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1.
P. Kakes 《Euphytica》1990,48(1):25-43
Summary Cyanogenesis, the production of HCN is a trait that can be found in all the major taxa. The system is particularly important in higher plants, both in view of the specialized mechanisms found in plants and with regard to the physiological and ecological function of HCN production. The present paper discusses the long history of cyanogenic research, the distribution of the cyanogenic substances among the taxa of higher plants, their localisation in the plant organs and their biosynthetic pathways. The same topics are discussed with regard to the specialized -glucosidases found in plants that play a role in the catabolism of the cyanogenic substances and in HCN production.The physiological and ecological functions of the cyanogenic systems are discussed with emphasis on the few species studied so far that are polymorphic, i.e. contain cyanogenic and acyanogenic individuals in the same population. Although research in this area is still in its infanthood, it is clear that cyanogenesis is part of a complex system that among others, gives protection against particular groups of herbivores. Apparently the defensive system is under some kind of constraint, developmental, selectional, or both, that prevents plants from having an absolute defense against herbivores. One such constraint viz. a negative effect of the cyanogenic system on growth and/or reproduction is discussed in some length. A number of cultivated species, i.e. cassava (Manihot esculenta), sorghum (Sorghum spp) and lima bean (Phaseolus lunatus) to mention a few, are cyanogenic. Cyanogenesis in species used for human or lifestock consumption is generally considered an undesirable trait. On the other hand low levels of cyanogenesis may cause greater susceptibility to herbivores and consequently lower the yield. Apparently cyanogenesis is a character of interest for plant breeders trying to improve cyanogenic species.  相似文献   

2.
The potential for gene flow between Camelina sativa, a promising edible and industrial oil crop in Canada, and its wild North American relatives C. alyssum, C. microcarpa and C. rumelica subsp. rumelica, was investigated. Sequence analysis of the nuclear ribosomal internal transcribed spacer region (ITS) was used to differentiate Camelina species and/or accession‐specific nucleotide markers and identify interspecific F1 hybrids. ITS analysis identified hybrids in progeny of C. alyssum × C. sativa, C. microcarpa accession 36010 × C. sativa and C. sativa × C. rumelica subsp. rumelica. Seed set on C. alyssum × C. sativa F1 and F2 progeny was similar to the parents; few seeds were produced on hybrid progeny of C. microcarpa accession 36010 × C. sativa and C. sativa × C. rumelica subsp. rumelica. The study provided evidence that should the species have sympatric distributions and overlapping flowering periods, gene flow between C. sativa and its wild North American relatives is possible and that it would most likely occur with C. alyssum given the high fertility of the F1 hybrids recovered.  相似文献   

3.
Successful commercial utilization of the meal by‐product of Brassica oilseed crops requires the cultivation of cultivars with low glucosinolate (GSL) content in the seeds; however, such cultivars are not yet available in Brassica carinata. The objective of the present research was to search for transgressive segregants with further‐reduced GSL content in the progeny of crosses involving four B. carinata lines with reduced GSL content (90 compared with 120 μmol/g seed in standard germplasm). The four lines were crossed following a diallel design and F2 phenotypes (F3 seed bulked) were analysed for GSL content. F2 phenotypes with a transgressive GSL content lower than the parents were identified in all crosses involving the line S2–1241, suggesting that this line carries alleles for reduced GSL content not present in the other lines. F3 : 4 lines from transgressive F2 phenotypes were evaluated for 2 years, which resulted in the selection of an F3 : 4 line with an average GSL content of 58 and 46 μmol/g seed, respectively compared with 84 and 62 μmol/g seed, respectively in S2–1241.  相似文献   

4.
Summary Morphology, flowering, cyanogenesis and leaf markings of 109 white clover (Trifolium repens L.) cultivars, grown as spaced plants and in small plots, were measured. Principal component analysis and cluster analysis were used to compare cultivars. Cultivars were classified into four broad groups. The most important criteria for distinguishing between groups were leaf size, cyanogenesis and combinations of these. Group I, termed small, included small-leaved, prostrate cultivars; Group II, termed intermediate, included the majority of the cultivars which were characterised by medium sized leaves and relatively low cyanogenesis levels; Group III, termed large, included the large-leaved highly cyanogenic cultivars; and Group IV, termed ladino, included large-leaved acyanogenic cultivars.  相似文献   

5.
Summary Twenty-one accessions of 3 wild Lactuca species which could be hybridised with L. sativa, the cultivated lettuce, were inoculated at different stages of plant development with 3 multivirulent isolates of Bremia lactucae. Nineteen sources of resistance to B. lactucae, not attributable to the previously recognised resistance factors 1–11 were identified. Two lines of L. serriola showed similar resistance patterns as lines carrying R11. The resistance of some accession was incomplete particularly at the seedling stage and this phenomenon may be race specific.Tests on segregating F2 populations of crosses between 2 different L. serriola accessions and L. sativa cultivars showed that the resistance in one line (LSE/18) appears to be inherited as a single dominant gene, which is sometimes incomplete in expression and allelic to either Dm6 or R7. The segregation patterns for resistance in PI 281876 did not give readily interpretable ratios.To assess the frequency of occurrence in B. lactucae populations of virulence factors to overcome this novel resistance, 11 of the novel sources of resistance were inoculated with numerous collections of the pathogen from the UK, Czechoslovakia and elsewhere and found to show a high level of resistance.  相似文献   

6.
Summary The antinutritional factors found in soybean, lectin (SBL) and Kunitz trypsin inhibitor (SKTI), are usually inactivated by heat treatment. However, residual activity of these factors can be found in several types of soy-derived products. Heat treatment does not completely eliminate these factors, and in addition it may considerably decrease protein solubility. The genetic elimination of these antinutritional factors could be an alternative to the heat treatment. This study aimed to develop soybean lines devoid of SKTI and SBL in their seeds. The population under study was obtained by crossing the normal cv. Monarca with a soybean line lacking SKTI and SBL. Specific DNA primers were designed for the identification of the recessive alleles that condition the absence of SKTI and SBL. F2 seeds presenting the DNA markers that identify the recessive alleles were selected and the corresponding F2 plants were backcrossed with the recurrent parent (‘Monarca’), producing the BC1F1 generation. The F2 generation was analyzed by SDS-PAGE in order to confirm the genotypes of the F2 selected. The segregation tests confirmed that these traits are governed by two genes that segregate independently.  相似文献   

7.
Summary Although wild oats (Avena fatua L.) have been considered a potential source of genes for cultivated oat (Avena sativa L.) improvement, most progenies of A. sativa/A. fatua crosses have weak straw and are very susceptible to crown rust (Puccinia coronata CDA. var. avenae Fraser and Led.). Backcrossing to A. sativa has been suggested as a method of improving progeny lines while introducing new genes from wild oats to cultivated oats. In this study, A. sativa/A. fatua F1 hybrids were backcrossed twice to A. sativa, and lines from three backcross populations were selected on the basis of agronomic performance in segregating generations. The A. sativa recurrent parents were Dal (tall and late) and Stout (short and early).Backcross lines and recurrent parents were evaluated in five performance trails from 1983 through 1985. There was significant variation among backcross lines for most traits, but most backcross lines did not produce higher grain and straw yields than their A. sativa parent. Several backcross lines were higher than their recurrent parent in test weight and groat percentage. A line derived from Stout, 175BC2-6, was considered the most promising backcross line in the study. This line produced more grain, had heavier kernels, and headed 3.3 days earlier than Stout. Although 175BC2-6 does not have sufficient straw strength and crown rust resistance to be released as a cultivar, it is considered to be a new source of high grain yield, high test weight and earliness for oat breeding.  相似文献   

8.
The genetics of resistance of common vetch (Vicia sativa L.) to broomrape (Orobanche crenata Forsk.) was studied for two years by using the P1, P2, F1, BC1, BC2, F2 F3, and F4 generations obtained from crosses between resistant and susceptible lines. Resistant lines were selected by screening a world collection m a naturally infested plot. Resistance was tested both under field and greenhouse conditions. The best index to measure resistance was the number of emerged broomrapes per host plant. The results fit the additive-dominance model. The main component of the variation was additivity; dominance and interaction effects seemed to depend on the environment. When dominance is expressed, a low number is dominant over a high number of broomrapes per host plant.  相似文献   

9.
Modification of plant height via RNAi suppression of OsGA20ox2 gene in rice   总被引：1，自引：0，他引：1  
GA 20-oxidase (GA20ox) is a regulatory enzyme for the syntheses of biologically active GAs in plants. The loss-of-function mutations in OsGA20ox2 of rice (Oryza sativa L.) generate the well-known Green Revolution gene sd-1, which cause the semi-dwarfism phenotype. In our present investigation, semi-dwarf plants were generated from a taller rice variety QX1 by RNAi suppression on the expression of OsGA20ox2. The 531bp-fragment of OsGA20ox2 was amplified by PCR from genomic DNA of QX1 and used to construct the hairpin RNAi vector pCQK2. The wild type QX1 was transformed with pCQK2 by Agrobacterium-mediated transformation and some independent transgenic RNAi lines exhibited semi-dwarfism. RT-PCR and Northern blot analyses showed that the expression of OsGA20ox2 was specifically suppressed in the RNAi semi-dwarf lines. Endogenous GA assays revealed that the contents of the GA20ox2-catalyzed products GA19, GA20 and the down-stream biologically active GA1 were drastically reduced in the RNAi semi-dwarf lines. We further showed that the RNAi semi-dwarf lines could be restored to normal plant height by applying exogenous GA3. The results indicated that the semi-dwarfism of the RNAi semi-dwarf lines was associated with the decreased expression of OsGA20ox2 gene and the reduced content of endogenous biologically active GA1. Analyses of panicle length, seeds per panicle and 1000-grain weight suggested that the RNAi semi-dwarf lines showed stable grain yield compared with the wild type plants. It is demonstrated that the RNAi approach could be useful for plant breeding purposes in the future. Qing Yang, Chun-Lian Wang have contributed equally to this work.  相似文献   

10.
Maize is an important food and feed crop worldwide. Phytic acid (PA), in maize kernel, is an antinutritional factor. PA chelates mineral cations and causes mineral deficiency in humans and phosphorous deficiency in animals. The undigested PA excreted by monogastric animals causes phosphorous eutrophication. Therefore, development of low‐phytate maize is indispensable. The low‐phytate locus (lpa2 allele) has been transferred from low‐phytate mutant line ‘EC 659418’ into an elite inbred UMI 395 through marker‐assisted backcross breeding (MABB). The MABB involved three backcrosses followed by two selfing steps, including ‘foreground selection’, that is, selecting lines with lpa2 allele with the help of a codominant SSR marker ‘umc2230’ and ‘background selection’, that is, selecting plants having genetic background similar to that of the recurrent parent using 50 codominant SSR markers. Two low‐phytate lpa2 lines with genome similar (>90% similarity) to that of recurrent parent have been identified. These lines can be used as parent in future hybridization programmes for obtaining low‐phytate high‐yielding maize hybrids.  相似文献   

11.
Lectin is one of the known antinutritional factors that deteriorate the soybean protein quality and development of cultivars with low lectin content will help to improve nutritional quality of soybean [Glycine max (L.) Merrill]. Therefore, attempts were made to induce mutations for low lectin content in the cultivar ‘MACS 450’. Soybean cultivar ‘MACS 450’ was subjected to combination treatments of γ‐rays and ethyl methane sulphonate (EMS) with an objective to induce variability for low lectin content. The treatments of different combinations of γ‐rays and EMS were 50 Gy + 0.2% EMS, 50 Gy + 0.4% EMS, 100 Gy + 0.2% EMS and 100 Gy + 0.4% EMS. Of the 3200 treated M1 seeds sown, 16 400 M2 plants were raised. In M2, 72 plants were identified for low lectin content [<40 × 105 haemagglutination unit (HAU)/mg] and were carried up to M5 generation. In M5 generation, lectin content in ‘MACS 450’ was 39.23 to 50.0 × 105 HAU/mg, and was compared with the nine true breeding lines identified having low lectin content, ranging from 2.3 × 105 to 27.46 × 105 HAU/mg. Three mutants were found to possess very low lectin content (ranging from 2.0 × 105 to 3.0 × 105 HAU/mg). Thus, the identified mutant lines with low lectin content will greatly improve soybean protein quality, thereby reducing financial burden on the soybean industry for processing soybean meal and also making it suitable for human consumption. All the mutants showed normal seed development, having soluble protein content similar or higher than that in the parent (32.0 mg/ml). This indicates that the change in lectin content does not have any negative impact on the plant growth and protein content.  相似文献   

12.
Among one hundred lines of Medicago rigidula (L.) Allioni, fifteen (5 high-producing, HP, 5 intermediate-producing, IP, and 5 low-producing, LP) were chosen as experimental material because of their different dry-matter production when grown at 0.5 mg L-1 of P2O5 in hydroponic solution (critical level). The aim of this work was to evaluate the response to selection with respect to dry-matter yield (DMY), made at 0.5 mg L-1 of P2O5 and to check if superior lines could also be isolated when plants were grown at 20 and 200 mg L-1 of P2O5. Results show that HP lines were also superior with respect to DMY (g/plant) at the higher phosphorus concentrations. Highly-productive line selection in M. rigidula can also be achieved when plants are grown at a critical level of phosphorus in the nutrient solution. Phosphate content in the dry matter produced and phosphatase activity were also analysed. Plants of the more-productive lines were characterized by lower phosphate content per unit dry matter and by a higher phosphatase activity.  相似文献   

13.
A protocol was established for high frequency cyclic somatic embryogenesis for different varieties of cassava. An efficient plant regeneration system was developed for the high cyanogenic variety PRC60a. Linamarin content and linamarase activity were determined in various tissues of secondary somatic embryos and regenerated plants of PRC 60a. Both linamarin and linamarase activity were not detected in embryogenic callus, roots induced from callus and somatic embryo tissues. The stems and leaves of regenerated plants (in vitro) and storage roots and leaves of mature plants (in vivo), however, contained variable amounts of linamarin and linamarase activity whereas in the non storage root tissues (in vitro) only linamarin was detected. The present study suggested that the linamarin biosynthetic pathway may be absent or not switched on in the embryogenic callus and somatic embryos. The ploidy level and somatic chromosome number of the regenerated plants were found to be same as the source plants. The availability of this regeneration system would be useful not only for investigating cyanogenesis but also for genetic manipulation in cassava. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

14.
Summary The fatty acid composition of seed-oil of breeding lines and F1 hybrids of Matthiola incana was analyzed, using direct esterification and gas chromatography. The breeding lines tested differed significantly with respect to the levels of palmitic, oleic, linoleic and linolenic acids. Embryonic-stage heterosis in linolenic acid concentration was demonstrated by F1 hybrid seeds, derived from mating horticulturally different lines of M. incana. Linolenic acid content was negatively correlated with both oleic acid content (r=–0.85) and linoleic acid content (r=–0.66). None of the breeding lines or the F1 hybrids significantly passed the limit of 67% linolenic acid. Possible genetic and biochemical explanations for the above phenotypic data are discussed.  相似文献   

15.
B. Campion    D. Perrone    I. Galasso    R. Bollini 《Plant Breeding》2009,128(2):199-204
In common bean, the most abundant proteins of the lectin family (arcelin, phytohaemagglutinin and α-amylase inhibitor – APA proteins) are major antinutritional factors of the seeds. Reduced protein digestibility and high toxicity at the intestinal level are the causes of their antinutritional effect. Bean lines producing seeds without the lectins mentioned above were developed to improve nutritional characteristics of bean seeds used for human consumption and, potentially, for animal feeding. The genetic trait was transferred from a wild bean accession into a number of bean cultivars. The 1 : 3 'lectin-free/lectin-containing seeds' segregation ratio hypothesis was confirmed by chi-square analysis in the F2 progenies. Four lectin-free stable lines, P500, P501, 938 and 586/8 (white seeded), and 44 climbing breeding lines, have been developed. The 'white seed coat' trait, correlated with a reduced amount of tannins and polyphenols in bean seeds, has been introduced in our lectin-free materials to further improve their nutritional characteristics. The field performance of P501, 938 and 586/8 and that of their lectin-containing parents, was evaluated on 2007 in two locations. Dry seed yield, seed emergence, plant height, plant growth duration, average weight and germination capacity of the produced seeds were surveyed and statistically analysed. At the location of Battipaglia (Salerno), the dry seed yield value of the lectin-free line 938 (3.74 t/ha) and that of one of its parent, the CIAT line BAT 881 (3.65 t/ha), were significantly higher than those of all other lines tested. Germination percentage of lectin-free lines, recorded 3 days after sowing, was significantly higher than that of controls.  相似文献   

16.
Few studies have examined the effects of selection for high oil or protein content on the chemical composition of cereal seeds. This study was conducted to examine agronomic and bioenergetic consequences that result with changes in the chemical composition of groats of oat (Avena sativa L.). Oat lines with low and high groat-oil content (GO) and with low and high groat-protein content (GP) were chosen from each of five cycles of a recurrent selection program for increasing GO and from each of four cycles of a recurrent selection program for increasing protein yield via elevating GP, respectively. These lines were evaluated at three Iowa locations in 1988. The results indicated that GP was not significantly affected by selection for high GO and that GO significantly increased during selection for high protein yield via elevating GP. Both selection procedures resulted in oat lines with higher groat-energy contents. A bioenergetic cost analysis showed that for GO in the oil population and GP in the protein population to be increased, additional photosynthate needed to be available.  相似文献   

17.
Water stress is a serious environmental restriction to banana productivity. Hence, the objective of this study was to employ in vitro mutagenesis in selection and characterization of drought tolerant lines in banana. In vitro culture responses of ethyl methanesulphonate induced variants of banana cultivars, ‘Berangan Intan’ and ‘Berangan’ were assessed concerning morphological, physiological and molecular characteristics involving mutated shoot tips on MS medium supplemented with 30 g L−1 PEG. The results showed that water stress tolerant lines could be obtained from induced variations. Variants L2–5 and L1–5 showed the highest number of leaves per shoot (2.37 and 2.06, respectively) and the lowest were recorded in the parental lines L1-1 and L2-1 (0.81 and 0.93, respectively). Fresh weight and shoot vigor rate indicated the maximum increase in the water stress tolerant lines compared with susceptible and non-mutated parental lines. L2–5 exhibited the most increase in the chlorophyll and the most reduction in H2O2 and MDA contents when exposed to water stress. Under PEG treatment, proline and relative water content was enhanced in L1–5, L2–5, L2–6, L1–6, L2–3, L2–4, and L1–4. RAPD analysis revealed polymorphism (18.35 and 21.48%) among variants derived from ‘Berangan Intan’ and ‘Berangan’, respectively. The amplified fragments generated by primers opc01, opc04, opa11, and opa20 observed to be specific for L2–5 and L1–5 as more tolerant followed by L2–3, L1–4, L2–6, and L1–6 as moderately tolerant lines against water stress. This study demonstrates the application of in vitro mutagenesis in selection of water stress tolerant lines of banana as a convenient, cheap, and rapid technique.  相似文献   

18.
C-banded karyotypes of somatic chromosomes and meiotic abnormalities were investigated in four crown rust resistant lines derived from interploidy crosses in Avena.C-banding revealed that line N770-165-2-1 contained a 6C/21translocation while line DCS1789 contained a pair of A. strigosa chromosomes substituted for A. sativachromosome 12. Line JR2-3-3-B contained both the 6C/21 translocation and the pair of substituted A. strigosachromosomes, but line MAM17-4 contained neither. Although meiotic irregularities, including mispositioned bivalents, occurred in all four lines and in their F1 hybrids with A. sativa, the percentages of normal meiosis ranged from 75.4 to 88.6%. This allowed for stability of line performance and for their use as breeding stocks. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

19.
Cadmium (Cd) is a toxic heavy metal that occurs naturally in soils. Durum wheat is known to accumulate generally more Cd than other cereal crops. The uptake of Cd in durum wheat is governed by the gene Cdu1, which co‐segregates with several DNA markers, such as the co‐dominant marker usw47 and the dominant marker ScOPC20. A panel of 314 durum wheat cultivars or lines originating from 16 countries or regions were assessed with usw47. The plant material was mainly comprised of cultivars and modern breeding lines. From this set, 165 durum wheat lines were classified as low‐Cd accumulators, 144 high‐Cd accumulators and five were heterogeneous. A smaller subset of 16 cultivars had previously been evaluated for Cd accumulation in replicated field trials. Lines with the high‐Cd allele showed a 2.4‐fold higher Cd content in the seeds than lines with the low‐Cd allele. We also compared the utility of markers usw47 and ScOPC20 as selection tools. Marker‐assisted selection appears as a robust and practicable tool for breeding durum cultivars with low‐Cd content.  相似文献   

20.
A. M. Abd El  -Moneim 《Plant Breeding》1993,110(2):168-171
Loss of seeds from mature pods is common in Vicia sativa L., an important annual, resown forage legume in West Asia and North Africa. Pod shattering restricts its use as a leguminous forage crop. This paper reports the results of germplasm evaluation for non-shattering pods and of breeding and selection to improve seed retention. Wide variation in pod-shattering exists between common vetch ecotypes collected from different regions. Three wild mutants with almost completely non-shattering pods were identified and isolated for use as a genetic resource in cross breeding programmes. Genetic studies revealed that the non-shattering character in the wild types of common vetch is due to a simple recessive gene, whereas shattering in the cultivated types is due to an allelic dominant pair of genes. Incorporation of the non-shattering gene into agronomically-promising lines was achieved by back-crossing. Lines having an average of 95—97 % non-shattering pods were obtained, as compared to 40—50 % in the original cultivated lines which represents a major agronomic advance in common vetch breeding. The importance of seed retention to the economics of seed production is discussed.  相似文献   

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