C-band polymorphism and structural rearrangements detected in common wheat (Triticum aestivum)

Summary Giemsa C-banding allows for the identification of all 21 chromosome pairs of hexaploid wheat. However, variation in banding patterns of individual chromosomes and structural rearrangements exist between different cultivars making chromosome identification more difficult. The paper summarizes the available data on C-band polymorphism and structural rearrangement present in wheat cultivars and germplasms.     

Relationship between common wheat (Triticum aestivum L.) gluten proteins and dough rheological properties

This paper reports the correlation between the rheological properties of bread wheat dough and the types and quantities of endosperm proteins in 28 common wheat cultivars. Different methods were used to analyse the allelic composition of these cultivars and the relative quantities of the different proteins contributing to the gluten structure. Neither dough strength (W) nor tenacity/extensibility (P/L) correlated with allelic composition. Different wheats with the same allelic composition (i.e., with respect to glutenins) showed different rheological properties. The glutenins were the most influential components of W and P/L, especially the high molecular weight (HMW) glutenin subunits and in particular the type x form. These proteins seem to increase W and are the main constituents of the gluten network. The gliadins and low molecular weight (LMW) glutenin subunits appear to act as a “solvent”, and thus modify the rheological properties of the dough by either interfering with the polymerisation of the HMW glutenin subunits, or by altering the relative amounts of the different types of glutenin available. Thus, the protein subunits coded for by the alleles Glu-B1x7 and Glu-D1x5 stabilised the gluten network, whereas those coded for by Glu-B1x17 and Glu-D1x2 had the opposite effect. Dough properties therefore appear to depend on the glutenin/gliadins balance, and on the ratio of the type x and type y HMW proteins. The influence of external factors seems to depend on the allelic composition of each cultivar.     

Physiological studies on grass-dwarf selection lines in wheat (Triticum aestivum L.)

Summary Low power heating wires insulated in a flexible plastic strip were used to heat the shoot meristematic region of grass-dwarf genotypes to a precise temperature. The results indicate that the shoot apical meristem is the region requiring 26°C for the initiation of reproductive development in these genotypes. A secondary effect of the reproductive growth induced by high temperature treatments, was a reduction in the high levels of peroxidase enzymes found in vegetative grass-dwarf plants. The heating wire provides a precise method to identify Type I, II and III grass-dwarf genotypes according to their temperature requirements, of 26°C, 21°C and 16°C respectively, for reproductive growth under the same temperature (16 C) and photoperiod (12 hours).     

Gametocidal properties of RH-531, RH-532, RH-2956, and RH-4667 on spring wheat (Triticum aestivum L.)

Summary Several chemicals were evaluated for their gametocidal properties to control pollination in hybrid wheat (Triticum aestivum L. em Thell.) seed production. In a preliminary study, four chemicals were applied to three cultivars of spring wheat at two application times. RH-532 was the most effective of the four gametocides, reducing fertility to a 0 10% level for all three cultivars.In a second experiment, RH-532 was applied to one cytoplasmic male-sterile and three normal spring wheats at four rates (0.56, 1.12, 2.24, and 4.48 kg/ha) and at two times of application. Alternate strips of pollinator were planted throughout the experiment. All treatments decreased fertility. plant height, and spike length of the three normal wheats. RH-532 did not inhibit spike emergence of two semidwarf cultivars or one of conventional height. Cultivars did not respond similarly to treatments.Yields of cross-pollinated seed were only 1 21% of the normal yield when fertility levels on treated plants reached 0 10%. Hybrid seed content of the harvested seed ranged from 2 55%. On the treated male-sterile line, yield was significantly reduced in comparison with the open-pollinated check. Inhibitory properties of this chemical suppressed the fertilization potential of the female as well as inducing male sterility.The differential response of genotypes to treatments indicates that cultivars should be screened for male and female sensitivity to this chemical. If differential sensitivity is found, breeding and selection to improve this trait may be possible. Different environmental conditions may alter the response of cultivars to this chemical, with less effect on the female structures.Published with the approval of the Director, North Dakota Agricultural Experiment Station, as journal article No 71a.     

Genetic variation for nitrogen use efficiency in winter wheat (Triticum aestivum L.)

Summary The new European Common Agricultural Policy and environmental considerations are certainly to change agricultural practices toward low input cultivation systems. Nitrogen is one of the main inputs of winter wheat in northern France and it contributes highly to phreatic water pollution. A research programme has then been set up in order to study whether it is possible to breed for winter wheat cultivars using more efficiently N fertilisers. Less nitrogen would be applied, decreasing pollution risks and operational costs. It has been shown that a large variation exists for N related traits and for the resistance against N deficiency. On the one hand the cv Arche is very resistant to N deficiency, its yield on low N conditions (with no N fertiliser) is on average 89% of its yield on high N conditions (with a high N application). On the other hand, cv Récital is very susceptible to N deficiency as this same percentage is only 61%. A study on 10 hybrids showed that heterosis for grain yield was higher at low N level than at high N level. This was due to a higher number of grains per m².     

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.     

Production and genetic characterization of the co-isogenic lines of a common wheat Triticum aestivum CV. S-615 for ten major genes

Summary Co-isogenic lines of a common wheat, Triticum aestivum, cv. S-615 with each of the following ten major genes were produced by repeated backcrosses; The gene C on 2D chromosome for the compactum character, s on 3D for the sphaerococcum character, Hd on 4B, B1 on 5A, and B2 on 6B for awn suppression, Hg on 1A for glume hairiness, Hp on 4A for peduncle hairiness, Ne1 on 5B and Ne2 on 2B for hybrid necrosis, and v1 on 3B for virescence. Seven of them showed the typical mendelian fashion of inheritance, while three others (C, s and v1) were transmitted at lower frequencies than their corresponding normal alleles.The effects of those major genes on 24 characters of cv. S-615 were investigated, which are summarized as follows: C: Increased node diameter, number of spikelets per ear and spike density, but decreased lengths of all ear rachis, awn, anther, empty and outer glumes, and grain, and grain index. s: Increased culm diameter and thickness, and spike density, reduced lengths of all 1st and 2nd internodes, culm, flag leaf, rachis, awn, anther, empty and outer glumes, and grain, and grain index, and accelerated heading. Hd: Increased number of spikelets per ear and anther length, while decreased length of awn, and empty and outer glumes. B1: Increased 1st internode, rachis, and anther lengths, and grain index, but decreased spike density, awn length and grain thickness. B2: Increased rachis length, number of spikelets per ear, empty and outer glume lengths and grain index, but reduced awn length and grain thickness. Hg: No effects. Hp: Increased number of spikelets per ear. Ne1: Accelerated heading, and increased empty glume length. Ne2: Increased node and culm diameters. v1: No effects.Two species-specific genes, C and s, affected a large number of characters expressed in various developmental stages. These genes were found to have pleiotropic effects, namely, they influenced, at least, two groups of interdependent characters. Three awn suppressors influenced a limited number of characters, but no evidence of their pleiotropic effects was obtained.Contribution from the Laboratory of Genetics, Faculty of Agriculture, Kyoto University, Japan, No. 422. The work was supported in part by a Grant-in-Aid (No. 148,004) from the Ministry of Education, Japan.     

Effects of nucleus,cytoplasm and male sterile nucleus-cytoplasm combinations on callus initiation in anther culture of wheat

Summary Nuclear and cytoplasmic factors affect tissue culture response in wheat (Triticum aestivum), and cytoplasmic male sterility may enhance callus initiation in anther culture. Three wheat nuclear genotypes, each in normal and two alien cytoplasms conferring cytoplasmic male sterility, were evaluated for callus initiation frequency in anther culture. Nuclear genotype had the greatest effect on callus initiation, but cytoplasm and nucleus X cytoplasm interaction also produced significant effects. The nuclear genotype of Chris outperformed Butte and Coteau in all cytoplasms. Ordinary wheat and Triticum timopheevi cytoplasms outperformed Aegilops speltoides cytoplasm. Cytoplasmic male sterility did not increase callus initiation. This suggests manipulating the nuclear genotype is the best strategy for improving the capacity of wheat to initiate callus in anther culture.     

The effect of gibberellic acid on male fertility in bread wheat

Summary The effect of gibberellic acid (GA₃) on male fertility was investigated in wheat. Greenhouse and field experiments were carried out. GA₃ induced high levels of male sterility both in gibberellin (GA)-sensitive and GA-insensitive genotypes. The optimum concentration was 2000 ppm of GA₃ when applied at successive sprays. The critical period for GA₃ treatment, in the general sense, extended from glume differentiation to premeiotic interphase in the oldest florets of the spike, though differences were found between GA-sensitive and GA-insensitive genotypes in the extension of this period. The effect of GA₃ on plant height was also studied. The potential use of GA₃ as a chemical hybridizing agent in wheat breeding is discussed.Abbreviations GA gibberellin - GA₃ gibberellic acid - ms male sterility Scientific Paper GEN-810 of the Instituto de Gen]'etica, CICA, INTA, Castelar, Argentina     

Genetic basis of grain filling rate in wheat (Triticum aestivum L. emend. Thell.)

Summary Grain filling rate in wheat (Triticum aestivum L. emend. Thell.) positively influences grain yield under a wide range of conditions. The effective utilization of this trait in breeding depends on an understanding of its genetic control. A study was, therefore, conducted to determine the genetic basis of grain filling rate in six crosses of wheat. Higher order genic interactions and/or linkage were important in the genetic regulation of grain filling rate (GFR) in the majority of crosses. Additive ([d]) and dominance ([h]) gene effects were important in the control of GFR in main ears (ME) and whole plant ears (WPE). Additive and additive × additive epistatic effects were the most important in the genetic control of GFR in last ears (LE). Location effects on genetic effects for GFR were significant (P < 0.05) in all ear types of some crosses except in ME. Genotype × environment interaction effects were important (P < 0.001) in LE and WPE.It was concluded that the inheritance of GFR is complex and is dependent on ear type. Breeding procedures that facilitate the exploitation of non-additive and additive gene effects were recommended for the genetic improvement of grain filling rate of wheat.     

QTL mapping of male sterility-related traits in a photoperiod and temperature-sensitive genic male sterile wheat line BS366

The photoperiod/temperature-sensitive genic male sterile (P/TGMS) character is important for use of heterosis in hybrid wheat. In the present study, the fertility of 172 doubled haploid (DH) lines derived from the cross between a P/TGMS wheat line BS366 and a restorer wheat line Baiyu149 was investigated under both fertile and sterile environments during three cropping seasons. The phenotype was recorded based on the international seed setting rate. A total of 167 SSR and 1,278 SNP markers were used to construct a linkage map, with a total length of 3,748.94 cM and an average marker interval of 2.59 cM. Three QTLs were identified and designated as QF.bhw-2DS, QF.bhw-4BS and QF.bhw-7Al, explaining 6.9%–12.8%, 19.7%–25.6% and 7.2%–8.8% of the phenotypic variances, respectively. These results lay a good basis for application of male sterility-related molecular markers in improvement of two-line hybrid wheat breeding system.     

Stability analysis over seasons and locations of multilines of wheat (Triticum aestivum L.)

Summary Three multilines each of Kalyansona and PV 18 varieties of wheat were compared for their stability of yield and agronomic characters and disease resistance against the respective recurrent parents. The experiments were conducted for four years at nine locations.The multilines had more tillers and bolder seeds than the recurrent parents. There were, however, no differences for plant height, ear length and number of spikelets per spike.The genotypes x years x locations interaction was much more important than genotypes x years or genotypes x locations interaction as well as the main effects for genotypes. It is suggested that the number of test locations should be increased while decreasing the number of years.The stability parameters indicated that the multilines had a higher mean yield in the case of Kalyansona multilines whereas the yield of multilines of PV 18 was not significantly inferior to that of the recurrent parent. The regression coefficients were very close to unity except for KSML 3 (b=1.132). The deviations from regression were much larger for the multilines than for the recurrent parents.For rust resistance the multilines were superior over the varieties Kalyansona and PV 18.This is publication No. 9 of the series Studies on multilines in wheat (Triticum aestivum L.)     

Evidence for a ‘uniculm effect’ in spring wheat (Triticum aestivum L.) in a mediterranean environment

Summary The concept of the uniculm habit as an important feature of a wheat ideotype for a mediterranean environment was evaluated under field conditions. A uniculm plant produces a single shoot and when sown in a stand exemplifies a non-tillering crop with a fixed density of shoots throughout the growing season. Yield and harvest index of normal tillering spring wheat was compared with that of the same crop surgically detillered throughout the growing season to a constant density of 2 shoots per plant. The use of a biculm, whilst retaining the uniculm principle of a fixed density of shoots throughout the growing season, permitted comparison on a single crop sowing at normal field density.The control plots followed the usual pattern of tillering for the region attaining a maximum of about 4.0 shoots per plant by early spring. Shoot number declined to 2.3 and 2.6 per plant by maturity in 1978 and 1979, respectively.Detillered plots outyielded the controls by 14 per cent in 1978 (2.05 v. 1.80 tonnes ha^-1) and 22 per cent in 1979 (1.84 v. 1.51 tonnes ha^-1). Harvest indices were 0.39 v. 0.35 in 1978 and 0.30 v. 0.24 in 1979 for detillered and control plots, respectively.Higher leaf area indices and better water relations after anthesis in biculm stands indicated more efficient water use when shoot population was controlled at near optimum level. Irrigation at anthesis reduced the difference in yield between detillered and control plots.Although the uniculm principle was demonstrated with biculms in practice control of shoot number will require the use of genetic uniculms.     

Monosomic analysis of Russian wheat aphid (Diuraphis noxia) resistance in Triticum aestivum line PI137739

Summary The Russian wheat aphid, Diuraphis noxia (Mordvilko) (Homoptera: Aphididae), has become an important pest of wheat (Triticum aestivum L.) in the United States. The aphid causes a phytotoxemic reaction in wheat evidenced by local and systemic chlorosis and rolling of infested leaves. Developing resistance in wheat cultivars to D. noxia is an essential factor in controlling the damage caused by this pest. Several sources of genetic resistance to D. noxia have been identified in wheat germplasm. Monosomic analysis of the monogenic resistant T. aestivum accession PI137739 has shown that the gene (Dn1) for resistance is carried on chromosome 7D. It appears that chromosome 7B may carry a second resistance gene for D. noxia that might be a source of minor or complementary gene action for resistance.     

The genetics of auricle colour of wheat (Triticum aestivum L.): A review

Summary Only a few publications deal with the genetics of auricle colour of wheat. They report that red pigmentation is conditioned by one dominant gene, symbolized Ra. Ra is present in Egyptian local wheat cultivars. My own research showed the great instability of this character.     

Chromosomal location of genes controlling grain size in a large grained selection of wheat (Triticum aestivum L.)

Summary Grain size in wheat is the most stable yield component and has a favorable effect on flour yield. To identify the chromosomes associated with the large grains of line G603-86, (grain weight over 60 mg and grain length of about 9 mm), F₃ lines, extracted from F₂ populations obtained from F₁ monosomics of crosses between G603-86 (P₁) and the monosomic set of Favorit (P₂) were tested in the field. ANOVA showed significant differences among parents for grain weight and grain length, but not for grain width or the factor expressing the difference in grain form and density. Homoeologous groups had significant effects on grain weight and on all components of grain weight, while genomes were not significantly different for any of these characters. Grain weight was significantly increased by chromosomes 6D and 4A of G603-86. Grain length was significantly increased by chromosomes 4A, 4B, 2B, 3A and 1B, grain width by chromosomes 1A and 1B, and the factor form-density by chromosomes 6D and 6A. The high grain size in G603-86 results from the effects of genes located on many chromosomes which affect grain dimensions, form and density.     

Boron deficiency induced male sterility in wheat (Triticum aestivum L.) and implications for plant breeding

Boron (B) deficiency causes grain set in wheat to fail. A wide range of genotypic variation in the response to low B has been observed. Genotypes were screened in low B in soil and sand culture, and classified into five groups, namely, very sensitive, sensitive, moderately sensitive, moderately tolerant and tolerant. At very low levels of B, the very sensitive to sensitive genotypes were completely male sterile and set only a few or no grain, while the tolerant genotypes set grain normally. Natural outcrossing was detected in these male sterile plants when a tolerant genotype was growing nearby. Grain set by cross fertilisation was markedly enhanced by a B application directly on the ear of the male sterile plants. Three practical implications are suggested. Firstly, genotypes that are tolerant to low B can provide a solution for grain set failure caused by B deficiency. Secondly, the potential for outcrossing in male sterile B deficient wheat has to be taken into account in the maintenance of pure lines in low B soils even though wheat is normally self pollinated. Thirdly, a simple and novel method for hybridization is suggested, in which B deficiency is used as fertility selective medium and male sterile female parents and fertile male parents are provided by genotypic variation in the response to low B. This revised version was published online in July 2006 with corrections to the Cover Date.