Effects of the Gpc‐B1 locus on high grain protein content introgressed into Argentinean wheat germplasm

Wheat grain protein content (GPC) is important for human nutrition and has a strong influence on the quality of pasta and bread. The objective of this study was to analyse the introduction of the Gpc‐B1 allele into two Argentinean bread wheat cultivars. Near‐isogenic lines were developed in ‘ProINTA Oasis’ and ‘ProINTA Granar’ using marker‐assisted selection. Gpc‐B1 lines showed a significant (P = 0.01) increase in GPC and a significant (P = 0.001) decrease in grain weight in comparison with control lines without Gpc‐B1. Differences in yield were not significant (P = 0.49) between lines. Gpc‐B1 lines significantly reduced (P = 0.02) straw nitrogen concentration at maturity and significantly increased (P = 0.02) the nitrogen harvest index. When data were analysed by genotype and environment, differences in some analysed parameters were found, indicating that Gpc‐B1 expression may be affected by different genetic backgrounds and environmental conditions. These results suggest that the introgression of the Gpc‐B1 allele into Argentinean wheat germplasm could be a valuable resource for improving GPC with no detrimental effect on grain yield.     

Carbon Isotope Discrimination, Leaf Ash Content and Grain Yield in Bread and Durum Wheat Grown under Full-Irrigated Conditions

Integrative physiological criteria, such as carbon isotope discrimination (Δ) and (mineral) ash content (m_a) have been found to be very useful, under drought conditions, to elucidate the association between yield gains and variation of photosynthesis‐related traits and orientate future breeding efforts. Information on this association is scarce under irrigated conditions. The relationships between Δ, m_a and yield were studied in bread wheat (Triticum aestivum L.) and durum wheat (Triticum turgidum L. var. durum) under optimal (drip) irrigation in the arid conditions of north‐west Mexico. Carbon isotope discrimination was analysed on leaves at booting stage and anthesis and on grain at maturity, whereas ash content was measured on the flag leaf at anthesis and maturity. At anthesis, there were differences between bread and durum wheat during grain filling for Δ, but not for m_a. No relationship was found between grain yield and Δ. Leaf ash content at anthesis and maturity showed a broad variability within each species and were associated with grain yield. These results suggest that ash content in leaves could be also used as predictive criteria for yield not only under drought, but also under irrigated conditions, particularly when evaporative demand is high.     

Contribution of Different Organs to Grain Filling in Durum Wheat under Mediterranean Conditions I. Contribution of Post‐Anthesis Photosynthesis and Remobilization

Under Mediterranean conditions, drought affects cereals production principally through a limitation of grain filling. In this study, the respective role of post‐anthesis photosynthesis and carbon remobilization and the contribution of flag leaf, stem, chaff and awns to grain filling were evaluated under Mediterranean conditions in durum wheat (Triticum turgidum var. durum) cultivars. For the purpose, we examined the effects of shading and excision of different parts of the plant and compared carbon isotope discrimination (Δ) in dry matter of flag leaf, stem, chaff, awns and grain at maturity and in sap of stem, flag leaf, chaff and awns, this last measurement providing information on photosynthesis during a short period preceding sampling. Source–sink manipulations and isotopic imprints of different organs on final isotope composition of the grain confirmed the high contribution of both carbons assimilated by ears and remobilized from stems to grain filling, and the relatively low contribution of leaves to grain filling. Grain Δ was highly and significantly associated with grain yield across treatments, suggesting the utilization of this trait as an indicator of source–sink manipulations effects on grain yield. Chaff and awns Δ were better correlated with grain Δ than stem and leaf Δ, indicating that chaff were more involved in grain filling than other organs. Moreover, in chaff, sap Δ was highly significantly correlated with dry matter Δ. These results suggest the use of Δ for a rapid and non‐destructive estimation of the variation in the contribution of different organs to grain filling.     

Increased grain protein content and its association with agronomic and end-use quality in two hard red spring wheat populations derived from Triticum turgidum L. var. dicoccoides

Suitability of wheat (Triticum aestivum L.) for many food products depends on its unique protein. Elevated grain protein content (GPC) and its quality influences the bread making properties of wheat. The objective of this study was to examine the association of elevated GPC with agronomic and end-use quality in two hard red spring wheat recombinant inbred (RI) populations derived from wild emmer (Triticum turgidum L. var. dicoccoides). The two hard red spring populations (ND683/Bergen and Glupro/Bergen) were developed using a single-seed-descent method. ND683 and ‘Glupro’ are high in GPC (180 g kg^-1), presumably due to the introgression of gene(s) from Triticum turgidum L. var. dicoccoides and ‘Bergen’ is low in GPC (145 g kg^-1). From each of the two populations 12 high- and 12 low-GPC RI lines (F_5:7) were selected for replicated testing at two North Dakota (ND) locations in 1995. In both populations, the high-GPC lines had significantly (p < 0.05) higher values compared to the low-GPC lines for mean GPC and water absorption. Mean grain yield of the high-GPC lines was not significantly different from the low-GPC lines in both populations. In the ND683/Bergen population, the high-GPC lines had significantly (p < 0.05) higher values than the low-GPC lines for mean plant height, days to heading, and flour extraction. GPC was significantly (p < 0.05)and negatively associated with test weight and also significantly (p < 0.01) and positively associated with water absorption in the Glupro/Bergen population. In these populations, results suggested that it may be possible to select lines that combine higher GPC and acceptable yield level, but later in maturity and taller in plant height. This revised version was published online in July 2006 with corrections to the Cover Date.     

Relationship between Carbon Isotope Discrimination and Grain Yield in Spring Wheat under Different Water Regimes and under Saline Conditions in the Ningxia Province (North-west China)

The relationship between grain yield and carbon isotope discrimination (Δ) was analysed in wheat grown under different water regimes in the Ningxia Province (north‐west of China). When the association was significant, the relationships between grain yield, Δ and other drought tolerance related traits, such as leaf ash content (m_a), chlorophyll concentration (Chl), relative water content (RWC), stomatal conductance (g_S) and the ratio of internal CO₂ leaf concentration to ambient CO₂ concentration (C_i/C_a), were also examined. Using correlation analysis, the relationships were determined during two consecutive years in a set of 20 spring wheat cultivars (landraces, improved varieties and advanced lines) under rainfed and irrigated conditions, including saline conditions. The relationship between Δ and yield within environments highly depended on the quantity of water stored in the soil at sowing, the quantity and distribution of rainfall during the growth cycle, and the irrigation before anthesis. Δ predicted grain yield under limited irrigation (post‐anthesis water stress) but not under pre‐anthesis water stress (rainfed conditions), fully irrigated and saline conditions. Under limited irrigation, grain Δ correlated significantly to grain yield leaf m_a at heading and maturity. It also significantly positively correlated to Chl, RWC, g_S and C_i/C_a assessed at anthesis. A precise characterization of the timing and intensity of the abiotic constraints experienced by the crop is consequently needed before implementing the use of Δ in wheat breeding programmes.     

The effects of homoeologous group 3 chromosomes on grain colour dependent seed dormancy and brittle rachis in tetraploid wheat

`Langdon' (LDN), a durum wheat (Triticum turgidum L. var. durum) cultivar, and a set of chromosome substitution lines of Langdon, where A or B genome chromosome were replaced with a homologous chromosome of wild emmer wheat, T. turgidum ssp. dicoccoides (DIC), were used to assess the effect of the specific chromosome on seed dormancy in tetraploid wheat. The LDN(DIC 3A) and LDN (DIC 313) lines showed significantly lower seed germination than Langdon. It appears that LDN(DIC 3A) and LDN(DIC 3B) have red grain whose allele were designated as R-A1b and R-B1b, respectively and the rachises of LDN(DIC 3A) and LDN(DIC 3B) were fragile. The alleles for brittle rachis were designated as Br ₂ for LDN(DIC 3A) and Br ₃ for LDN(DIC 3B). From the F₂ of the crosses, Langdon/LDN(DIC 3A) and Langdon/LDN(DIC 3B), Br ₂ was located approximately 44.2 cM from the R-A1b locus and Br ₃ approximately 47.0 cM from the R-B1b locus, respectively. Recombinant inbred chromosomal lines for 3A and 3B were used to assess (1) the linkage relationship between grain colour and fragile rachis, and (2) the effect of grain colour on germination. Estimated distance between R-B1b – Br ₂ was 39.6 cM. For the 3A population, germination percentage of both colour groups was 12.4% for the red grain group and 68.6% for the amber group, respectively. For the 3B population, germination percentage of the red group was 7.3% and that of the amber group was 82.1%. For both populations, differences were statistical significant by t-tests. We considered that seed dormancy of T. turgidum ssp. dicoccoides was dependent on grain colour. It raised the possibility that brittle rachis is due to a paralogous gene set on homoeologous group 3 chromosomes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Leaf Photosynthesis During Grain Filling Under Mediterranean Environments: Are Barley or Traditional Wheat More Efficient Than Modern Wheats?

Barley is one of the most popular crops in dryland agricultural systems of Mediterranean areas, where it is assumed that barley, or traditional wheat cultivars, performs better than modern wheat under low‐yielding conditions. It was tested whether variations in net leaf photosynthetic rate (P_N) during grain filling provide any basis for the potential better performance of barley and traditional wheat compared to modern wheats in Mediterranean areas. Two groups of field experiments were conducted in Agramunt (NE Spain) during 2005/06 (06) and 2006/07 (07) growing seasons combining low and high nitrogen (N) availabilities under rain‐fed and irrigated conditions. Cultivars used in the first group of experiments were a traditional (Anza) and a modern (Soissons) wheat, whilst in a second group of experiments, a wheat (Soissons) and a barley (Sunrise) modern cultivars were used. Both wheat cultivars showed a similar P_N during grain filling but higher than that of the modern barley cultivar. Differences between species in P_N were maximized under high‐yielding conditions. There were no differences between cultivars in instantaneous water‐use efficiency. The barley cultivar showed a higher specific leaf area, but lower N content per unit of leaf area, than wheat. Photosynthetic nitrogen‐use efficiency was similar between the traditional and the modern cultivar but lower than barley. Decreases in P_N after anthesis were not exactly observable in SPAD measurements. In conclusion, we found no consistent differences between cultivars in terms of post‐anthesis photosynthetic activity to support the assumption of better performance under Mediterranean farm conditions of traditional wheat or barley against modern wheat.     

The Influence of Different Nitrogen Levels and Seeding Rates on the Dry Matter Production and Nitrogen Uptake of Spelt (Triticum spelta L.) and Wheat (Triticum aestivum L.) under Field Conditions

Dry matter production of two different spelt (Oberkulmer, Hercule) and wheat varieties (Arina, Iena) were investigated at two different seeding rates (S1 = 200 grains/m²; S2 = 400 grains/m²) and two nitrogen levels (N1 = 80 kg N/ha; N2 = 110 kg N/ha). The plot experiments were carried out at two contrasting locations (Muri: altitude 459 m asl); Oberwallestalden: altitude 1011 m asl) over three years (1988–1990). In addition nitrogen uptake and the photosynthetic rate of flag leaves was measured. Neither growth regulators nor fungicides were applied. The average grain yield of spelt was 25 % lower than that of wheat (32 % at Muri, 18 % at Oberwallestalden). At the reduced seeding rate (S1) grain weight and grain number per ear was increased by 33 % and 31 %, respectively as compared to the normal seeding rate (S2). The increase of the grain weight and the grain number per ear was larger for the two varieties of spelt (47 % and 42 %, respectively) than for the wheat varieties (23 % and 22 %, respectively). The photosynthetic rate of the flag leaf of spelt and wheat was not significantly different, at the two growth stages measured (anthesis, anthesis + 23 days). Nitrogen yield in the above ground biomass (g N/m²) was not significantly different between spelt and wheat, neither at the beginning of stem elongation, nor at anthesis. At anthesis the nitrogen yield at the reduced nitrogen level (N1) was 16 % and 13 % lower than at the higher level (N2) for spelt and wheat respectively. A higher nitrogen efficiency of spelt under low input conditions was not apparent. Therefore it was concluded that under low input conditions, spelt is not more efficient in dry matter production than wheat. By comparing the “husked” yield of spelt (grains + glumes; representing the trade form) with the grain yield of wheat, spelt is higher yielding than wheat but only at marginal areas of cereal production.     

Relationship between Carbon Isotope Discrimination, Ash Content and Grain Yield in Wheat in the Peninsular Zone of India

Carbon isotope discrimination (Δ) and ash content (m_a) have been proposed as indirect selection criteria for grain yield in wheat. The associations between Δ, m_a and grain yield were found, however, to depend highly on the environmental conditions, the organ sampled and the time of sampling. In this study, carried out in the warm conditions of the Peninsular Zone of India, the relationship between Δ, m_a and yield was studied in 30 bread and durum wheat cultivars under residual soil moisture stress (RSMS), post‐anthesis water stress (PAWS) and well‐watered (WW) conditions. Both Δ and m_a were analysed in young seedlings (four‐leaf stage), leaves at anthesis and grain at maturity. Ash content was also evaluated in leaves at booting stage and maturity. Grain Δ was lower under PAWS and RSMS than under WW, while seedling and leaf Δ did not significantly differ among water regimes. Grain yield was positively correlated to grain Δ under PAWS and negatively correlated to grain m_a under RSMS. A significant positive correlation was noted under RSMS and WW treatments between m_aL_m and grain yield. Ash content in leaf at maturity consequently appears to be a useful indirect selection criterion in environments where Δ does not show any correlation with yield. The results highlight the potential of Δ and m_a as indirect selection criteria for wheat yield in the conditions of the Peninsular Zone of India.     

Bread and Durum Wheat under Heat Stress: A Comparative Study on the Photosynthetic Performance

The photosynthetic responses to heat stress, during grain filling, in four genotypes of Triticum aestivum L. (Sever and Golia) and Triticum turgidum subsp. durum (Acalou and TE 9306), chosen according to its genetic background diversity, were investigated. All wheat genotypes (excepting Golia) showed synergistic trends implicating the internal CO₂ concentration, net photosynthesis and stomatal conductance. Additionally, the modifications of net photosynthesis were associated with changes in stomatal control. Chlorophyll a fluorescence parameters (minimal fluorescence, maximal and variable fluorescence, intrinsic efficiency of PSII in darkness, non‐photochemical quenching, photochemical quenching and energy‐dependent chlorophyll fluorescence quenching) further pointed heat protective mechanisms, implicating F_v/F_m stabilization (i.e. maintaining the efficiency of PS II) and electron transport rate preservation. It is concluded that, comparatively to bread wheat, the photosynthetic performance of durum wheat is more tolerant to heat stress, as stomatal conductance and transpiration are less affected.     

Wheat Cellular Membrane Thermotolerance Under Heat Stress

Four genotypes of Triticum aestivum L. and Triticum turgidum subsp. durum chosen according to their genetic background diversity were subjected to heat stress after anthesis. Membrane permeability, lipid peroxidation and fatty acids (C14:0, C16:0, C16:1c, C16:1t, C18:0, C18:1, C18:2 and C18:3) were quantified. The estimation of the quantum yield of non‐cyclic photosynthetic electron transport was used as well as a test system to further evaluate the implications on thylakoid functioning. It was found differences within bread and durum wheat species concerning the capability to cope with high temperatures at the stage of grain filling. The genotype Sever showed high thermal sensitivity concerning membrane lipid peroxidation and membrane permeability, as evaluated by the increased production of ethylene and MDA, as well as by the impact on TFA (at the middle term of grain filling). In the durum wheat genotypes, differences were also found, with TE 9306 displaying high membrane stability, with no increases on membrane permeability, MDA and ethylene content. In this way, the observed changes on TFA in this genotype might have constituted a mechanism to allow qualitative lipid changes, reflected in lower unsaturation level of membrane FAs which is a positive trait under high temperatures.     

Nitrogen Accumulation and Translocation for Winter Wheat under Different Irrigation Regimes

The translocation of pre‐anthesis nitrogen to the grain is an important source for winter wheat. The relation between the nitrogen translocation and irrigation regime was studied in the field under a rain‐proof trough shelter. Nitrogen (N) translocation amount, N translocation efficiency decreased with a decline in irrigation amount or by excessive irrigation. Compared with different organs, the leaf and stem had higher N translocation amounts, and contributions to grain for both cultivars – Jinan 17 and Lumai 21, indicating that stem also is a major N source for grain development. The contribution of pre‐anthesis total above ground N to grain N ranged from 57 to 76 %, indicating the importance of pre‐anthesis storage of N for achieving high grain N concentrations. Grain nitrogen and yield (kg ha^?1) were positively and significantly correlated with the N translocation amounts and contributions, respectively, suggesting that the sink strength may be involved in the translocation of N from a vegetative organ to the grain. N harvest index (NHI) was significantly correlated with N translocation efficiency, suggesting that the latter is a prerequisite for increasing grain N and improving grain quality. The experiment showed that N translocation status is enhanced by better irrigation practices, but limited by severely deficient or excessive irrigation.     

The high and low molecular weight glutenin subunit polymorphism of Algerian durum wheat landraces and old cultivars

The high molecular weight (HMW) and B‐zone low molecular weight (B‐LMW) glutenin subunit composition of 45 Algerian durum wheat (Triticum turgidum L. var. durum) landraces and old cultivars were examined by sodium‐dodecyl‐sulphate polyacrylamide gel electrophoresis (SDS‐PAGE). Nine accessions were heterogeneous and presented two or three genotypes. All together, 33 glutenin patterns were detected, including 12 for HMW and 15 for B‐LMW glutenin subunits. Twenty‐four different alleles were identified for the five glutenin loci studied, Glu‐A1 (3), Glu‐B1 (6), Glu‐A3 (8), Glu‐B3 (5) and Glu‐B2 (2). Five new alleles were found, three at Glu‐A3 and two at Glu‐B3. At the Glu‐1 loci, the Glu‐A1c‐Glu‐B1e allelic composition was predominant (31%). For the B‐LMW glutenins, the most common allelic composition was Glu‐A3a‐Glu‐B3a‐Glu‐B2a (36%). The collection analysed shows a high percentage of glutenin alleles and allele combinations related to high gluten strength, together with some others that have not been tested so far. This information could be useful to select local varieties with improved quality and also as a source of genes to develop new lines when breeding for quality.     

Expression of a Triticum turgidum var. dicoccoides source of Fusarium head blight resistance transferred to synthetic hexaploid wheat

Yield and quality reductions caused by Fusarium head blight (FHB) have spurred spring wheat (Triticum aestivum L.) breeders to identify and develop new sources of host plant resistance. Four wheat synthetic hexaploids (×Aegilotriticum sp.) were developed, each having a quantitative trait locus (QTL), Qfhs.ndsu‐3AS, providing FHB resistance from Triticum turgidum L. var. dicoccoides chromosome 3A. Synthetics were produced by hybridizing a ‘Langdon’‐T. dicoccoides‐ recombinant chromosome 3A substitution line (2n = 4x = 28, AABB with two accessions of T. tauschii (2n= 2x = 14, DD). Synthetics were inoculated and evaluated for FHB resistance in two separate greenhouse seasons. One synthetic, 01NDSWG‐5, exhibited FHB severity ratings of 36% and 32% in the separate seasons, compared with ratings of 9% and 30% for ‘Alsen’, a FHB‐resistant spring cultivar, and ratings of 70% and 96% for ‘McNeal’, a susceptible spring cultivar, respectively. Synthetic × Alsen backcross‐derived lines were produced to initiate combining different sources of FHB resistance.     

Quantitative trait loci influencing grain protein content in tetraploid wheats

Seed storage protein content of durum wheat (Triticum turgidum var. durum) has an important effect on nutritional value and pasta-making characteristics. The objective of this study was to determine by association with genetic markers the number, chromosomal location, and magnitude of effect of quantitative trait loci (QTLs) controlling protein concentration in kernels. A set of 65 recombinant inbred lines (RIs) was developed by single seed descent from a cross between cultivated durum wheat cv. ‘Messapia’ (low protein content) and accession MG4343 of the wild tetraploid wheat var. dicoccoides (high protein content). This population was characterized for eight morphological, six storage protein, one isozyme and 124 RFLP loci. Field trials were conducted in one location in 1993 and two locations in 1994. QTLs were mapped by regression analysis on each marker locus for each location and for the average across environments. A total of six putative QTLs were located on chromosome arms 4BS, SAL, 6AS, 6BS and 7BS. The number and size of QTLs detected varied across environments. The marker with the highest r² value per QTL in each environment and across environments was chosen for a multiple linear regression analysis, which explained 49.2- 56.4% of the phenotypic variation for protein content. Only some of the markers were found to be negatively associated with plant grain yield and/or seed weight in one or two of the environments.     

Evaluation of Grain Filling Rate and Duration in Bread and Durum Wheat, under Heat Stress after Anthesis

Bread and durum wheat genotypes were submitted to heat stress during the grain filling period, and relationships between grain weight and accumulated time from anthesis until maturity, using days after anthesis and growing degree days, were described by cubic polynomials. Maximum grain weight and the duration and rate of grain filling were estimated from the fitted curves. It was found that bread and durum wheat exposure to high temperatures significantly decreased grain weight and hastens physiological maturity (shortening the grain filling period). High temperatures significantly affected the rate (on a growing degree day basis) and duration (on Julian day units) of grain filling. The grain filling rate, on a thermal time basis, was positively associated with the final grain weight and the estimated maximum grain weight. The duration of grain filling does not appear to be a limiting factor for genotype grain weight stability, being mainly fixed by temperature. Grain weight of the controlled plants was positively correlated with the final and maximum grain weight of heat stressed plants. It was concluded that a high grain filling rate and a high potential grain weight are major traits that can be useful to improve heat tolerance of Triticum under Mediterranean environments.     

Increase in grain protein percentage in high-yielding common wheat breeding lines by genes from wild tetraploid wheat

Summary Forty-one breeding lines of common wheat, derived from crosses between the Israeli cultivars Miriam and Lakhish and high-protein lines of wild tetraploid wheat, Triticum turgidum var. dicoccoides, were tested for various protein and yield parameters in field trials, under typical agronomic conditions. All lines had a higher grain protein percentage (GPP) than the leading Israeli cultivar Deganit, which was grown as a control. Grain yield (GY) ranged in the breeding lines from a low of 2.44 t/ha to as high as that of Deganit (6.95 t/ha). Despite the weak negative correlation between GPP and GY, several lines excelled both in GPP and in GY. The grain protein yield (GPY) of some of these selected breeding lines was higher than that of Deganit; e.g., 1.19 t/ha in the best line vs. 1.02 t/ha in Deganit. The 16.7% increase in GPY in this line reflected a more efficient utilization of nitrogen.     

Resistance to Fusarium head blight and deoxynivalenol accumulation in wheat

Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe (telomorph =Gibberella zeae (Schw.)), is an important wheat disease world‐wide. Production of deoxynivalenol (DON) by F. graminearum in infected wheat grain is detrimental to livestock and is also a safety concern in human foods. An international collection of 116 wheat lines was evaluated for FHB resistance and concentration of DON in grain. Plants were inoculated with mixed isolates of F. graminearum in the greenhouse by injecting conidia into a single spikelet of each spike and in the field by scattering F. graminearum‐infected wheat kernels on the soil surface. FHB symptoms were evaluated by visual inspection in both the greenhouse and field, and DON was analysed by HPLC. Significant differences in FHB ratings and DON levels were observed among cultivars. In the greenhouse test, visual symptoms varied from no spread of FHB from the inoculated spikelet to spread throughout the spike, and DON levels ranged from trace levels to 283 mg/kg. In the field test, DON ranged from 2.8 to 52 mg/kg. The greenhouse test identified 16 wheat lines from various origins that accumulated less than 2 mg/kg DON. These lines may be useful as sources for breeding wheat cultivars with lower DON levels. Correlation coefficients were significant between FHB symptom ratings, seed quality traits, and DON levels. Thus, the percentage of scabbed spikelets and kernels can be generally used to predict DON levels in harvested wheat grain. In breeding programmes, selection for plants having few scabbed spikelets and scabbed kernels is most likely to result in low DON levels.     

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.     

Anther culture response of F1 durum × bread wheat hybrids after colchicine application

The effect of colchicine on the androgenic response of durum × bread wheat F₁ hybrids was studied. For this, three Greek durum wheat cultivars, exhibiting good yield and pasta quality, were crossed to two bread wheat cultivars with good response to anther culture. Spikes of the resulting hybrids, containing microspores in the mid to late uninucleate stage, were selected and cultured on two different media (W₁₄ and solid potato‐2) with and without colchicine. A negative effect on anther culture response was observed when colchicine was added to the W₁₄ induction medium. A similar effect was observed in two of the hybrids when they were cultured on to potato‐2 induction medium. In both induction media, green plant production was influenced negatively by colchicine treatment. The same was observed in albino plant production. The results of the present study support the view that anther culture response is strongly genotype dependent. Finally, potato‐2 induction medium was the most suitable one for the material studied.