Interspecific hybridization between Vicia faba (L.) and Vicia narbonensis (L.): Early pod growth and embryo-sac development

Summary Fertilized embryo-sac development and pod growth was studied in one Vicia faba cultivar, one Vicia narbonensis population and their reciprocal crosses. The initial development of endosperm and embryo was at least four days faster in V. narbonensis than in V. faba. Pods and ovules developed also faster in V. narbonensis than in V. faba. The growth rate of the hybrid pods followed the growth rate of the mother species, but was slower than that of the pods from selfed flowers. In the cross V. narbonensis × V. faba the ovules stopped growing 9 days after pollination, while in the reciprocal cross they stopped growing 15 days after pollination. Hybrid embryo-sacs from V. faba × V. narbonensis were aborted before they reached the stage of 256 endosperm nuclei or 200 embryo cells. Selfed V. faba embryo-sacs reached this stage in less than 9 days after pollination. In the reciprocal cross the embryo-sacs were aborted before they reached the stage of 128 endosperm nuclei or 80 embryo cells. Selfed V. narbonensis embryo-sacs reached this stage at the 4th day after pollination. Given that at these stages the embryo has less than 200 cells it was concluded that an in-ovule embryo culture technique should be developed to obtain hybrid plants.     

Intraspecific Variation in Mean Endosperm Cell Cycle Time in Vicia faba (L.) and Interspecific Hybridization with Vicia narbonensis (L.)

The rate of early embryo-sac development was studied in seven faba bean (Vicia faba L.) cultivars grown in a controlled environment. The embryo-sac stage was determined from the number of endosperm nuclei per embryo-sac and the number of embryo cells during the first 12 days after pollination. Differences in early embryo-sac development were observed between the genotypes studied. In addition, five different V. faba×V. narbonensis crosses and reciprocals were made using genotypes with small differences in mean endosperm cell cycle time and genotypes with large differences. The percentage of success (pod set) in V. faba×V. narbonensis crosses ranged between 9 % and 59 % while in the reciprocals it ranged from 12 % up to 30 %. However, cytological studies showed that the high percentage of success (pod set) observed in the cross A-107 × A-202 was not associated with a higher percentage of interspecific hybrid embryos. The results indicate that genotypes of the two species with smaller differences in mean endosperm cell cycle time result neither in a higher percentage pod set nor in bigger hybrid embryos.     

An embryological study of a Pisum sativum x Vicia faba cross

Summary Flowers of Pisum sativum plants grown in the field and greenhouse were self-pollinated and pollinated with Vicia faba. Germination of pollen and pollen tube growth were slower in the Pisum x Vicia cross. About 2% fertile ovules in the field and 8% in the greenhouse were obtained from the Pisum x Vicia cross, compared to 26% and 48% for Pisum x Pisum. Development of the Pisum x Vicia embryo was normal in form, though much slower than the Pisum x Pisum embryo, and about the sixth day it began to collapse. The greatest difference between the two types of crosses was observed in the endosperm. While the Pisum x Pisum endosperm nuclei divided normally and endosperm developed throughout the ovule cavity and around the embryo, the Pisum x Vicia endosperm nuclei formed only scattered masses of densely stained nuclei which were not always in close proximity to the hybrid embryo. It was concluded that faillure of some ovules to develop following Pisum sativum x Vicia faba cross pollination was the result of slow germination of pollen and slow growth of the Vicia pollen tubes, with subsequent lack of fertilization. Collapse of fertilized ovules was associated with abnormal and limited development of the hybrid endosperm, possibly leading to lack of nourishment and eventual collapse of the hybrid embryo.     

The crossing of common wheat (Triticum aestivum L.) with cultivated rye (Secale cereale L.). II. Fertilization and early post-fertilization developments

Summary Fertilization and early seed development was studied in the variety Chinese Spring of common wheat (Triticum aestivum L.) after pollination with rye (Secale cereale L.) and selfing, and in the common wheat variety Hope after selfing. In all three combinations the first pollen tube reached the micropyle in about 40 min after pollination. When pollinated with rye the migration of the sperm nuclei to the egg cell and the polar nuclei was delayed by about an hour. In the subsequent development until 72 hours after pollination the average cellular and nuclear doubling times of embryo and endosperm were about 16 and 8 hours for the interspecific combination. 18 and 9 hours for Chinese Spring selfed and 20 and 12 hours for Hope selfed.     

Sources of resistance to broomrape (Orobanche crenata Forsk.) in narbon vetch

Little is known about the levels of resistance to Orobanche crenata available in narbon vetch. A germplasm collection of 200 accessions of narbon vetch (Vicia narbonensis L.) originating from different countries was screened for resistance to crenate broomrape under field conditions. Thirteen accessions were selected for more detailed screening under controlled conditions and for additional field testing. Resistance to O. crenata was manifested by lower germination of broomrape seeds, reduced emergence of Orobanche shoots and fewer root attachments per narbon vetch plant. Differences in pod yield among narbon vetch accessions were also found in response to Orobanche infestation. Finally, eight accessions were selected and identified as new sources of narbon vetch resistant to broomrape.     

Electrophoresis of the Seed Proteins of Vicia faba L. and Its Immediate Progenitors — A Reappraisal

Electrophoretic patterns of total seed protein analyzed by polyacrylamide gel electrophoresis under non-dissociating and dissociating conditions were found to have diagnostic value for the Vicia species. The close similarity in the seed protein profiles of the cultivated species and Vicia narbonensis narbonensis indicated that this last species can be considered as the immediate progenitor of V. faba. The study also indicated that V. serratifolia should be included as a subspecies in V. narbonensis. The broad bean, Vicia faba, is one of the most important leguminous pulses cultivated over a wide range (from Central Asia to Western Europe and from Ethiopia and Sudan to Scandinavia). Schultz -Motel (1972) was the first to identify remains of V. faba seeds from archeological sites of the Bronze Age, mainly from Central and Southern Europe. Recently, Kislev (1985) found charred seeds of horsebean (V. faba L.) from the 7th millennium B.C. Thus, horsebean should be included among the legumes grown by some early Neolithic people. Zohary and Hopf (1973) have suggested that the wild ancestors of V. faba are species belonging to section Faba. In particular, the French vetch V. narbonensis L., was the promosing candidate; most probably, because the area of distribution of V. narbonensis coincides with that of V. faba. On the other hand, Ieibe (1934), Ladizinsky (1975), and Abdall and Gunzel (1979) refuted the reports that V. narbonensis (and wild species from the section Faba) may be considered as immediate ancestors of the cultivated species of V. faba. These authors reported on the albumin profile of seed protein in Vicia. This study aims to reassess the relationships between V. faba and its taxonomically related species in terms of their storage protein profiles and present some information on the evolution of V. faba.     

Histological Observations on Interspecific Crosses in the Genus Lupinus

The hybridization barriers of interspecific lupin crosses were determined by histological investigations. The cross Lupinus hartwegii×L. mutabilis (both of American origin) revealed embryos in the cotyledonary stage as well as cellular endosperm. In the reciprocal combination, L. mutabilis×L. harwegii, embryo development stopped at the end of the globular stage, and simultaneously the coenocytic endosperm did no differentiate into the cellular state. In the combination L. luteus (European origin) ×L. hartwegii, embryo as well as endosperm development were initiated. Embryo development ended at any early globular stage. Twelve days after pollination the coenocytic endosperm had almost degenerated. With L. hartwegii as the female, no pollen germination could be observed.     

Sugar characteristics of sweet corn populations from a sugary enhancer breeding program

Summary Endosperm sugars and sorbitol were determined on 18 sweet corn (Zea mays L.) populations from a breeding program undertaken to transfer the sugary enhacer (se) gene into diverse sugary (su) backgrounds. Three subpopulations of IL677a, the source of se, and six su Se inbreds were included for comparison. Mature dry kernels of between two and four successive generations of these populations were analyzed. Immature kernels at two developmental stages (21 and 35 days after pollination) were also analyzed for one generation.Eleven of the breeding populations closely resemble IL677a, with high sucrose at the edible stage (21 days after pollination) and maltose accumulating as the seeds matured. In most instances, the distinctive sugar profiles were observed consistently in dry seeds of various generations. Hence, it appears that the se trait can be transferred successfully into su cultivars having various genetic backgrounds. The remaining seven breeding populations possessed elevated sucrose and glucose compared to most of the standard su Se inbreds, but maltose did not accumulate during seed maturation. It is not clear whether se was transferred to these populations and its expression modified or whether another trait was responsible. There were also marked differences in glucose levels among the su Se populations examined.Supported by the National Science Foundation (Grant No. 7922 686) and the Illinois Agriculture Experiment Station (Project No. 65-0330).     

Gamma-irradiation of cacao (Theobroma cacao L.) pollen: Effect on pollen grain viability,germination and mitosis and on fruit set

Summary Theobroma cacao pollen fertilization capability was studied after 0, 50, 100, 200, 500 and 1000 Gy gamma-irradiation. For all irradiation doses, no alteration of pollen grain viability and in vitro germination was observed. In situ, for all doses, pollen tubes penetrated into the styles and reached the ovules 20 hours after pollination. In vitro observations of the pollen grain nuclei after 20 hours incubation showed that pollen irradiation causes inhibition of the division of the generative nucleus. Fruit survival rate 30 days after pollination decreased as irradiation doses increased from 0 to 100 Gy, and over 100 Gy no fruit set was obtained. The possibility of using irradiated pollen as a method for obtaining haploid cacao plantlets is discussed.     

The reproductive biology of three perennial Sesbania species (Leguminosae)

Summary The reproductive biology of Sesbania sesban, S. goetzei and S. keniensis (Leguminosae; Papilionoideae) was studied. Fifty percent flowering was observed at 102 to 153 days after germination for S. sesban accessions; 96 to 146 days for S. goetzei and 131 to 176 days for S. keniensis accessions. Flowers opened in the afternoon and remained fresh for 2–3 days. Bee species including Xylocopa sp., Apis mellifera, Megachile bituberculata and Chalicodoma sp. visited the flowers. Hand pollination experiments showed that all three species were self and cross compatible. The percentage of fully developed seeds was greater in pods formed after cross pollination compared to self pollination. No evidence was found for stigmatic or stylar self incompatibility. Outcrossing is probably the common method of reproduction under natural conditions, although in isolated trees substantial seed set by selfing might occur. Pod production under natural conditions was 34% for S. sesban; 49% for S. goetzei and 39% for S. keniensis. Considerable variation was found in pod production under open pollination between accessions of the same species. Selective abortion was observed within pods, with more mature seeds formed at the distal end of the pod.     

Genotypic variation and polymorphism of 2S albumins of sunflower

Summary An early postfertilization ovule culture technique in Alstroemeria was described in which young ovules were cultured in vitro two days after pollination. This resulted in the direct production of seedlings in a normally incongruous cross combination. A histological study of the in vitro cultured ovules revealed the development of the embryo inside the ovule in the absence of normal endosperm. The in vivo grown ovules showed a total breakdown of the developing seed within four weeks after pollination due to a postfertilization barrier. This ovule culture technique was applied in a diallel cross of seven Alstroemeria species, five from Chile and two from Brazil. The selfings and the reciprocal crosses between the Brazilian species A. inodora and A. brasiliensis were congruous and gave seed set. The cross A. inodora x A. pelegrina gave viable seeds. In all other 39 combinations no viable seeds were harvested. In those cross combinations both pre-and postfertilization barriers were found. After early ovule culture hybrid plants were obtained in 27 of the 39 incongruous species combinations of the diallel.Abbreviations DAP days after pollination - MS medium medium according to Murashige & Skoog (1962)     

Effects of Duration of Waterlogging at Different Growth Stages on Grain Growth of Summer Maize (Zea mays L.) Under Field Conditions

A field experiment was performed to study the effects of waterlogging for different durations (3 and 6 days) on grain filling and endosperm cell proliferation of summer maize hybrids DengHai605 (DH605) and ZhengDan958 (ZD958) at the third leaf stage (V3), the sixth leaf stage (V6) and the 10th day after the tasselling stage (10VT). Results showed that waterlogging damages on grain filling and endosperm cell proliferation varied with growth stage and duration of waterlogging. The most significant effect of waterlogging was observed at V3, followed by V6 and 10VT. Endosperm cell content, average endosperm cell proliferation rate, grain weight and grain‐filling rate were reduced significantly with increasing waterlogging durations, with the most significant (P < 0.05) reduction in V3‐6 with a decrease of 37.1 %, 51.9 %, 13.6 % and 12.1 % for DH605, and 27.3 %, 51.1 %, 17.4 % and 14.3 % for ZD958, respectively. Waterlogging damages on grain filling and endosperm cell proliferation resulted in a significant reduction in grain yield. Waterlogging at V3 had the most yield reduction, followed by V6 and 10VT. Yield reduction after waterlogging for 6 days at different stage was about twice as much as that after waterlogging for 3 days. Clearly, the most significant inhibition of grain growth for waterlogging was observed at V3, followed by V6 and 10VT. The inhibition was enhanced significantly with increasing waterlogging durations. Endosperm cell number and grain weight was decreased by 8.3–24.1 % and 1.2–10.8 % after waterlogging for 3 days, while decreased by 12.9–32.2 % and 4.6–14.7 % after waterlogging for 6 days, compared to CK.     

Abnormalities of endosperm development inLilium hybrids

Summary Of 191 interspecific crosses attempted between 27 different species representing different subgenera ofLilium only 14 gave rise to seeds and only 6 of these were viable. Sterility was associated with various types of abnormality in endosperm development. Many of these irregularities involved chromosome breakage and reunion but others entailed abnormal DNA replication and chromosome coiling. In one cross the individual endosperm nuclei contained four stranded structures, the behaviour of which at division was similar to that of bivalents at meiosis. The embryo-sac ofLilium is of theFritillaria type, containing both haploid and triploid polar nuclei. As a consequence the balance between the number of chromosome sets in the embryo, endosperm and maternal tissue is 2:5:2 and not 2:3:2 as is more commonly found in diploid species. It is suggested that sterility results from genetic imbalance of the endosperm itself rather than interaction of the endosperm with either embryo or maternal tissue.     

Embryo development in two barley genotypes after self pollination and pollination with Hordeum bulbosum L.

Summary Embryo development in vivo was compared in the two barley genotypes VK 16032 and Vogelsanger Gold after self pollination and after pollination with H. bulbosum. Embryo growth in VK 16032 after crossing with H. bulbosum showed a similar growth pattern to that of the self pollinated embryos, although the size increase was smaller. The hybrid embryos continued to grow until day 18 after pollination. The embryos from the cross between Vogelsanger Gold and H. bulbosum ceased to grow 8 days after pollination. Arrested embryo growth with subsequent abortion in Vogelsanger Gold was associated with a very early depletion and break down of the endosperm. Use of barley genotypes less sensitive to the genomic disturbances after crossing with H. bulbosum in combination with genotypes like Vogelsanger Gold is recommended in haploid breeding work.     

Problems in breeding and cytology of sugar cane

In connection with the increase of chromosome number found in species hybrids of Saccharum the author studied embryo-sac development within several Saccharum froms from early stages of meiosis in the embryo-sac mother cells to stages where fertilization already had taken place.Normally by meiosis within E M C's a row of four haploid megaspores is formed from which the innermost, the chalazal megaspore, develops into an embryo-sac and the other three degenerate.Haploid embryo-sacs, thus formed, may occur in Saccharum. Frequently however, in Saccharum endo-duplication takes place, that is splitting of the chromosomes within the nucleus of the chalazal megaspore, through which the chromosome number is increased.It is described how within Saccharum by this phenomenon embryo-sacs may be formed with diploid and tetraploid chromosome numbers and with numbers between haploid and diploid.The increase of chromosome number, observed in the young megaspore after meiosis, could be confirmed by counting the chromosomes of dividing nuclei within young embryo-sacs.Chromosome numbers found in dividing zygotes and endosperm nuclei within fertilised embryo-sacs also pointed to the occurrence of egg-cells and polar nuclei that must be haploid, diploid and tetraploid.The significance of this research in relation to plant breeding will be discussed in Part V.     

Inheritance pattern for pod lenghth and ovule number in wide crosses among Cajanus and Atylosia species

Summary Six interspecific/intergeneric F₂ populations involving two cultivars of C. cajan and five Atylosia species were scored for segregation patterns for pod length and ovule number. It was observed that for both characters the F₂ means and the ranges were correspondingly lower than the midparent values and the spread of the two parents. However, the intrageneric cross of A. lineata and A. scarabaeoides showed transgressive segregation for pod length and the F₂ mean and range were correspondingly larger than the midparent value and spread of the two parents, suggesting the usefulness of combining ability test for choice of suitable parents.     

Development of self-incompatible Brassica napus: (I) introgression of S-alleles from Brassica oleracea through interspecific hybridization

Cultivars in Brassica napus var. oleifera, a self‐pollinating, self‐compatible species, have traditionally been developed as open‐pollinated lines or populations. Significant yield gains in this species have been realized through the exploitation of heterosis. Commercial hybrid production has been possible as a result of the development of a number of pollination control systems. Self‐incompatibility was transferred from B. oleracea var. italica to B. napus var. oleifera through interspecific hybridization. The response to interspecific pollination, as measured by pod elongation and initial stages of ovule development, was genotype dependent, and two highly responsive B. napus genotypes were identified. Embryo rescue was used to produce the interspecific hybrids. Isoelectric focusing of stigma proteins was used to identify S‐alleles in the interspecific hybrids to facilitate backcrossing. Segregation of the S‐locus through a series of back‐crosses to B. napus was complicated by aneuploidy; however, the S‐locus was found to segregate as a single gene. Usefulness of B. oleracea as a source of S‐alleles for pollination control in B. napus is discussed.     

Genetic analyses of agronomic and seed quality traits of doubled haploid population in Brassica napus through microspore culture

Summary The results showed that the F1 genotype from the cross (Brassica napus cv. Zheshuang 758 × cv. Z-4115) had good response to embryogenesis, and their embryo yield and rate of plant regeneration reached 69.8 embryo/bud and 46.9%, respectively. Characters from the doubled haploid (DH) populations in B. napus were analyzed and it was showed that the means of each agronomic trait were between their parents, but they were nearer to the paternal in 6 agronomic traits (plant height, branch position, number of pods in the main raceme, length of pod, number of pods/plant and number of seeds/pod). The number of genes controlling each agronomic trait was analyzed based on the DH populations. The results showed that the number of genes controlling number of pods in the main raceme was the highest (15.6), and the least number of genes was involved for stem width (only 7.9). According to estimated coefficients of skewness and kurtosis of the traits tested, gene interaction was found to be absent for stem width, plant height, length of main raceme, number of primary and secondary branches, pod density in the main raceme and seed weight/plant. Complementary interaction was also observed in five agronomic traits (number of pods in the main raceme, length of pod, number of pods/plant, number of seeds/pod and 1000-seed weight). A significantly positive correlation was observed between seed yield/plant and four agronomic traits (length of main raceme, length of pod, number of pods/plant and 1000-seed weight). The experiment also showed that the erucic acid, glucosinolate, oil and protein contents of DH populations were 34.23%, 87.09 μmol/g, 44.09% and 42.67%, respectively. The numbers of genes controlling each quality trait were 7.8, 9.7, 9.4 and 8.7, respectively. Partial correlations between the seed quality traits and the agronomic characters of DH populations were analyzed. In this experiment, the partial correlations among seed quality traits were also analyzed and it was found that the oil content had a negative correlation with the other three seed quality traits.     

Variation in sweet corn kernel characteristics associated with stand establishment and eating quality

Summary A better understanding of the relationships between kernel characteristics associated with eating quality and stand establishment could be helpful in selection of superior genotypes by the sweet corn industry. A set of sweet corn (Zea mays L.) inbred lines with different endosperm mutations (su1, su1 se1 and sh2) were evaluated for field emergence and seedling growth rate at two locations over two years. Kernel characteristics associated with eating quality (kernel moisture concentration, kernel tenderness, sugars, phytoglycogen and dimethyl sulfide (DMS) concentrations were determined for the same inbreds by laboratory analysis from ears harvested at 18 and 22 days after pollination (DAP). Amounts of sugars, phytoglycogen and starch were also measured in mature dry kernel samples of the same inbreds. Extensive genetic variability was found among endosperm mutations and among genetic backgrounds within the different endosperm groups for most of the characteristics under study. Most of the kernel attributes associated with eating quality were uncorrelated indicating that selection to improve specific eating quality characteristics can be conducted simultaneously. A negative correlation between field emergence and sugar concentrations in immature kernels suggests that in breeding programs designed to develop germplasm with improved germination and stand establishment, concurrent attention must be given to the fresh quality of the harvested product. This information is of value to breeders and commercial growers for selection of sh2 and su1 se1 lines with superior field emergence and eating quality.Abbreviations (DAP) days after pollination - (DMS) dimethyl sulfide     

Controls over pollination and ovule fertilization in Vicia faba

Summary Variation in the frequencies of pollination and ovule fertilization was generated among faba bean (Vicia faba L.) genotypes in experiments which compared self-and open-pollination, natural and extended photoperiods, presence and absence of honey bees and a range of plant populations.There was a near-1:1 relationship between the frequencies of pollination of stigmas and the fertilization of at least one ovule within the pistil. Pollination was the major barrier to fertilization of the pistil, and ovules, since no mechanism was evident in the style to prevent pistil fertilization. The frequency with which single ovules were fertilized in pollinated pistils fell as their distance from the stigma increased, and averaged 83.5% overall.The frequency of pollination was most influenced by the level of autofertility possessed by the genotype, and the activity of pollinators. Provision of honey bees to plants in caged plots showed that high levels of pollination could be achieved under open-pollinated conditions, but this was also influenced by autofertility. Increasing plant population in the field had only a small effect on pollination, but extending photoperiod caused the levels and timing of self-pollination in three genotypes to vary.Large differences were found among genotypes in their early stigma receptivity, that is, the frequency of stigmas found to be pollinated at the erect standard stage, prior to the flower opening and being visited by bees. The implications of early stigma receptivity for producing new cultivars were discussed.