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PubMed2005

A wheat intervarietal genetic linkage map based on microsatellite and target region amplified polymorphism markers and its utility for detecting quantitative trait loci.

Efficient user-friendly methods for mapping plant genomes are highly desirable for the identification of quantitative trait loci (QTLs), genotypic profiling, genomic studies, and marker-assisted selection. SSR (microsatellite) markers are user-friendly and efficient in detecting polymorphism, but they detect few loci. Target region amplification polymorphism (TRAP) is a relatively new PCR-based technique that detects a large number of loci from a single reaction without extensive pre-PCR processing of samples. In the investigation reported here, we used both SSRs and TRAPs to generate over 700 markers for the construction of a genetic linkage map in a hard red spring wheat intervarietal recombinant inbred population. A framework map consisting of 352 markers accounted for 3,045 cM with an average density of one marker per 8.7 cM. On average, SSRs detected 1.9 polymorphic loci per reaction, while TRAPs detected 24. Both marker systems were suitable for assigning linkage groups to chromosomes using wheat aneuploid stocks. We demonstrated the utility of the maps by identifying major QTLs for days to heading and reduced plant height on chromosomes 5A and 4B, respectively. Our results indicate that TRAPs are highly efficient for genetic mapping in wheat. The maps developed will be useful for the identification of quality and disease resistance QTLs that segregate in this population.

Chromosome Mapping↗

PubMed2005

Environmental biogeochemical behaviors of rare earth elements in soil-plant systems.

With the continual increase in the utilization of rare earth elements (REEs) for industrial and agricultural purposes in China, the research into the environmental biogeochemical behavior of REEs has become a pressing issue. The REEs' content in soil and various parts of wheat under different conditions in soil-plant systems were measured by INAA and ICP-MS. The results showed four aspects. (1) The mean value of total REEs in soil of China was 176.8 mg kg(-1). The mean ratio of SigmaLREE/SigmaHREE in soils was 8.0 and cerium accounts for 42% of the total REEs. The content of REEs in wheat seed ranged between 10(-11) and 10(-8) g g(-1), 3-4 orders of magnitude lower than that in soil. (2) The REEs contents in ryegrass, especially in roots, were significantly related to that of soil. The bioavailability of REEs in soil mainly depended on the exchangeable fraction of REEs, which was strongly affected by the physico-chemical properties of the soil. (3) Long-term foliage-dressing with Changle microfertilizer of REEs did not affect the contents and distribution patterns of REEs in soil. At the maturing stage of spring wheat, the REEs content was in the order of root > leaf >stem and crust. Compared with the control, foliage-dressing has a higher accumulation of REEs in root and leaf. However, no significant difference was found in stem and crust between the two treatments. (4) There was no significant accumulation with the soil-dressing method. When comparing controls in both foliage- and soil-dressing methods, no distinct residue of REEs in grains was found.

Fertilizers↗

PubMed2003

Molecular characterization of a wheat--Thinopyrum ponticum partial amphiploid and its derivatives for resistance to leaf rust.

Leaf rust (caused by Puccinia triticina Eriks.) occurs annually in most wheat-growing areas of the world. Thinopyrum ponticum (Podp.) Z.-W. Liu & R.-C. Wang has provided several leaf rust resistance genes to protect wheat from this fungal disease. Three chromosome substitution lines, Ji806, Ji807, and Ji859, and two chromosome addition lines, Ji791 and Ji924, with a winter growing habit were developed from crosses between wheat (Triticum aestivum L. em Thell.) and the wheat - Th. ponticum partial amphiploid line 693. These lines were resistant to leaf rust isolates from China. Sequence-tagged site (STS) analysis with the J09-STS marker, which is linked to the gene Lr24, revealed that the partial amphiploid line 693 and all of the substitution and addition lines carried gene Lr24. Genomic in situ hybridization (GISH) analysis was carried out on chromosome preparations using total genomic DNA from Pseudoroegneria strigosa (M. Bieb) A. Löve (St genome, 2n = 14) as a probe in the presence of total genomic DNA from T. aestivum 'Chinese Spring' wheat (ABD genomes, 2n = 42). The GISH analysis demonstrated that these lines had a pair of chromosomes displaying the typical pattern of a Js genome chromosome. This indicates that the chromosome that carries gene Lr24 belonged to the Js genome of Th. ponticum. In addition to 40 wheat chromosomes, eight Js and eight J genome chromosomes were also differentiated by GISH in the partial amphiploid line 693. Since most sources of Lr24 have a red grain color, the white-colored seeds in all of these substitution and addition lines, together with high protein content in some of the lines, make them very useful as a donor source for winter wheat breeding programs.

Chromosomes, Plant↗

PubMed1997

Immunological detection of potential signal-transduction proteins expressed during wheat somatic tissue culture.

An immunochemical approach was used to detect the expression of putative guanine nucleotide-binding proteins (G-proteins), arrestin, and nucleoside diphosphate kinases during wheat (Triticum aestivum) tissue culture initiated from immature embryos. Both the soluble and membrane extracts from the immature embryos revealed bands of 58, 40, and 16 kD with antibodies to G-protein (alpha subunit), arrestin, and nucleoside diphosphate kinase, respectively. These proteins were overexpressed in vitro in both nonembryogenic callus and embryogenic cultures. An additional soluble protein (32 kD) was detected by anti-G alpha antibodies in cultured tissues but not in immature embryos, suggesting a possible function in cell multiplication. Moreover, somatic embryogenesis was associated with the appearance of a 29-kD protein reactive with anti-arrstin antibodies, both in soluble and membrane fractions. Tissue-cultured genetic stocks of Chinese Spring wheat, including the disomic, 36 ditelosomic, and 6 nullisomic-tetrasomic wheat lines, were used to ascertain the chromosomal location of the genes encoding the 29-kD arrestin-like protein. The lack of a signal with the nonembryogenic ditelosomic 3 D short chromosome arm line suggests that the 3 D long chromosome arm possesses at least one gene involved in the expression of the 29-kD protein. The putative role of the 29-kD protein in signal-transduction regulating embryogenesis is discussed.

Amino Acid Sequence↗

PubMed2004

Chemical alteration of the rhizosphere of the mycorrhizal-colonized wheat root.

Plexiglass pot growth chamber experiments were conducted to evaluate the chemical alterations in the rhizosphere of mycorrhizal wheat roots after inoculation with Glomus intraradices [arbuscular mycorrhizal fungus (AMF)]. Exchange resins were used as sinks for nutrients to determine whether the inoculated plant can increase the solubility and the uptake of P and micronutrients. Treatments included: (1) soil (bulk soil); (2) AMF inoculation no P addition (I-P); (3) no inoculation with no P addition (NI-P); (4) AMF inoculation with addition of 50 mg P (kg soil)(-1) (I+P), and (5) no inoculation with addition of 50 mg P (kg soil)(-1) (NI+P). The AMF inoculum was added at a rate of four spores of G. intraradices (g soil)(-1). The exchange resin membranes were inserted vertically 5 cm apart in the middle of Plexiglass pots. Spring wheat (Triticum aestivum cv. Len) was planted in each Plexiglass pot and grown for 2 weeks in a growth chamber where water was maintained at field capacity. Rhizosphere pH and redox potential (Eh), nutrient bioavailability indices and mycorrhizal colonization were determined. Mycorrhizal inoculation increased the colonization more when P was not added, but did not increase the shoot dry weight at either P level. The rhizosphere pH was lower in the inoculated plants compared to the noninoculated plants in the absence of added P, while the Eh did not change. The decrease in pH in the rhizosphere of inoculated plants could be responsible for the increased P and Zn uptake observed with inoculation. In contrast, Mn uptake was decreased by inoculation. The resin-adsorbed P was increased by inoculation, which, along with the bioavailability index data, may indicate that mycorrhizal roots were able to increase the solubility of soil P.

Anion Exchange Resins↗

PubMed2006

Candidate gene identification of an aluminum-activated organic acid transporter gene at the Alt4 locus for aluminum tolerance in rye (Secale cereale L.).

Among cereal crops, rye is one of the most tolerant species to aluminum. A candidate gene approach was used to determine the likely molecular identity of an Al tolerance locus (Alt4). Using PCR primers designed from a wheat aluminum tolerance gene encoding an aluminum-activated malate transporter (TaALMT1), a rye gene (ScALMT1) was amplified, cloned and sequenced. Subsequently, the ScALMT1 gene of rye was found to be located on 7RS by PCR amplification using the wheat-rye addition lines. SNP polymorphisms for this gene were detected among the parents of three F(2) populations that segregate for the Alt4 locus. A map of the rye chromosome 7R, including the Alt4 locus ScALMT1 and several molecular markers, was constructed showing a complete co-segregation between Alt4 and ScALMT1. Furthermore, expression experiments were carried out to clarify the function of this candidate gene. Briefly, the ScALMT1 gene was found to be primarily expressed in the root apex and upregulated when aluminum was present in the medium. Five-fold differences in the expression were found between the Al tolerant and the Al non-tolerant genotypes. Additionally, much higher expression was detected in the rye genotypes than the moderately tolerant "Chinese Spring" wheat cultivar. These results suggest that the Alt4 locus encodes an aluminum-activated organic acid transporter gene that could be utilized to increase Al tolerance in Al sensitive plant species. Finally, TaALMT1 homologous sequences were identified in different grasses and in the dicotyledonous plant Phaseolus vulgaris. Our data support the hypothesis of the existence of a common mechanism of Al tolerance encoded by a gene located in the homoeologous group four of cereals.

Aluminum↗

PubMed2026

Identification of Novel Sources and Genetic Mapping for Bacterial Leaf Streak Resistance in a Geographically Diverse Panel of Wheat.

Bacterial leaf streak (BLS), caused by Xanthomonas translucens pv. undulosa (Xtu), has recently emerged as a significant threat to wheat production in the Northern Great Plains region of the United States. Deploying resistant cultivars is an economical and practical method of controlling BLS. To identify novel sources of BLS resistance, we screened a set of 355 bread wheat landraces and cultivars representing global diversity for their response to BLS. A wide distribution of seedling responses against BLS was observed, with most genotypes displaying a moderately to highly susceptible response. Notably, we identified 5 resistant and 33 moderately resistant responses. A high-resolution genome-wide association study using 302,524 high-quality single-nucleotide polymorphisms (SNPs) identified 10 significant marker-trait associations (MTAs) on chromosomes 1A, 1D, 3B, 4A, and 5A corresponding to unique genomic regions associated with BLS resistance. Compared with previous studies, four of these genomic regions are likely novel. Of these, MTA 'scaffold15531_2782724' associated with q5A.1 was highly significant (-log10P = 9.39) and exhibited the highest SNP effect (0.35). An association on chromosome 3B validated a previously identified 3B quantitative trait locus (QTL) mapped at approximately 6 Mbp in the hard red spring wheat cultivar 'Boost', and the high-resolution mapping from our study further refined the interval for this QTL. Furthermore, the narrow haplotype blocks reported in this study could be valuable for fine mapping of important regions. The novel resistant sources, along with identified genomic loci and corresponding SNP markers from this study, would be helpful for wheat-breeding programs to enhance BLS resistance.[Formula: see text] Copyright © 2026 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

BLS↗

PubMed2003

Contact activity of difenzoquat differs from that of paraquat.

Difenzoquat herbicide is used for post-emergence control of wild oat (Avena fatua L) in small grain crops. Its mechanism of action is not known, but appears to have both paraquat-like contact activity and systemic growth-inhibition activity. Experiments were conducted in vitro to compare the contact activity of difenzoquat and paraquat, to examine the contact activity of difenzoquat in difenzoquat-resistant (accession LCS) and -susceptible (accession SB 18) A fatua biotypes and -tolerant 'Ernest' and -susceptible 'Verde' hard red spring wheat (Triticum aestivum L) cultivars, and to investigate the role of differential DNA synthesis as a mechanism for difenzoquat resistance. Difenzoquat at 1 mM induced significant electrolyte leakage from resistant and susceptible A fatua leaf tissue in both light and dark, but paraquat at 1 mM induced electrolyte leakage only in light and not in dark. Difenzoquat at 1 mM under light induced more electrolyte leakage from resistant and susceptible A fatua than from tolerant 'Ernest' and susceptible 'Verde' wheat. Paraquat under light conditions induced more electrolyte leakage than difenzoquat, but no significant differences among A fatua accessions and wheat cultivars were detected. Difenzoquat under light did not decrease chlorophyll levels for either A fatua accessions or wheat cultivars, whereas paraquat decreased chlorophyll content of all four plant types. Inhibition of DNA synthesis was not significantly different between susceptible and resistant A fatua, but was significantly greater in susceptible 'Verde' than tolerant 'Ernest' wheat. These data suggest that difenzoquat and paraquat, have different modes of contact activity.

Chlorophyll↗

PubMed1993

Levels of five mycotoxins in grains harvested in Atlantic Canada as measured by high performance liquid chromatography.

An analytical protocol using high performance liquid chromatography (HPLC) was used to analyze samples of spring wheat, winter wheat, 2-row barley, and 6-row barley over a period of three years for the presence of five mycotoxins. These included deoxynivalenol, zearalenone, T-2 toxin, HT-2 toxin, and diacetoxyscirpenol. The protocol employed a single extraction step using acetonitrile-water and two cleanup procedures. One utilized a solid-phase extraction column and the other a charcoal-alumina column. Detection limits ranged from 0.02 to 0.15 micrograms of mycotoxin g-1 grain. Little T-2 toxin, HT-2 toxin, or diacetoxyscirpenol was found in the samples. Deoxynivalenol was detected in 53 to 62% of the samples tested and zearalenone in 25-29% of the samples. Several enzyme-linked immunosorbent assays were used for comparison purposes with deoxynivalenol, zearalenone, and T-2 toxin. These kits provided reliable qualitative, but not quantitative, data.

Canada↗

PubMed1977

[On the determination of chlorocholine chloride (CCC) in cereals (author's transl)].

For the determination of CCC residues samples of grains and straw of four varieties of spring wheat and oat were extracted with ethanol. CCC was purified by column chromatography with an ion exchanger and alumina as well as by TLC. After its identification by the Rf and a colour reaction on the thin layer plate a colorimetric method with dipicrylamine was used for the quantitative estimation of CCC. The recovery rate amounts to 98+/-5% for wheat grains and straw and to 80 +/- 5% for oat grains. The detection limit is at 0.1 ppm. The amounts of CCC reach in wheat grains 0.3--0.7 ppm, in wheat straw 1--7 ppm and in oat grains 0.9--3.4 ppm in the dry matter. In oat straw CCC could not be detected with this method.

Chlorides↗

PubMed2006

Short-term bioassay responses to sludge products and leachate.

Recycling of sewage sludge is needed in a sustainable society. Quality aspects of sludge include hygiene (pathogens), nutrients (N and P), and toxicants (metals and organics). Metals are of particular concern because they are not degradable, but their hazards are related to their bioavailability and chemical speciation. In this article, the effect on sludge quality of two treatment methods, incineration and pelletization, has been determined for digested sludge from two treatment plants. The combined effect of nutrients and toxicants in sludge and sludge product was determined for spring wheat, Triticum aestivum, and the toxicity of the leachate water was determined for water fleas, Daphnia magna, and seeds of lettuce, Lactuca sativa. Toxicity Identification Evaluation was used to determine whether metals were possible toxicants. The results indicated that incineration decreased toxicity, whereas leachability of metals and the fertilizing effect was unaffected. Pelletization seemed to increase toxicity and leachability of metals and also decreased the fertilizing effect of the sludge. Thus, the results suggest that pelletization of digested sewage sludge increased the toxicity of the sludge and thus decreased the quality of the sludge, whereas incineration apparently reduced toxicity for the two sludges tested.

Animals↗

PubMed2002

Changes in mass and energy transfer between the canopy and the atmosphere: model development and testing with a free-air CO2 enrichment (FACE) experiment.

The rationale for this study is found in the probable higher temperatures and changes in rainfall patterns that are expected in the future as a result of increasing levels of CO2 in the atmosphere. In particular, higher air temperatures may cause an increase in evapotranspiration demand while a reduction in rainfall could increase the severity and duration of drought in arid and semi-arid regions. Representation of the water transfer scheme includes water uptake by roots and the interaction between evapotranspiration and CO2 enrichment. The predicted response of a spring wheat (Triticum aestivum L. cv. Yecora rojo) canopy in terms of energy exchange processes to elevated atmospheric CO2 level was tested against measurements collected at the FACE (Free Air Enrichment Experiment) site in 1994. Simulated and measured canopy conductances were reduced by about 30% under elevated [CO2] under optimum conditions of water supply. Reductions in latent heat fluxes under elevated instead of ambient [CO2] caused reductions in both simulated and measured seasonal water use of 6% under optimum and 2% under suboptimum irrigation. The soil-plant-atmosphere water transfer scheme proposed here offers several advances in the simulation of land surface interactions. First, the stomatal resistance model minimizes assumptions in existing land surface schemes about the effects of interactions among environmental conditions (radiation, temperature, CO2) upon stomatal behavior. These interactions are resolved in the calculation of CO2 in which processes are already well understood.

Air↗

PubMed2005

Absence of Hg transpiration by shoot after Hg uptake by roots of six terrestrial plant species.

In this paper we investigated if, and to what extent, six different plant species accumulate, translocate and emit mercury (Hg) into the air. The Hg uptake by roots, distribution of Hg to the shoot and release of Hg via shoots of garden pea, spring wheat, sugar beet, oil-seed rape, white clover and willow were investigated in a transpiration chamber. The airborne Hg was trapped in a Hopcalite trap or a gold trap. Traps and plant materials were analysed for content of Hg by CVAAS. The results show that all plant species were able to take up Hg to a large extent from a nutrient solution containing 200 microg L(-1) Hg. However, the Hg translocation to the shoot was low (0.17-2.5%) and the Hg that reached the leaves was trapped and no release of the absorbed Hg to the air was detected.

Beta vulgaris↗

PubMed2001

Interception, retention and translocation under greenhouse conditions of radiocaesium and radiostrontium from a simulated accidental source.

The behaviour of radioactive aerosols released from a severely damaged nuclear reactor and deposited on cereals was simulated under controlled conditions. 137Cs- and 90Sr-labelled aerosols were generated by volatilisation at high temperature of an artificially spiked pellet of depleted UO2. After cooling and maturation the aerosols were allowed to deposit on spring wheat (Triticum aestivum L. var. Arbon) cultures grown on lysimeters under greenhouse conditions. At the time of contamination the wheat plants were at different stages of development, from early vegetative growth (two leaves) until nearly mature (end of flowering). The estimated interception coefficient (micro) amounted to 13.1 m2 kg(-1); such a high value may be explained by the experimental conditions that created an over-saturated atmosphere during the contamination process and wet leaf surfaces. The first simulated rain, applied 6 days after the contamination, removed four times more 137Cs (54%+/-12 of the intercepted radionuclides) than 90Sr (15%+/-20) from the aerial parts. At harvest approximately 2% of the Sr and less than 1% of the Cs initially intercepted by the aerial parts is recovered for plants contaminated during the early development stages. A significantly higher proportion of the intercepted activity is still present for plants contaminated in the late development stages. The translocation to grains (TLF) increases when deposit occurs closer to the mature stage of the plant. The initial decrease of TLF values that we observed for strontium contamination in the earliest development stages is most probably due to the contribution of root uptake. Ploughing and re-sowing after the first rain, applied as a countermeasure reduced the 137Cs content in leaves and stems at harvest approximately 3 times but had no effect on the 90Sr content in vegetative organs. It reduced the 137Cs-contamination level in edible parts (grain) by a factor of 2 compared to the unploughed control, but doubled the 90Sr content.

Aerosols↗

PubMed2002

Cadmium and zinc interactions and their transfer in soil-crop system under actual field conditions.

The transfer of Cd and Zn from calcareous soils nearby a non-ferrous mining and smelting bases to the spring wheat (Triticum aestivum L.) and corn (Zea mays L.) tissues and the interactions between the two metals concerned were investigated under actual field conditions. Samples of soils and entire crops were randomly collected during harvest time in 1998 in the Baiyin region. The soil metal contents showed that the furrows had been polluted (mean values: 3.16 mg kg(-1) for Cd; 146.78 mg kg(-1) for Zn) and the significant spatial variation of the soil contamination existed here (ranges, Cd: 0.14-19.3 mg kg(-1); Zn: 43.5-565.0 mg kg(-1)). The translocation ratios of the two metals from soil to crop parts in the region studied were relatively lower and the order of the element transfer in different plant tissues was root > stem > grain. The transfer ratio of element Cd was lower than that of element Zn. Cd and Zn uptake by the crop structures could be best described by four models (P < 0.01): linear; exponential; quadratic; and cubic. Apart from a linear relationship between the element Cd in the corn grains and soils, models were generally non-lincar. An analysis of Cd-Zn interaction mechanism led to the conclusion that the effects of the two metals were synergistic to each other under field conditions, in which increasing Cd and Zn contents in soils could increase the accumulations of Zn or Cd in the two crops.

Cadmium↗

PubMed2003

From critical levels to critical loads for ozone: a discussion of a new experimental and modelling approach for establishing flux-response relationships for agricultural crops and native plant species.

Present critical levels for ozone (O3) for protecting vegetation against adverse effects are based on exposure-response relationships mainly derived from open-top chamber experiments and are expressed as an Accumulated exposure Over a Threshold of 40 ppb (AOT40). In that context with a revision of the UN (United Nations)-ECE (Economic Commission for Europe) Gothenburg protocol, AOT40 values should be replaced by flux-oriented quantities, i.e. in the end by critical loads. At present, the database for the derivation of critical loads for O3 is extremely inadequate. Furthermore, the currently available flux-response relationships are also derived from open-top chamber experiments. The use of a relationship for spring wheat in a risk assessment for an agricultural site in Hesse, Germany, demonstrates in principle, the applicability of the critical load concept for O3. Comparisons of diurnal variation of stomatal uptake and AOT40 showed that a major part of toxicologically effective stomatal uptake occurred before noon whereas the AOT40 values were dominated by the O3 concentrations during afternoon. In other words, the AOT40 exposure index do not adequately address the O3 burden during hours when plants are sensitive to O3 uptake. However, due to the differences in radiation, air temperature and humidity between the chamber and the ambient microclimates, a derivation of flux-response relationships from chamber experiments is likely to be questionable, especially for species rich ecosystems: Here, without any changes in the pollution climate, significant modifications of species composition as well as an earlier beginning of the growing season has been previously observed. To overcome the problems associated with chamber-derived flux-response relationships, a new experimental and modelling concept, was developed. The approach, briefly described in this paper, combines methods in air pollution toxicology and micrometeorology. As an analogy to the free-air fumigation concept, O3 is released into the air by an injection system above the plant canopy. The assessment of dispersion and surface deposition of O3 released is based on Lagrangian trajectory modelling. Depending on wind direction and velocity, atmospheric stratification and surface roughness, without any disturbance of the microclimate and micrometeorology, several sub-areas can be identified around the source position with differing deposition rates above the ambient level. Taking into account the actual O3 background deposition, deposition rates and vegetation responses observed in these sub-areas can easily be used to derive flux-effect relationships under ambient conditions and more realistic limiting values to protect our environment.

Air Pollutants↗

PubMed2001

Studies on rye (Secale cereale L.) lines exhibiting a range of extract viscosities. 2. Rheological and baking characteristics of rye and rye/wheat blends and feeding value for chicks of wholemeals and breads.

Five rye lines exhibiting a wide range of extract viscosities were evaluated for the rheological and baking properties of their flours, individually and in blends with hard red spring wheat flour. Commercial cultivars of rye and triticale were included in the study as controls. Extract viscosities of rye flours were higher than those of corresponding wholemeals, indicating shifting of water-extractable arabinoxylan into flour during roller milling. Falling numbers of the rye flours correlated positively with their extract viscosities in the presence (r = 0.73, p < 0.05) or absence (r = 0.65, p < 0.05) of an enzyme inhibitor. Farinograms revealed the weakness of rye and triticale flours compared to wheat flour. Extract viscosities of rye flours were negatively correlated (r = -0.65, p < 0.05) with mixing tolerance index and positively correlated (r = 0.64, p < 0.05) with dough stability, suggesting a positive impact of extract viscosity on dough strength. Extract viscosity was negatively correlated (r = -0.74, p < 0.05) with loaf volume and specific volume (r = -0.73, p < 0.05) and positively correlated (r = 0.73, p < 0.05) with loaf weight of rye/wheat bread. Overall, the results indicated that 30% of flour from high or low extract viscosity rye could be incorporated into rye/wheat breads without seriously compromising bread quality. Inclusion of rye, particularly high extract viscosity rye, in chick diets seriously impeded growth performance and feed efficiency. Part of the arabinoxylan survived bread-making and exerted an effect on chicks, although substantially lower digesta viscosities were observed in chicks fed rye bread diets than in those fed rye wholemeals.

Animal Feed↗

PubMed2000

Fate of multicentric and ring chromosomes induced by a new gametocidal factor located on chromosome 4Mg of Aegilops geniculata.

A new gametocidal (Gc) factor was identified on chromosome 4Mg of Aegilops geniculata Roth. When transferred to Chinese Spring wheat, monosomic and disomic Triticum aestivum-Ae. geniculata chromosome 4Mg addition plants undergo regular first and second meiotic divisions. Male gametogenesis in disomic 4Mg addition plants also is normal. However, chromosome breakage and anaphase bridges were observed at ana/telophase of the first (29%) and second (11%) pollen mitosis in monosomic 4Mg addition plants. Gc-induced multicentric and ring chromosomes can be transmitted to the offspring and initiate breakage fusion bridge (BFB) cycles in dividing root tip meristem cells of the derived sporophytes. The fate of multicentric and ring chromosomes was analyzed in root meristems at different time intervals after seed germination. The majority of the BFB cycles ceased about 32 days after germination. Broken chromosome ends were healed either by the fusion of a centric and an acentric fragment forming terminal translocation chromosomes or as deficiencies or telocentric chromosomes. Lack of cytologically detectable telomeric repeats at the stabilized newly broken termini suggests that chromosome healing by addition of telomeric repeats may be a gradual process.

Centromere↗