Effect of alien 5R(5A) chromosome substitution on ear-emergence time and winter hardiness in wheat-rye substitution lines

Ear emergence time and response to vernalization were investigated in 12 alien substitution lines in which a pair of chromosomes 5A of recipient spring wheat cultivars was replaced by a pair of chromosomes 5R of Siberian spring rye ‘Onokhoiskaya’. The recipients were 12 spring cultivars of common wheat, each carrying different Vrn genes. Spring rye ‘Onokhoiskaya’ had the Sp1 (now called Vrn-R1) gene for spring growth habit located on chromosome 5R, but its expression was weaker. The Vrn-R1 gene had no effect on growth habit, ear emergence time and response to vernalization in wheat-rye substitution lines. Ears emerged significantly later in the 5R(5A) alien substitution lines than in the recipient wheat cultivars with the Vrn-A1/Vrn-B1/vrn-D1 or Vrn-A1/vrn-B1/Vrn-D1 genotypes. No difference in ear emergence time was found between most of the 5R(5A) alien substitution lines and the cultivars carrying the recessive vrn-A1 gene. The presence of the Vrn2a and Vrn2b alleles at the Vrn2 (now called Vrn-B1) locus located on wheat chromosome 5B was confirmed.The replacement of chromosome 5A by chromosome 5R in wheat cultivars ‘Rang’ and ‘Mironovskaya Krupnozernaya’, which carries the single dominant gene Vrn-A1, converted them to winter growth habit. In field studies near Novosibirsk the winter hardiness of 5R(5A) wheat–rye substitution lines of ‘Rang’ and ‘Mironovskaya Krupnozernaya’ was increased by 20–47% and 27–34%, respectively, over the recurrent parents.     

QTL mapping of the domestication traits pre-harvest sprouting and dormancy in wheat (<Emphasis Type="BoldItalic">Triticum aestivum L.</Emphasis>)

A set of 75 recombinant inbred lines (RILs) of the ITMI mapping population was grown under field conditions in Gatersleben. The lines were evaluated for the domestication traits pre-harvest sprouting and dormancy (germinability). Main QTLs could be localized for pre-harvest sprouting on chromosome 4AL and dormancy on chromosome 3AL. In addition, 85 Triticum aestivum cv. “Chinese Spring”-Aegilops tauschii introgression lines grown under greenhouse conditions were researched. No QTL could be found for pre-harvest sprouting but a major QTL could be detected for dormancy on chromosome 6DL.     

黄淮冬麦区小麦冬、春性改良及分子标记辅助选择技术初探

通过对小麦品种石麦12春化特性的遗传和分子标记研究,探索黄淮冬麦区小麦冬、春性改良途径和分子标记辅助选择技术。石麦12与冬性品种石家庄8号杂交后代F_2:3株系中的春性株系、冬春性分离株系、冬性株系的分离比例符合1∶2∶1,表明石麦12具有一个显性春化基因,经已知春化基因的基因特异性标记鉴定为Vrn-D1。利用Vrn-D1的基因特异性标记对上述F_2:3株系进行冬、春性鉴定的结果与表型鉴定结果一致,说明该分子标记可用于小麦冬、春性改良中对Vrn-D1的辅助选择。在高海拔、长日照地区夏播是小麦冬、春性表型鉴定的一个快速、简便途径。     

Cytological and Microsatellite Mapping of the Gene for Brittle Rachis in a Triticum Aestivum-Aegilops Tauschii Introgression Line

Summary Aegilops tauschii (Coss.) Schmal. (2n = 2x = 14, DD), a wild relative of wheat has been considered to be a valuable source of variation for improvement of cultivated wheats. However, undesirable genes can be incorporated into the cultivated varieties from wild relatives. The spontaneous spike shattering caused by the brittle rachis character is of adaptive value in wild grass species, but not in cultivated varieties. The rachis of R-61, which was derived from the cross of T. aestivum cv. Bet Hashita with an accession of Ae. tauschii, was brittle. Using telosomic stocks, the brittle rachis gene Br ⁶¹ (tentatively designated) of B-61 was located on the short arm of chromosome 3D and the distance of Br ⁶¹ to the centromere was 31.9 cM. The distance of Br ⁶¹ from the centromeric marker Xgdm72 was 25.3 cM on the short arm of chromosome 3D. The location of Br ⁶¹ was similar to Br ₁ whose location was determined by telosomic mapping and microsatellite mapping. Discrepancy of disarticulation type was found between R-61 and Aegilops tauschii suggesting that the recombination around the regions of Br ₁ locus and Br ^t locus created the wedge type disarticulation of R-61.     

Variation of PGM and IDH isozymes for identification of alfalfa varieties

Growth habit, heading date and Vrn genotypewere examined for wheat landraces cultivated in China,Korea and Japan, to study their ecogeographicaldifferentiation in east Asia. Spring type landracesaccounted for 43.6% of the whole, and the frequencyvaried between the localities, being closely relatedto the degree of winter coldness. Spring typelandraces mainly adapted to north and south Chinawhere average January temperature is under –7 ^°Cand over 4 ^°C, respectively. On the contrary,winter type adapted to areas of average Januarytemperature from –7 ^°C to 4 ^°C. As toheading date, significant difference was not observedbetween spring and winter type landraces but betweenlocalities, and those cultivated in north China weresignificantly later in heading. It is thereforeindicated that spring type mainly adapts to areaswhere wheat is sown in spring to avoid frost injury,and where winter temperature is not low enough tovernalize winter type wheat. Genetic analysis forspring type landraces showed that the relativefrequency of four Vrn genes was different witheach other. Vrn3 was most widely and frequentlyfound among the four genes, followed by Vrn1 andVrn2. Only seven landraces proved to be thecarrier of Vrn4. The frequency was alsodifferent between localities. Genotype with Vrn1plus other dominant gene(s) adapted to spring sowingto avoid severely cold winter in north China, whilegenotype with only Vrn3 adapted to winter sowingin south China and southwest Japan. It is thereforeconcluded that at least three ecotypes, differing ingrowth habit and Vrn genotype, areallopatrically distributed in east Asia, as a resultof adaptation to winter coldness in each locality.     

Cytological and microsatellite mapping of the genes determining liguleless phenotype in durum wheat

Liguleless phenotypes of wheat lack ligule and auricle structures on all leaves of the plant. Two recessive genes principally control the liguleless character in tetraploid wheat. The F₂ progenies of k17769 (liguleless mutant)/Triticum dicoccoides and k17769/T. dicoccum segregated in a 15:1 ratio, whereas the F₂ progenies of k17769/T. durum and k17769/T. turgidum segregated in a 3:1 ratio. A new gene, lg₃, was found on chromosome 2A. Segregation of F₂ progenies between k17769 and chromosome substitution lines for homoeologous group 2 chromosomes suggested that the liguleless genotype had occurred by mutation at the lg₃ locus on chromosome 2A, and then by mutation at the lg₁ locus on chromosome 2B, in the process of domestication of tetraploid wheat. The gene (lg₁) was linked to Tc₂ (11.9 cM), which determines phenol colour reaction of kernels, on the long arm of chromosome 2B. The distance of lg₁ to the centromere was found to be 60.4 cM, and microsatellite mapping established the gene order, centromere – Xgwm382 – Xgwm619 – Tc₂ – lg₁ on the long arm of chromosome 2B.     

The use of wheat/goatgrass introgression lines for the detection of gene(s) determining resistance to septoria tritici blotch (Mycosphaerella graminicola)

At the IPK Gatersleben a series of 85 bread wheat (T. aestivum)/goatgrass (Aegilops tauschii) introgression lines was developed recently. Based on the knowledge that chromosome 7D of this particular Ae. tauschii is a donor of resistance to septoria tritici blotch (Mycosphaerella graminicola), a sub-set of thirteen chromosome 7D introgression lines was investigated along with the susceptible recipient variety ‘Chinese Spring’ (CS) and the resistant donor line ‘CS (Syn 7D)’. The material was inoculated with two Argentinian isolates of the pathogen (IPO 92067 and IPO 93014) at both the seedlings (two leaf) and adult (tillering) stages at two locations over 2 years (2003, 2004). The resistance was effective against both isolates and at both developmental stages, and the resistance locus maps to the centromeric region of chromosome arm 7DS. On the basis of its relationship with the microsatellite marker Xgwm44, it is likely that the gene involved is Stb5. Stb5 is therefore apparently effective against M. graminicola isolates originating from both Europe and South America.     

Expression of nucleolus, endosperm storage proteins and disease resistance in an amphiploid between Aegilops tauschii and Secale silvestre

Cytology and gene expression of an amphiploid between Aegilops tauschiiL., native to China, and Secale silvestre L. were studied to reveal the genomic interaction between the donor species. High frequencies of aneuploids were observed in the progenies of the amphiploid, indicating its cytological instability. Feulgen staining and Giemsa-C banding showed that only the nucleolar organizing region from chromosome 5D of Ae. tauschii existed in the amphiploid (2n = 28). The nucleolus of S. silvestre was not observed. Endosperm storage protein electrophoresis indicated most gliadin and glutenin genes from both parents were expressed in the endosperm of the amphiploid. When inoculated by wheat stripe rust and powdery mildew isolates,the amphiploid did not express the resistance from its Secale parent,suggesting the presence of disease resistance suppressor(s) in the D genome of Ae. tauschii as well as nucleolar organizer suppressors. This revised version was published online in July 2006 with corrections to the Cover Date.     

Telosomic mapping of the homoeologous genes for the long glume phenotype in tetraploid wheat

Triticum turgidum ssp. polonicum and T. ispahanicum were characterized by the long glume phenotype. P ₁ gene determines the long glume phenotype of T. polonicum, and locates on chromosome 7A. T. ispahanicum has shorter glume than T. polonicum and the long glumephenotype is determined by P ₂ gene located on chromosome 7B. In the present study, aneuploid stocks of `Langdon' durum wheat were used to map the genes, P ₁ and P ₂. P ₁ located on the long arms of chromosome 7A and its map distances from the centromere was 14.5 cM. On chromosome 7B, four loci located as cc (chocolate black chaff) – Pc (purple culm) – centromere – P ₂ – cn-BI (chlorina). P ₂ located on the long arms of chromosome 7B and its map distances from the centromere was 11.7 cM. It was suggested that a paralogous gene set conditions long glume phenotype in the homoeologous group 7 chromosomes. The P ₁ and P ₂ genes may be useful as genetic markers in tetraploid wheat.     

An intersubgeneric hybrid between Glycine tomentella Hayata and the soybean,G. max (L.) Merr.

Summary The objective of the present paper is to provide information on the morphology and cytology of an intersub-generic hybrid (2n=59) between Glycine tomentella Hayata (2n=78) and G. max (L.) Merr. (2n=40) obtained through in vitro immature seed culture. The hybrid plant was slow in vegetative growth and twinning like the female parent but morphologically was intermediate between both parents for several traits. At metaphase I, the average chromosome associations and ranges for 25 cells were 44.0 I (37–51)+7.5 II (3–11). The plant was completely pollen and seed sterile. The present investigation suggests that wild perennial Glycine species can be exploited as either the male or female parent in wide hybridization programs with the soybean, G. max.     

An induced brachytic mutant of chickpea and its possible use in ideotype breeding

Mutations were induced in chickpea (Cicer arietinum L.) cultivar ‘JG 315’ through treatment of seeds with ethyl methane sulphonate (EMS). One of the mutants, named JGM 1, had brachytic growth (compact growth), characterized by erect growth habit, thick and sturdy stem, short internodal and interleaflet distances and few tertiary and later order branches. It was isolated from M₂ derived from seeds treated with 0.6% EMS for 6 h. Segregation analyses in F₂ progenies of its crosses with normal chickpea genotypes (JG 315, ICC 4929, and ICC 10301) suggested that a single recessive gene controlled brachytic growth in JGM 1. This gene was not allelic to the br gene for brachytic growth in spontaneous brachytic mutant E100YM. Thus, the gene for brachytic growth in JGM 1 was designated br2 and the br gene of E100YM was redesignated br1. Efforts are being made to use JGM 1 in development of a plant type with short internodes and erect growth habit. Such plant type may resist excessive vegetative growth in high input (irrigation and fertility) conditions and accommodate more plants per unit area.     

Chromosomal and genic structure of Brassicoraphanus related to seed fertility and the presentation of an instance of improvement of its fertility

Summary In order to elucidate the mechanism of low fertility of Brassicoraphanus, i.e., amphidiploids between Brassica japonica Sieb. and Raphanus sativus L., the chromosome number of 253 plants was studied during the 3rd–9th generations for their seed fertility. Meiotic irregularity showed no connection with degree of sterility. Brassicoraphanus consisted of euploids (2n=38), hyperploids (2n=39–43) and hypoploids (2n=34–37) with white or yellow flowers. The number of plants was highest in euploids and became lower as the chromosome number diverged from the euploid number. Further, seed fertility was highest and the range of its variation widest in euploids. The seed fertility of aneuploids became lower and its variation narrower in proportion to the number of chromosomes additional to or missing from the euploid number. Yellow-flowered plants were superior in seed fertility to white-flowered plants. Seed fertility of plants is primarily affected by their chromosome numbers and secondarily modified by genic effects. As a whole, seed fertility of Brassicoraphanus increased gradually and its variation widened with the advance of generations. This was explained mainly by the increase of balanced combinations of genes.     

Colchine-induced aneuploids from cell culture of sugarcane

Summary Sugarcane (Saccharum spp.) clones are amenable to gross chromosome manipulation due to their high polyploid nature (2n=100–120). This study was conducted to analyze the effects on plant morphology of altering chomosome number via callus culture. Callus cultures from clone H69-9092 were established, and plants were regenerated following colchicine treatment of cultured cells. Cytological analysis showed that variant somaclones were aneuploids with a wide range in chromosome numbers (2n=66–196). Some 22 visually distinct somaclones were planted in 1.35 m² plots with five replications to compare morphological and quality characteristics with H69-9092 at 8 months of growth. Extreme morphological variation was observed between somaclones, but coefficients of variation for quality factors-fibers %, refractometer solids %, pol %, and juice purity-and stomatal length were smaller than those for morphological traits associated with stalk volume and leaf area. Significant negative correlations were found between chromosome number and most morphological traits, e.g., stalk length (r=-0.58), number (r=-0.69), diameter (r=-0.54) and volume (r=-0.65); internode length (r=-0.57); and leaf area (r=-0.48). A positive correlation was found between chromosome number and stomatal length (r=-0.66). No significant correlations were found between chromosome number and quality factors. Aneuploids with higher than parental chromosome number had reduced growth. However, depression in growth was generally not observed in somaclones lower in chromosome number than the parent.Published with the approval of the Director as Paper No. 598 in the Journal Series of the Experiment Station, Hawaiian Sugar Planters' Association.     

Genetic mapping of the genes for glaucous leaf and tough rachis in Aegilops tauschii, the D-genome progenitor of wheat

Glaucous leaf and tough rachis phenotypes are rare in Aegilops tauschii, the D genome donor to common wheat (Triticum aestivum). The genes for glaucous leaf and tough rachis were mapped using microsatellite probes in A. tauschii. The glaucous phenotype was suppressed by the inhibitor W2^I located on chromosome 2DS. The gene W2^I was mapped to the distal part of 2DS, and was unlinked to the centromere. This suggests that the distance of the W2^I locus from the centromere was maintained during the evolution of hexaploid wheat from its diploid progenitors as the inhibitor gene is at the same position in A. tauschii and bread wheat. The Br^t (Brittle rachis of A. tauschii) locus was located on the short arm of chromosome 3D, and was 19.7 cM from the centromeric marker, Xgdm72.3D. Br^t causes breakage of the spike at the nodes, thus creating barrel-shaped spikelets, while Br₁ in hexaploid wheat causes breakage above the junction of the rachilla with the rachis such that a fragment of rachis is attached below each spikelet.     

Production of intergeneric hybrid plants between <Emphasis Type="Italic">Sandersonia aurantiaca</Emphasis> and <Emphasis Type="Italic">Gloriosa rothschildiana</Emphasis> via ovule culture (Colchicaceae)

Intergeneric hybrid plants between Colchicaceous ornamental plants, Sandersonia aurantiaca and Gloriosa rothschildiana, have successfully been produced via ovule culture. After 5 days of reciprocal cross-pollination, a few pollen tubes were observed in the ovary. Although seeds were obtained in both reciprocal cross-combinations, they did not germinate under ex vitro conditions. Ovules with placental tissues isolated 14 days after cross-pollination of S. aurantiaca × G. rothschildiana were cultured on a medium containing 0.01 mg l^–1 each of -naphthaleneacetic acid (NAA) and 6-benzyladenine (BA), on which 41.5% of ovules swollen and produced callus-like structures within 10 weeks. When such swollen ovules were transferred to a medium containing 0.1 mg l^–1 each of NAA and BA, 7.5% of the initially cultured ovules produced rhizome-like structures within 6 weeks. Among the rhizome-like structures, those derived from two independent ovules (3.7% of the initially cultured ovules) produced multiple shoots following transfer to a medium containing 0.25 mg l^–1 NAA and 2.5 mg l^–1 BA. Multiple shoot-derived plantlets were established on a plant growth regulator-free medium, and they were successfully transplanted to pots. Early verification of their hybridity was accomplished by flow cytometry (FCM) analysis, chromosome observation and rDNA analysis.     

Cytogenetic analyses of sugarcane relatives (Andropogoneae: Saccharinae)

Summary Meiosis was studied in 31 wild Saccharum relatives, including Erianthus (8 clones), Miscanthus (5 clones), Narenga prophyrocoma (1 clone), S. robustum (3 clones), and S. spontaneum (14 clones). Chromosome number for 18 clones confirmed published counts or was typical of the particular species. Chromosome number for seven clones (Djatiroto 2n=58, Molokai 5099 2n=80, SES 84/58 2n=58, SES 114 2n=64, SES 260 2n=64, Taiwan 100 2n=112, and US 57-11-2 2n=60) differed from published counts (2n=112, 86-100, 64, 60, 60, 96, and 30, respectively). Counts were obtained for the first time for six clones (Local escape 2n=96, Nepal 2n=72, NG 77-77 2n=108–112, NG 77-199 2n=166, US 57-60-2 2n=20, and US 68-1-4 2n=38). Bivalent chromosome pairing predominated in all clones. Meiotic irregularity (numeric aberrations, univalents, multivalents, and telophase II micronuclei) tended to be associated with taxonomic grouping and level of polyploidy. Clones in Erianthus, Miscanthus, and Narenga were apparent euploids (2n=20–60) and tended to have fewer meiotic irregularities than Saccharum clones. Differences in level of meiotic stability among taxonomic groups may reflect error in chromosome association and synapsis associated with high chromosome number.     

Effects of moisture stress on leaf appearance,tillering and other aspects of development in Triticum tauschii

Summary A glasshouse study was conducted to describe the dynamics of leaf and tiller appearance of four accessions of T. tauschii (Tt 04, Tt 17, Tt 65 and Tt 74) and to determine the influence of moisture stress (treatments were high and low moisture, imposed seven days after transplanting) on these and other aspects of development in this wild wheat.Under high moisture conditions, accessions differed greatly in flag leaf dimensions, culm length and seed number per spike, the values being lower in Tt 04 than in the other accessions. Low moisture strongly reduced values for these traits, with Tt 04 being least affected, but overall, there was no apparent association between the values obtained for these variables in the high moisture conditions and the effects of moisture stress. For three of the four accessions, final leaf number on the main culm was significantly lower in the low moisture treatment than in the respective control (P<0.05), but the differences between treatments (ca. 0.5 leaves or less) were very small. Maximum tiller number, on the other hand, was strongly reduced by low moisture, and initiation of tillering was inhibited until water was reapplied. There were no apparent after-effects of the moisture regime on the rate of subsequent tiller appearance.The four accessions differed in their leaf appearance rates, giving phyllochron values (117–142° Cd leaf^-1) within the range reported for hexaploid wheat. Low moisture tended to increase phyllochron, but in only one accession was this effect significant. Thus, depending on the accession, low moisture did not affect, or slightly decreased (by ca. 15–20%) the rate of leaf appearance. These effects were similar to those reported for cultivated wheat suggesting that there would be little scope for using these accessions of T. tauschii in breeding for stress tolerance.     

Resistance to stripe rust in Triticum turgidum,T. tauschii and their synthetic hexaploids

Resistance to stripe rust (caused by Puccinia striiformis Westend.) of 34 Triticum turgidum L. var.durum, 278 T. tauschii, and 267 synthetic hexaploid wheats (T. turgidum x T. tauschii) was evaluated at the seedling stage in the greenhouse and at the adult-plant stage at two field locations. Mexican pathotype 14E14 was used in all studies. Seedling resistance, expressed as low infection type, was present in all three species. One hundred and twenty-eight (46%) accessions of T. tauschii, 8 (23%) of T. turgidum and 31 (12%) of synthetic hexaploid wheats were highly resistant as seedlings. In the field tests, resistance was evaluated by estimating area under disease progress curve (AUDPC). Synthetic hexaploid wheats showed a wide range of variability for disease responses in both greenhouse and field tests, indicating the presence of a number of genes for resistance. In general, genotypes with seedling resistance were also found to be resistant as adult plants. Genotypes, which were susceptible or intermediate as seedlings but resistant as adult plants, were present in both T. turgidum and the synthetic hexaploids. Resistances from either T. turgidum or T. tauschii or both were identified in the synthetic hexaploids in this study. These new sources of resistance could be incorporated into cultivated hexaploid wheats to increase the existing gene pool of resistance to stripe rust.     

Meiosis and pollen grain viability in Helianthus mollis,Helianthus salicifolius,Helianthus maximiliani and their F1 hybrids with cultivated sunflower

Three diploid perennial sunflower species are useful for variety improvement: Helianthus mollis, because of sessile leaves, H. salicifolius, because of a high oil concentration, and H. maximiliani, a potential source of resistance to Sclerotinia sclerotiorum. The crossability of these species to cultivated sunflower was examined.Hybrids were obtained from eight combinations, with 3–15 F₁ plants per combination. The F₁'s exhibited the dominant phenotype of the wild species. Pollen viability varied between 32.1 and 69.9%. Meiosis was irregular in the F₁ hybrids. At diakinesis, bivalents (62.7–97.9% of meiocytes), univalents (0–31.23%), and multivalents (3.84–7.68%) were detected. At anaphase I, chromosome bridges were detected in 6.77 to 11.44% of meiocytes. Fast chromosomes in metaphase I, and lagging chromosomes in anaphase I and telophase II were evidenced in a high percentage of meiocytes.     

Partial control of chromosome elimination by temperature in immature embryos of Hordeum vulgare L. x H. bulbosum L.

Summary Embryos derived from Hordeum vulgare L. x H. bulbosum L. were subjected in vivo to a range of temperatures, and the proportions of hybrid plants which retain both parental sets of chromosomes were determined. Elimination of the H. bulbosum genome was significantly increased at temperatures greater than 20°C and resulted in fewer hybrid plants compared with temperatures below 17.5°C. Embryos were also allowed to develop in situ at 15°C and then transferred to 26°C for 8, 16 or 24h during the first 7 days after pollination. A period of 16 h at 26°C (equivalent to at least one complete mitotic cycle) at 2–5 days after pollination was found to be sufficient to increase chromosome elimination significantly above the levels obtained at a constant 15°C. At this stage (2–5 days after pollination at 15°C) the mean embryonic cell number was 2.3–223.