The effect of in vivo and in vitro applications of ethrel and GA<Subscript>3</Subscript> on sex expression in bitter melon (<Emphasis Type="Italic">Momordica charantia</Emphasis> L.)

Bitter melon (Momordica Charantia L.) is an important vegetable crop with nutritional and medicinal qualities. As a member of cucurbitaceae it is monoecious with varying proportions of staminate and pistillate flowers. This study was undertaken to determine the effects of various applications of ethrel and gibberellic acid (GA₃) on sex modification in M. charantia. In the first set of experiments, various concentrations of hormones were added to the seed germination medium, in the second, adult plants growing in the field were sprayed with aqueous solutions of ethrel or GA₃ three times at three-day intervals. The number and sex of open flowers was recorded daily for 60 days after the first flower opened and total number of staminate and pistillate flowers was calculated at the end of the experiment. The highest frequency (29.5%) of pistillate flowers was observed in plants treated with 500 ppm ethrel at germination. Similarly, spraying of adult plants with 100 ppm GA₃ increased the proportion of pistillate flowers to 26% relative to 15% in untreated controls. Both ethrel and GA₃ induced significantly higher number of pistillate flowers than control. In vitro hormone application during seed germination was much more successful than spraying of field grown plants.     

Synthesis and preliminary characterization of a new species (amphidiploid) in Cucumis

A successful interspecific hybridization between cucumber (Cucumis sativus L., 2n = 14) and a wild it Cucumis species, C. hystrix Chakr. (2n = 24) was made via embryo rescue. Hybrid plants (2n = 19; 7 from cucumber and 12 from C. hystrix) were sterile, but morphologically uniform. Self-pollination and backcrossing of F₁ hybrid plants to either parent confirmed presence of both male- and female-sterility that were likely caused by lack of homology and improper pairing during meiosis. While the multiple-branching habit, densely brown hairs (on corolla and pistil), orange-yellow corolla, and ovate fruit of F₁ hybrid plants were similar to that of the C. hystrix parent, the appearance of the first pistillate flower was more similar to that of C. sativus parent. The diameter and internode length of the stem, and the shape and size of leaves and flowers were intermediate when compared to the parents. The chromosome number in the hybrid was doubled through somaclonal variation during embryo culture and regeneration process to restore the fertility. Pollen grains were released and fruits with viable seeds matured on fertile, synthetic amphidiploid plants. The results from flow cytometry indicated that, on average, 7.3% of the morphologically unique regenerants had the 4C DNA content of 2.35 pg relative to the 2C DNA content of the original F₁ hybrid at 1.17 pg and, therefore, were likely chromosome-doubled F₁ hybrids (2n = 38). Nutrition alanalysis indicated that the synthetic species had higher protein (0.78%)and mineral (0.35%) content compared to the normal pickling cucumber(0.62% and 0.27%, respectively), and could be considered a new Cucumis crop having a special place in the future agriculture. Preliminarily evaluation indicates that C. hystrix possesses a high level of root-knot nematode resistance, and that this resistance is partially expressed in the interspecific F₁ and chromosome-doubled F₁. This and the fact that the fruit morphology of the fertile amphidiploid differs during the growing season (e.g., short and long fruit) suggest that it could be useful in broadening the germplasm base of cucumber. This revised version was published online in July 2006 with corrections to the Cover Date.     

Comparative study on vegetative,reproductive and qualitative traits of seven diploid and tetraploid watermelon lines

Seven tetraploid watermelon lines developed by colchicine treatments were compared with their diploid counterpart for plant, flower, fruit, seed and qualitative characteristics. Tetraploid genotypes attained statistically higher vine thickness (8.04 mm), leaf area (298.9 cm²) and chlorophyll content (55.6) while internode length and chlorophyll fluorescence was similar to their corresponding diploid. Both pistillate and staminate flower organs (pedicel, anther, ovary, stigma, petals) were larger in tetraploid plants; however, the percent increase in flower components varied across the tetraploid lines. Fruit weight and total sugar content (^∘Brix) in both ploidy fruits was similar. Rind thickness in fruits varied significantly and averaged 12.7 and 17.2 mm in diploid and tetraploid fruits, respectively. Tetraploid genotypes showed sterility, yielded lower number of seed per fruit (37.9), and tetraploid seed was larger and thicker than diploid seed. Overall β-carotene (0.89), lycopene (1.16), fructose (5.43%) and glucose (2.38%) contents were higher in tetraploid than diploid fruits.     

Studies on habit of flowering and its relation to shape of fruit in an inbred line of watermelon,Citrullus vulgaris schrad.

Attempts have been made to describe the interaction between the shape of fruit and habit of flowering in two watermelon plants found in the multiplication plot of a new variety. The first plant Gol-43-1 had staminate and perfect flowers; the shape of fruit was oblate to oblong. The other, Gol-43-2, bore pistillate, staminate and perfect flowers; the shape of fruit was oblate to spherical. By selfing and sibbing different offsprings of these two plants and considering the segregants, definite monohybrid ratios were obtained. This indicated that a pair of independent genes control habit of flowering and that monoecious habit of flowering is dominant over andromonoecious habit of flowering. No definite ratios indicative of an interaction between shape of fruit and habit of flowering could be established. Plants bearing defective reproductive organs had fruits which were intermediate in shape. It is our belief that more than two pairs of genes are responsible for the gradation in fruit shape and the interaction between habit of flowering and shape of fruit.Publication No. 4, Department of Agronomy, College of Agriculture, Pahlavi University, Shiraz, Iran.Department of AgronomyDepartment of Agronomy     

Genetic analysis in Chrysanthemum morifolium. I. Flowering time and flower number at low and optimum temperature

Summary The number of days to flowering and the number of flowers per plant were studied at 12, 13, 15 and 17 C night temperature in 79 F₁ populations from 15 parents. Only a few F₁ plants flowered earlier than their parents; the majority flowered at the same time, later or not at all. The number of flowers of the F₁ plants was higher than that of the parents.Genetic analyses showed a broad sense heritability of 70% for days to flowering and flower number and a highly significant GCA effect for days to flowering.The progenies and parents that flowered early at one temperature were generally early at all temperatures.     

Barriers to hybridization of Solanum bulbocastanum Dun. and S. Verrucosum Schlechtd. and structural hybridity in their F1 plants

Summary Results of reciprocal crosses between Solanum verrucosum (2n=2x=24) and S. bulbocastanum (2n=2x=24) are described in terms of pollen tube behaviour in styles, of berry and seed set, of fertility and of meiotic behaviour of the F₁ hybrids. Pollen tube growth of S. verrucosum is strongly inhibited in styles of S. bulbocastanum, whereas no inhibition is observed in the reciprocal cross. Therefore S. bulbocastanum x S. verrucosum fails to set berries or seeds, whereas the reciprocal cross produces both berries (54.4% berry set) and seeds (0.3 per berry). Only 14.6% of the seeds germinate. Both the diploid and corresponding tetraploid hybrid plants are vigorous, flower abundantly, have a rather regular meiosis (mainly rod bivalents), but show a high degree of cytoplasmic-genic male sterility. Crossability of the diploid hybrid plants is nil when used as pollen parents and near to zero when used as pistillate parents. The barriers to hybridization of the parent species (unilateral inhibition of pollen tube growth, somatoplastic sterility, cytoplasmic-genic male sterility and structural differences of the parental chromosomes) are discussed and methods are suggested to overcome these barriers.     

The increase of seed fertility of Brassicoraphanus through cytological irregularity

Summary Amphidiploids (Brassicoraphanus) were produced by means of colchicine treatment of F₁ hybrids between Brassica japonica Sieb. and Raphanus sativus L. The cytology of the amphidiploids was studied from F₁ to F₃ generations. Some plants had the euploid chromosome number 2n=38, whereas others had the aneuploid number 2n=37. One or two of either quadrivalents or trivalents, as well as some univalents, were seen in most of the plants examined. All the plants showed a low seed fertility. In F₃ generation there arose some yellow-flowered plants, all of which showed a higher seed fertility than normal white-flowered plants. It is postulated that the change of flower colour might originate in the segmental exchange of only partially homologous chromosomes following multivalent formation. A gene causing white flower colour was perhaps closely linked to a gene causing sterility, and both genes were probably excluded together through the segmental exchange of the chromosomes. Therefore, it can be said that the increase of fertility was induced by cytological irregularity.     

Sex modification in Actinidia deliciosa var. deliciosa

Summary The aim of the trial was to determine whether growth regulators and injuries could affect sex expression in the cultivated kiwifruit. Growth substances (NAA, BAP, GA, ethephon, ABA, TIBA, and CCC) were applied at 1% concentration in lanolin (w/w) to shoots of 17-year old plants of the staminate clone Matua and the pistillate clone Hayward. Injuries consisted in shoot defoliation or removal of a ring of phloematic tissue from the laterals. Both the application of growth regulators and injuries were done about 5 weeks before anthesis. In the pistillate clone, no treatment resulted in overcoming pollen grain sterility; ABA and GA mereased the stigma-style number as well as the density of papillae on the stigma surface. A positive correlation was found between stigma-style number and pedicel length (r=0.660). In the staminate clone, pollen grain viability was significantly altered by treatment; the highest (79.2%) and lowest (10.3%) values were recorded for ABA and GA, respectively. A negative correlation was found between pollen grain viability and pedicel length (r=–0.648). As a general rule, treatments which depressed pollen grain viability allowed the development of a variable number of styles. About 20 styles were consistently produced when GA was applied; the gibberellin-caused feminization of kiwifruit was confirmed in a repeated trial. The data collected also suggest that sex expression can be slightly changed by injuries; contrariwise, rather good results can be achieved by using a growth regulator earlier in the season or before flower initiation.     

Identifying apomixis in matroclinal progeny from an interspecific crossing between <Emphasis Type="Italic">Iris domestica</Emphasis> and three different colors of <Emphasis Type="Italic">Iris dichotoma</Emphasis>

In a previous investigation on the reciprocal difference of interspecific hybridization between three different flower colors of Iris dichotoma and Iris domestica in the F₁ offspring from crosses where I. domestica was a maternal parent were similar in morphological and cytological characters to their maternal parent. This could be evidence of apomixis; however, matroclinal progeny with complete morphological similarity to the maternal parent could be attributed to the heterozygosity for these characters in the pollen parent. The F₁ plants were investigated in order to identify apomixis in I. domestica. Four matroclinal plants were randomly selected from each F₁ population produced from Iris domestica × Iris dichotoma that had three different colors of flowers and were allowed to self-pollinate to establish an F₂ population. All of the F₂ plants had no segregation to I. domestica in their morphological characters. In addition, 13 reciprocal F₁ plants were detected by 25,719 single nucleotide polymorphism (SNP) markers. When I. dichotoma plants with three different flower colors were used as maternal parents, all the progenies were genuine hybrids. When I. domestica were used as maternal parents, all the F₁ plants were apomictic progenies. Apomixis of I. domestica was successfully identified and SNP markers identified F₁ hybrids derived from six interspecific crosses between I. dichotoma and I. domestica, which provides a reference for authenticating offspring identity during Iris cross breeding in the future.     

RAPD and SCAR markers linked to sex determination in Eucommia ulmoides Oliv.

Eucommia ulmoides Oliv. is strictly a dioecious perennial tree native to China. The pistillate plants are economically more useful than the staminate plants. The random amplified polymorphic DNA (RAPD) technique was used to screen markers of sex determination in this species. A 569 bp RAPD marker, marker linked to sex determination in E. ulmoides (MSDE), was found in all the pistillate but not in the staminate plants; its exclusiveness to pistillate plants was confirmed by Southern blotting. MSDE was sequenced and specific primers were synthesized to generate a 569bp pistillate-specific SCAR marker, SCARmr. SCARmr could be useful for screening E. ulmoides plants for gender even before they reach reproductive maturity, resulting in considerable saving of time and economic resources.     

The transfer of triazine resistance from Brassica napus L. to B. oleracea L. III. First backcross to parental species

Summary Atrazine resistant Brassica napus × B. oleracea F₁ hybrids were backcrossed to both parental species. The backcrosses to B. napus produced seeds in both directions but results were much better when the F₁ hybrid was the pollen parent. Backcrosses to B. oleracea failed completely but BC₁s were rescued by embryo culture both from a tetraploid hybrid (2n = 4x = 37; A₁C₁CC) and sesquidiploid hybrids (2n = 3x = 8; A₁C₁C). Progeny of crosses between the tetraploid hybrid and B. oleracea had between 25 and 28 chromosomes. That of crosses between the sesquidiploid hybrid and B. oleracea had between 21 and 27. A few plants that had chromosome counts outside the expected range may have originated from either diploid parthenogenesis, unreduced gametes or spontaneous chromosome doubling during in vitro culture. Pollen stainability of the BC₁s ranged from 0% to 91.5%. All the BC₁s to B. oleracea were resistant to atrazine.     

Interspecific hybrids between kenaf (Hibiscus cannabinus) and roselle (H. sabdariffa)

The successful interspecific cross is reported for the first time between kenaf (Hibiscus cannabinus L.), a diploid species (2n=36) and roselle (Hibiscus sabdariffa L.), a tetraploid species (2n=72). Kenaf, grown for its bast fiber and also under investigation as a source of paper pulp, is fast-growing and well adapted to mechanical harvesting, but susceptible to root-knot nematodes. Roselle, also grown for its bast fiber, is slower growing, not well adapted to mechanical harvesting, but certain varieties are resistant to root-knot nematodes. Five hybrid plants were produced from the pollination of 4,445 flowers of kenaf with pollen from roselle; no hybrid plants were produced from 2,655 pollinations made in the reciprocal direction. One line of roselle was the parent of 3 of the 5 hybrids; one line of kenaf was the parent of 2 of these 3. The F₁ hybrids were triploid, and varied in vigor, growth habit and vegetative morphology, but had similar flowers. Two of the F₁ hybrids showed high pollen fertility, apparently as a result of restitution at first meiotic division leading to unreduced spores. These two hybrids each produced a small amount of seed, which gave rise to an F₂ population of 22 plants. The F₂ plants vary in vigor but are morphologically uniform, have thick leaves with mosaic sectors, and are presumably spontaneous allohexaploids. The theoretical possibilities of increasing the percentage of recovery of the F₁ interspecific hybrids and of developing a synthesized hybrid variety useful for bast fiber and paper pulp are discussed.     

Interspecific hybrids between helianthus PetiolarisNutt. and H. Annuus L.: Effect of backcrossing on meiosis

Summary Interspecific substitutions of the nucleus of Helianthus annuus (2n=34) into the cytoplasm of H. petiolaris (2n=34) were obtained by successive backcrossing using cultivated sunflower, H. annuus, as the recurrent pollen parent.Meiosis in the F₁ was characterized by multivalents, suggesting that 10 of the 34 chromosomes were heterozygous for chromosomal interchanges. An additional pair of chromosomes also contained a paracentric inversion. Continued backcrossing resulted in rapid elimination of the meiotic aberrations evident in the F₁. In the BC₁, 1 of 11 plants had normal meiosis and by the BC₂, only 13 of 54 plants had meiotic aberrations similar to those of the F₁. However, trisomic progeny (2n=35) were found in 3 of the 11 BC₁ plants and 20 of the 54 BC₂ plants. No meiotic aberrations were observed in BC₃ or BC₄ plants. Plants with indehiscent anthers, and considered to be male sterile (M.S.), first occurred in the BC₁ and, by the BC₂, 51 of 54 plants were M.S. All 19 BC₃ and 16 BC₄ plants were M.S. Preliminary investigations suggest that the pollen from such plants is sterile and that the sterility is cytoplasmic rather than genetic.Disc-flower measurements were a useful technique for selecting samples at the correct stage of microsporogenesis, but could not be used to distinguish between successive backcrosses.     

Chasmogamous mutant,a novel character enabling commercial hybrid seed production in mungbean

Mungbean (Vigna radiata (L.) Wilczek) is a self-pollinating crop that displays significant hybrid vigor in seed yield of F₁ hybrids. Thus there is the possibility to use hybrid varieties as a breakthrough to raise the yield plateau of mungbean. However, hybrid mungbean seeds can only be accomplished by hand-pollination and thus commercial production is not possible. To encourage hybrid seed set, the plant breeder needs to develop characters that promote higher outcrossing rate such as open flower (chasmogamy). In this experiment, new chasmogamous mutants were induced by gamma irradiation at the rate of 100 and 200 Gy. The mutants were identified at a low rate of 0.4–0.7% in the M₂ generation of accession V1197, and observed for their purity by growing in plant-to-row in the M₃ and M₄ generations. A uniform chasmogamous line was hybridized to normal flower lines to study the inheritance of this character. All F₁ plants had normal flowers, while the F₂ plants segregated well with 3 normal : 1 chasmogamous ratio. When the F₁ was backcrossed to the chasmogamous parent, the progeny gave a ratio of 1 normal to 1 chasmogamous. Thus, chasmogamy was controlled by a single recessive gene, cha.     

Generation and characterisation of colchicine-induced polyploid Lavandula × intermedia

Double podding in cultivated chickpeas (Cicer arietinum L.) can increase yield and yield stability. In the present study, we performed reciprocal crosses of ‘kabuli’ (double podded) and ‘desi’ (single podded) chickpeas to determine (i) the expressivity and penetrance of double podding, (ii) the correlations of yield and yield components, and (iii) the heritability of double podding, flower color, and stem pigmentation in F₂ plants. Reciprocal crosses were performed with two genotypes, AC 2969 (kabuli) and ICC 4969 (desi), to generate F₁ and F₂ plants. The results indicated hybrid vigor (heterosis) for yield in F₁ plants and better performance of F₂ plants. Yield and yield components of some lines in F₂ were superior to the best parent, indicative of transgressive segregation. In particular, the presence of double podding (‘s’ allele) significantly increased yield in some of the transgressive segregants. Expressivity and penetrance of the ‘s’ allele depends on the background of the female parent. Some of the double podding progeny had greater seed yields than those of the single podding progeny and greater seed yields than the best parents. Double podding, stem pigmentation, and pink flowers each appears to be governed by a single recessive gene. Stem pigmentation and pink flowers appear to be linked traits that depend on the genetic background of the crossed chickpeas. Taken together, our studies of reciprocal crosses of kabuli and desi chickpeas clearly showed that yield could be improved by selection for transgressive phenotypes that have double podding.     

Inheritance of two components of early maturity in groundnut (Arachis hypogaea L.)

Summary Knowledge of inheritance of early maturity or its components is important to groundnut breeders in developing short-duration cultivars. This study was conducted to determine the inheritance of two components of early maturity: days to first flower from sowing, and days to accumulation of 25 flowers from the appearance of first flower, using three groundnut genotypes. Two early-maturing (Chico and Gangapuri) and one late-maturing (M 13) genotypes were crossed in all possible combinations, including reciprocals. The parents, F₁, F₂, F₃, and backcross populations were evaluated for days to first flower from sowing, and for days to accumulation of 25 flowers. The data suggest that days to first flower in the crosses studied is governed by a single gene with additive gene action. Chico and Gangapuri possess the same allele for this component of earliness. Three independent genes with complete dominance at each locus appear to control the days to accumulation of 25 flowers. In crosses between late (M 13) and early (Chico or Gangapuri) parents, a segregation pattern suggesting dominant-recessive epistasis (13 late:3 early) was observed for this component. Segregation in the F₂ generation (1 late:15 early) of both early parents (Chico x Gangapuri) indicated that the genes for early accumulation of flowers in these two parents are at different loci.Submitted as ICRISAT J.A. No. 1557.     

The inheritance of days to flowering in broccoli (Brassica oleracea var. italica)

Summary Crosses between an early flowering inbred broccoli (Brassica oleracea L. var. italica) HS140 and four later maturing inbred lines, S301, S310, s318, and S258, were studied to determine the inheritance of earliness as expressed by days to first open flower. Mean days to first flower for F₁ and F₂ were almost identical, and were close to the mean of the two parents in three crosses, indicating additive inheritance. In the cross HS140×S258, for which no F₁ plants were available, the F₂ mean was closer to the mean of the early parent, but this was likely due to a distortion of the data caused by the very late maturation of S258, the latest maturing parent in the study. Frequency distribution for parents and progenies supported the conclusions from parent and progeny mean values and indicated that days to maturity is a quantitative character, with mostly additive inheritance.Oregon Agricultural Experiment Station Technical Paper No. 7578.     

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 hybridization between Coffea arabica L. and tetraploid C. canephora P. Ex Fr. II. Meiosis in F1 hybrids and back crosses to C. Arabica

Summary Melosis was studied in Coffea arabica, in induced tetraploid C. canephora, in their F₁ hybrid (arabusta hybrid) and in backcross generations of the hybrid with C. arabica as recurrent parent. Irregularities were observed, consisting of univalents (especially in the arabusta hybrid), multivalents (especially in tetraploid C. canephora) and uneven distribution of chromosomes at first anaphase. Chromosome distribution was improved by backcrossing. Meiotic irregularities wer negatively correlated with pollen fertility.     

Interspecific hybridization between Brassica carinata and Brassica rapa

The crossability between Brassica carinata (BBCC, 2n=34) and Brassica rapa (AA, 2n=20), and the cytomorphology of their F₁ hybrids were studied. Hybrids between these two species were only obtained when B. carinata was used as the female parent. The hybrid plants exhibited intermediate leaf and flower morphology, and were found to be free from white rust and Alternaria blight diseases. One of the four F₁ plants was completely male sterile, while the remaining plants had 4.8, 8.6, and 10.9% stainable pollen, respectively. No seed was produced on hybrid plants under self pollination or in backcrosses; but seed was obtained from open pollination. The occurrence of the maximum of 11 bivalents as well as up to 44.8%) of cells with multivalent associations in the form of trivalents (0‐2) and a quadrivalent (0‐1) in the trigenomic triploid hybrid (ABC, 2n = 27) revealed intergenomic homoeology among the A, B and C genomes. Meiotic analysis of F₁ hybrids indicated that traits of economic importance, such as disease resistance, could be transferred from B. carinata to B. rapa through interspecific crosses.