Resistance to wheat leaf rust in Aegilops tauschii Coss. and inheritance of resistance in hexaploid wheat

A collection of 164 Aegilops tauschii accessions, obtained from Gatersleben, Germany, was screened for reaction to leaf rust under controlled greenhouse conditions. We have also evaluated a selection of synthetic hexaploid wheats, produced by hybridizing Ae. tauschii with tetraploid durum wheats, as well as the first and second generation of hybrids between some of these resistant synthetic hexaploid wheats and susceptible Triticum aestivum cultivars. Eighteen (11%) accessions of Ae. tauschii were resistant to leaf rust among which 1 was immune, 13 were highly resistant and 4 were moderately resistant. Six of the synthetic hexaploid wheats expressed a high level of leaf rust resistance while four exhibited either a reduced or complete susceptibility compared to their corresponding diploid parent. This suppression of resistance at the hexaploid level suggests the presence of suppressor genes in the A and/or B genomes of the T. turgidum parent. Inheritance of leaf rust resistance from the intercrosses with susceptible bread wheats revealed that resistance was dominant over susceptibility. Leaf rust resistance from the three synthetics (syn 101, syn 701 and syn 901) was effectively transmitted as a single dominant gene and one synthetic (syn 301) possessed two different dominant genes for resistance.     

Sources of Resistance to Stem Rust (<Emphasis Type="Italic">Puccinia graminis</Emphasis> f. sp. <Emphasis Type="Italic">tritici</Emphasis>) in Ethiopian Tetraploid Wheat Accessions

Seedlings of 41 emmer (Triticum dicoccon Schrank) and 56 durum (T. durum Desf.) wheat accessions were evaluated for their response to stem rust (Puccinia graminis f. sp. tritici) infection under greenhouse condition at Kulumsa Agricultural Research Center, Ethiopia. The objectives were to identify tetraploid wheat accessions that could serve as sources of resistance to stem rust, and postulate the stem rust (Sr) resistance genes through multipatotype testing. The test included screening of accessions for stem rust resistance and multipatotype testing. To ensure vigorous screening, a mixture of six isolates (Si-1a, Am-2, Ku-3, Dz-4a, Ro-4 and Na-22) that were collected from severely infected emmer, durum, and bread wheat (Triticum aestivum L.) varieties of major wheat growing areas of Ethiopia was used as inocula. Out of the tested accessions, 18 emmer and 6 durum accessions exhibited low infection types (0–2) response and hence selected as a source of resistance to stem rust infection. Multipatotype testing was done to postulate Sr genes in the selected accessions. In the test, 10 different stem rust races (A2, A9, A11, A14, A16, A17, B3, B7, B15, and B21), 33 stem rust differential lines, and a universal susceptible check variety, Morocco were used, The high (3–4) and low infection type reaction patterns of the tested accessions and differential lines were used to postulate the genes that exhibit gene-for-gene relationship. The presence of Sr 7b, 8b, 9a, 9b, 10, 14, 24, 27, 28, 29, 30, 31, 32 and Tt-3+10 genes were postulated in 16 selected emmer and 5 durum wheat accessions. Efforts to transfer these valuable Sr genes from cultivated tetraploid wheats could be rewarding to get stem rust resistant varieties and boost wheat production.     

Evaluation for resistance to Pyrenophora tritici-repentis in Aegilops tauschii Coss. and synthetic hexaploid wheat amphiploids

Summary A total of 59 diploid Aegilops tauschii Coss. (syn. Aegilops sguarrosa auct. non L.) and 39 synthetic hexaploid wheat accessions were evaluated for reaction to Pyrenophora tritici-repentis (Died.) Drechs. in a controlled environment, and classified using a disease rating system based on lesion type. 27 Ae. tauschii and 20 synthetic wheats were found to be resistant to tan spot disease. The overall mean disease ratings of Ae. tauschii and the synthetic wheat lines scored on a scale of 1 (resistant) to 5 (susceptible) were 1.80 and 2.38, respectively. Synthetic wheats generally showed a decrease in resistance, although several lines of synthetic wheat expressed a higher resistance than the diploid parents. Five synthetic wheat lines exhibited higher resistance than the standard resistant common wheat cultivar Red Chief.     

Identification of resistant sources in Cicer species to Liriomyza cicerina

Summary Leaf miner (Liriomyza cicerina Rond.) causes considerable damage to chickpea (Cicer arietinum L.) in West Asia, North Africa and Southern Europe. Use of resistant cultivar is the economical method of control. Screening of over 7000 germplasm accessions did not result in identification of highly resistant accessions to this insect. Therefore, 200 accessions of eight wild Cicer species were evaluated in search of resistance to leaf miner between 1988 and 1991 at ICARDA, Syria. Accessions of Cicer species were screened under natural insect infestation in the field during spring (March–June), along with a susceptible-cum-indicator line. Two accessions of C. cuneatum (ILWC-40 and -187) and 10 accessions of C. judaicum (ILWC-44, -46, -56, -57, -58, -95, -103, -196, -206, and -207) were rated 2 on a 1–9 scale, where 1 = free from any damage and 9 = maximum damage. Another 18 lines of C. judaicum, four lines of C. pinnatidum and one line of C. reticulatum were rated 3 (resistant). Currently three species are incompatible in crossing with chickpea, but C. reticulatum is being used in breeding programme.Joint contribution from ICARDA and ICRISAT (Inter-national Crops Research Institute for the Semi-Arid Tropics), Patancheru P.O., AP 502 324, India.     

Powdery mildew resistance in Aegilops tauschii coss. and synthetic hexaploid wheats

Summary A collection of 400 Ae. tauschii (syn. Ae. squarrosa) Coss. accessions were screened for powdery mildew resistance based on the response patterns of 13 wheat cultivars/lines possessing major resistance genes to nine differential mildew isolates. 106 accessions showed complete resistance to all isolates, and 174 accessions revealed isolate-specific resistance, among which were 40 accessions exhibiting an identical response pattern as wheat cultivar Ulka/^*8Cc which is known to possess resistance gene Pm2. Expression of both complete and isolate-specific resistance from Ae. tauschii was observed in some synthetic hexaploid wheats derived from four mildew susceptible T. durum Desf. parents, each crossed with five to 38 resistant diploid Ae. tauschii accessions. Synthetic amphiploids involving different combinations of T. durum and Ae. tauschii generally showed a decrease in resistance compared with that expressed by the Ae. tauschii parental lines.     

Sources of Resistance to Anthracnose (Colletotrichum truncatum) in Wild Lens Species

Lentil anthracnose (Colletotrichum truncatum (Schwein.) Andrus et W.D. Moore is a potential threat in many lentil (Lens culinaris Medik.) production regions of North America. In the lentil germplasm maintained in Germany and North America, 16 lines were reported to have resistance to race Ct1, but none has resistance reported to race Ct0. The objective of this study was to examine accessions of wild Lens species for their resistance to races Ct1 and Ct0 of lentil anthracnose. Five hundred and seventy-four wild accessions of six species and control lines were screened in two replications under both field and greenhouse conditions using a 1–9 scoring scale (1, highly resistant; 2–3, resistant; 4–5, moderately resistant; 6–7, susceptible; and 8–9, highly susceptible). Indianhead and PI 320937 were resistant while Eston and Pardina were susceptible to race Ct1 as expected. However, none of the check lines were resistant to race Ct0. Among the six Lens wild species tested, accessions of Lens ervoides (Brign.) Grande had the highest level of resistance, 3–5 to race Ct1 and Ct0 followed by L. lamottei Czefr. in the field and greenhouse. Lens orientalis (Boiss.), L. odemensis L., L. nigricans (M. Bieb.) Godron and L. tomentosus L. were highly susceptible, 8–9 to race Ct0 in the greenhouse. The highest frequency of resistance, especially in L. ervoides (Brign.) Grande, was found in accessions originating from Syria and Turkey. The usefulness of these L. ervoides (Brign.) Grande accessions as sources of resistance to the more virulent race of anthracnose in a lentil breeding program is discussed.     

Evaluation of Indian coriander accessions for resistance against stem gall disease

Seventy accessions of coriander (Coriandrum sativum L.) were screened for resistance against stem gall, a severe disease caused by Protomyces macrosporus Unger., with the goal to select the resistant cultivars. The accessions PH-7, Pant Haritima, COR-17 and COR-2 were highly resistant. These may be used as the parents to breed high yielding accessions resistant to stem gall disease.     

Sources of resistance in primary synthetic hexaploid wheat (Triticum aestivum L.) to insect pests: Hessian fly, Russian wheat aphid and Sunn pest in the fertile crescent

Hessian fly, Mayetiola destructor (Say), Russian wheat aphid (RWA), Diuraphis noxia (Kurdjumov), and Sunn pest, Eurygaster integriceps (Puton), are among the most important insect pests of wheat in North Africa, West and Central Asia. Host plant resistance is the most economical, environmentally friendly and practical means of controlling insect pests. Through field and greenhouse screening, several sources of resistance to Hessian fly, RWA and Sunn pest have been identified in wheat and its wild relatives. To further broaden the genetic base of resistance to these pests, 914 fixed lines of synthetic hexaploid wheat (SHW) commonly designated as primary synthetic wheat were evaluated for resistance to Hessian fly, RWA and Sunn pest. The initial screenings for RWA and Sunn pest were carried out in the field at Tel Hadya, Aleppo, Syria, and for Hessian fly in the greenhouse at Tel Hadya during the 2009 and 2010 seasons. Promising accessions from the initial screening for Hessian fly, RWA and Sunn pest were evaluated for confirmation in replicated trials in the greenhouse and field. Fifteen SHWs showed high levels of resistance to Hessian fly and four showed moderate resistance. A wheat line derived from the cross (Triticum turgidum/T. dicoccoides) also showed a high level of resistance to Hessian fly. The level of resistance to RWA in SHW was considerably lower; only one SHW and one durum wheat ‘Altar 84’ exhibited a high level of resistance, while four SHW were moderately resistant. There were 21 SHW genotypes and one durum wheat ‘Langdon’ found resistant to Sunn pest feeding at the vegetative stage. Crosses between these potentially novel resistance sources and elite bread wheat were initiated. Genetic and genomic studies using these accessions are ongoing to identify and characterize the resistance genes and reveal potentially new resistance genes, which will be useful in breeding programs to develop wheat germplasm with multiple resistances to these pests.     

Sources of resistance to Hessian fly (Diptera: Cecidomyiidae) in Syria identified among Aegilops species and synthetic derived bread wheat lines

The Hessian fly, Mayetiola destructor (Say), is a major pest of wheat in North Africa, southern Europe, North America, and northern Kazakhstan. It is believed this pest (like wheat) originated in West Asia. The Syrian Hessian fly biotype has been found to be the most virulent worldwide, and has been used at the International Center for Agricultural Research in the Dry Areas (ICARDA) for screening wheat and its wild relatives to identify new sources of resistance. The screening was conducted in an insect rearing room set at 20°C and 70% RH using a Hessian fly population collected from Lattakia region, Syria. The experimental design was a randomized complete block with four replications. ‘Nasma’ (bread wheat) and ‘Cando’ (durum wheat) were used as susceptible and resistant checks, respectively. A total of 623 lines/accessions of wheat and its wild relatives (Aegilops and Triticum) were evaluated. Twenty-nine Aegilops accessions and four synthetic derived bread wheat lines were found resistant. The presence of dead first instars confirmed the resistance reaction and also showed that antibiosis is the major mechanism of resistance in these materials. These sources of resistance are used in ICARDA’s wheat breeding programs for the development of Hessian fly-resistant germplasm/varieties.     

Carbon isotope discrimination and water use efficiency in Iranian diploid,tetraploid and hexaploid wheats grown under well-watered conditions

Carbon isotope discrimination (Δ) has been proposed as physiological criterion to select C₃ crops for yield and water use efficiency. The relationships between carbon isotope discrimination (Δ), water use efficiency for grain and biomass production (WUE_G and WUE_B, respectively) and plant and leaf traits were examined in 20 Iranian wheat genotypes including einkorn wheat (Triticum monococcum L. subsp. monococcum) accessions, durum wheat (T. turgidum L. subsp. durum (Desf.) Husn.) landraces and bread wheat (T. aestivum L. subsp. aestivum) landraces and improved cultivars, grown in pots under well-watered conditions. Carbon isotope discrimination was higher in diploid than in hexaploid and tetraploid wheats and was negatively associated with grain yield across species as well as within bread wheat. It was also positively correlated to stomatal frequency. The highest WUE_G and grain yield were noted in bread wheat and the lowest in einkorn wheat. Einkorn and bread wheat had higher WUE_B and biomass than durum wheat. WUE_G and WUE_B were significantly negatively associated to Δ across species as well as within bread and durum wheat. The variation for WUE_G was mainly driven by the variation for harvest index across species and by the variation for Δ within species. The quantity of water extracted by the crop, that was closely correlated to root mass, poorly influenced WUE_G. Environmental conditions and genetic variation for water use efficiency related traits appear to highly determine the relationships between WUE_G and its different components (water consumed, transpiration efficiency and carbon partitioning).     

Analysis of Wheat Disease Resistance Data Originating from Screenings of Gatersleben Genebank Accessions during 1933 and 1992

Series of 10,348 accessions belonging to 21 species (hexaploid, tetraploid, diploid) of the genus Triticum and 489 accessions belonging to 20 species of the genus Aegilops were scored for disease resistance during a period of 60 years. Tests were performed at the seedling stage for powdery mildew (Erysiphe graminis DC. f. sp. tritici March.), leaf rust (Puccinia recondita Rob. ex Desm. f. sp. tritici Erikss.), stripe rust (Puccinia striiformis West. f. sp. tritici Erikss.) and eyespot (Pseudocercosporella herpotrichoides (Fron.) Deight.) but also at the adult plant stage considering powdery mildew, leaf rust, stripe rust, eyespot and glume blotch (Septoria nodorum Berk.). About 150,000 disease scores recorded on index cards using different scoring scales were transferred to the computer, converted into a 1–9 scale and used to summarise the results. Within the genus Triticum 20% of the material analysed was classified as heterogeneous. For the accessions without detectable segregation a large variability for resistance/susceptibility was detected. At the adult plant stage resistant accessions without visible infections were identified for all diseases. The percentages of resistant accessions at that growth stage were always higher than the ones found in the material tested at the seedling stage. The probability for finding resistant material was shown to be highest in the diploid species ( > 50%) but decreased with increasing ploidy level to about 10% in the hexaploids. For Aegilops it was shown that most of the accessions were homogeneous and highly resistant against powdery mildew (seedling and adult plant stage), leaf rust (adult plant stage) and eyespot (seedling and adult plant stage/natural infection). The data obtained for the individual accessions are available via Internet (http://www.ipk-gatersleben.de). An erratum to this article is available at .     

Variation in resistance to the cabbage aphid ( Brevicoryne brassicae) between and within wild and cultivated Brassica species

Seven Brassica species were evaluated for their resistance to the cabbage aphid, Brevicoryne brassicae, in a series of field experiments. Four wild Brassica species, two 8 chromosome species with similarities to the B genome of Brassica nigra (Brassica fruticulosa and Brassica spinescens) and two 9 chromosome species containing the C genome (Brassica incana and Brassica villosa) were identified as possessing consistently high levels of antibiosis mediated resistance to B. brassicae. None of the species were shown to possess consistently high levels of antixenosis resistance. In more detailed glasshouse experiments one B-like genome species, B. fruticulosa, showed considerable variation between accessions collected from different sites for resistance to B. brassicae. In addition, individual accessions of one A genome species (Brassica rapa) and one C genome species (Brassica alboglabra) were shown to be highly variable in their resistance to B. brassicae, some plants of each accession being highly resistant and others very susceptible. The implications of the variability in resistance to B. brassicae within wild Brassica species for exploitation in Brassica breeding programmes are discussed.     

First sources of resistance to Sitona weevil (Sitona crinitus Herbst) in wild Lens species

Lentil is one of the important cool-season food legumes grown in many countries in the Mediterranean region. But a substantial yield loss is observed every year due to various biotic stresses. The Sitona weevil (Sitona crinitus Herbst) is a major insect pest limiting lentil productivity mainly in the countries of West Asia and North Africa region. The adult insects feed on the leaflets at seedling stage, and the plant suffers due to reduced photosynthesis. The larvae feed on the root systems and on the nodules, thus decreasing the ability of the plant to fix atmospheric nitrogen. Since sources of resistance to this pest in the cultivated lentil Lens culinaris Medikus subsp. culinaris are lacking, we searched for resistant sources in a collection of wild Lens species available in the ICARDA Gene Bank. We screened 315 accessions of wild lentil covering all known species/sub-species based on nodule damage at ICARDA’s main experimental station (Tel Hadya, Aleppo), a hot-spot for the pest in the region. Large variation was observed in the percent nodule damage among accessions across species. Eight accessions, ILWL 110, ILWL 136, ILWL 166, ILWL 203, ILWL 207, ILWL 245, ILWL 254 and ILWL 258 were identified as resistant, with ≤10% nodule damage, compared to >56% damage recorded on the cultivated lentil. This is the first report of resistance against Sitona weevil in lentil. One resistant accession ILWL 245 belongs to the species L. culinaris Medikus subsp. orientalis (Boiss.) Ponert, progenitor of the cultivated lentil, which is crossable with the cultivated lentil. This line is being used to introgress resistance genes to cultivated lentil and to understand the inheritance of Sitona weevil resistance.     

Detection of adult-plant resistance to Puccinia triticina in a collection of wild Triticum species

Three hundred and fifty three Triticum accessions, several also classified as Aegilops and comprising 13 diploid, tetraploid or hexaploid species, were screened for seedling and adult-plant resistance to Puccinia triticina Eriks. using a mixture of pathotypes UVPrt2, 3, 9 and 13. Seedlings were spray-inoculated with a suspension of freshly collected urediospores in distilled water containing Tween 20^® seven days after planting. Infection types (ITs) were scored 10 days post-inoculation (d.p.i.). Fully expanded flag leaves were inoculated and ITs and leaf rust severity were scored 16 d.p.i. One hundred and eighty two of the accessions were resistant to moderately resistant in the adult stage, whereas 126 were resistant or moderately resistant as seedlings to the pathotype mixture. Hypersensitive adult-plant resistance was particularly apparent in lines of T. timopheevii, T. sharonense, T. longissimum, T. searsii and T. turgidum. In T. turgidum, which comprised 272 accessions, approximately 44% of the adult plants were resistant to moderately resistant compared to 28% of the seedlings. The expression of these adult-plant resistances varied between hypersensitive flecking of flag leaves, and small pustules commonly associated with chlorosis and/or necrosis of leaf tissue. Partial resistance, expressed by small pustules without any apparent chlorosis, was observed in species such as T. tauschii, T. turgidum ssp. durum and T. turgidum ssp. pyramidale.     

Reaction to powdery mildew and stripe rust in related species and landraces of wheat

Field and controlled environmental tests indicated that the 49 accessions of closely related species and 12 landraces of wheat (Triticum aestivum L. em. Thell.) from the National Gene Bank of China showed different reactions to powdery mildew (Blumeria graminis (DC.) E. O. Speer. f. sp. tritici) and stripe rust (Puccinia striiformis Westend f. sp. tritici) at adult and seedling stages. Unknown Pm genes or alleles were postulated with Triticum baeoticum Boiss. accessions BO 3 and Triticum monococcum L. MO 4 and MO 5 when inoculated with 21 powdery mildew isolates at seedling stage. Fourteen accessions of T. baeoticum, T. monococcum, Triticum durum, and wheat landraces were inoculated with 30 stripe rust isolates at seedling stage. Unknown Yr genes or alleles were postulated with T. baeoticum Boiss. accession BO 5, as well as wheat landraces Xiaobaimai, Laomangmai, and Shaanxibai. Heterogeniety in reaction to powdery mildew isolates and stripe rust races were observed in related species and landraces of wheat.     

Phenotypic responses of the wild wheat relative Aegilops geniculata Roth and wheat (Triticum durum Desf.) to experimentally imposed salt stress

In order to study the salt effect on the wild wheat and durum wheat, three accessions of Aegilops geniculata L. from Ain zana, Zaghouan, and Sbitla and one variety of wheat (Triticum durum L.) have been grown in the INRAT green house and treated with different salt concentrations. The morphological, phenological and yield characters have been measured for each plant and analyzed using SAS software. This study has shown a high degree of variation of these characters mainly related to geographical origin. It was observed also that Sbitla accession was less affected by the imposed salt stress than all the others while Ain zana was the most affected one.     

Sources of resistance to ascochyta blight in wild species of lentil (<Emphasis Type="Italic">Lens culinaris</Emphasis> Medik.)

Cultivated lentil (Lens culinaris Medik. subsp. culinaris) has a relatively narrow genetic base and many commercial cultivars are susceptible to ascochyta blight caused by Ascochyta lentis Vassilievsky. A total of 375 accessions of six wild species of lentil received from ICARDA and 18 cultivated genotypes were screened for resistance to A. lentis under both field and greenhouse conditions in Saskatoon, Canada. A mixture of three monoconidial isolates of A. lentis was used as an inoculum and the level of infection rated using the Horsfall-Barratt scale (0–11). Accessions with resistance to A. lentis were observed in all wild species except for L. culinaris subsp. tomentosa (Ladiz.) Ferguson et al. showing no resistant accessions. Several consistently resistant accessions were found among entries of L. ervoides (Brign.) Grande and L. nigricans, (M. Bieb.) Godr., both of which belong to the secondary gene pool and a few in L. culinaris subsp. orientalis (Boiss.) Ponert and L. culinaris subsp. odemensis (Ladiz.) Ferguson et al. belonging to the primary gene pool. Some accessions of L. ervoides exhibited lower disease ratings and AUDPC values than the resistant control cv. ‘Indianhead.’ Thirteen accessions, previously reported as resistant to Syrian isolates of A. lentis were also resistant to the Canadian isolates; some also had resistance to anthracnose. The highest frequency of resistance was found in accessions of L. ervoides which originated from Syria and Turkey. These wild accessions represent a useful and untapped source for improving disease resistance in lentil.     

Feeding damage effects of three aphid species on wheat root growth

Cereal aphid infestations have considerable impact upon productivity and profitability of United States agriculture. A comparison study of the influence of different aphid species (Russian wheat aphid, Duraphis noxia Mordvilko; greenbug, Schizaphis graminum Rondani; and bird cherry oat aphid, Rhopalosiphum padi L.) upon shoot characteristics and root growth of hard red spring wheat (Triticum aestivum L.) was conducted in an attempt to better understand the mechanisms of yield loss in aphid damaged plants. Plants infested with aphids showed similar reductions in shoot growth regardless of aphid species. Shoot chlorophyll concentrations were lowest in greenbug‐infested plants. Root length and dry weight were also equally reduced by feeding damage by the three aphid species. Upon removal of the aphids, shoot dry weights of plants damaged by each aphid species remained unchanged for 10 days. Shoot dry weights for aphid‐damaged plants were about half the magnitude seen in the control plants after 15 days. Chlorophyll concentrations seen in greenbug and Russian wheat aphid‐infested plants initially were lower than the concentrations seen in bird cherry oat aphid‐infested and control plants. Within 10 days after aphid removal, however, chlorophyll concentrations across all treatments were essentially equal. Root lengths in plants previously infested with greenbugs or Russian wheat aphids were lower than control plants four days after aphid removal. Within 10 days after aphid removal, root lengths in plants previously infested with greenbugs or Russian wheat aphids did not differ from control plants. Root lengths in plants previously damaged by bird cherry oat aphids did not reach the same magnitude as that of the other treatments until 27 days after aphid removal. These results indicate that aphid feeding damage to wheat plants can have significant effects on root growth, suggesting that crop management practices that promote root growth could play important roles in improving plant tolerance to aphid damage.     

Genetic diversity in Ethiopian hexaploid and tetraploid wheat germplasm assessed by microsatellite markers

The genetic diversity of a subset of the Ethiopian genebank collection maintained at the IPK Gatersleben was investigated applying 22 wheat microsatellites (WMS). The material consisted of 135 accessions belonging to the species T. aestivum L. (69 accessions), T. aethiopicum Jacubz. (54 accessions) and T. durum Desf. (12 accessions), obtained from different collection missions. In total 286 alleles were detected, ranging from 4 to 26 per WMS. For the three species T. aestivum, T. aethiopicum and T. durum on average 9.9, 7.9 and 7.9 alleles per locus, respectively, were observed. The average PIC values per locus were highly comparable for the three species analysed. Considering the genomes it was shown that the largest numbers of alleles per locus occurred in the B genome (18.4 alleles per locus) compared to A (10.1 alleles per locus) and D (8.2 alleles per locus) genomes. Genetic dissimilarity values between accessions were used to produce a dendrogram. All accessions could be distinguished, clustering in two large groups. Whereas T. aestivum formed a separate cluster, no clear discrimination between the two tetraploid species T. durum and T. aethiopicum was observed.     

Protein and Starch Properties of Some Tetraploid Wheats

The tetraploid relatives (subspecies) of commercial durum wheat (Triticum turgidum L. subsp. turgidum conv. durum (Desf.) MacKey) offer a source of economically useful genes for the genetic improvement of durum cultivars. Thirty‐two accessions, representing five different subspecies: var. durum (13 accessions), polonicum (7), persicum (3), turanicum (5), and turgidum (4) were grown at Tamworth, Australia, in 1997 and 1999. These accessions were compared with three durum cultivars: Wollaroi and Kamilaroi (in both years) and Yallaroi (in 1998 only). In this study, the glutenin subunit composition and molecular weight distribution, together with starch properties of these accessions, were studied. A much wider range in both the glutenin subunit composition and the starch RVA paste viscosities and gelatinization profiles were found in the accessions compared with the cultivated durum wheats. Most of the accessions had lower gluten strength and the presence of poor quality LMW alleles, and low proportions of unextractable polymeric protein could explain this. For starch, RVA peak viscosity correlated strongly with cooking loss of pasta, the only significant correlation between starch properties and measured aspects of pasta quality.