Nucleolus organizer competition in Triticum aestivum — Aegilops umbellulata chromosome addition lines

Summary The nucleolar organizer activity of wheat (Triticum aestivum, AABBDD) and Aegilops umbellulata (UU) chromosomes have been analyzed in the complete set of the chromosome addition lines by using a highly reproducible silver-staining procedure. Chromosomes 1U and 5U produce the partial inactivation of wheat nucleolar organizer chromosomes 6B, 1B and 5D. The chromosomes D and G from Ae. umbellulata, which are not SAT-chromosomes, seem to specifically influence the activity of wheat NORs. The predominant status of the U genome with respect to nucleolar competition in the Triticeae is confirmed.     

Molecular cytogenetic identification of a wheat–Psathyrostachys huashanica Keng 5Ns disomic addition line with stripe rust resistance

We developed a new stripe rust resistant line of common wheat–Psathyrostachys huashanica Keng (2n = 2x = 14, NsNs) from a cross between wheat cv. 7182 and P. huashanica via embryo culture, and we refer to this line as 3-8-10-2. We characterized this new line by cytology, genomic in situ hybridization (GISH), EST-SSR, EST-STS, and disease resistance screening. GISH using P. huashanica genomic DNA as the probe indicated that a pair of Ns chromosomes with strong hybridization signals was introduced into 3-8-10-2. We screened 255 EST-SSR and EST-STS multiple-loci markers from seven wheat homoeologous groups in the parent lines. Of these, 90 markers were polymorphic with a polymorphism frequency of 40 %, while two EST-SSR markers and six EST-STS markers located on wheat chromosome group 5 produced specific bands in P. huashanica and 3-8-10-2, respectively. This suggested that the introduced Ns chromosome pair belonged to homoeologous group 5, which was identified using new genome-specific markers. After inoculation with stripe rust isolates, 3-8-10-2 exhibited stripe rust resistance that probably originated from its P. huashanica parent. 3-8-10-2 can be used as a donor source for introducing novel disease resistance genes into wheat during breeding programs with the assistance of molecular and cytogenetic markers. Moreover, 3-8-10-2 had improved agronomic characteristics compared with its parents. Therefore, the addition line could be exploited as an important bridge for wheat breeding and chromosome engineering.     

Molecular cytogenetic evidence for a high level of chromosome pairing among different genomes in Triticum aestivum–Thinopyrum intermedium hybrids

Intergeneric hybrids (ABDJJ^sS genomes) were made between Triticum aestivum cv. Chinese Spring (CS) and Thinopyrum intermedium. Genomic in situ hybridization (GISH) using genomic DNA probes from Pseudoroegneria libanotica (Hackel) D.R. Dewey (genome S, 2n = 14) was used to study chromosome pairing among J, J^s, S and wheat ABD genomes in the hybrids. It was shown that in the hexaploid (ABDJJ^sS) hybrids, high pairing occurred among wheat chromosomes and among Thinopyrum chromosomes. A closer relationship was observed among the three genomes of Th. intermedium than among the three genomes of T. aestivum. It was further discerned that S genome chromosomes paired with J- and J^s-genome chromosomes at a high frequency. The frequency of heterologous pairing between S and J or S and J^s chromosomes was higher than those between J and J^s chromosomes, indicating that the S-genome was more closely related with these two genomes. Our results provided direct molecular cytogenetic evidence for the hypothesis that S-genome chromosomes are genetically similar to the J-genome chromosomes and, therefore, genetic exchange between these genomes is possible. The discovery of a close relationship among S, J and J^s genomes provides valuable markers for molecular cytogenetic analyses using S-genomic DNA probes in monitoring the transfer of useful traits from Thinopyrum species into wheat. Received: 23 August 2000 / Accepted: 5 September 2000     

A self-fertile trigeneric hybrid,Triticum aestivum ×Agropyron michnoi ×Secale cereale

Trigeneric hybrids between the (Triticum aestivum ×Agropyron michnoi) F₁ (CM, 2n=5x=35; ABDPP) and two winter rye (Secale cereale L., 2n=2x=14; RR) cultivars, Wugong 774 and AR-132, were synthesized. Such trigeneric hybrids could be used to transfer resistance genes for powdery mildew from rye to CM and subsequently to common wheat and to identify (1) the effects of the P genome ofAgropyron on the self-fertility of the hybrids and (2) the differences in genetic background between rye cultivars with marked differences in pollinating habit. The trigeneric hybrids varied widely in morphology and showed a high level of resistance to such diseases as barley yellow dwarf virus (BYDV), stripe rust, leaf rust, stem rust, and powdery mildew. Selfed and many backcross derivatives were obtained from the trigeneric hybrids. The results indicated that rye cvs Wugong 774 and AR132 arose from different gene pools and that the P genome ofAgropyron carries gene(s) responsible for chromosome segregation, leading to functional gamete formation and self-fertility of the hybrids. The F₂ and BC₁ plants could be obtained in two ways — fusion of the unreduced gametes and the assumed apomixis of unreduced female gametes in the trigeneric hybrid plant II-4 — which indicates that this trigeneric hybrid may be a special genetic stock. Chromosome pairing in the trigeneric hybrids and ways of producing wheat/rye and wheat/Agropyron translocations are discussed.     

Molecular and cytogenetic characterization of an Oryza officinalis–O. sativa chromosome 4 addition line and its progenies

The wild species Oryza officinalis Wall. ex Watt (2n = 24, CC) is a valuable genetic resource for rice (O. sativa L., 2n = 24, AA) breeding and genomics research. Genomic in situ hybridization (GISH) and molecular approaches were used to determine the nature and composition of the additional chromosome in a monosomic alien addition line (MAAL) of O. officinalis and its backcross progenies. The extra wild species chromosome in the MAAL (2n = 2x = 25) was a mosaic one, comprising of the long arm of chromosome 4 from O. officinalis and the short arm from O. sativa. Comparative analysis showed that O. sativa and O. officinalis shared high synteny of restriction fragment length polymorphism (RFLP) markers and low synteny of simple sequence repeat (SSR) markers. A DNA methylation alteration was revealed at C619 in the MAAL and progenies. Analysis of progenies of the MAAL indicated that introgression segments were small in size and introgression was not evenly distributed along the long arm. One recombination hot spot between C513 and RG177 was identified, which is in a gene-rich region.     

C-banding pattern and polymorphism of Aegilops caudata and chromosomal constitutions of the amphiploid T. aestivum — Ae. caudata and six derived chromosome addition lines

Summary C-banding patterns were analysed in 19 different accessions of Aegilops caudata (= Ae. markgrafii, = Triticum dichasians) (2n = 14, genomically CC) from Turkey, Greece and the USSR, and a generalized C-banded karyotype was established. Chromosome specific C-bands are present in all C-genome chromosomes, allowing the identification of each of the seven chromosome pairs. While only minor variations in the C-banding pattern was observed within the accessions, a large amount of polymorphic variation was found between different accessions. C-banding analysis was carried out to identify Ae. caudata chromosomes in the amphiploid Triticum aestivum cv Alcedo — Ae. caudata and in six derived chromosome addition lines. The results show that the amphiploid carries the complete Ae. Caudate chromosome complement and that the addition lines I, II, III, IV, V and VIII carry the Ae. caudata chromosome pairs B, C, D, F, E and G, respectively. One of the two SAT chromosome pairs (A) is missing from the set. C-banding patterns of the added Ae. caudata chromosomes are identical to those present in the ancestor species, indicating that these chromosomes are not structurally rearranged. The results are discussed with respect to the homoeologous relationships of the Ae. caudata chromosomes.     

Two isovitexin 2″-O-glycosides from primary leaves of Secale cereale

Two isovitexin 2″-O-glycosides have been isolated from primary leaves of rye and identified as isovitexin 2″-O-arabinoside and isovitexin 2     

Molecular characterization of a wheat–Psathyrostachys huashanica Keng 2Ns disomic addition line with resistance to stripe rust

We characterized a wheat–Psathyrostachys huashanica derived line 3-6-4-1 based on genomic in situ hybridization (GISH), molecular marker analysis, and agronomic trait evaluations. The GISH investigations showed that the 3-6-4-1 contained 42 wheat chromosomes and a pair of P. huashanica chromosomes. The homoeologous relationships of the introduced P. huashanica chromosomes were determined using EST-STS multiple loci markers from seven wheat homoeologous groups in the parents and the addition line. Twelve EST-STS markers located on the homoeologous group 2 chromosomes of wheat amplified polymorphic bands in 3-6-4-1, which were unique to P. huashanica. An introduced Ns chromosome pair that belonged to homoeologous group 2 was identified using chromosome-specific markers. Inoculation with isolates of the stripe rust pathotypes, CYR31, CYR32, and SY11-14, and mixed races (CYR31, CYR32, and SY11-14) in the seeding and adult stage, respectively, showed that 3-6-4-1 was generally resistant to stripe rust, which was probably attributable to its P. huashanica parent. We also compared a complete set of wheat–P. huashanica disomic addition lines (1Ns–7Ns, 2n = 44 = 22II) to assess their agronomic traits and morphological characteristics, which showed that 3-6-4-1 had improved spike traits compared with its parents. The P. huashanica 2Ns chromosome-specific molecular markers in 3-6-4-1 could be useful for marker-assisted selection in breeding programs to combat stripe rust. This line can be used as a donor source to introduce novel excellent genes from P. huashanica into wheat to widen its genetic diversity, thereby providing new germplasms for wheat breeding.     

Genetic analysis of transgenome structure and size of chromosome—mediated gene transfer lines

The TK-selected chromosome-mediate gene transfer lines were analysed using DNA dot blot method G-11 banding and in situ hybridization.The results showed that CMGT can provide a wide variety of intermediate size of the transgenome from greater than 80,000kb to less than 2,000kb,Some of transfectants are intergrated into mouse chromosome which can be detected by G-11 banding and in situ hybridization.     

Marker-assisted characterization of durum wheat Langdon–Golden Ball disomic substitution lines

The durum wheat cultivar ‘Golden Ball’ (GB) is a source of resistance to wheat sawfly due to its superior solid stem. In the late 1980s, Dr. Leonard Joppa developed a complete set of 14 ‘Langdon’ (LDN)–GB disomic substitution (DS) lines by using GB as the chromosome donor and LDN as the recipient. However, these substitution lines have not been previously characterized and reported in the literature. The objectives of this study were to confirm the authenticity of the substituted chromosomes and to analyze the genetic background of the 14 LDN–GB DS lines with the aid of molecular markers, and to further use the substitution lines for chromosomal localization of DNA markers and genes conferring the superior stem solidness in GB. Results from simple sequence repeat marker analysis validated the authenticity of the substituted chromosomes in 14 LDN–GB DS lines. Genome-wide scans using the target region amplification polymorphism (TRAP) marker system produced a total of 359 polymorphic fragments that were used to compare the genetic background of substitution lines with that of LDN. Among the polymorphic TRAP markers, 134 (37.3%) and 185 (51.5%) were present in LDN and GB, respectively, with only 10 (2.8%) derived from Chinese Spring. Therefore, marker analysis demonstrated that each LDN–GB DS line had a pair of chromosomes from GB with a genetic background similar to that of LDN. Of the TRAP markers generated in this study, 200 were successfully assigned to specific chromosomes based on their presence or absence in the corresponding LDN–GB DS lines. Also, evaluation of stem solidness in the substitution lines verified the presence of a major gene for stem solidness in chromosome 3B. Results from this research provides useful information for the utilization of GB and LDN–GB DS lines for genetic and genomic studies in tetraploid wheat and for the improvement of stem solidness in both durum and bread wheat.     

Generation and characterization of Brassica rapa ssp. pekinensis – B. oleracea var. capitata monosomic and disomic alien addition lines

Journal of Genetics - Five monosomic alien addition lines (MAALs) of Brassica rapa ssp. pekinensis – B. oleracea var. capitata were obtained by hybridization and backcrossing between B. rapa...     

Production of wheat–<Emphasis Type="Italic">Leymus racemosus</Emphasis> chromosome addition lines

We produced ten wheat–Leymus racemosus chromosome addition lines. Eight chromosomes (A, C, F, H, I, J, k, and l) were recovered as disomic additions and two (E and n) as monosomic. Screening of the addition lines was done by fluorescence in situ hybridization using several repetitive sequences as probes, which allowed us to identify different L. racemosus chromosomes and find many aberrant L. racemosus chromosomes. RFLP analysis revealed partial conservation of homology between L. racemosus and wheat chromosomes, depending on the homologous groups. Chromosomes A and l belonged to group 2, chromosomes C and I to group 5, and chromosome k to group 6. Chromosomes H and J were a mixture of groups 1, 3, and 7, chromosome n of groups 3 and 7, and chromosomes E and F were of group 4 and others. Comparison of our addition lines with other addition lines showed large cytological differences.Communicated by B. Friebe     

Molecular cytogenetic characterization of the spring triticale line 131/7 carrying a rye—wheat translocation

The chromosomal composition of the spring triticale line 131/7 carrying a rye—wheat translocation was studied using GISH, C-banding, and SSR analysis. The complex analysis revealed the presence of a pair of 2D chromosomes and T2RS.2RL-2BL translocation in the genome of the hexaploid triticale line 131/7. The break point in the translocated chromosome is between the markers Xwmc592 and Xwmc441, loci 63.9 cM and 76.8 cM on the linkage map (Wheat, Consensus SSR, 2004 NA-SSR-2004-2B) and in the region C-2BL2-0.36 on the physical map (Wheat, Physic al, SSR). The analysis of the line enables its use in breeding programs and in genetic studies.     

Molecular cytogenetic identification of a wheat–<Emphasis Type="Italic">Aegilops geniculata</Emphasis> Roth 7M<Superscript>g</Superscript> disomic addition line with powdery mildew resistance

Aegilops geniculata Roth is an important germplasm resource for the transfer of beneficial genes into common wheat (Triticum aestivum L.). A new disomic addition line NA0973-5-4-1-2-9-1 was developed from the BC₁F₆ progeny of the cross wheat cv. Chinese Spring (CS)/Ae. geniculata SY159//CS. We characterized this new line by morphological and cytogenetic identification, analysis of functional molecular markers, genomic in situ hybridization (GISH), fluorescence in situ hybridization (FISH), and disease resistance evaluation. Cytological observations suggested that NA0973-5-4-1-2-9-1 contained 44 chromosomes and formed 22 bivalents at meiotic metaphase I. The GISH investigations showed that the line contained 42 wheat chromosomes and a pair of Ae. geniculata chromosomes. EST-STS multiple loci markers and PLUG (PCR-based landmark unique gene) markers confirmed that the introduced Ae. geniculata chromosomes belonged to homoeologous group 7. FISH identification suggested that NA0973-5-4-1-2-9-1 possessed an additional pair of 7M^g chromosomes, and at the same time, there were structural differences in a pair of 6D chromosomes between NA0973-5-4-1-2-9-1 and TA7661 (CS-AEGEN DA 7M^g). After inoculation with powdery mildew (Blumeria graminis f. sp. tritici, Bgt) isolates E09, NA0973-5-4-1-2-9-1 exhibited a powdery mildew resistance infection type different from that of TA7661, and we conclude that the powdery mildew resistance of NA0973-5-4-1-2-9-1 originated from its parent Ae. geniculata SY159. Therefore, NA0973-5-4-1-2-9-1 can be used as a donor source for introducing novel disease resistance genes into wheat during breeding programs with the assistance of molecular and cytogenetic markers.     

The impact of wood-derived biochar on the survival of Trichoderma spp. and growth of Secale cereale L. in sandy soil

The interrelations between biochar (BC) and soil microbiota remain unclear. Addressing this will be important for understanding how BC affects soil properties and plant growth. Here, we tested the influence of wood-derived BC with immobilised Trichoderma viride on rye Secale cereale L. in sandy soil. We found that the addition of BC leads to a significant (P?2+ and Mg²⁺, as well as a decrease in the concentration of Al³⁺, irrespective of BC particle size and the presence of T. viride. Plant growth was stimulated in the presence of small (<2?mm) particle-sized BC. Fungal diversity, as well as an absolute and relative abundance of Trichoderma spp., was tested by cultivation-dependent methods and qPCR. Both of these approaches revealed a positive effect of BC on the survival of Trichoderma spp. under the tested conditions, especially in the presence of a small particle size fraction.     

Isolation and chromosomal distribution of a novel Ty1-copia-like sequence fromSecale, which enables identification of wheat—Secale africanum introgression lines

A repetitive sequence of 411 bp, named pSaO5₄₁₁, was identified in theSecale africanum genome (R^a) by random amplified polymorphic DNA (RAPD) analysis of wheat and wheat—S. africanum amphiploids. GenBank BLAST search revealed that the sequence of pSaO5₄₁₁ was highly homologous to a part of a Ty1-copia retrotransposon. Fluorescence in situ hybridization (FISH) analyses indicated that pSaO5₄₁₁ was significantly hybridized toS. africanum chromosomes of a wheat—S. africanum amphiploid, and it was dispersed along theSecale chromosome arms except the terminal regions. Basing on the sequence of pSaO5₄₁₁, a pair of sequence-characterized amplified region (SCAR) primers were designed, and the resultant SCAR marker was able to target both cultivated rye and the wildSecale species, which also enabled to identify effectively theS. africanum chromatin introduced into the wheat genome.     

Review: The cytogenetic and molecular architecture of chromosome 1R—one of the most widely utilized sources of alien chromatin in wheat varieties

Conclusions The evolution of chromosome 1R has resulted in a structure with genes that are similar enough, qualitatively and quantitatively, to those in wheat to allow substitution for wheat chromosomes. The sequences dispersed between the genes, and those arranged tandemly in large blocks, have however undergone major quantitative changes (and possibly qualitative changes as well). Amplification events since the time that wheat and rye have been separated in an evolutionary sense have generated arrays of repetitive sequence families that characterize the rye chromosomes (including 1R) and distinguish them from wheat chromosomes. The genetic mapping of chromosome 1R at the level of DNA has provided a range of probes for the study of 1R chromosome segments as they are manipulated in commercial wheat cultivars.The extensive utilization of chromosome 1R as a source of disease resistance genes in wheat implies that rye genes are normally expressed in a wheat background. This is, however, not always the case and a particularly well studied example is the suppression of rRNA gene expression (reviewed in Applels et al. 1986a). These isolated examples of modified expression of rye genes in a wheat background are presumably the result of evolutionary change in the rye promoter regions resulting in their reduced competitiveness when combined with wheat genes in a common cytoplasmic environment. The cytoplasm of wheat plants carrying rye chromosome fragments would be dominated by protein molecules adapted to wheat promoters.     

The mechanism of cytogenetic genotoxicity of exogenous glutathione in V-79 cells in vitro—implication of hydrogen peroxide and general traits of oxidative chromosome damage

The mechanism of cytogenetic genotoxicity (clastogenicity, induction, cell cycle delay) of 10^–3 M glutathione in V79-E cells, as described by Thust and Bach (1985), was studied in detail by using different treatment conditions. It was found that I-cystine is the essential cofactor in the incubation system. Catalase, but not superoxide dismutase, abolished the genotoxic effect, and the iron chelator desferoxamine, as well as the hydroxyl radical scavenger mannitol, diminished the activity. It is suggested that glutathione, in combination with V79-E cells and cystine, forms a hydrogen peroxide-generating system which provokes the adverse effects. Glutathione as well as I-cysteine and 2-mercaptopropionylglycine, which were checked for comparison, show a paradoxic genotoxicity, i.e., at 10^–2 M the effects return almost to the level of controls. Concentration dependence and other criteria of cytogenetic genotoxicity observed with glutathione show obvious similarities to those of other oxidatively acting agents and reveal striking differences to the cytogenetic effects of typical genotoxins.Abbreviations BUdR 5-bromodeoxyuridine - EMEM Eagle's minimum essential medium - GSH glutathione - MPG 2-mercaptopropionylglycine - SCE sister chromatid exchange - SOD superoxide dismutase - TPA 12-0-tetradecanoylphorbol-13-acetate     

The Effect of Rye Chromosomes on Callus Induction and Regeneration in Callus Cultures of Immature Embryos of Wheat–Rye Substitution Lines,Triticum aestivum L. Cultivar Saratovskaya 29–Secale cereale L. Cultivar Onokhoiskaya

The effect of individual rye chromosomes on the induction of callus and the character of its regenerating capacity was studied with cultured immature embryos of wheat–rye (Triticum aestivum L. cv. Saratovskaya 29–Secale cereale L. cv. Onokhoiskaya) substitution lines. The genotypic diversity of the substitution lines proved to significantly affect variation of parameters characterizing the major types of callus cultures, that is, frequencies of embryogenic calli, which are capable of shoot regeneration, and of morphogenic calli, which produce root structures. Functioning in the genotypic background of common wheat cultivar Saratovskaya 29, chromosomes 2R and 3R of rye cultivar Onokhoiskaya stimulated significantly the induction of embryogenic callus highly capable of shoot regeneration. Rye chromosome 2R present in place of chromosome 2D in the common wheat genome suppressed the induction of callus producing root structures. Rye chromosomes 1R and 6R suppressed the induction of embryogenic callus capable of shoot regeneration.     

中国春(T.aestivum)与黑麦(Secale cereale)可交配性基因的染色体定位再研究及其与Ta_1基因的关系

利用中国春-Cheyenne二体代换系及中国春缺体-四体、Ta1中国舂、兰州黑麦等,对中国春可交配性基因的定位及与Ta1的关系进行了研究。在中国春染色体2B、6D及7A上,第一次发现了可交配性基因kr存在,同时证明了Ta1基因与kr基因不存在相互干挠。在北京条件下利于kr基因表达。