Phylogenetic relationships in Lens species and their interspecific hybrids as measured by morphological characters

Phylogenetic relationships of 15 genotypes of the genus Lens and 7 of their interspecific hybrids were determined by morphological (quantitative and qualitative) characters. The first multivariate analysis was conducted on quantitative characters and second analysis was conducted on qualitative characters. In the first analysis on the basis of two canonical variates, accessions of Lens nigricans, L. odemensis and L. culinaris ssp. orientalis grouped together, while L. ervoides and L. culinaris ssp. culinaris formed two different groups. The second analysis yielded different results based firstly on two canonical variates where L. nigricans and L. culinaris ssp. culinaris formed two separate groups but the other three (sub)species clustered together when the third canonical variate was included. L. odemensis separated from this larger group and formed a separate group. The phylogenetic relationships of parents and their hybrids have also been discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genetic structure of landrace populations of the New World grain amaranths

Summary Grain amaranth populations from their centers of origin in the New World had shown a pattern of allozyme variation that suggested most landraces to be highly homozygous mixtures of genotypes. To compare this pattern of variation with the variation for morphological traits, 15 selfed families from each of six populations were grown in a replicated field experiment. Four pigmentation traits known to be smiply inherited were scored along 18 other morphological traits. Populations varied for the amount of polymorphism for marker loci, and exhibited little heterozygosity. Analysis of variance for the quantitative traits showed significant interpopulation differences for each of the observed characters. Populations differed for the number of metric traits showing significant between-family differences for just one of the metric traits whereas another had between-family differences for all ten. These results suggested high levels of homozygosity within these landraces; thus, variation for quantitative traits conformed well with the allozyme variation patterns.Stepwise multiple regression of all characters on yield as the dependent variable was used to compare the relative contributions of specific characters to yield within individual populations. Plant height, days to flowering, and leaf length were included in the regression equations for 6, 5, and 5, of the populations, respectively. Days to floweing was negatively correlated with yield, while plant height and leaf length were positively correlated. These correlations suggest the potential for developing early flowering, high yielding cultivars having short stature, selected by breaking its correlation with yield. Several breeding strategies based on these findings on genetic resources are discussed briefly.     

Interspecific hybrids of Cyclamen persicum and C. graecum

Summary Interspecific crosses were made to introduce the disease resistance of Cyclamen graecum into C. persicum cultivars and the abortive hybrid embryos were rescued by ovule culture. Diploid and tetraploid cultivars of C. persicum (CPD, 2n=2x=48; CPT, 2n=4x=96) were the pistillate parents and wild form of C. graecum (CG, 2n=84) were the staminate parents. After pollination, crossed ovaries were periodically collected and examined using paraffin sections. Histological observations suggested that both hybrid ovules of CPD × CG and CPT × CG should be transferred to the culture medium 35 days after pollination. Based upon this observation, crossed ovaries were collected 35 days after pollination, then ovules with placenta were explanted on culture medium and cultured in the dark at 25°C. Plantlets were induced from ovules cultured in MS medium containing 3% sucrose and 10% coconut milk. The hybrids (2n=66) derived from CPD × CG failed to yield viable seeds by self-pollination, although they showed some pollen fertility. In contrast, the hybrids (2n=90) derived from CPT × CG showed high pollen fertility and yielded viable seeds by self-pollination. Furthermore, they were resistant to disease caused by Fusarium oxysporum f. sp. cyclaminis, Erwinia herbicola pv. cyclamenae and Pseudomonas marginalis pv. marginalis.Abbreviations CPD C. persicum diploid - CPT C. persicum tetraploid - CG C. graecum     

Inheritance of some morphological traits in grain amaranthus

Summary Intraspecific crosses involving five cultivars of Amaranthus hypochondriacus and two from A. caudatus were studied to investigate the inheritance of five morphological traits (seed coat colour, inflorescence colour, seedling colour, oval leaf mark and purple leaf mark). Seedling colour, inflorescence colour, seed coat colour and oval leaf mark segregated to a 3:1 ratio and therefore each was controlled by a single dominant gene. The purple leaf mark segregated in 9:7 ratio and hence may be controlled by two dominant genes. Simultaneous segregation for seed coat colour and inflorescence colour gave a ratio of 9:3:3:1. Similar genetic ratio was observed for the simultaneous segregation for oval leaf mark and inflorescence colour. It was suggested that each of these traits is controlled by independent genes.     

Interspecific hybrids of Cyclamen persicum Mill. and C. purpurascens Mill. produced by ovule culture

Summary Interspecific crosses were made to introduce the scent of flowers of C. purpurascens into C. persicum cultivars and ovule culture was used to rescue the abortive hybrid embryos. Cultivars of C. persicum diploid (CPD, 2n=2×=48) and C. persicum tetraploid (CPT, 2n=4×=96) were the pistillate parents and wild species of C. purpurascens (CP, 2n=34) were staminate parents. After pollination, crossed ovaries were collected periodically and examined using paraffin sections. Histological observations suggested that both hybrid ovules of CPD x CP and CPT x CP should be transferred to culture medium 35 days after pollination. Based up on this observation, crossed ovaries were collected 28 days after pollination and ovules with placenta were transferred to MS (1962) medium containing 3% sucrose. These ovules were cultured in the dark at 25° C. The hybrids (2n=41) derived from CPD x CP had the scent of C. purpurascens, whereas the hybrids (2n=65) derived from CPT x CP had the scent of C. persicum. Although both hybrids had complete genomes from the parents and produced a few viable pollen grains, they failed to yield viable seeds by self- and cross-pollination with fertile pollen grains of C. persicum cultivars.Abbreviations CPD C. persicum diploid - CPT C. persicum tetraploid - CP C. purpurascens     

Interspecific hybrids from cross incompatible relatives of sweetpotato

Summary Hybrids were obtained from Ipomoea interspecific crosses through ovule culture. The hybridity of the progeny obtained from I. triloba × IitI. trifida and (I. triloba × I. lacunosa) × I. batatas (4x) crosses was established by comparisons of floral morphology and analyses of peroxidase and esterase isozymes. The hybrids displayed the inflorescence type and sepal shape and texture of their male parents, while corolla size and anther and nectary color tended to be intermediate to their parents. The isozyme banding patterns of the hybrids contained bands present in the patterns of each of their parents. Pollen grain viability, measured by aceto-carmine stainability, was 44.1%, 92.3% and 82.4%, respectively, for the I. triloba × I. trifida hybrid and the (I. triloba × I. lacunosa) × I. batatas (4x) hybrids, H₁ and H₂. A controlled pollination study revealed that the I. triloba × I. trifida, and the (I. triloba × I. lacunosa) × I. batatas (4x) hybrids, H₁ and H₂ were partially self fertile with 6%, 70% and 13%, respectively, of the pollinated flowers producing viable seed. Success in backcrossing and sib-mating varied with the cross combination.     

Interspecific hybrids betweenAllium fistulosumandAllium schoenoprasumreveal carotene-rich phenotype

Interspecific hybridization is an effective method to generate a new crop that gains available functions in a short time. Interspecific hybrids (2n= 16) betweenAllium fistulosumL. (2n= 16) andAllium schoenoprasumL. (2n= 16) were produced by reciprocal crossings through ovary culture, but the hybrids were much fewer in the combination usingA. schoenoprasumas a seed plant. All the hybrids have eight long chromosomes originated fromA.fistulosumand eight short chromosomes originated fromA. schoenoprasum. In addition, the hybridity was confirmed by randomly amplified polymorphic DNA (RAPD) analysis and cleaved amplified polymorphic sequence (CAPS) analysis of the rDNA internal transcribed spacer (ITS) region. The interspecific hybrids showed a vigorous growth habit; their foliage was slightly bloomy and deep green. The hybrids did not form bulbs, but rather propagated vegetatively by tillering. Carotene contents of the hybrids and both parents were quantified using high-performance liquid chromatography (HPLC). The contents of all edible parts of the hybrids were approximately seven times higher than those of either parent. These results indicate that the hybrid is a new and carotene-rich vegetable ofAlliumspecies.     

Meiosis and pollen grain viability in Helianthus mollis,Helianthus salicifolius,Helianthus maximiliani and their F1 hybrids with cultivated sunflower

Three diploid perennial sunflower species are useful for variety improvement: Helianthus mollis, because of sessile leaves, H. salicifolius, because of a high oil concentration, and H. maximiliani, a potential source of resistance to Sclerotinia sclerotiorum. The crossability of these species to cultivated sunflower was examined.Hybrids were obtained from eight combinations, with 3–15 F₁ plants per combination. The F₁'s exhibited the dominant phenotype of the wild species. Pollen viability varied between 32.1 and 69.9%. Meiosis was irregular in the F₁ hybrids. At diakinesis, bivalents (62.7–97.9% of meiocytes), univalents (0–31.23%), and multivalents (3.84–7.68%) were detected. At anaphase I, chromosome bridges were detected in 6.77 to 11.44% of meiocytes. Fast chromosomes in metaphase I, and lagging chromosomes in anaphase I and telophase II were evidenced in a high percentage of meiocytes.     

Inheritance of isozymes in peach x Prunus kansuensis and peach x Prunus davidiana hybrids

Summary Isozyme variation and inheritance were investigated with starch gel electrophoresis in peach (Prunus persica L. Batsch) x P. kansuensis Rehd. and peach x P. davidiana (Carr.) Franch. interspecific hybrids. Of five enzyme systems surveyed for polymorphism, four systems were identified as polymorphic [isocitrate dehydrogenase (IDH, EC 1.1.1.41), phosphoglucomutase (PGM, EC 2.7.5.1), aspartate aminotransferase (AAT, EC 2.6.1.1), and 6 phosphogluconate dehydrogenase (PGD, EC 1.1.1.44)] and may be useful as genetic markers in future cultivar and rootstock development. Analysis of progenies segregating for pairs of loci suggests a possible linkage between the loci coding for Aat-1 and Pgd-2. Independent assortment was observed for isozyme loci Idh/Pgm-2, Idh/Aat-1, Idh/Pgd-2, Pgm-2/Aat-1, Pgm-2/Pgd-2, and Aat-2/Aat-1. The red leaf locus, Gr, assorted independently of the isozyme loci: Idh, Pgm-2, Aat-1, and Pgd-2.     

Genetic diversity in advanced derivatives of Brassica interspecific hybrids

Genetic diversity among the 88 entries including eighty F₄ derivatives i.e., 20 each selected from Brassica crosses viz., B. juncea × B. napus, B. juncea × B. rapa var. toria, B. juncea ×B. rapa var. yellowsarson and B. tournefortii × B. juncea, and eight parent genotypes was assessed through multivariate analysis (D² statistic). Significant differences among the family groupsas well as within the family were recorded for all the 14 characters studied. The D² analysis revealed enormous diversity among the interspecific cross derivatives. The genetic distances calculated among different Brassica species revealed that B. tournefortii had maximumdiversity with B. juncea followed by B. napus, B.rapa var. toria and B. rapa var. yellow sarson.Amongst interspecific crosses, maximum diversity was noticed indescendants of cross B. tournefortii × B. juncea followed byB. juncea × B. napus, B. juncea × B.rapa var. toria and the least in the cross B. juncea ×B. rapa var. yellow sarson. These results indicated that the derivatives selected from cross of diverse parents revealed greater diversity. The clustering pattern showed that many derivatives of the cross fell into the same cluster but in many cases in spite of common ancestry many descendants of the cross spread over different clusters. The characters, namely, plant height, secondary branches per plant, days to flowering and1000-seed weight were contributed maximum towards genetic divergence. This revised version was published online in August 2006 with corrections to the Cover Date.     

Chromosome association and pollen fertility in some interspecific hybrids of Lilium

Summary Meiotic observations in PMCs were made in eight kinds of interspecific hybrids in Lilium. Three hybrids, 6134-S × L. cernuum. L. regale × L. leichtlinii maximowiczii and L. auratum platyphyllum × L. henryi showed respectively the mean chromosome association frequencies of 1.4_II, 0.8_II and 1.5_II per cell at MI which were the lowest values hitherto reported in Lilium hybrids. In L. longiflorum × L. henryi, 33.3° of the cells had 1 or 2 multivalents of three to five chromosomes in addition to uni- and bivalents. 12° bivalents and 12 univalents were invariably observed in the triploid hybrid L. longiflorum × L. cernuum. The hybrids between the species belonging to the different sections of the genus generally showed high pollen sterility, with some exceptions. A more or less remote genomic homology was found between the different sections in Lilium.     

Rapid estimation of ploidy levels in in vitro-regenerated interspecific Arachis hybrids and fertile triploids

Summary A significant correlation among chromosome number, chloroplast number and pollen grain size was observed using interspecific hybrids (2n=30,60), Arachis hypogaea (2n=40), A. stenosperma (PI 338280) (2n=20), A. batizocoi (PI 468329) (2n=20) and A. villosulicarpa Hoehne (PI 336984) (2n=20), representing four ploidy groups. Both chloroplast number in guard cells and pollen grain size were found to be positively correlated with ploidy, and provided a reliable method to distinguish diploid, triploid, tetraploid and hexaploid plants from each other regardless of their taxonomic backgrounds. These methods in combination with root-tip chromosome counts enabled us to confirm ploidy determinations on all three dissue layers, L₁, L₂ and L₃ (guard cells, microsporocytes and root meristematic cells, respectively), and to detect the chimeric nature of some colchicine-treated tissue culture-derived plants. Screening pollen grains by size and the detection of highly stainable and viable, 30-chromosome pollen grains have enhanced the use of triploid hybrids in peanut breeding programs.     

Cytology and digoxin production in hybrids between Digitalis lanata and D. grandiflora

Summary Digitalis lanata is the only commercial source of the cardiac glycoside digoxin. It is an outbreeder and displays considerable variation. An attempt to increase uniformity was made by making D. lanata × D. grandiflora diploid hybrids and from these produce allotetraploid hybrids using colchicine treatment. Such tetraploid plants would be homozygous. Tetraploid hybrids were shown to contain digoxin but at lower levels than in D. lanata. Progeny of selfed tetraploid hybrids were significantly more uniform than D. lanata grown from commercial seed, but were considerably less vigorous.     

Interspecific hybridization between Coffea arabica L. and tetraploid C. canephora P. ex Fr. I. Fertility in F1 hybrids and backcrosses to C. Arabica

Summary The interspecific (C. arabica × tetraploid C. canephora) F₁ hybrid showed a low but highly variable fertility. An almost complete restoration to normal fertility was observed in individual trees of BC₁ and BC₂ generations with C. arabica as recurrent parent. From a comparison of various tests of fertility, it was found that pollen viability is a satisfactory measure of fertility.     

Heterosis in growth and photosynthetic rate in hybrids of cotton

Summary The intraspecific (Gossipium hirsutum) and interspecific (G. hirsutum x G. barbadense) F₁ hybrids of cotton were found to exhibit a high degree of heterosis in the production of fruiting branches, number of bolls (fruits), yield of seed cotton and photosynthetic rates over the parent plants. The developing bolls of the hybrids had significantly higher weights than their parents until the 20th day after anthesis. The patterns of leaf area development among interspecific hybrids differed when compared with the parent plants. The photosynthetic rates of the hybrids were comparable with those of maize and sorghum and much higher than the average rate reported so far for the cotton plant.     

New interspecific hybrids in the genus Agropyron

Summary Fifteen species from the genus Agropyron were crossed together. Fourteen of the crosses did not produce fruits. Twenty crosses produced varying numbers of caryopses. Of the fruits produced, 22% contained no embryos. For a variety of reasons it was possible to obtain only 2 plants from the remaining 140 embryos. The crosses which yielded viable plants were between A. trachycaulum cv. Primar (2n=28) and A. intermedium cv. Chief (2n=42) as well as between A. trachycaulum from Lethbridge (2n=28) and A. desertorum cv. Nordan (2n=28). The somatic chromosome numbers for the hybrids are 37 and 28. respectively. Studies of vegetative plant character are presented.     

Interspecific hybridization in the genus Arachis through embryo culture

Summary The embryos of a cultivated tetraploid peanut (Arachis hypogaea), a wild diploid species (A. villosa), and their hybrid embryos, which generally abort in nature, were cultured in vitro and the plants have been successfully transferred to the soil. The hybrids showed triploid chromosome number (3x=30). The significance of wide hybridization in peanut-improvement programs is discussed.     

Quality characteristics of backcross hybrids between Trifolium repens and Trifolium ambiguum

Two generations of novel backcross hybrids between white clover (Trifolium repens L.) and the related species Trifolium ambiguum,with white clover as the recurrent parent, were analysed for forage quality characteristics. Water soluble carbohydrate (WSC) levels, nitrogen concentrations (%N), and dry matter digestibility (DMD) were recorded for the hybrids and parental species grown in deep soil bins with and without a companion grass. Half the experimental material was subjected to moisture stress by being left unwatered through the four-week period when measurements were made. Four such four -week cycles of drought were imposed. The first and second generation backcrosses had the highest values for WSC, but were lowest for N%. There was no difference between the different legume lines (parents and backcrosses) for DMD. No effects of either moisture stress or presence of a grass companion on quality traits were observed. The WSC and %N of the grass component differed significantly depending on which legume line it was grown with. The importance of these results for the potential use of these hybrids in agriculture is discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Cytology and leafspot resistance in Arachis hypogaea x wild species hybrids

Summary Introgression of germplasm from diploid wild Arachis species to A. hypogaea has great potential for improving pest resistance in cultivated peanuts. This investigation evaluated methods for incorporating exotic germplasm into cultivated peanuts, especially for Cercospora arachidicola Hori resistance. Interspecific hybrids between A. hypogaea (cvs. NC 2 and NC 5) and the wild species A. cardenasii Krap. et Greg. nom. nud. and A. chacoense Krap. et Greg. nom. nud. were analyzed cytologically and for leafspot resistance. All F₁ hybrids were sterile, had irregular meiosis, and very few multivalents. They were highly resistant to C. arachidicola in field tests and had a 10-fold reduction of conidia per lesion in the greenhouse as compared to A. hypogaea cultivars. After colchicine treatments of F₁ hybrids, hexaploids (2n=60) and aneuploids (2n=54, 56, 63) were observed. The hexaploids had up to 18 univalents per pollen mother cell and very few multivalents, indicating a low frequency of intergenomic chromosome pairing. For C. arachidicola resistance, significant differences were not found among wild species parents, F₁ hybrids and two generations of hexaploids. Most hexaploids were stable at 2n=60 and embryos aborted when backcrosses with the respective wild species were attempted. However, when hexaploids were backcrossed to A. hypogaea, several fertile pentaploid (2n=50) offspring were obtained. Use of self-pollinating pentaploids is believed to be the quickest method to recover 40-chromosome hybrid derivatives in these hybrids.     

DNA fingerprint of F1 interspecific hybrids from the Triticeae tribe using ISSRs

Inter-simple-sequence repeat (ISSR) were used to fingerprint three kinds of F1 interspecific hybrids: the Portuguese durum wheat cultivar ‘Candial’ × tritordeum, the Portuguese bread wheat cultivar ‘Barbela’ × tritordeum and the Portuguese triticale cultivar ‘Douro’ × tritordeum. Among the 30 primers tested, the number of discriminative primers varies from 13 to 20 in each hybrid combination, the total number of ISSR loci analysed ranged from 101 to 183, and the number of discriminative ISSR loci varied from 50 to 71. ISSR-PCR technique revealed to be a valuable fingerprint system for all F1 hybrid combinations and respective parents analysed here. The complementary use of molecular cytogenetic techniques and molecular markers could allow a more accurately evaluation and characterisation of different plant species.