Showing papers in "Euphytica in 1980"
TL;DR: Over the past eight years, significant progress has been made at the International Institute of Tropical Agriculture (IITA) and resistance to CMD has been successfully incorporated into high yielding cultivars of acceptable quality.
Abstract: Cassava mosaic disease (CMD) is one of the most serious and widespread diseases throughout cassava growing areas in Africa, causing yield reductions of up to 90%. Early research on breeding of cassava (Manihot esculentaCrantz) for resistance to CMD in Africa is reviewed. Changes in population size and in activity of the white-fly vector to CMD (Bemisia tabaciGenn.) in relation to changes in environmental conditions such as amount and distribution of rainfall, light intensity and temperature are discussed in relation to screening for resistance to CMD. Over the past eight years, significant progress has been made at the International Institute of Tropical Agriculture (IITA). Resistance to CMD has been successfully incorporated into high yielding cultivars of acceptable quality. The CMD resistant material has been evaluated and many promising clones have been selected in various countries in tropical Africa and India. The resistance has been effective in those countries.
227 citations
TL;DR: It is expected that the latter types, the Miros group, will soon completely supersede the spontaneous or radiation-induced Horim sports and mutants and take over the leading position of the Horim group in the production of all-year-round (AYR) cut flowers.
Abstract: Radiation-induced sports in Chrysanthemum morifolium Ram. have been reported for several years. It has become an everyday practice to produce flower-colour mutants from outstanding cross-breeding products, even before they are distributed for the commercial production of cut flowers.
205 citations
TL;DR: The growing of crops isolated from the TMV reservoirs in the soil considerably reduces the likelihood of even this occurring, and the possible development of aggressive isolates capable of affecting Tm- 22/Tm-22 plants is discussed.
Abstract: There are three known tomato mosaic virus (TMV) resistance factors, Tm-1, Tm-2 and Tm-2
2, in the tomato. Tm-2
2 is currently the most widely utilised in glasshouse cultivars. Both Tm-2 and Tm-22 can induce systemic necroses in response to virus infection. These are considered to be hypersensitive resistance reactions in view of the low virus concentrations in affected plants and because sub-inoculation usually fails to infect all plants possessing the same resistance gene. The literature relating to TMV resistance at the Tm-2 locus in the tomato is reviewed. Virulent strains may readily establish when Tm-1 or Tm-2 are used, but Tm-2
2 confers more effective resistance. The possible development of aggressive isolates capable of affecting Tm-2
2/Tm-22 plants is discussed. The establishment of virus types which cause systemic necrosis at normal growing temperatures is considered more likely than widespread infection from fully virulent strain 22 mutants. However, the growing of crops isolated from the TMV reservoirs in the soil considerably reduces the likelihood of even this occurring.
123 citations
TL;DR: It is concluded that tolerance to water stress in growing seedlings can be screened for by using PEG-containing nutrient solutions, and can not be predicted from germination tests in osmotica.
Abstract: A series of experiments was performed in order to evaluate the significance of seed germination and seedling growth in osmotic media as screening methods for drought tolerance. Ten spring wheat (Triticum aestivum L. em Thell.) and one durum wheat (Triticum durum
Desf.) were tested under controlled environments, using polyethylene glycol-6000 (PEG) solutions as the moisture stress inducing media. Tolerance in the rate of endosperm utilization, under stress, prior to the onset of germination varied among cultivars. Germination rate or injury to germination at various concentrations of PEG differed significantly among cultivars. Cultivar rating with respect to injury to germination changed with stress levels. Injury to germination did not correlate with endosperm utilization rate in PEG or in water. Germinating seedlings were tolerant to extreme desiccation up to the stage of emergence of the first leaf from the coleoptile. Growth of photosynthesizing seedlings was monitored as they were carried through an increasing concentration gradient of PEG solutions, ranging from −5.9 to −11.3 bars of water potential. Cultivars significantly differed in seedling growth tolerance to increasing levels of water stress. Seedling growth tolerance across cultivars was not correlated with their germination responses under srress. It is concluded that tolerance to water stress in growing seedlings can be screened for by using PEG-containing nutrient solutions. It can not be predicted from germination tests in osmotica. Work was done under a US-Israel Binational Science Foundation (BSF) Grant no. 1654/78.
99 citations
TL;DR: The genes for resistance to pepper strains of TMV in five C. chinenseJacq.
Abstract: The genes for resistance to pepper strains of TMV in five C. chinense
Jacq. accessions, the PI numbers 152225, 159236, 315008, 315023 and 315024, were investigated for allelism. The resistance of these five C. chinense accessions was found to be inherited monogenically and to be partially dominant. The resistance genes in these accessions appeared to be allelic and were also found to be allelic with the known alleles L1 and L. It is proposed to use the symbol L3 for these resistance genes.
97 citations
TL;DR: Cluster analysis techniques were used to examine phenotypic variation within the USDA Soybean Germplasm Collection and G. gracilis was found to be conspecific with G. max.
Abstract: Cluster analysis techniques were used to examine phenotypic variation within the USDA Soybean Germplasm Collection. This study included ten Plant Introductions each of the domesticated soybean, Glycine max (L). Merr., the ‘wild’ soybean, G. soja
Sieb. & Zucc., and a disputed species, G. gracilis
Skvortz.
G. max and G. soja were found to be morphologically distinct entities and G. gracilis was found to be conspecific with G. max. Because G. gracilis probably represents weedy races associated with the cultivated soybean and because ‘gracilis’ phenotypes can be distinguished from G. max, the designation, G. max forma gracilis, is recommended.
87 citations
TL;DR: A stochastic model has been developed which describes the process of apex formation and by which the expected relative chimera percentages E(RCP's) are calculated and leads to the postulate that the apex of the adventitious shoot is formed from only one (epidermal) cell of the meristem or the callus.
Abstract: One of the bottle-necks in mutation breeding of vegetatively propagated crops is the chimera formation after irradiation of multicellular apices in buds of vegetative material. This difficulty can be overcome with in vivo or in vitro adventitious bud techniques which, in combination with radiation, give almost exclusively solid, non-chimeric mutants and unmutated plants. This is usually explained on the basis of the ultimate development of the apex of adventitious shoots from single (epidermal) cells.
70 citations
TL;DR: Clone 58308, derived from the third backcross of the interspecific cross of cassava, showed a high level of resistance to both diseases, and the correlated response to selection for CMD and for CBB was estimated.
Abstract: The two most serious diseases of cassava (Manihot esculenta
Crantz) are cassava mosaic disease (CMD) and cassava bacterial blight (CBB) (Xanthomonas manihotis
Starr). Clone 58308, derived from the third backcross of the interspecific cross of cassava (M. esculenta) x ceara rubber (M. glaziovii), showed a high level of resistance to both diseases. Crosses of 58308 with several other clones which varied from susceptible to moderately susceptible to both diseases gave progenies with a significant genotypic correlation between resistance to both diseases (r=0.90), apparently due to linkage. The heritabilities of resistance to the diseases were estimated at 50–70% for CMD and 25–65% for CBB. Resistance to both diseases is assumed to be polygenic. The correlated response to selection for CMD and for CBB was estimated.
66 citations
TL;DR: It seems that H. spontaneum can be a useful source of favorable genes for quantitative traits, especially for grain yield, which could be incorporated into barley varieties readily by backcrossing.
Abstract: Six populations of F2-derived lines of barley and their parents were evaluated for heading date, plant height, grain yield, bundle weight, and harvest index in a replicated experiment in the field. These data were used to estimate the minimum number of effective factor pairs segregating for each trait, the number of favorable factors contributed by each parent in a cross, and the frequencies and magnitudes of transgressive segregates. Heading date, plant height, and harvest index were controlled by three to four effective factor pairs, whereas grain yield and bundle weight were controlled by five or more. All three H. spontaneum strains used in our study contributed one or more useful genes for each of the traits, grain yield, heading date, plant height, bundle weight, and harvest index. Therefore, it seems that H. spontaneum can be a useful source of favorable genes for quantitative traits, especially for grain yield, which could be incorporated into barley varieties readily by backcrossing. Transgressive segregates for grain yield in the interspecific crosses may provide the basic materials for improving the productivity of cultivated barley varieties.
61 citations
TL;DR: Selection for partial resistance appears very well possible at all stages of the selection program, particularly in the seedling, the single adult plant, and the small plot stage.
Abstract: The partial resistance to leaf rust (Puccinia hordei) of 40 West-European spring barley cultivars was measured in plots isolated from one another to reduce inter plot interference. The leaf area affected by leaf rust was also measured in small plots of 0.5 m2 adjacent to each other, and on individual plants. The latent period was measured in the seedling stage and the adult plant stage, the infection frequency in the seedling stage only. The cultivars varied widely for partial resistance, many cultivars carrying a considerable level. Both the small adjacent plots and the single plants showed a marked inter plot interference strongly reducing the difference between cultivars. H wever, the ranking order of the cultivars was hardly, if at all, affected. Both latent period and the infection frequency showed large differences between cultivars, the latent period in the adult plant stage being highly correlated (r=0.82) with partial resistance, infection frequency in the seedling stage only rather weakly (r=−0.33). Selection for partial resistance appeared very effective in all stages tested; the seedling, the single adult plant, and the small plot stage. Selection in the small plot stage was the most effective followed by selection in the seedling stage. Selection for partial resistance therefore appears very well possible at all stages of the selection program.
60 citations
TL;DR: The results indicate that the crossability genes have little effect on pollen germination and on the time taken for the pollen tubes to reach the microphyle, irrespective of their crossabilities with rye.
Abstract: Seven genotypes of common wheat (Triticum aestivum L.) were crossed with rye (Secale cereale L.) in order to find the site or sites of action of the crossability genes, Kr1 and Kr2, of wheat. The data obtained, by fluorescence microscopy, were compared to the controls (wheat x wheat). The results indicate that the crossability genes have little effect on pollen germination and on the time taken for the pollen tubes to reach the microphyle, irrespective of their crossabilities with rye. The number of pollen tubes reaching the microphyle is, however, affected by the Kr-genes, as high crossable genotypes have more pollen tubes than the low crossable ones. There was a high correlation between the mean number of pollen tubes at the micropyle with seed set, which also reflects the crossability. The Kr-genes seem to manifest themselves in the retardation and inhibition of pollen tube growth between the style base and the top of the embryo sac, where the effect is most distinct in the low crossable genotypes.
TL;DR: Self- pollinations and cross-pollinations within species gave normal pollen tube growth and seet set and the different accessions within a species, as a rule reacted alike in interspecific crosses.
Abstract: The crossability of 12 Cucumis species of African and Asiatic origin was studied in a diallel cross, in order to find ways to realise the cross between the common cucumber (C. sativus L.) and its wild relatives which carry resistances against diseases and pests. Self-pollinations and cross-pollinations within species gave normal pollen tube growth and seet set. The different accessions within a species, as a rule reacted alike in interspecific crosses. In crosses between African species different crossing patterns were found, viz. bilateral congruity, bilateral incongruity and unilateral incongruity. Within C. sativus all accessions intercrossed freely, except one, which displayed unilateral incongruity. Good seed was harvested from several crosses and in some cases embryo culture was needed for further development of seeds. No good seeds were obtained from any cross between a species of the African group and C. sativus L.
TL;DR: There is circumstantial evidence that the resistance to CBD is of a stable nature, but it is advisable to accumulate in one genotype as many resistance genes as possible by combining in the breeding programme the resistance of Rume Sudan with that of Hibrido de Timor.
Abstract: The inheritance of resistance to coffee berry disease (CBD) has been studied by applying a preselection test to F2 progenies of a half diallel cross between 11 coffee varieties with different degrees of resistance and to sets of parental, F1, F2, B11 and B12 generations of crosses between resistant and susceptible varieties. True resistance to CBD appears to be controlled by major genes on three different loci. The highly resistant variety Rume Sudan carries the dominant R- and the recessive K-genes. The non-allelic interaction between these two genes is of a duplicate nature. The R-locus has multiple alleles with R1R1alleles present in Rume Sudan and the somewhat less effective R2R2alleles in a variety like Pretoria, which also has the K-gene. The moderately resistant variety K7 carries only the recessive K-gene. The arabica-like variety Hibrido de Timor (a natural interspecific arabica x robusta hybrid) carries one gene for CBD resistance on the T-locus with intermediate gene action. It probably inherited this gene from its robusta parent. There is circumstantial evidence that the resistance to CBD is of a stable nature, but it is advisable to accumulate in one genotype as many resistance genes as possible by combining in the breeding programme the resistance of Rume Sudan with that of Hibrido de Timor.
TL;DR: Even very strongly female lines can be induced to male flowering with silver ions, thus increasing the feasibility of large scale seed production of gynoecious × gynOecious cucumber hybrids.
Abstract: Silvernitrate (AgNO3) and silverthiosulphate (Ag(S2O3)23-) effectively induced male flowering in many nodes of 7 gynoecious cucumber genotypes in 3 glasshouse trials. A single spraying of the plants in the first true leaf stage with 3 mM Ag+ as Ag(S2O3)23- or AgNO3 (500 ppm) yielded many more staminate flowers than GA-3 (1500 ppm) and almost as many as 3 consecutive sprayings of GA-4/7 (50 ppm).
TL;DR: Progeny analysis showed that yellow-flowered chrysanthemum sports with carotenoid only in L1 are indistinguishable from their white progenitors in breeding behaviour; those with carOTenoid in L2 breed quite differently.
Abstract: Progeny analysis showed that yellow-flowered chrysanthemum sports with carotenoid only in L1 are indistinguishable from their white progenitors in breeding behaviour; those with carotenoid in L2 breed quite differently. Chimerical structure has, therefore, to be considered when analysing flower colour inheritance data. Segregations were consistent with the action of the single dominant gene I. Such simply inherited characters may be useful in studies to distinguish between the several alternative patterns of inheritance which can be suggested in the species.
TL;DR: Pollinating apple cultivars twice with compatible pollen at an interval of one or two days produced about twice as many seeds per pollinated flower as a single pollination.
Abstract: Pollinating apple cultivars twice with compatible pollen at an interval of one or two days produced about twice as many seeds per pollinated flower as a single pollination. With the aid of scab- or mildew resistant ‘marker pollen’, it could be shown that the second pollen formed on average twice as many seeds as the first. The first pollen appears to ‘pave the way’-partly at its own cost-for the second and was therefore called ‘pioneer pollen’.
TL;DR: The varietal and ploidy richness of two potato fields cultivated by the Quechua Indians was determined, and Tetraploid primitive varieties were the most common, representing 95% of all plants sampled, but diploids and triploids were also found.
Abstract: In field studies carried out at Cuyo-Cuyo, southern Peru, an area of traditional agriculture, the varietal and ploidy richness of two potato fields cultivated by the Quechua Indians was determined. Tetraploid primitive varieties were the most common, representing 95% of all plants sampled, but diploids and triploids were also found. The tuber crops agricultural system on the Incaic terraces was documented, and factors affecting the selection of potato varieties were assessed. Flavour and dry matter content were the most important quality factors indicated by local farmers.
TL;DR: Fundamental differences were found between the Italian population and those of other countries with regard to virulence patterns and the urgent need for resistance genes to be incorporated in the cultivated material is indicated.
Abstract: Barley in Italy has recently been seriously affected by Rhynchosporium secalis. The pathogenic variation of the fungus was studied and 17 races were differentiated on 13 barley cultivars carrying most of the currently known genes for resistance. RC 1, the most virulent and most frequent race, was virulent on 10 out of the 13 differentials and the remaining races proved to be less virulent variants of RC 1. Atlas (C.I. 4118), Atlas 46 (C.I. 7323) and Osiris (C.I. 1622) were the only three differentials resistant to all the analyzed single-spore isolates. Differential cultivars previously assumed to have identical resistance factors did not react in the same way to all the Italian races, thereby revealing either undisclosed differences in the genes described or the presence of additional unidentified ones. Our findings were compared with previous data about virulence of scald populations from different countries, on the basis of tests with common differentials: fundamental differences were found between the Italian population and those of other countries with regard to virulence patterns. The susceptible reactions to race RC 1 of most barley cultivars grown in Italy indicate the urgent need for resistance genes to be incorporated in the cultivated material. Seventy-one barley accessions, known as sources of resistance in different parts of the world, were screened for their behaviour to races RC 1 and RC 13. Twenty-two appeared resistant to both of them.
TL;DR: The method was checked using data from the Western Australian Department of Agriculture regional wheat variety testing programme, and it was found possible to identify combinations of localities which produced significant predictions over both years and genotypes.
Abstract: The choice of localities for initial yield testing of selections in a plant breeding programme is often arbitary. We describe a method that allows a more objective approach based on the correlation between the performance of varieties in a locality and their performance over a large area. The method was checked using data from the Western Australian Department of Agriculture regional wheat variety testing programme, and it was found possible to identify combinations of localities which produced significant predictions over both years and genotypes.
TL;DR: The glycoalkaloids α-solanine, α-chaconine, tomatine, demissine and α- and β-solamarine are shown to be useful taxonomic characters which confirm earlier hypotheses on the origin of S. juzepczukii and S. curtilobum.
Abstract: This study investigated the possibility of recombining anew the genomes of the wild and cultivated progenitors of triploid S. juzepczukii and pentaploid S. curtilobum by following the known evolutionary pathway of these two species. Before starting the actual breeding work, the natural variation of S. juzepczukii, S. curtilobum and their wild progenitor S. acaule was studied from the point of view of morphology, quantitative and qualitative tuber glycoalkaloid content and frost resistance. The morphological study was supplemented by a study of the soluble tuber proteins employing polyacrylamide slab-electrophoresis. From 137 accession of S. juzepczukii only 19 morphotypes were identified, 18 of which were also different in their protein spectra. The only red-tubered S. juzepczukii revealed a protein spectrum identical to that of the largest white-tubered group. On phylogenetic grounds, the occurrence of a red-tubered S. juzepczukii cannot be explained. It is concluded that this red clone is a somatic mutant for tuber colour which arose from a whitetubered clone. S. curtilobum was restricted in its variation to just two morphotypes differing only in tuber colour which are, however, identical chemotypes. This would be the case if one of the clones was a somatic mutant for tuber colour from the other one. The glycoalkaloids α-solanine, α-chaconine, tomatine, demissine and α- and β-solamarine are shown to be useful taxonomic characters which confirm earlier hypotheses on the origin of S. juzepczukii and S. curtilobum. Laboratory tests showed the two cultivated species to be resistant to about −3°C whereas S. acaule is resistant to temperatures sometimes below−5°C. The diploid progenitor of S. juzepczukii, S. stenotomum, also has forms resistant to −3°C. The results of this study demonstrate that the proposed breeding scheme is possible.
TL;DR: The appearance of specific Atylosia bands in some of the electrophoretic variants of Cajanus suggests that gene flow is still effective between pigeon pea and various ATYlosia species, and the poor solubility of the ATylosia seed protein in comparison to Cajan indicates that domestication of Cjanus was coupled with increased solubilities and perhaps a better nutritional value of this pulse as well.
Abstract: The seed protein profile of pigeon pea (Cajanus cajan) appeared to be highly stable. The standard profile of this cultigen was found in 86 of the 90 accessions examined. Each of the Atylosia species, A. lineata, A. platycarpa, A. cajanifolia and A. scarabaeoides has its own profile but each band of the Atylosia species had a homologue in the standard profile of Cajanus or in one of its variants. This was taken as an indication for the polyphyletic origin of Cajanus from several Atylosia species. The appearance of specific Atylosia bands in some of the electrophoretic variants of Cajanus suggests that gene flow is still effective between pigeon pea and various Atylosia species. The poor solubility of the Atylosia seed protein in comparison to Cajanus indicates that domestication of Cajanus was coupled with increased solubility and perhaps a better nutritional value of this pulse as well.
TL;DR: Roots, leaf petioles, shoot tips and immature fruits of female date palm formed the source material for in vitro cultures and calluses were established from seedling sections but the growth conditions propitious for explants of seedlings were not suitable for femaledate palm tissues.
Abstract: Roots, leaf petioles, shoot tips and immature fruits of female date palm formed the source material for in vitro cultures. Isolated embryos excised from mature seeds were also cultured. Of all the tissues, some of the leaf petioles and fruit mesocarp gave rise to calluses in the media of Staritsky (1970) and Eeuwens (1976). Isolated embryos germinated to produce seedlings in MS (Murashige & Skoog, 1962) medium. Calluses were established from seedling sections but the growth conditions propitious for explants of seedlings were not suitable for female date palm tissues. The main problem in establishing long term tissue cultures has been the browning of the tissues and media. This problem was, at least partially, overcome by adding activated charcoal to the liquid media and cysteine to the solid madia. So far, shoot regeneration in the calluses could not be induced.
TL;DR: Variation in the responses of selected genotypes of spring rape to infection by a wide range of isolates of Leptosphaeria maculans was analyzed and the significance of host-pathogen interactions in the B. napus-L.
Abstract: Variation in the responses of selected genotypes of spring rape to infection by a wide range of isolates of Leptosphaeria maculans was analyzed in this study.
TL;DR: The dominant gene conferring mildew resistance has been transferred from the tetraploid weed species A. barbata into the cultivated oat and can be used to induce pairing between alien chromosomes and their corresponding chromosomes in A. sativa.
Abstract: The regular meiotic behaviour of the cultivated oat Avena sativa (2n=6x=42) is genetically controlled. The factors which control the diploid-like meiotic behaviour also restrict the amount of pairing that occurs between alien chromosomes and their homoeologues in A.sativa, and hence increases the difficulties of introducing desirable variation from wild species into the cultivated oat. A genotype of the diploid species A.longiglumis which interferes with the regular meiotic behaviour of A. sativa can be used to induce pairing between alien chromosomes and their corresponding chromosomes in A. sativa. Using this procedure the dominant gene conferring mildew resistance has been transferred from the tetraploid weed species A. barbata into the cultivated oat.
TL;DR: The merits of mentor pollen in certain interspecific hybridizations in the genus Cucumis L. and C. africanus were evaluated and a number of relatively large seeds (with enlarged embryosac) were obtained.
Abstract: The merits of mentor pollen in certain interspecific hybridizations in the genus Cucumis L. were evaluated. African wild cucumber species Cucumis metuliferusNaud. and C. africanus L. and Asian species C. sativus var. hardwickiiAlef and var. sikkimensisHook, were reciprocally crossed. Pollen tube growth was arrested halfway down the style in all combinations except in C. sativus × C. africanus. Mentor pollen irradiated with 100 and 200 krad grew through the style and into the ovules in all species. Fruitset was obtained in all cases when mentor pollen was used either alone or in mixtures. Fruits set after self pollination with mentor pollen yielded only seeds without embryos.
TL;DR: It is suggested that direct selection for yield or seed weight in diseased plots is likely to achieve more desirable goals than selection for seed weight %.
Abstract: A population of 572 F2 derived F3 lines from six crosses were used to estimate parameters relevant to selection for resistance to Septoria nodorum of wheat. Lines were grown in disease free (fungicide sprayed) and inoculated microplots in 2 replications of a split-plot design in a single environment in 1977. Average yield reduction due to disease was approximately 50%; this was associated with an average septoria score of 50% on the flag leaf, an average septoria score of 42% on the head, and a reduction of 37% in seed weight. Low S. nodorum scores were correlated with late heading date, tall plant height, high grain yield, and high seed weight in diseased plots, and high seed weight % (seed weight in diseased plots expressed as a percentage of seed weight in fungicide sprayed plots).
TL;DR: The results of the experiment indicate that breeding work in autotetraploid caraway may result in a new cultivar.
Abstract: An autotetraploid population of caraway (Carum carvi L.) was produced by treating the growing points of young plants with a 0.2% colchicine solution. Selection on morphology, pollen size and pollen shape, followed by a selection on seed size proved to be an effective way to identify the mixoploid C0 plants. Three percent of the treated plants produced a tetraploid progeny. Moderate selection in the C1 and the C2 population resulted in an improvement of the average seed-set to the amount of 50% of the diploid control, with a range of 21–78%. The 1000-kernel weight of the tetraploid material was 7 g, compared to 3 g in the diploid control. The oil content of the autotetraploid seed was increased with 35.6%; the increase in carvone amounted to 6.9%. The results of the experiment indicate that breeding work in autotetraploid caraway may result in a new cultivar.
TL;DR: Ten peanut (Arachis hypogaea L.) lines, two from each of five centers of diversity in South America, and the F2 generation of all possible crosses among them were used to characterize the variation for yield, fruit and seed traits and protein and oil content and to determine the breeding potential of the parents.
Abstract: Ten peanut (Arachis hypogaea L.) lines, two from each of five centers of diversity in South America, and the F2 generation of all possible crosses among them were used to characterize the variation for yield, fruit and seed traits and protein and oil content and to determine the breeding potential of the parents. Two of the parental lines belong to subspecies hypogaea and the other eight to subspecies fastigiata.
TL;DR: The callus of most triticale lines used differentiated into organs more readily on MS medium supplemented with 0.1 mg/l 2,4-D than on medium without growth regulators.
Abstract: Callus was obtained from immature excised embryos of triticale using MS medium supplemented with 3 mg/l 2,4-D and 1 mg/l kinetin. The presence of 2,4-D was essential for continued callus proliferation. Plantlets were induced from the calli by sub-culturing on medium either devoid of auxin or containing 0.1 mg/l 2,4-D. The capacity to produce callus and to form organs and plantlets differed markedly among the genotypes used. Lines also had distinct response to presence and absence of 2,4-D in the regeneration media. The callus of most triticale lines used differentiated into organs more readily on MS medium supplemented with 0.1 mg/l 2,4-D than on medium without growth regulators. Very high frequencies (up to 75%) of plantlet regeneration were observed in several of the triticale lines studied.
TL;DR: Backcross substitution lines are a new source of cytoplasmic male sterility in Helianthus annuus, suggesting that the inheritance of restoration of pollen shed was complex and not fully elucidated.
Abstract: Interspecific substitutions of the nucleus of Helianthus annuus (2n=34) cv. Saturn into the cytoplasm of H. petiolaris (2n=34) by successive backcrossing, resulted in progenies with indehiscent anthers containing white, rather than normal yellow, pollen. Further backcrossing by cv. Saturn failed to restore pollen shed, suggesting that the male sterility was cytoplasmic. In vivo germination tests of pollen from 23 such plants from eight BC5 lines, indicated complete pollen sterility for 14 plants, but normal seed set, suggesting that female fertility was not affected. Meiosis in all plants examined was normal.