, Cyprinidae)

In bitterlings (Acheilognathinae) C- and Ag-banding karyotypes of 6 species-subspecies collected in China and South Korea were analyzed. The chromosomal constitution of 2n=46 (4SM+42ST) in Rhodeus atremius fangi was quite different from that of 2n=48 (8M+20SM+20ST) in other species-subspecies in Rhodeus. It was concluded from the analysis of banded chromosomes that the increase in number of ST during the karyotype change from 2n=48 to 2n=46 was achieved by a series of pericentric inversions from 24 M-SM to 24 ST, and the decrease in the diploid number was caused by an additional tandem fusion of 4 ST chromosomes, forming a new ST pair in the 2n=46 karyotype. The karyotype of Tanakia koreensis, T. signifer, and Acheilognathus macropterus is 2n=48 (8M+20SM+20ST), 2n=48 (8M+20SM+14–16ST+4–6 A), 2n=44 (14M+16SM+14ST), respectively. In R. ocellatus ocellatus, T. koreensis, T. signifer and A. macropterus, karyotype changes from 2n=48 to 2n=44 due to centric fusion and inversion have also been estimated. It was suggested that C-banding heterochromatin was greatly concerned with the karyotype evolution in bitterlings.