Development of photoperiod-sensitive cytoplasmic male sterile (PCMS) wheat lines showing high male sterility under long-day conditions and high seed fertility under short-day conditions

A “two-line system” using photoperiod-sensitive cytoplasmic male sterility (PCMS) caused by Aegilops crassa cytoplasm under long-day photoperiods (≧15 h) has been proposed as a means of producing hybrid varieties in common wheat (Triticum aestivum). The PCMS line is maintained by self-pollination under short-day conditions, and hybrid seeds can be produced through outcrossing of the PCMS line with a pollinator line under long-day conditions. Our previous studies revealed that PCMS lines showing complete male sterility under long-day conditions are necessary for practical hybrid wheat breeding, especially to obtain high hybrid purity in F₁ seeds. Furthermore, practical PCMS lines should have high seed fertility under short-day conditions, which is associated with female fertility. Wheat cv. Norin 26 with Ae. crassa cytoplasm exhibits high seed fertility under short-day conditions, and cv. Fujimikomugi with Ae. crassa cytoplasm shows high male sterility under long-day conditions. Here we developed practical PCMS lines derived from the F₁ generation of Norin 26 and Fujimikomugi (with Ae. crassa cytoplasm) that were then backcrossed to elite wheat lines.     

Transfer of rust resistance from Aegilops ovata into bread wheat (Triticum aestivum L.) and molecular characterisation of resistant derivatives

An interspecific cross was made to transfer leaf rust and stripe rust resistance from an accession of Aegilops ovata (UUMM) to susceptible Triticum aestivum (AABBDD) cv. WL711. The F₁was backcrossed to the recurrent wheat parent, and after two to three backcrosses and selfing, rust resistant progenies were selected. The C-banding study in a uniformly leaf rust and stripe rust resistant derivative showed a substitution of the 5M chromosome of Ae. ovata for 5D of wheat. Analysis of rust resistant derivatives with mapped wheat microsatellite makers confirmed the substitution of 5M for 5D. Some of these derivatives also possessed one or more of the three alien translocations involving 1BL, 2AL and 5BS wheat chromosomes which could not be detected through C-banding. A translocation involving 5DSof wheat and the substituted chromosome 5M of Ae. ovata was also observed in one of the derivatives. Susceptibility of this derivative to leaf rust showed that the leaf rust resistance gene(s) is/are located on short arm of 5M chromosome of Ae. ovata. Though the Ae. ovatasegment translocated to 1BL and 2AL did not seem to possess any rust resistance gene, the alien segment translocated to 5BS may also possess gene(s) for rust resistance. The study demonstrated the usefulness of microsatellite markers in characterisation of interspecific derivatives. This revised version was published online in August 2006 with corrections to the Cover Date.     

Production and cytogenetics of intergeneric hybrids between Triticum durum-Dasypyrum villosum amphidiploid and Psathyrostachys huashanica

Summary Intergeneric crosses between Triticum durum-Dasypyrum villosum (2n=42, AABBVV), and Psathyrostachys huashanica (2n=14, N ^h N ^h ) were made, the seed set was 1.67%. Intergeneric hybrid were successfully obtained by means of embryo culture for first time. The average chromosome pairing in the hybrid (ABVN ^h ) was 26.61% univalents, and 0.69 bivalents. The chiasmata per cell was 0.69. The chiasmata was higher than that in Triticum durum dihaploid (AB), and lower than that in T. durum-Dasypyrum villosum trihaploid (ABV). The result indicated that the N ^h genome of Psathyrostachys huashanica has no homology with the V genome of Dasypyrum villosum, and the A and B genomes of Triticum durum. The coenocytism, micronuclei cell and variation in chromosome numbers were also observed. The F₁ hybrid was crossed with Triticum aestivum (AABBDD), and resulted in seed set. The hybrid of T. durum-D. villosum amphidiploid x P. huashanica showed partial fertility. It made the possibility for chromosome manipulation among Triticum aestivum, Dasypyrum villosum and Psathyrostachys huashanica.     

Analysis of stability for some characters in Kabuli Chickpea

Summary The meiotic behaviour of a hybrid between Triticum aestivum and the amphiploid Hordeum chilense x T. turgidum conv. durum, was studied using a C-banding staining method. This hybrid has the genome formula of AA BB D Hch with 2n=6x=42 chromosomes. The durum wheat chromosomes (genomes A and B) were easily recognized, whereas the D and Hch chromosomes were recognized as a whole. Meiotic pairing was homologous, as expected (14 bivalents from A and B genomes +14 univalents from D and Hch genomes). However, some pollen mother cells at metaphase-I presented pseudobivalents that could have been caused by either homoeologous or autosyndetic pairing amongst D and Hch chromosomes.     

Photoperiod-sensitive cytoplasmic male sterility in wheat with Aegilops crassa cytoplasm

Summary Triticum aestivum cv. Norin 26 with Aegilops crassa, Ae. juvenalis or Ae. vavilovii cytoplasm (all D² type) has been studied relative to its photoperiodic response of male sterility and fertility restoration patterns. Alloplasmic lines of Norin 26 with a D² type cytoplasm showed almost complete male sterility under long-day conditions (15 h), but high male fertility under short-day conditions (14.5 h). No significant influence of temperature on reduction in male fertility was observed. Thus, this type of male sterility is called photoperiod-sensitive cytoplasmic male sterility (PCMS). The PCMS is expressed in the form of pistillody of stamens. Histological studies revealed that there were incomplete ovule-like structures instead of tapetal cells and pollen grains in the pistillate stamens. The floret differentiation stage of the plant is the stage that is sensitive to photoperiod. The PCMS can be used as a new means for hybrid wheat production, named two-line system. The PCMS line is maintained and multiplied by self-fertilization under short-day conditions, and hybrid seed can be produced by crossing the PCMS line with a pollinator line under long-day conditions. In contrast to the system of hybrid wheat production using the T. timopheevi cytoplasm, the present system requires only PCMS and pollinator lines.Abbreviation CS Chinese Spring - N26 Norin 26 - PCMS photoperiod-sensitive cytoplasmic male sterility     

Cytoplasmic and cytogenetic relationships among tetraploid Triticum species

Summary The F₁ hybrids from crosses of 59 accessions of wild and cultivated Triticum types including amphidiploids T. boeoticum-Ae. squarrosa, T. timopheevi-Ae. squarrosa, T. timopheevi-T. monococcum, T. boeoticum (4n), T. macha, and T. Zhukovskyi with T. durum Sel. 56-1 and/or T. aestivum were examined for male sterility and chromosome pairing at metaphase I of meiosis in pollen mother cells. Those hybrids which produced male-sterile F₁'s were recurrently backrossed with pollen from T. durum or T. aestivum to study segregation for male sterility and/or to confirm cytoplasmic male sterility.All T. timopheevi and T. araraticum accessions and several T. dicoccoides types, including T. dicoccoides var. nudiglumis from the Turkey-Iran-Iraq area, had male sterility inducing cytoplasm. The chromosome pairing in the F₁ hybrids indicated that all tetraploid Triticum accessions with male sterility inducing cytoplasm had genome AAGG. T. dicoccoides Körn types from the Turkey-Iran-Iraq area had genomes AABB and did not have male sterility inducing cytoplasm. Therefore, T. dicoccoides Körn and the T. timopheevi complex differ from each other cytoplasmically and cytogenetically and occur sympatrically in the Turkey-Iran-Iraq area.Possibly, the cytoplasm of the emmers was not derived from the putative diploid progenitors, T. boeoticum, Ae. speltoides, or Ae. bicornis as indicated by their nucleo-cytoplasmic and cytogenetic relationships with the tetraploid Triticum species. The cytoplasmic differences among Ae. speltoides, T. araraticum and T. timopheevi are of a relatively smaller magnitude than the cytoplasmic differences among T. timopheevi, T. boeoticum, and the emmers. A complete analysis of nucleo-cytoplasmic relationships among Triticum and Aegilops species may indicate the cytoplasmic donor(s) to the two tetraploid Triticum species complexes.Authorized for publication 19 July, 1972 as Paper No 397 in the Journal Series of the North Dakota Agricultural Experiment Stations.     

Investigation of possible associations between partial fertility restoration and agronomic traits in Triticum aestivum L.

Summary Many conventional hard red spring wheat (Triticum aestivum L. em Thell) lines, including several North Dakota cultivars, carry a gene (or genes) which restore partial male fertility to male sterile plants with Triticum timopheevi Zhuk. cytoplasm. Since this gene has no fertility restoration function in T. aestivum cytoplasm, the postulation can be made that it is being retained in conventional lines because of pleiotropic effects, favorable linkages or chance. The research reported in this paper examined these possibilities. Forty F₆ lines, derived from a single F₂ plant which was heterozygous for a gene (or genes) for partial fertility restoration, were evaluated for two years in a yield trial planted at Fargo, North Dakota. The 40 lines were testcrossed to a male sterile line having T. timopheevi cytoplasm, and the mean seed set of testcrosses was used as a measure of a line's fertility restoration potential. Twenty-seven lines had the gene for partial fertility, and 13 lines apparently lacked this gene. The 40 lines differed for heading date, anther extrusion, plant height, grain yield, 200-kernel weight, test weight, and grain protein percentage. However, comparisons of lines having the restorer gene with those lacking the gene did not provide any obvious explanation for the retention of the partial fertility restorer gene in the breeding stocks of the North Dakota conventional hard red spring wheat breeding program. The possibility that the restorer gene was linked with genes for resistance to stem rust or leaf rust also was evaluated by testing lines for their reaction to several races of rust. No conclusive association was found.Contribution from the Agric. Exp. Sta., North Dakota State University, Fargo, ND 58105, Journal Article no.     

Ph I-induced transfer of leaf and stripe rust-resistance genes from Aegilops triuncialis and Ae. geniculata to bread wheat

Leaf and stripe rusts are severe foliar diseases of bread wheat. Recently, chromosomes 5M^g from the related species Aegilops geniculata that confers resistance to both leaf and stripe rust and 5U^t from Ae. triuncialis conferring resistance to leaf rust have been transferred to bread wheat in the form of disomic DS5M^g(5D) and DS5U^t(5A) chromosome substitution lines. The objective of this study was to shorten the alien segments in these lines using Ph ^I-mediated, induced homoeologous recombination. Putativerecombinants were evaluated for their rust resistance, and by genomic in situ hybridization and microsatellite analyses. One agronomically useful wheat-Ae. geniculata recombinant resistant to leaf and stripe rust was identified that had only a small terminal segment of the 5M^gL arm transferred to the long arm of an unidentified wheat chromosome. This germplasm can be used directly in breeding programs. Only one leaf rust-resistant wheat-Ae. triuncialis recombinant, which consists of most of the complete 5U^t chromosome with a small terminal segment derived from 5AS, was identified. This germplasm will need further chromosome engineering before it can be used in wheat improvement. This revised version was published online in August 2006 with corrections to the Cover Date.     

Allelic variation of the HMW glutenin subunits in Aegilops tauschii accessions detected by sodium dodecyl sulphate (SDS-PAGE), acid polyacrylamide gel (A-PAGE) and capillary electrophoresis

Variability of high molecular weight glutenin subunits (HMW-GS) was studied in198 accessions of Ae. Tauschii (2n=2x=14, DD) by sodium dodecyl sulphate(SDS-PAGE) and acid polyacrylamide gel electrophoresis (A-PAGE) and capillary electrophoresis (CE). A high allelic variation of HMW-GS, including some novel x- and y-type subunits and variable subunit combinations were observed. One accession(TD159) showed a x-type null form. The results by A-PAGE analysis revealed that the subunits Dx5 ^t and Dy10 ^t encoded by Glu-D ^t 1 locus in Ae. tauschii were different in relative mobilities in comparison with the subunits Dx5 and Dy10 found in bread wheats, whereas they had the same mobilities, respectively, when separated by SDS-PAGE. The higher resolution of Ae. tauschii HMW-GS separated by CE method showed two clear peaks in accordance with x- and y-type subunits, respectively,except the accession TD151 which possessed only subunit Dy12.1^*t. The electro elution time of the x-type and y-type subunits were about 13–14 and 7–8minutes, respectively. Characterization of wheat HMW-GS was facilitated by using CE which provides high resolution and increases the speed of analysis in conjunction with the traditional gel electrophoretic methods. A total of 42HMW-GS alleles were identified, among which were several alleles not presently detected in bread wheats. Hence Ae. tauschii is potentially a valuable genetic resource for quality improvement of bread wheat. This revised version was published online in August 2006 with corrections to the Cover Date.     

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.     

Effects of Hordeum chilense and Triticum Cytoplasms on Agronomical Traits in Hexaploid Tritordeum

The genome of Tritordeum, AABBH^chH^ch, was substituted into the cytoplasms of Triticum aestivum, T. turgidum and Hordeum chilense by repeated back-crossing to produce alloplasmic lines. This substitution did not greatly affect the characters studied, except yield per plot and fertile ears per plant, which were lower on T. turgidum cytoplasm. Cytoplasm from either H. chilense or T. aestivum could be used for breeding tritordeum.     

Land-races of wheat from the northern Negev in Israel

Summary Wheat has traditionally been grown by the Beduin population in the semi-arid (150 to 200 mm, mean total annual rainfall) northern Negev region of Israel.A collection was made in this area (the size of which is 150 km²) from small (0.1 to 0.5ha) fields of mixed wheat, resulting in 1553 collected spikes. Each spike was planted in a 1 m row at Bet Dagan, and grown under favorable conditions. Qualitative and quantitative data were collected from each row. Qualitative data were submitted to hierarchial clustering and the results were compared with published information on the identification, classification and distribution of the land-races of wheat in the Middle East. Triticum durum was represented in 84% of the collection. It was clustered into 22 populations, identified as 11 known varietas of T. durum. They were aggregated into five groups, similar to groups of old varieties recognized by Jacubziner (1932). While 38.5% of the collection consisted of T. durum groups villosa and sinaica, aboriginal to the northern Negev, it included also forms similar to several land-races found in the past in other parts of the Middle East. Each of the populations, and the durum collection as a whole, was very diverse for the quantitatively measured plant attributes. Triticum aestivum was represented in 15.6% of the collection, clustered into six populations. Most of the common wheat accessions were analogous to the old locally grown variety Hirbawi. Triticum compactum was represented in only eight accessions.The collection is now being evaluated as a potential genetic resource for durum wheat breeding.Contribution from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel No. 374-E, 1982 series.     

N-banded karyotype of Aegilops ovata and chromosomal constitution of its amphiploid with Triticum aestivum

The N-banded karyotype of an Aegilops ovata (2n = 4x = 28) accession was produced, and the chromosomal constitution of its partial amphiploid with bread wheat Triticum aestivum‘Chinese Spring’ was established. All A. ovata chromosomes showed specific N-banding patterns and can easily be distinguished from each other. As a result of irregular meiotic behaviour of the chromosomes in the amphiploid, some structural rearrangements have probably occurred in most of the A. ovata chromosomes. The wheat chromosomes remained unmodified in their morphology and the N-banding patterns.     

Genetic polymorphisms at Gli-Dt gliadin loci in Aegilops tauschii as revealed by acid polyacrylamide gel and capillary electrophoresis

Gliadin variation at Gli‐D^t1 and Gli‐D^t2 loci in 198 Aegilops tauschii accessions was studied by acid polyacrylamide gel electrophoresis (A‐PAGE) and capillary electrophoresis (CE). High genetic polymorphisms were found at both gliadin coding loci, revealing a total of 184 and 169 gliadin variants at the Gli‐D^t1 and Gli‐D^t2 loci, respectively. In particular, 12 gliadin blocks encoded by different alleles were apparently expressed and readily identified in six synthetic hexaploids produced by hybridization between Triticum durum and Ae. tauschii accessions. Compared with Ae. tauschii ssp. eusquarrosa, the gliadin profile of the D genome in Ae. tauschii ssp. strangulata more resembles that of T. aestivum, supporting the view that the subspecies strangulata is the most likely progenitor of bread wheat. Capillary electrophoresis analysis showed that the method is capable of separating and characterizing gliadins with speed, in high resolution using small sample amounts, and is well‐suited to detect protein alleles and to identify desirable genotypes in wheat quality improvement.     

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.     

黄河中游粗山羊草三种y-型高分子量谷蛋白亚基的鉴定、克隆及系统进化分析

粗山羊草(Aegilops tauschii, 2n = 2x = 14, DD)是六倍体普通小麦的祖先之一,其高分子量谷蛋白亚基(HMW-GS)变异类型丰富,是小麦品质改良的重要基因资源。利用十二烷基硫酸钠聚丙烯酰胺凝胶电泳(SDS-PAGE)分析了黄河中游地区161份粗山羊草的HMW-GS,发现3种编码序列未知的y-型亚基,即Dy10.5^t、Dy10.4^t和Dy10.5^*t亚基。通过AS-PCR扩增、克隆、测序和氨基酸序列推导,发现3种未知序列均具有典型HMW-GS的序列结构特征且较为相似,仅Dy10.4^t与Dy10.5^t亚基存在一个氨基酸重复单元的缺失,Dy10.5^t与Dy10.5^*t亚基在信号肽部位有一个氨基酸的替换(L-F)。通过对这3种HMW-GS与32个已知氨基酸序列的HMW-GS多序列比对和系统进化关系分析,证实Dy10.5^t、Dy10.4^t和Dy10.5^*t 3个亚基是D基因组编码的高分子量谷蛋白y-型亚基家族的新成员。     

Relative susceptibility of different male-sterile cytoplasms in sorghum to shoot fly, <Emphasis Type="Italic">Atherigona soccata</Emphasis>

Summary The shoot fly, Atherigona soccata is an important pest of sorghum, and host plant resistance is one of the most effective components for managing this pest. Most of the hybrids grown in India based on milo cytoplasm (A₁ cytoplasm) are highly susceptible to shoot fly. Therefore, the present studies were undertaken to evaluate different male-sterile cytoplasms (CMS) for their relative susceptibility to sorghum shoot fly. Oviposition and deadheart formation were significantly lower on the maintainer lines as compared to the corresponding male-sterile lines. Among the cytoplasms tested, A₄M cytoplasm showed antixenosis for oviposition and suffered lower deadheart formation than the other cytoplasms tested. The A₄G₁ and A₄M cytoplasms suffered lower deadhearts in tillers than the other cytoplasms. Recovery following shoot fly damage in A₄M, A₃, and A₂ cytoplasms was better than in the other cytoplasms tested. The larval and pupal periods were longer and male and female pupal weights lower in A₄M and A₄VzM CMS backgrounds compared to the other CMS systems. Fecundity and antibiosis indices on CMS lines were lower than on the B-lines. The A₄M cytoplasm was found to be relatively resistant to sorghum shoot fly, and can be exploited for developing shoot fly-resistant hybrids for sustainable crop production in future.     

Wheat pre-breeding using wild progenitors

To facilitate the use of wheat wild relatives in conventional breedingprograms, a wheat pre-breeding activity started at ICARDA in 1994/1995season. Preliminary results of gene introgression from wild diploidprogenitors, Triticum urartu, T. baeoticum, Aegilops speltoides andAe. tauschii and tetraploid T. dicoccoides are described. Crosseswith wild diploid Triticum spp. yielded high variation in plant andspike morphology. Synthetic hexaploids were produced from crosses of alocal durum wheat landrace `Haurani' with two Ae. tauschiiaccessions. Both Ae. tauschii accessions carry hybrid necrosis allelesthat gave necrotic plant phenotypes in crosses with some bread wheats.Backcross progenies with agronomical desirable traits, i.e. high spikeproductivity, short plant stature, earliness, drought tolerance and highproductive tillering, were identified in crosses of durum wheat with wild Triticum spp. and in a cross of one of the hexaploid synthetics with alocally adapted bread wheat cv. `Cham 6'. Resistance to yellow rust wasfound in durum wheat crosses with the three wild Triticum spp. andAe. speltoides and leaf rust resistance was identified in crosses withT. baeoticum and Ae. speltoides. The results show that wheatimmediate progenitors may be a valuable and readily accessible source ofnew genetic diversity for wheat improvement.     

Use of the gene pools of Triticum turgidum ssp. dicoccoides and Aegilops squarrosa for the breeding of common wheat (T. aestivum), through chromosome-doubled hybrids

Summary Triticum turgidum ssp. dicoccoides (wild emmer wheat, AABB, 2n=28) and Aegilops squarrosa (goat grass, DD, 2n=14) comprise a rich reservoir of valuable genetic material, which could be useful for the breeding of common wheat (T. aestivum, AABBDD, 2n=42). Many accessions of both wild species, most of them selected for resistance to stripe rust, were used to make amphiploids. Two strategies were applied: (1) the production of autopolyploid cytotypes of the wild species, followed by hybridisation, and (2) the production of allotriploid interspecific hybrids, followed by doubling of the number of chromosomes. The first route was unsuccessful because of failure of the crosses between the autopolyploid cytotypes, possibly due to incongruity between the two species and to reduced fertility in the autopolyploid cytotypes. The second route yielded the desired synthetic hexaploids. However, the rate of success of the crosses was low and there were great differences between years, and within years between crosses. Embryo rescue was applied to obtain the primary hybrids (2n=21), which were highly sterile and had on average 0.3 bivalents and 20.4 univalents per pollen mother cell. Various abnormalities were recorded. Doubling of the number of chromosomes sometimes occurred spontaneously or was brought about by colchicine treatment. The large scale of the interspecific hybridisation programme ensured that one-third of the female and one-sixth of the male accessions were represented in the synthetic hexaploids.     

Interaction ofTriticum boeoticum cytoplasm and genomes ofT. aestivum andT. durum: Restoration of male fertility and plant vigor

Summary Male-sterile plants of reduced vigor were obtained by substitutingT. aestivum and/orT. durum genomes into the cytoplasm ofT. boeoticum, T. monococcum and amphidiploidT. boeoticum-A. squarrosa. Apparent segregation for plant vigor occurred even in advanced generations of the following backcross progenies:T. boeoticum/12*T. durum, T. monococcum/10*T. durum, T. boeoticum/2*T. durum//7*T. aestivum, amphidiploidT. boeoticum-A. squarrosa/6*T. durum and amphidiploidT. boeoticum-A. squarrosa/8*T. aestivum. Highly fertile F₁ hybrids of normal vigor were obtained from crosses of A lines of common wheat in the cytoplasm of amphidiploidT. boeoticum-A. squarrosa orT. timopheevi with R lines having male fertility restoring factors fromT. boeoticum, T. boeoticum-A. squarrosa andT. zhukovskyi. Apparently, vigor-genes complemented the male fertility restoring genes to produce fertile hybrids of normal plant vigor in the crosses amphidiploidT. boeoticum-A. squarrosa/6*T. aestivum, Chris//amphidiploidT. boeoticum-A. squarrosa/T. durum/T. aestivum, Chinese Spring, andT. zhukovskyi/3*T. aestivum, Justin F₈ R lines.Published with the approval of the Director, North Dakota State Agricultural Experiment Station, as Journal Article No. 231Associate Professors of Agronomy.