Salt Tolerance of an Amphiploid between Triticum aestivum and Agropyron junceum

The main objective of this work is to demonstrate the expression of salt tolerance genes in a wheat-Agropyron amphiploid. Salt tolerance tests were carried out on wheat varieties, ‘Chinese Spring,’ and ‘Glenn-son 81’ the amphiploid between ‘Chinese Spring’ and A. junceum, A. junceum and amphiploid × wheat hybrids, Apart from germination in petridishes all other tests were carried out on plants grown in saline hydroculture tanks. Fresh weight measurements are given for stressed and non-stressed plants as well as measurements of harvest ripe plants. The utility of A. junceum as a source of salt tolerance genes for wheat is discussed.     

Cytology and Fertility of Hybrids and Amphiploids between Aegilops caudata L. ×Triticum turgidum (L.) Thell

Interspecific hybrids and amphiploids between Aegilops caudata L. (2n = 2x = 14, CC) and Triticum turgidum (L.) Thell. conv. durum Desf M. K. (2n = 4x = 28, AABB) were produced. Such hybrids can be used to introduce desirable traits such as disease resistance into cultivated durum wheats. One of the durum parents was a ph I mutation of the cv. ‘Cappelli’ used for testing the possibility of direct introduction of alien variation into cultivated species. The amphiploids were obtained both through colchicine chromosome doubling and as natural non-reductional mciosis products. In both hybrids and amphiploids, meiotic pairing and fertility were studied. Hybrids showed varying degrees of pairing and, in addition to the one involving the ph 1 mutant, one high pairing hybrid was found (Ae. caudata× cv. ‘Capinera’). Cytological examination of microsporogenesis in amphiploids revealed a high frequency of bivalent formation. Fertility proved to be a very variable character since some of the amphiploids were almost completely sterile. The use of amphiploids in breeding programmes is discussed in relation to meiotic and fertility data.     

Distribution and Origin of Hybrid Necrosis Genes in German Winter Wheat (Triticum aestivum L.) Cultivars

Hybrid necrosis in Triticum is known to be caused by the interaction of two complementary dominant genes. In the present paper, the genotypes for hybrid necrosis of 64 winter wheat cultivars are presented. 41 cultivars were found to possess the Ne₂ necrosis gene, whereas 23 cultivars were non-carriers. The Ne₁ gene was not found in any of the cultivars analyzed.     

Nearly Total Absence of Homoeologous Pairing in a Hybrid between Tetraploid Hordeum chilense and Triticum aestivum

A hybrid between an induced tetraploid of Hordeum chilense (2n = 28 = H^chH^chH^chH^ch) and Triticum aestivum var. ‘Chinese Spring’ (2n = 42 = AABBDD) has been produced to test gene effects of this wild barley on homoeologous pairing in wheat. Cytological investigations in metaphase I have shown that the hybrid, which is perennial like H. chilense but morphologically more similar to the wheat parent, possesses the expected genome composition H^chH^ch ABD and a stable euploid chromosome number of 2n = 35. Pairing among the homologous H. chilense chromosomes was almost complete. The level of non-homologous chromosome association proved to be lower than the range of pairing known from euhaploids of ‘Chinese Spring’.     

Effect of Mutagenic Treatments on Somaclonal Variation in Wheat (Triticum aestivum L.)

Different wheat genotypes were treated with gamma-rays, sodium azide (SA) and EMS before tissue culture and immature embryos from M₁ plants or plants shortly after exposure to gamma-rays were used to initiate callus culture. Thousands of plants were regenerated and used to investigate the effect of mutagenic treatments on the regenerated plants and somaclonal variation in the M₃R₂ and M₂R₂ generations. The results showed that mutagen-induced damage in terms of reduction in plant height, fertility and spike length were not outstanding in the regenerated plants as compared with the untreated control. In the M₃R₂ generation, only SA treatment had significantly higher frequencies of somaclonal variations than the control. Increases in the variation frequencies were observed when explant embryos were irradiated with 2.5 and 5 gy gamma-rays and the highest frequency appeared when embryos were exposed to 5 gy gamma-rays on the 5th day after anthesis. Increased variation spectra also resulted from mutagenic treatments and most of the variants recovered were unsuitable for plant improvement.     

Hybrids of Bread Wheat (Triticum aestivum) with Thinopyrum scirpeum (4x) and Thinopyrum junceum (6x)

Hybrids were obtained by crossing Thinopyrum scirpeum (4x) and T. junceum (6x) onto Triticum aestivum cv, ‘Chinese Spring’. An average meiotic pairing of 24.44^I+ 5.07^II+ 0.14^IIIin the ‘Chinese Spring’×T. scirpeum hybrid (ABDE₁E²) is attributed to two similar genomes from T. scirpeum (E₁E₂E₃E₄). An average meiotic chromosome pairing in the other hybrid (ABDJ₁J₂E₃) was 31.70^I+ 3.80^II+ 0.90^III and is attributed to autosyndetic pairing between the three genomes of T. junceum.     

Inheritance of Cold Hardiness in Triticum aestivum × Synthetic Hexaploid Wheat Crosses

Synthetic hexaploid wheat, produced by combining tetraploid wheat (AB genome) with Triticum tauschii (D genome), was crossed to modern hexaploid wheat (Triticum aestivum ABD genome) in an attempt to introduce new cold hardiness genes into the common hexaploid wheat gene pool. The cold hardiness levels of F) hybrids ranged from similar to parental means to equal to the hardy parent, indicating that cold hardiness was controlled by both additive and dominant genes. As expected when dominant gene action is involved, differences between F₂ and parental means were smaller than comparable differences in the F., Frequency distributions of F₂—derived F₃ lines also suggested that dominant genes were involved in the control of cold hardiness in some crosses. Heritability estimates for cold hardiness ranged from 63 to 70 % indicating that selection for cold hardiness should be effective in populations arising from crosses between common and synthetic hexaploid wheat. However, high selection pressure on the progeny of crosses that included the most hardy T. aestivum, T. durum, and T. tauschii accessions as parents did not identify transgressive segregates for improved cold hardiness. These observations indicate that the close wheat relatives, sharing common genomes with T. aestivum, are not promising sources of new genes to increase the maximum cold hardiness potential of common hexaploid wheat.     

Somaclonal Variation in Tissue Culture of Triticum aestivum×Agropyron desertorum F1 Hybrid

Callus induced from immature inflorescences of the partially self-fertile hybrids (2 n = 35; ABDPP) between Triticum aestivum (2n = 42; AABBDD) and Agropyron desertorum (2n = 28; PPPP) led to the regeneration of 88 plants on MS medium supplemented with 2 mg/l of 2,4-D. These regenerants were used to investigate somaclonal variation and to obtain more selfed derivatives. Immature inflorescences at the stage of developing floral primordia gave the best response in terms of callus induction and plant regeneration. The regenerants exhibited great variability for most morphological traits. Although the regenerants did not exhibit variation in chromosome number, they did show a higher degree of meiotic instability than the initial hybrid. In particular, the regenerants gave much higher selfed seed-set (5.49 %) than the donor hybrid (0.46 %), so that a total of 484 selfed seeds were obtained.     

小麦株高近等基因系的RAPD标记研究

采用ＲＡＰＤ技术,以４个小麦株市基因近等基因系（分别含有rht、Ｒht1、Rht2、Rht3)为材料,对２９６个单一随机引物（１０个核苷酸）进行了筛选。发现２５个引我的扩增产物的近等基因系间表现出特异性,在６次重复试验中,有１８个引物的特异护增片段不能重复,６个引物可以重复２－３资,唯有ＯＰＡＭ０１在全部试验中均能稳定重复,其特异扩增版段ＯＰＡＭ０１１８６０可以作为rht基因的ＲＡＰＤ标记。     

Genotypes of Hybrid Necrosis in 25 Spring Varieties of Common Wheat (Triticum aestivum L.)

Book reviewed in this articles: Cereal Grain Protein Improvement. Shivanna, K. R., and B. M. Johri, The Angiosperm Pollen. Structure and Function. Gustafson, J. P., Gene Manipulation in Plant Improvement. Backer, A. W., Manual of Quantitative Genetics. Fishbeck, G., W. Plarre und W. Schuster (Hrag.) , Hoffmann , W., A. Plarre : Lehrbush der Züchtung landwirtschaftlicher Kulturflanzen, Bd. 2, Spezieller Teil, 2. Auflage. Dodds, J. H. (editor and author), Plant Genetic Engineering. Fiechter, A. (managing editor), Advanced in Biochemical Engineering/Biotechnology. Vol. 31. Plant Cell Culture.     

The Growth in Culture of Detached Ovaries of Wheat (Triticum aestivum L. em. Thell)

Viable embryos have been recovered from fertilized wheat (Triticum aestivum) ovaries detached on the day of, or up to 7 days post-, anthesis and cultured aseptically fur up to 18 days. The most significant factors in determining the yield of embryos was the plating density, age and complexity of the explants. 26% of ovaries excised on the day of anthesis produced viable embryos if cultured as pairs of florets. The potential use of detached ovary cultures in gametophyte microinjection experiments, rescuing embryos from wide crosses and in chemically manipulating the early stages of embryo development are discussed.     

Agronomic and Physiological Study of Cold and Flooding Tolerance of Spelt (Triticum spelta L.) and Wheat (Triticum aestivum L.)

Flooding of soil occurs all over the world in areas of crop production. The resulting lack of available oxygen in the soil can hinder the establishment of field crops such as wheat ( Triticum aestivum L.) and thus lead to a decrease in yield. The current study compares the tolerance of spelt ( Triticum spelta L.) and wheat to wet and cold stress during germination and early growth. Two specific traits seem to be related to the superior early flooding tolerance of spelt: (1) fast growth of the coleoptile, which reaches the soil surface rapidly, thus reducing the time span of hypoxia sensitivity, independent of temperatures between 10 and 20 °C; (2) the improved physiological adaptation for coleoptile growth under hypoxia is probably due to lower oxygen consumption between germination and emergence. Because of this high level of flooding tolerance, spelt would also be a good source for breeding for stress tolerance in wheat. These findings will help to detect quantitative trait loci (QTL) for characters such as growth rate, flooding tolerance and oxygen consumption in future studies. A marker-assisted introgression of spelt into wheat is necessary to avoid combination with undesirable agronomic traits of spelt.     

Variation in Relative Amounts of Isolectins in Bread Wheat (Triticum aestivum) Landraces from Northern Nigeria and Chad

Wheat germ agglutin (WGA) present in the embryo of a bread wheat grain is a mixture of three isolectins, viz CL_A, CL_B and CL_D which are coded by genes located on die chromosomes 1A, 1B and 1D. Their respective absolute amounts were determined in 62 Nigerian and five Chad landraces. Added was the Madagascar variety ‘Kanem’ which is stated to be selected from Chad material. Some of the Nigerian landraces were formerly identified as derived from Indian Pakistani wheat varieties/landraces introduced into Northern Nigeria before 1940. These had relatively high CL_D/GL_A and CL_B/CL_A ratios. Other Nigerian landraces with such high ratios were postulated to come from India/Pakistan, too. The Chad wheats, except ‘Kanem’, have WGA amounts and-ratios similar to those native to Northern Nigeria. This may point to a common history. ‘Kanem’ is said to be bred in Madagascar from Chad wheats. Apparently it has a different origin. So the determination of the WGA amount and its isolectin composition is a helpful means to identify the history of a land race or of an improved variety.     

The Transfer of Resistance to the Russian Wheat Aphid from Triticum monococcum L. to Common Wheat

Two Triticum monococcum accessions were found to be highly resistant to the Russian wheat aphid. An attempt was made to transfer the resistance to common wheat through direct hybridization or by using bridge species. In each of the four crossing strategies tried, a gradual loss of resistance occurred as hybrids with higher ploidy levels were obtained. It appeared that the level of resistance observed was directly proportional to the ratio of the Triticum monococcum genome relative to other genomes. This would indicate suppression of the resistance gene(s) by the added genomes or dilution of its product(s) by those of homoeoloci. The degree of protection afforded by the gene(s) at the hexaploid level may prove to be small. Plants suspected to be homozygous for the resistance gene(s) were identified; however, further backcrossing to common wheat will be required to improve their agronomic types and meiotic regularities.     

云南小麦亚种和四个稀有小麦种的遗传关系

利用和小麦断穗基因有关联的8对SSR引物,探讨了云南小麦亚种和乌拉尔图小麦、粗山羊草、一粒小麦和圆锥小麦4个稀有小麦种及普通小麦亚种中国春之间的亲缘关系。结果表明,8对SSR引物在云南小麦亚种的37份材料中共检测到387条等位片段,每对引物扩增到35~71条,平均48.375条;在已报道的小麦断穗基因Br2、Br3、Br1、Brt和Br61所在的三个位点,即xgwm32-3AS、xgwm72-3BS和xgdm72-3DS上云南小麦都有很高的遗传多样性,3个位点的多态性信息含量(PIC)在0.7639～0.8713之间,多样性指数(I)为1.6097~2.2018;云南小麦同粗山羊草种的亲缘关系较远,与乌拉尔图小麦、一粒小麦和圆锥小麦种的关系较近,尤其和普通小麦亚种中国春的亲缘关系最近,但是,只有8份云南小麦和中国春被划分在同一组。     

Nitrate Assimilation and Nitrogen Harvest in Uniculm 'Gigas' Wheat (Triticum aestivum L.)

Contribution of the upper laminae designated as 7, 8 and 9 (flag), to the total reduced nitrogen was determined by two different methods; integration of nitrate reductase activity over the entire growing season of individual laminae, and laminae removal at ear emergence. The values obtained by these methods were: 20, 14, and 12 %, and 23, 15, 12 %, respectively. The in vivo nitrate reductase activity was relatively higher in the lamina 9, which contributed an extra 8 % towards total reduced nitrogen when the other laminae were removed from the shoot. No such compensatory response was observed when either lamina 7 or 8 was retained.     

普通小麦(Triticum aestivum L.)T型细胞质雄性不育系及其保持系的线粒体DNA比较研究(英文)

mtDNAs of T type wheat cytoplasmic male sterile lines Ning Drawf 14(ND14) and their maintainers Ning Drawf 13 (ND13) were isolated and digested completely with restriction endonucleases EcoRI, PstI, EcoRV, BamHI. The results revealed that the molecular structure of mtDNAs from ND14 and ND13 cytoplasms were significantly deviated. The mitochondrial genomic difference between CMS line and maintainers were uncovered by southern hybridization with probes of 18S 5S rRNA、atpA genes from wheat and pea mitochondria, respectively. Due to the complexity of mtDNA and no proof of protein difference, it has not yet been demonstrated whether mtDNA difference of Normal and Male Sterile Cytoplasm of wheat is associated with CMS.     

Single and Multiple Traits Selection in a Segregating Population of Wheat, Triticum aestivum L.

The breeding materials used in this study were the F₃, F₄ and F₅-generations of the cross between Giza 158 × Sonora 64 (Triticum aestivum L.). The objective of this study was to compare the relative merits of Smith-Hazel, desired gain selection indices, independent culling levels and single trait selection in improving grain yield, heading date and several agronomic traits. Highly significant differences among F₃ families and a satisfactory genotypic coefficient of variability were obtained for all the traits studied. The genotypic correlations were high between yield and each of spike weight, kernels/spike and spikes; plant, intermediate with 1000 kernel weight and very low with heading date, plant height and spike1 length-After two cycles of selection, the results of the gains realized indicated that the most effective method for improving yield was the Smith-Hazel index (SH₇) of seven traits followed by the desired gain index of seven traits (DG₇), SH₅, independent culling levels, DG₅ and direct selection (or grain yield/plant. Direct selection for heading date, plant height and spike length was the best method for improving these traits, but undesirable correlated responses in the other traits were obtained.     

小麦株高近等基因系的RAPD标记研究

采用RAPD技术, 以4个小麦株高近等基因系(分别含有rht、 Rht1、 Rht2、 Rht3基因)为材料, 筛选了296个单一随机引物(10个核苷酸)。 发现25个引物的扩增产物在近等基因 系间表现出特异性。 在6次重复试验中, 有18个引物的特异扩增片段不能重复, 6个引物 可以重复2～3次, 唯有OPAM01在全部试验中均能稳定重复, 其特异扩增