Effect of variation at Glu-D1 on club wheat end-use quality

Club wheats (Triticum aestivum L.), having the allele at the C locus conferring short spike rachis internodes and giving compact appearance of spikes, which have unique and highly desirable soft white wheat end-use quality characteristics are a vital submarket class of soft white wheat in the US Pacific Northwest. Two important varieties, ‘Tyee’ and ‘Albit’, are heterogeneous for high molecular weight glutenin subunits 2 + 12 and 5 + 10 encoded by the Glu-D1 locus. Replicated near-isogenic lines (NILs) of club wheats ‘Tyee’ and ‘Albit’ were grown in four field environments and used to determine the effect of Glu-D1 coded high molecular weight glutenin subunits (HMWGS) 5 + 10 and 2 + 12 on various end-use quality traits. The greatest effect of variation at this locus was observed for mixing time to peak, where there was significant variation (P < 0.01) between each 5 + 10 and 2 + 12 NIL group in each environment. Mixing time values for the 2 + 12 NILs for both ‘Albit’ and ‘Tyee’ ranged from 0.60 to 1.23 min lower than the 5 + 10 NILs. Mean values for traits mixing time to peak, cake volume, and viscosity were more favourable for the 2 + 12 NIL groups for all genotypes in all environments. No effects of these HMWGS were detected for test weight, kernel hardness, whole wheat protein, flour yield, ash, flour protein or cookie diameter. Selection for HMWGS 2 + 12 in club wheat breeding programmes should have positive effects on end-use quality.     

Copper‐Induced Oxidative Stress and Responses of the Antioxidant System in Roots of Medicago sativa

The effects of various copper (Cu) concentrations on the antioxidative system in the roots of Medicago sativa were explored. The results indicated that the Cu content of the roots reached a value of 854 μg g^?1 DW at 10 μm Cu and a value of 4415 μg g^?1 DW at 100 μm Cu, suggesting that M. sativa has better ability to tolerate and accumulate Cu than other Cu‐bioaccumulators, and is a potential plant for phytoremediation. Treatment with Cu resulted in a significant increment in the levels of H₂O₂, O₂˙^? and OH˙. The reduced form of ascorbate and glutathione reached a peak at 30 μm Cu, and was followed by a sharp depletion to a lower level than that of the control. In contrast, the levels of the oxidised forms of ascorbate and glutathione showed a progressive increment with increasing Cu concentrations, suggesting that the antioxidant system was unable to cope with Cu stress at higher Cu levels. Under the Cu concentrations tested, the activity of catalase (CAT, EC 1.11.1.6), ascorbate peroxidase (APX, EC 1.11.1.11) and glutathione reductase (GR, EC 1.6.4.2) increased at lower Cu concentrations, and then decreased, reaching a maximum at 30 μm of Cu for APX and GR, at 10 μm for CAT, whereas the activities of guaiacol peroxidase (POD, EC 1.11.1.7) were gradually increased with increasing Cu concentrations. PAGE analysis of superoxide dismutase (SOD, EC 1.1.5.1.1) revealed that one band is a Mn‐SOD and five bands are identified as Cu, Zn‐SOD, whereas Fe‐SOD isoforms were not found in the roots of alfalfa. Cu at 10–100 μm increased the intensity of constitutive isozymes of CAT, APX and POD, whereas it decreased the intensity of isozymes of glucose‐6‐phosphate dehydrogenase (G6PDH, EC 1.1.1.49) significantly. The activities of lipoxygenases (LOX, EC 1.13.11.12) were gradually augmented with increasing Cu concentrations, demonstrating that LOXs are probably involved in production of lipid hydroperoxides and superoxide anion. There was a continuous and pronounced enhancement in the activity of esterase (EST, EC 3.1.1.1) in roots treated with 10–30 Cu μm , whereas EST activity in roots exposed to above 30 μm Cu declined, suggesting that EST plays a protective role under lower Cu concentrations stress.     

Effects of Salinity on Growth, Ionic Relations and Physiological Traits of Wheat, Disomic Addition Lines from Thinopyrum bessarabicum, and Two Amphiploids

The effects of NaCl on the growth, ion relations and physiological characteristics at early stages of growth of bread wheat (Triticum aestivum) varieties ‘Chinese Spring’ and ‘Glennson 81’, ‘Chinese Spring’ lines tetrasomic for chromosomes 5A, 2B and 5B, ‘Chinese Spring’ disomic addition lines for chromosomes 2E^b and 5E^b from Thinopyrum bessarabicum (formerly Agropyron junceum), and amphiploids between ‘Chinese Spring’ and Thinopyrum bessarabicum and ‘Chinese Spring’ and Lophopyrum elongatum (formerly Agropyron elongatum) were examined. Plants were grown in a controlled environment cabinet, in nutrient solution with or without addition of 200 mol m^?3 NaCl. Growth in terms of leaf area, shoot and root weights was reduced by salt treatment. Salinity conditions gradually reduced the osmotic potential, though there was little effect on water potential. Turgor pressure was not much affected by salt. There was variation between genotypes for all the characteristics studied, especially in the extent of Na accumulation by leaves and roots. The amphiploids and 5E^b addition line accumulated the least Na in comparison with other genotypes. Generally roots accumulated lower quantities of Na than leaves. Genotype K contents were not affected by salt treatment. Stomatal conductance also declined whilst the ABA content increased in the salt treated seedlings. With respect to growth, the amphiploids and 5Eb addition line were most tolerant to salt while ‘Glennson 81’, tetrasomic 2B and tetrasomic 5B lines were most susceptible. The addition of homoeologous group 2 and 5 chromosomes reduced the tolerance to salt relative to ‘Chinese Spring’ euploid. It is concluded that chromosome 5E^b of Thinopyrum bessarabicum carries gene(s) for tolerance to salt and this tolerance may be due to the ability to exclude Na ions from the leaves and roots.     

Doubled haploid production in Turkish durum wheats using crosses with maize

Durum wheats cultivated in the Middle Anatolia region of Turkey (Triticum durum cvs ‘Kunduru’, ‘Berkmen’ and ‘Cakmak’) were crossed with maize to evaluate their capacity for haploid embryo and doubled haploid (DH) plant production. A total of 2960 florets were crossed with maize and 13.7% of the florets produced haploid embryos across the three varieties. Haploid embryo and plant regeneration frequencies were highest in ‘Kunduru’, but colchicine doubling was less successful with this genotype. There were statistically significant differences between ‘Cakmak’ and other genotypes for embryo yield (P < 0.01). Overall, 52.3% of all embryos differentiated, but there were no geno-typic differences in differentiation frequencies.     

Variation for tolerance to high concentration of ferrous iron (Fe<Superscript>2+</Superscript>) in Australian hexaploid wheat

High concentration of reduced iron (Fe²⁺) in waterlogged acid soils is a constraint for growing wheat in high rainfall (waterlogged-prone) areas of Western Australia. Growing crop genotypes tolerant to high Fe²⁺ concentrations may be desirable in such situations, but there is no knowledge about the extent of variability in Fe²⁺ tolerance in the wheat germplasm. A bioassay for tolerance to high concentrations of iron in wheat was developed and optimised using Siete Cerros (Fe-tolerant) and BH1146 (Fe-intolerant) as control genotypes and a range of FeSO₄ concentrations (36, 313, 625, 1250, 1875, 2500 and 3125 μM Fe²⁺) in nutrient solution in a controlled-temperature environment. Increasing external concentration of iron decreased both shoot and root dry weight, increased shoot iron concentration and intensified the development of toxicity symptoms to a greater degree in intolerant BH1146 as compared to tolerant Siete Cerros. Increased iron supply negatively affected uptake of Ca (r = −0.41) and Mg (r = −0.40). The tolerant genotype Siete Cerros showed an improved avoidance/exclusion of high external concentration of Fe²⁺ compared with intolerant BH1146. The genotypic discrimination based on relative root dry weight and the development of toxicity symptoms was most pronounced at 625 μM Fe²⁺. This concentration was chosen for screening of 20 bread wheat and one durum genotype chosen from a preliminary screening of 94 Australian wheat genotypes. A relatively narrow but significant variation (22–38%) in terms of relative root dry weight under Fe²⁺ toxicity was observed among Australian advanced breeding lines and varieties. The presence of genotypic variation for Fe²⁺ tolerance across and within the Australian breeding programs could be exploited in a deliberate selection process to enhance Fe²⁺ tolerance in wheat. Durum wheat (Arrivato) and several Australian wheat varieties and advanced lines in this study were as tolerant to Fe²⁺ toxicity as Siete Cerros, a variety representing common parentage of iron-tolerant genotypes.     

Relationships between different prolamin proteins and some quality properties in durum wheat

The objective of this paper was to study the differences between some prolamin variants coded at the loci Glu-3/Gli-1, Glu-1 and Gli-A2 and their relative roles in durum-wheat quality. F₃ lines from four durum wheat crosses (‘Abadia’בMexicali’. ‘Oscar’בArdente’, ‘Oscar × Mexicali’ and ‘Alaga’בC. of Balazote’) were analysed for gliadin and glutenin composition by electrophoresis. Whole-grain-derived samples were analysed for SDS sedimentation (SDSS) value, mixing properties, and contents of protein and vitreousness. The glutenin patterns LMW-2. LMW-2^? and LMW-2 (CB) at Glu-B3/Gli-B1 were associated with better gluten quality than were LMW-1 and LMW-2*. The glutenin subunits LMW4 and LMW3 + 15 at Glu-A3/Gli-A1 and HMW-1 showed better mixing properties than LMW7 + 12, LMW5 and the null phenotype. respectively. The HMW glutenin subunits 20 + 8 at Glu-B1 showed a negative association with gluten quality, but the rest of the HMW glutenin subunits and α-gliadins did not show any influence on gluten quality. Correlations between the results of the SDSS test and the mixograph were highly significant, but no correlation was found between these results and protein and vitreousness contents. The results are discussed in relation to the development of durum wheat varieties with improved qualities.     

Genotypic variation for competitive ability in spring wheat

Herbicides are the primary method of weed control for crop production in developed countries. For economic and environmental reasons alternative control strategies are being devised. One of these strategies is the development of competitive crop cultivars. The objectives of this research were to establish whether spring wheat (Triticum aestivum L.) genotypes differed in competitive ability and if those differences were related to specific growth characteristics. Sixteen genotypes of spring wheat were grown under simulated weed competition conditions at Saskatoon, Canada over a 3–year period. Four high and four low tillering genotypes from each of two crosses (Neepawa/M1417 and Ingal/M1417) were studied. Weeds consisted of cultivated oat (Avena saliva cv. ‘Waldern’) and oriental mustard (Brassicajuncea cv. ‘Cutlass’) sown at two densities (48 and 96 seeds/m² per weed species). Seedling establishment, ground cover, and seed yield for the three species were determined, as was wheat tiller number, spike number, maximum height, leaf area index, leaf orientation, and flag leaf length and size. Significant (P = 0.001) weed rate by genotype interactions involving changes in genotype rank were detected for wheat grain yield, indicating that the 16 wheat genotypes differed in competitive ability. Wheat grain yield reductions averaged over the two weed densities ranged from 45% to 59%. The highest-yielding genotypes under weed-free conditions were not necessarily the highest yielding under weedy conditions. Genotypes which suffered smaller yield reductions were more effective in suppressing weed growth. Although competitive genotypes were generally taller than non-competitive genotypes, other traits such as large seedling ground cover and flag leaf length were associated with wheat yield under competitive conditions.     

Differential tolerance to Fe and Zn deficiencies in wheat germplasm

Tolerance to Fe deficiency of wheat genotypes exhibiting differential tolerance to Zn deficiency is not known, even though the relationship between Fe nutrition and differential tolerance of wheat genotypes to Zn deficiency has been hypothesised frequently. In the present experiment, eight Triticum aestivum and two T. turigidum L. conv. durum cultivars were grown in nutrient solution deficient in either Znor Fe. Three indices of tolerance to nutrient deficiency were compared: relative [(-nutrient/+nutrient) × 100] shoot growth, shoot dry weight under nutrient deficiency and relative shoot/root dry weight ratio. Genotypes Aroona, Excalibur, Stilleto and Trident were classified as tolerant to both Zn and Fe deficiency, while durum wheats Durati and Yallaroi were sensitive to Zn deficiency and moderate to sensitive to Fe deficiency. Genotypes Excalibur, Stilleto and Trident come from the same breeding programme and have the common parent (line MEC3 =Sonora64//TZPP/YAQUI54) that could have been the donor of the genes for tolerance to Zn deficiency. When Fe-deficient, all wheat genotypes were severely chlorotic but kept producing shoot and root dry matter at a relatively high rate, making the relationship between the relative shoot growth and the relative leaf chlorophyll content poor. This is the first report of wheat genotypes exhibiting multiple tolerance to Zn and Fe deficiencies. This revised version was published online in July 2006 with corrections to the Cover Date.     

Potential use of doubled haploid lines for the screening of resistance to yellow rust (Puccinia striiformis) in hexaploid wheat

Doubled haploid lines derived from anther culture of two Iranian spring wheat genotypes‘Ghods’susceptible and‘9106’resistant to yellow rust in Iranian field conditions, and their F₁ hybrids were used in this study. Seedlings of 36 doubled haploid lines, selected out of 96 according to their agronomic traits and the two parental genotypes were inoculated with eight races of yellow rust. The parental genotypes (‘Ghods’and‘9106’) were segregating for some of the races but their doubled haploid lines were either resistant or susceptible to them.‘Ghods’was susceptible to three of the races studied but three doubled haploid lines derived from it were resistant to them. Five selected doubled haploids from the‘9106’genotype and six from F₁ hybrid plants were resistant to all eight races tested. After further investigations in Iranian field conditions it was found that some of these lines can be used as donor genotypes for resistance to yellow rust in wheat breeding programmes. Use of these genotypes should be possible if the French yellow rust races used for selection also represent the dominant races in Iran. It can be concluded that anther culture provides an efficient method for fixing genes of resistance to yellow rust and desirable doubled haploids from F₁ plants can be derived.     

A Robertsonian translocation from Thinopyrum bessarabicum into bread wheat confers high iron and zinc contents

Development of wheat–alien translocation lines has facilitated practical utilization of alien species in wheat improvement. The production of a compensating Triticum aestivum–Thinopyrum bessarabicum whole‐arm Robertsonian translocation (RobT) involving chromosomes 6D of wheat and 6E^b of Th. bessarabicum (2n = 2x = 14, E^bE^b) through the mechanism of centric breakage–fusion is reported here. An F₂ population was derived from plants double‐monosomic for chromosome 6D and 6E^b from crosses between a DS6E^b(6D) substitution line and bread wheat cultivar ‘Roushan’ (2n = 6x = 42, AABBDD) as female parent. Eighty F₂ genotypes (L1–L80) were screened for chromosome composition. Three PCR‐based Landmark Unique Gene (PLUG) markers specific to chromosomes 6D and 6E^b were used for screening the F₂ plants. One plant with a T6E^bS.6DL centric fusion (RobT) was identified. A homozygous translocation line with full fertility was recovered among F₃ families and verified with genomic in situ hybridization (GISH). Grain micronutrient analysis showed that the DS6E^b(6D) substitution line and T6E^bS.6DL stock have higher Fe and Zn contents than the recipient wheat cultivar ‘Roushan’.     

Inheritance of resistance to Karnal bunt (Tilletia indica Mitra) in bread wheat (Triticum aestivum L.)

The mode of inheritance and allelic relationships among genes conferring resistance to Karnal bunt were studied in seven bread-wheat (six resistant and one susceptible) genotypes. The resistant genotypes originated in China (‘Shanghai#8’), Brazil (PF71131), the USA (‘Chris’), and Mexico (‘Amsel’, CMH77.308 and ‘Pigeon’). The susceptible line WL711 was from India. Evaluation of these wheat lines and all possible crosses among their F₁ and F₃ generations (about 100 progenies in each cross) revealed that two partially recessive genes conferred the resistance to Karnal bunt in ‘Pigeon’, whereas four partially dominant genes were present in the other genotypes. ‘Chris’, ‘Amsel’ and PF71131 carry one gene, whereas ‘Shanghai#8’ and CMH77.308 have two genes. ‘Chris’, ‘Amsel’, and PF71131 have different genes, whereas one gene was common to PF71131, CMH77.308 and ‘Shanghai#8’, and another to ‘Chris’ and CMH77.308. Gene symbols were formally designated to the resistant stocks. Resistance was incomplete and stable.     

Genetic Variation for Anther Callus Inducibility in Crosses of Highly Culturable Winter Wheats

Heritability studies suggest that variation among genotypes for callus inducibility should respond to selection. The objective of this study was to determine if crosses among parents with high callus initiation frequencies would produce segregation from which genotypes with improved callus inducibility could be selected. The winter wheat (Triticum aestivum L.) cultivars‘Centurk 78’, ‘Norstar’ and ‘Norwin’ were chosen as parents, based on their high callus initiation frequencies and diverse parentage. F₂ populations from crosses between each of these parents were evaluated for callus initiation frequencies and callus vigor as determined by growth rate and healthy appearance. Heterosis was detected for callus initiation in the‘Norwin’בNorstar’ cross and for callus vigor in all crosses. Broad sense heritability estimates of 0.25 and 0.37 for callus initiation in the ‘Centurk 78’בNorstar’ and ‘Norwin’בNorstar’ crosses, respectively, suggest this trait can be improved by selection. Heritability estimates for callus vigor were less promising, ranging from 0.11 to 0.24.     

Genotypic differences in wheat Al tolerance

Summary Aluminium tolerance of 83 genotypes from Croatian and Yugoslav Triticum aestivum germplasm was evaluated in nutrient solutions having Al³⁺ activities of 0, 12.5 and 25 M. Relative root length (25 M Al³⁺/0 Al) of various genotypes ranged from 2 to 97% (from very sensitive to tolerant to Al). No genotype with Al tolerance close to that of very tolerant cultivar Atlas-66 was found. Soil, climatic, fertilization, and liming effects that wheat plants giving seeds for the nutrient solution Al-tolerance screening had been subjected to during their growth cycle did not influence the Al-tolerance ranking. Significant correlation was found between screening wheat for Al tolerance in nutrient solutions and in acid Pseudogley soil amended with five rates of limestone in a greenhouse experiment. Seed protein concentration was significantly related to the Al-tolerance ranking (r² = 0.962). Such a significant correlation was not obtained in a case of rheological and other quality characteristics of seeds. Al-tolerant wheat genotypes identified in this study will be used in breeding for improved Al tolerance.Abbreviations HSD Tukey's Honestly Significant Difference - RRL-2 relative root length, in % (12.5 M Al³⁺/0 Al) - RRL-4 relative root length, in % (25 M Al³/0 Al)     

Die Nutzung der Antherenkulturmethode im Zuchtprozeß von Winterweizen

The use of anther culture in breeding winter wheat. II. Production of new doubled haploid lines of winter wheat with 1AL—1RS-translocation A total of 4472 anhers was cultured from 8 F¹ populations of winter wheat with the 1AL—1RS wheat-rye translocation cultivar ‘Amigo’ as one of the crossing arents. When averaged over all populations a frequency of embruoid formation of 10% and of regeneration efficiency of green plants of 1% were observed. In addition to the 45 green regenerated plants, 93 albinos were obtained. 44% of the green plantlets had 21 chromosome in root tips and 29% were spontaneous diploids. Multiple peroxidases were used a biochemical markers in the subsequent characterization of the homogeneous breeding material. The electrophoretic patterns showed that 16 doubled haploids without rye chromosome segments were produced. In addition the features of dh₀- plants showed, that several of the new 1AL—1RS-translocation lines were awnless.     

The 1BL/1RS chromosome translocation effect on yield characteristics in a Triticum aestivum L. cross

Comparisons involving 28 random F₂-derived F₆ wheat (Triticum aestivum L.) lines from the cross, ‘Nacozari’/‘Seri 82’, suggested that advanced derivatives with the 1BL/1RS chromosome translocation possess superior agronomic performance in both full and reduced irrigation conditions when compared with 1B derivatives. This performance advantage was attributed to high grain yield, above-ground biomass at maturity, grains/spike, 1000-grain weight and test weight. The 1BL/1RS lines were shorter with delayed flowering and maturity. The superiority of the 1BL/1RS translocation group on grains/m² was expressed only under the full irrigation environment. Higher harvest index, longer spike-length and grain-filling period were detected only under reduced irrigation conditions. A significant grain yield relationship with test weight was detected only among the 1BL/1RS genotypes, indicating that they possess heavier and plumper grains than the 1B genotypes.     

Chromosome location of genes affecting polyphenol oxidase activity in seeds of common and durum wheat

This study used cytogenetic stocks to investigate the chromosomal location of genes responsible for polyphenol oxidase (PPO) activity in common and durum wheat seeds. Substitution lines of chromosome 2A of hexaploid varieties ‘Cheyenne’, ‘Thatcher’ and ‘Timstein’ in ‘Chinese Spring’ showed significantly higher PPO activity than all other substitution lines of the same variety, with the exception of substitutions of ‘Cheyenne’ chromosome 3A and ‘Thatcher’ chromosome 4B. Substitution lines of chromosome 2A of Triticum turgidum var. dicoccoides and of chromosome 2D of ‘Chinese Spring’ into the tetraploid variety ‘Langdon’ showed a significant increase in PPO activity relative to all other substitution lines in Langdon. The gene(s) responsible for high PPO activity in chromosome 2D from ‘Chinese Spring’ was mapped on the long arm within a deletion that represents 24% of the distal part of the arm. This study shows that genes located in homoeologous group 2 play a major role in the activity of PPO in wheat.     

Variation in resistance to the grain aphid, Sitobion avenae (Sternorhynca: Aphididae), among diploid wheat genotypes: Multivariate analysis of agronomic data

A collection of 87 ancient wheat genotypes, 67 Triticum monococcum, 13 Triticum boeoticum, seven Triticum urartu and one cultivar of the modern wheat Triticum aestivum (variety ‘Arminda’) were evaluated for resistance to the cereal aphid Sitobion avenae, the main damaging aphid pest on winter wheat in Europe. The intrinsic rate of natural increase (r_m), which is regarded as a good estimate of the fitness of an aphid population, was used as an indicator for the level of plant resistance. Differentiation of the 88 plant genotypes into four distinct groups was achieved with a cluster analysis of the r_m values. The modern wheat ‘Arminda’ was more susceptible than any of the ancient wheat genotypes tested (r_m= 0.24, i.e. the aphid population doubled every 2.6 days). A second group of 19 plants ranged from relatively susceptible to moderately resistant (0.17 < r_m < 0.21). Fifty–one plants were allocated to a third group and classified as resistant (0.09 < r_m < 0.16). The last group contained 17 genotypes with a high level of resistance where aphid fitness was greatly reduced (0.02 < r_m < 0.09, i.e. the aphid population doubled every 11.4 days or 7.7 days, respectively). Clustering of the accessions into the different phenetic groups did not follow the geographical origin of the wheat genotypes or the species to which they belong. These results show that ancient diploid wheats, all characterized by the genome A, present considerable interest for plant breeding for resistance to S. avenae in modern wheat. The potential use of these strong and partial sources of resistance for introduction of a stable and durable form of resistance to S. avenae in wheat is discussed.     

Assessing diversity in Triticum durum cultivars and breeding lines for high versus low cadmium content in seeds using the CAPS marker usw47

Cadmium (Cd) is a toxic heavy metal that occurs naturally in soils. Durum wheat is known to accumulate generally more Cd than other cereal crops. The uptake of Cd in durum wheat is governed by the gene Cdu1, which co‐segregates with several DNA markers, such as the co‐dominant marker usw47 and the dominant marker ScOPC20. A panel of 314 durum wheat cultivars or lines originating from 16 countries or regions were assessed with usw47. The plant material was mainly comprised of cultivars and modern breeding lines. From this set, 165 durum wheat lines were classified as low‐Cd accumulators, 144 high‐Cd accumulators and five were heterogeneous. A smaller subset of 16 cultivars had previously been evaluated for Cd accumulation in replicated field trials. Lines with the high‐Cd allele showed a 2.4‐fold higher Cd content in the seeds than lines with the low‐Cd allele. We also compared the utility of markers usw47 and ScOPC20 as selection tools. Marker‐assisted selection appears as a robust and practicable tool for breeding durum cultivars with low‐Cd content.     

Cadmium Enhances Generation of Hydrogen Peroxide and Amplifies Activities of Catalase, Peroxidases and Superoxide Dismutase in Maize

Maize (Zea mays L. cv. 777) plants grown in hydroponic culture were treated with 50 μm CdSO₄. Growth and metabolic parameters indicative of oxidative stress and antioxidant responses were studied in leaves of plants treated with Cd. Apart from increasing lipid peroxidation and H₂O₂ accumulation, supply of Cd suppressed growth, fresh and dry mass of plants and decreased the concentrations of chloroplastic pigments. The activities of catalase (CAT; EC 1.11.1.6), peroxidase (POD; EC 1.11.1.7), ascorbate peroxidase (APX; EC 1.11.1.11) and superoxide dismutase (SOD; EC 1.15.1.1) were increased in plants supplied 50 μm Cd. Localization of activities of isoforms of these enzymes (POD, APX and SOD) on native gels also revealed increase in the intensities of pre‐existing bands. Stimulated activities of CAT, POD, APX and SOD in maize plants supplied excess Cd do not appear to have relieved plants from excessive generation of reactive oxygen species (ROS). It is, therefore, concluded that supply of 50 μm Cd induces oxidative stress by increasing production of ROS despite increased antioxidant protection in maize plants.     

Variation at Glu-1 Loci in Club Wheats

Hexaploid club wheats (Triticum aestivum L.) possess unique end-use quality characteristics and are grouped as a U.S. market subclass of soft white common wheat. Although there have been many reports on associations among high-molecular-weight glutenin storage protein (HMW-Glu) sub-units with end-use quality in hard wheats; there has been very limited work done on surveying the club wheats for these subunits. The HMW-Glu subunits, spike types and grain color were determined for 41 U.S. club wheat cultivars and 79 club accessions obtained from the National Small Grains Collection (NSGC), USDA-ARS. Accession ‘Harlan JR 35’ (PI 420948), which appears morphologically to be a hexaploid club wheat, was determined to be tetraploid. Egyptian line ‘Maya II-Tel's’ (PI 422288) was shown to have previously undescribed HMW-Glu subunits. In the U.S. club wheats the most common HMW-Glu subunits were: null, 49 % (Glu-A1); 6, 37 % (Glu-B1); and 2 + 12, 94 % (Glu-D1). In the NSGC group the most common HMW-Glu sub-units were: 2*, 52 % (Glu-A1); 7 + 8, 31 % (Glu-B1); and 2 + 12, 92 % (Glu-D1). The high frequency of subunits 2 + 12 in the club wheat groups has not been observed previously in numerous surveys of diverse wheat cultivars. The Glu-B1 subunits 6 (without subunit 8) and 20 which have not been reported in US red wheats, were shown to be common in both club wheat groups. A comparison of diversity indices, including previous studies on HMW-Glu subunit frequencies on all market classes of wheat, showed that the club groups are as diverse for the Glu-A1 and Glu-B1 loci and less diverse for the Glu-D1 locus.