Genomic Affinity Relationships in the Genus Avena

Many interspecific hybrids between diploid, tetraploid and hexaploid Avena species were obtained without artificial embryo cultures. Most of the hybrids showed variable chromosome pairing with univalents, bivalents and multiple associations, even in PMC in the same hybrid, at first metaphase; making ii very difficult to understand the degree of genome affinity between parent species, and especially between different species. The basic or theoretical chromosome pairing consisting of bivalents and univalents is presented, in which the chromosome ratios (%) statistically agree with observations. In addition, the per cent frequency of chromosomes forming multivalents is calculated. On the bases of these numerical data, the genomic affinity relationships are discussed for present and previously reported interspecific hybrids or Avena.     

Origin of Sv Genome of Aegilops variabilis and Utilization of the Sv as Analyser of the S Genome of the Aegilops Species in the Sitopsis Section

Hybrids of Aegilops variabilis (2n = 28, UUS^vS^v) with the low-pairing type lines of Ae. longissima, Ae. bicornis, Ae. searsii, Ae. speltoides and Ae. umbellulata were obtained. This is the first report of successful hybridization between Ae. variabilis and Ae. searsii. Meiotic analysis of these hybrids showed that the U genome of Ae. variabilis donated by Ae. umbelltilata remained nearly unchanged and Ae. longissima is the possible donor species of the S genome to Ae. variabilis. But the S^v genome and the S¹ genome of Ae. longissima are not completely homologous and are structurally differentiated by at least one interchange. According to their levels of homology with S^v through the means of chromosome associations, the four genomes of Sitopsis section species can be classified as follow: S^v? S¹ > S^b > S^s > S. The meiotic behaviour of the hybrids between the wheat ‘Chinese Spring’ and the four Sitopsis section species studied has not supported the view that one of the four species is the donor of the B genome of wheat.     

Tolerance of Triticum Species to Aluminum*

A total of 523 accessions of 25 Triticum species were screened for tolerance of aluminum in solution. Only 22 accessions were identified with some root re growth following exposure w culture solutions containing 12 ppm aluminum. Interestingly, 15 of these 22 accessions were species with the Un genome (T. uniaristatum). The level of aluminum tolerance of none of these 22 accessions is as high as that of the cultivar ‘Atlas 66’.     

The Attempted Transfer of Male Sterility from the Cornerstone Mutant of Tetraploid Wheat to Diploid Wheat

An attempt was made to transfer male-sterility, mslc, from the Cornerstone mutant of tetraploid wheat to diploid wheat. The N-banding technique revealed that chromosome 4 A of tetraploid wheat does not pair with chromosome 4 of diploid wheat in triploid F₁ hybrids: consequtntly the transfer of male-sterility gene(s) from tetraploid wheat to diploid was not successful. The culchiane induced ampliploids possessing AAAABB in mslc background were fully fertile indicating the complete compensation of mslc by the newly introduced A genome of T. monocaccum. The fertility compensating gene(S) presumably located on chromosome 4 of diploid wheat may be used to produce hybrid wheat by the XYZ system.     

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.     

Genomic constitution of a partial amphiploid OK7211542 used as a source of immunity to barley yellow dwarf virus for bread wheat

A combination of genomic in situ hybridization (GISH) and meiotic pairing analysis of crosses between a series of 2n= 56 partial amphiploids confirmed that the alien genome of the BYDV-immune Agro-tricum line OK7211542 is derived from Thinopyrum ponticum and not from Thinopyrum intermedium. The evidence from meiotic pairing analysis indicated that the chromosome constitution of OK7211542 is similar to another Agrotricum line, ORRPX, which was derived from a cross of wheat and Th. ponticum, but different from other Agrotricum lines, Zhong 5 and TAF 46 which were derived from the crosses between wheat and Th. intermedium. The GISH analysis confirmed that OK7211542 contained one complete set of 14 Th. ponticum chromosomes, in which no S chromosome was present in the alien genome. GISH also detected a small alien translocation attached to one of the wheat chromosomes, a result that was consistent with the pairing data.     

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’.     

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。     

四倍体栽培棉与二倍体野生棉杂种PMC-FISH研究

 首次将PMC-FISH（花粉母细胞荧光原位杂交）技术应用于四倍体栽培棉与二倍体野生棉杂交所形成的三倍体杂种棉F₁中,成功的鉴定了目标染色体中的单价体、双价体、多价体,还发现在非目标染色体上有星状和片段状的杂交信号。在以A组棉基因组DNA作为探针的PMC-FISH中,分别对三倍体杂种棉F₁及其母本四倍体栽培棉的减数分裂中期I的染色体构型进行了鉴定。结果显示,四个三倍体杂种棉F₁的减数分裂时期染色体的构型分别是：陆地棉(AD)₁×雷蒙德氏棉（D₅）为1IIIaad + 1IIaa + 4IIad + 7IIdd + 5Ⅰa + 7Ⅰd;海岛棉(AD)₂×旱地棉（D₄）为1Ⅴaaaad +1IIIadd + 2IIad + 8IIdd + 6Ⅰa + 5Ⅰd;陆地棉(AD)₁×澳洲棉（C₃）为2IIIadd (adc or acc) + 1IIaa + 9Ⅰa + 4IIcc (dc or dd) + 14Ⅰd (c);陆地棉(AD)₁×南岱华棉（C_1-n）为：1IIaa + 1IIad (ac)+ 10Ⅰa + 6IIcc (dc or dd) + 13Ⅰd (c)。然而,两个四倍体棉染色体的构型都是13IIaa + 13IIdd。上述结果还显示, AD×D的两个杂种组合中,二价体多,单价体少,AD×C的两个杂种组合中,二价体少,单价体多;并且AD×D型杂种中A亚组染色体单体的数目比其在AD×C型杂种中的更少。这说明,与C染色体组相比较,D染色体组与四倍体棉种的亲缘关系更近。同时,我们的结果也证明PMC-FISH技术在分析三倍体杂种棉F1的亲缘关系中起着不可取代的作用。     

Cytogenetic Studies of Different Miscanthus Species with Potential for Agricultural Use

Four morphologically different clones of Miscanthus sinensis‘Giganteus’, presently grown in Austria, one ornamental, M. sinensis, and two cultivars of M. sacchariflorus, were studied to determine their chromosome number, chromosome morphology and meiotic behaviour. The clones of M. sinensis‘Giganteus’ uniformly showed a somatic chromosome number of 57. The ornamental M. sinensis, and one M. sacchariflorus cultivar had 38 and the second M. sacchariflorus genotype had 76 chromosomes. While the ornamental M. sinensis exhibited a regular meiosis with predominantly ring bivalents, M. sinensis‘Giganteus’ displayed a highly irregular meiosis with stickiness, frequent occurrence of trivalents and a large number of laggards in both the first and second anaphases. The presence of two satellited chromosomes suggests an allotriploid genome constitution; the trivalents indicate the involvement of closely related species in the amphiploid. Triploidy of the plants is supposed to be the major cause of their sterility. Suggestions are made for further cytogenetic studies including genome analysis and an attempt to resynthesize M. sinensis‘Giganteus’ to provide an insight into the genetic architecture of the plant and to generate new genetic variations for breeding purposes.     

Effect of the ph1b mutant on chromosome pairing in hybrids between Dasypyrum villosum and Triticum aestivum

Chromosome pairing was analysed in F₁ hybrids of the wheat cultivar ‘Chinese Spring’ (CS) and its ph1b mutant (CSphlb) with Dasypyrum villosum. On average, 1.61 chromosomes per cell paired in the hybrid CS ×D. villosum, but 14.43 in the hybrid CS ph1b×D. villosum. Genomic fluorescence in situ hybridization (GISH) revealed three types of homoeologous association between wheat (W) and D. villosum (D) chromosomes (W‐D, D‐W‐W and D‐W‐D) in pollen mother cells of the CS ph1b×D. villosum hybrid, and only one type (W‐W), in the CS ×D. villosum hybrid. Both F₁ hybrids were self‐sterile. The seed set of the backcross of CS ×D. villosum with CS was 6.67% and that of CS ph1b×D. villosum with CS or CS ph1b was only 0.45%. The chromosome number of BC₁ plants varied from 48 to 72. Translocations of chromosome segments or entire arms between wheat and D. villosum chromosomes were detected by GISH in the BC₁ plants from the backcross of CS ph1b×D. villosum to CS ph1b.     

Comparative Analysis of High-Molecular-Weight Glutenin Subunit Composition in Various Triticum Species

Variation in high-molecular-weight glutenin subunit composition amongst Triticum durum cvs. of different origins was investigated by SDS-PAGE and compared with that reported for T. dicoccum and T. aestivum. Tetraploid wheat collections (408 cvs.) were found to carry nearly twice as many Glu-A1 and Glu-B1 alleles as a hexaploid wheat sample of comparable size. In each of the taxa considered, allelic variation at the Glu-B1 locus was markedly greater than that observed for Glu-A1. However, because all the Glu-B1 subunits so far discovered exhibit a restricted and distinctive mobility range during. SDS-PAGE, it is suggested that they are derived from a single source, possibly from Aegilops searsii. Most durum cvs. carried a ‘null’Glu-A1 allele and therefore fewer subunits than dicoccums and common wheats. It is argued that differences in the frequency of occurrence of ‘null’Glu-1 alleles between taxa probably resulted from random samplings made by early agriculturalists and breeders, rather than from an inherent tendency of polyploid wheats to suppress the activity of “redundant” genes.     

Metaphase-I analysis of a Triticum aestivum x T. monococcum hybrid by the C-banding technique

Summary The meiotic pairing behaviour at metaphase I of a Triticum aestivum×Triticum monococcum hybrid has been studied by means of the C-banding technique to ascertain the homology between the chromosomes in the A genome of the two species. The technique allowed the A and B genome chromosomes and the 2D, 3D and 5D chromosomes to be identified. Differences in the level of chromosome pairing in the A genome were noted. The T. monococcum 4A chromosome did not pair with any of the T. aestivum chromosomes in any of the metaphase I cells analysed. Two reciprocal translocations between the 2B and 2D chromosomes on one side and the 2A and 3D on the other side have been identified. The usefulness of the C-banding technique in the study of chromosome homology among species related to wheat is discussed.     

Performance of Selected Strains of 'Farro' (Triticum monococcum L., Triticum dicoccum Schübler, Triticum Spelta L.) and Durum Wheat (Triticum Durum Desf. cv. Trinakria) in the Difficult Flat Environment of Southern Italy

The aim of this study was to evaluate the performance of three species of unhulled-wheat (Triticum monococcum L., Triticum dicoccum Schubler and Triticum spelta L.) with respect to durum wheat (Triticum durum Desf. cv. Trinakria) in southern Italy's flat environment.
As far as yield is concerned, the mean yield was significantly different among species. Durum wheat yielded 16.1 %, 37.6% and 69.5 % more than dicoccum, spelta and monococcum species, respectively.
Among unhulled-wheat species, only Triticum dicoccum showed some similarity with durum wheat, such as one-thousand kernels weight, plant height and number of spikes per m².
Among the factors studied, the days to reach heading represented the factor that mostly influenced yield     

Polymorphism of two waxy proteins in the emmer group of tetraploid wheat, Triticum dicoccoides, T. dicoccum, and T. durum

Gel-electrophoretic analyses detected polymorphism of two waxy (Wx) proteins, Wx-Al and Wx-Bl, in 334 accessions of the emmer group of tetraploid wheat, Triticum dicoccoides, T. dicoccum and T. durum. The null allele for the Wx-Al protein (Wx-Alb) was found in one accession of T. dicoccoides and seven of T. dicoccum, but it was not present in those T. durum accessions analysed. The null allele for the Wx-Bl protein (Wx-Blb) did not occur in three emmer-wheat species. Wx-Al and Wx-Bl proteins showing alteration in mobility in SDS-PAGE gel or in isoelectric points were found in five accessions and considered to be the products of new alleles, Wx-Ald, Wx-Ale and/or Wx-Bld. Densitometric analysis of Wx protein bands revealed that Wx-Al was present in smaller amounts than Wx-B1 in almost all accessions.     

Interspecific reproductive barriers and genomic similarity among the rough-seeded Lupinus species

The nature of reproductive barriers and meiotic behaviour of chromosomes were studied in interspecific hybrids among the six rough-seeded Lupinus species. Out of 30 different interspecific crosses attempted in all possible combinations, eight produced viable F, seeds. These successful crosses involved L. cosentinii, L. digitatus, L. atlanticus and L. pilosus. Crosses of L. princei with other species resulted in shrivelled F, seed in all combinations. In contrast to previous reports, crosses of L. palaestinus with all other rough-seeded lupins were incompatible as no F₁ hybrids were obtained. Barriers to interspecific reproduction were identified as nucleo-cytoplasmic and embryo-endosperm incompatibility in unsuccessful crosses, and chromosomal imbalances in F₁ hybrids. Gene transfer is possible among L. cosentinii, L. digitatus and L. atlanticus, which produced F₂ seed. Patterns of chromosome configurations in F₁ meiotic cells suggested that these species have at least two genomes partially in common, but include inversions and translocations. The genome of L. atlanticus is closer to L. digitatus than to L. cosentinii, and that of L. pilosus is closer to L. atlanticus than to L. cosentinii. L. princei appears to have an isolated genome within the rough-seeded Lupinus species.     

Evaluation of Genetic Diversity in Wild Diploid Wheat Triticum boeoticum from Iran Using AFLP Markers

Although Iran is a main center of distribution of wild wheats, but little information is available regarding genetic variation in wild wheat relatives from this country （Tabatabaei and Massoumi, 2001）. The habitats of wild wheats in the west of Iran （east of Fertile Crescent） are potentially the ideal areas to explore the suitable genes for further transferring into the cultivated wheat. In the Near East, primary habitats of Z boeoticum occur in the northern and eastern parts of the Fertile Crescent （Harlan and Zohary, 1996）.Various sites of excavations such as Ali KOSH （Iran）, Catal HUYUK and HACILAR （Turkey）, from where specimens of Z monococcum have been recovered are within the general area of distribution of Z boeoticum （Harlan and Zohary, 1996）. Iran is a main center of distribution of wild wheats and the associated compositions of Z boeoticum with Aegilops spp. as the ＂richest wheat gene pool＂ has been found in this region （Tabatabaei and Massoumi, 2001）.Therefore, it is supposed that the populations of Z boeoticum in this region contain high levels of genetic diversity and may provide significant information regarding their potential for breeding purposes. In this study,     

Improving male fertility restoration of common wheat for Triticum timopheevii cytoplasm

The fertile pure line R3‐37 of common wheat with cytoplasm of Triticum timopheevii Zhuk. is an R‐line (restorer) that can restore the male fertility of A‐lines (male sterile lines) with T. timopheevii cytoplasm. In breeding hybrid wheat, the hybrid of the cross R3‐37/ Baimian3 was found to be completely male sterile, indicating that Baimian3 has some genes that are epistatic to the Rf genes in R3‐37. In order to elucidate the essence of this phenomenon, the male fertilities of the hybrids of 27 crosses including R3‐37 and/or Baimian3 were studied. The results show that inheritance of male fertility of the hybrid R3‐37/Baimian3 involves interactions among Rf alleles, male fertility‐inhibiting genes and genetic background. Although more than 70 different kinds of male sterile cytoplasm to common wheat have been discovered, the systems of hybrid wheat production based on male sterile cytoplasm are all the A‐line/R‐line type and all have similar problems of hybrid fertility restoration. This study confirmed that there is a new model (A‐line/R*‐line//R‐line) for producing hybrid wheat with high fertility restoration. In the new model, the completely male sterile hybrids of A‐line/R*‐line can act as common A‐line.     

Further Studies on the Restoration of Fertility in Triticum durum×T. timopheevi Hybrids

Twenty one F₁ hybrids involving three Triticum durum cultivars and eleven forms of T. timopheevi were backcrossed to their respective durum parents. Backcross fertility (BC₁ grain set) of these sterile hybrids improved with the rise in temperature at the time of pollination. A mean temperature of less than 20 °C results in poor seed set while higher mean temperatures around 24 °C result in increased seed set. It is suggested that a large number of backcross seeds can be produced by pollinating these hybrids late in the season, i.e., after 20th of March in northern India.