ITEMS FROM ITALY

EXPERIMENTAL INSTITUTE FOR CEREAL RESEARCH

Via Cassia 176, 00191 Rome, Italy.

Awned and awnless near-isogenic durum wheat lines.

V. Vallega and J.M. Clarke.

Eight pairs of NILs of durum wheat with different degrees of awnedness were developed from crosses between an awnless accession of T. turgidum var. dicoccum (PI 355491) and the semidwarf durum wheat cultivars Valriccardo and Aldura. Each pair comprises an awnless, awnletted, or apically awnletted isoline and either a short-awned (30-60 mm) or long-awned (80-110 mm) isoline. Five of these pairs are of semidwarf stature, and three are medium tall (about 110 cm). Threshability ranges from 80 to 100 %.

Seed from F8 plants of each of the isolines was deposited at the USDA-ARS Small Grains Collection (Aberdeen, ID, USA) and assigned PI numbers from 596597 to 596612. Preliminary observations on these isolines indicate that the absence of awns is associated with lower kernel weight, test weight, and grain yield in the semidwarf pairs, but not in the tall ones.

Genes for awnlessness transferred from Triticum dicoccum to Triticum durum.

V. Vallega.

The modern cultivars of common wheat are either awned or awnless, whereas those of durum wheat are all awned. In 1987, a small program was initiated to develop agronomically acceptable awnless durum wheat lines to be used for study purposes and as possible parents in breeding programs. Crosses were made between an awnless accession (PI 355491) of T. turgidum var. dicoccum and various Italian semidwarf durum wheat cultivars. Subsequently, the offspring were selected for awnlessness, free-threshing ability, and lodging resistance.

As a result of the program, 16 completely awnless lines were developed. Twelve of these lines (now in F10) are semidwarf, and four are medium-tall. Given the small size of the program and the 'primitive' nature of the awnless parent, each of the lines developed has one or more obvious defects as expected, including low kernel weight, low test weight, and/or late maturity. Therefore, a new cycle of crosses especially oriented to enhance kernel weight will be initiated.

Development of further pair of durum wheat lines near-isogenic for glaucousness.

V. Vallega and J.M. Clarke.

Another pair of NILs, PI593000 (glaucous) and PI593001 (nonglaucous), was developed. The lines were obtained from the cross 'Valgerardo / Trinakria' by maintenance of heterozygosity for glaucousness (waxy bloom on upper leaves, peduncle, and spike) in the F4 through the F13 generations, followed by selection of homozygous glaucous and nonglaucous lines. The lines are of semidwarf stature and very early heading. The original cross was made by G. Zitelli.

Seed of the isolines was deposited at the Small Grains Collection (Aberdeen, ID, USA). This near-isogenic pair and seven others developed in the past few years (Clarke et al. 1995) will be useful for studying the effects of glaucousness on the agrobiological performance of T. durum.

Development of a partially free-threshing bulk population of Triticum monococcum.

V. Vallega.

The diploid wheat T. monococcum, often viewed as merely a source of useful genes, may still play a role in modern agriculture as a crop in itself. MONOC BULK 1 VV (PI584654) represents a first, tentative step towards the development of commercial cultivars of T. monococcum. The line is a bulk of equal quantities of seed from 34 F5 lines of T. monococcum var. sinskajae selected from a cross between WIR 48993 (a soft-glumed, partially free-threshing line) and VV 307 (a tenacious-glumed accession). The bulked population, was selected for soft glumes, early maturity, and agronomic type using the classical pedigree method.

In order to obtain competitive diploid wheats, selections from the bulk should be crossed with diploid wheat accessions having greater gluten strength, as well as shorter and stronger straw.

Introgression of friabilin gene into durum wheat by allosyndesis.

A. Niglio, A. Gallelli, L. Gazza, and N.E. Pogna.

Kernel hardness strongly affects flour yield after milling, starch damage, and water absorption of dough. The genetic basis of grain hardness/softness is relatively well known. The major locus Ha, which controls this character, is on the short arm of chromosome 5D and is present in two allelic forms (Ha/ha soft/hard texiture) in hexaploid wheat, although it is absent in the tetraploid durum wheat.

Friabilin, which is considered the principal marker of kernel softness, is a low molecular weight protein (15 KD) localized in bread wheat endosperm of both hard and soft wheats where it interacts with starch granules. The strength of this interaction affects the endosperm texture. However, friabilin has never been found in any varieties of durum wheat so far tested.

Cosegregation studies on NILs for grain hardness have strengthened the idea that friabilin is the genetic product of the Ha locus. In addition, by PCR analysis with specific primers for the Ha locus, we verified that the locus is absent in tetraploid durum wheat, although it is present in both hexaploid wheat and diploid species such as T. monococcum that express the normal pattern of friabilin. Thus, the absence of friabilin in durum wheat is not due to regulation of the genetic expression but to the absence of the relative gene.

Our work hopes to transfer the friabilin gene into durum wheat in order to produce durum wheat genotypes with increased flour yield , reduced starch damage, and water absorption. The substitution line Langdom 5D(5B) was crossed with a mutant line of Cappelli with a deletion of the ph gene whose expression prevents pairing of homoeologous chromosomes.

The resulting F2 seeds have been analyzed for friabilin expression by Western-immunoblotting and also for IEF pattern of the Ibf-1 isozyme. The latter protein is codified by genes on the long arms of the homoeologous group 5 chromosomes. In this way, we have selected friabilin-expressing seeds in the absence of the typical Ibf-1 pattern for chromosome 5D. The progeny of these plants currently is being investigated for chromosome constitution and quality characteristics.

Production of bread wheat genotypes lacking the Gli-1 and Gli-2 loci.

A.M. Monari, N.E. Pogna, and M. De Vincenzi*.

*Istituto Superiore di Sanità, Rome, Italy.

Coeliac disease is a gluten-sensitive enteropathy that occurs in genetically predisposed individuals. The toxicity of wheat flour results from the presence of alcohol-soluble proteins. Earlier studies showed that alpha-gliadins are much more toxic than the beta-, gamma-, and omega-gliadins.

To determine whether the suppression of certain gliadin loci can significantly reduce bread wheat toxicity in coeliac disease, we crossed the bread wheat line TM, lacking the Gli-B1, Gli-D1, and Gli-A2 loci, encoding for some alpha-, beta-, gamma-, and omega-gliadins, and the mutant bread wheat lines 96-250 and 96-252, which lack the Gli-A1 and Gli-D2 gliadin loci, respectively.

In the F2 progeny of the cross 'TM / 96-250' novel genotypes lacking Gli-A1 plus the Gli-B1, Gli-D1, or Gli-A2 locus have been selected (see Table 1). Furthermore,in the F2 progeny from the cross 'TM / 96-252', two novel double mutants (Gli-B1/Gli-D2 null and Gli-D1/Gli-D2 null) and a triple-mutant (Gli-B1/Gli-D1/Gli-D2) were obtained (see Table 2). These mutants currently are being tested for their toxicity in coeliac disease.

Pathogenicity of Puccinia recondita f.sp. tritici in Italy during 1997.

M. Pasquini, F. Casulli, L. Sereni, and F. Casini.

Wheat is one of the most important crops in Italy covering an area of 2,482,119 ha (ISTAT 1996) of which 63 % is durum wheat and 37 % is bread wheat. Durum wheat is grown mainly in southern Italy, and bread wheat is present in the central and northern regions. Wheat yield may be reduced annually by many fungal diseases, among which leaf rust is the most frequent and widespread in the Italian cereal growing areas.

Pathogenicity surveys were made during the last wheat growing season in critical areas of northern, central, and southern Italy. Data were obtained in the field and in greenhouse on the reactions of durum and bread wheats, NILs, and new wheat selections.

The climatic conditions of the previous season were not particularly favorable to disease development. However, leaf rust was present in many locations. High percentages of infection were observed in northern regions and in the South (Sicily). Genes Lr2b, Lr9, Lr19, Lr24, and Lr29 were effective in all the locations where NILs with these genes were grown. These genes were effective to all the isolates identified in greenhouse tests. Other genes, such as Lr13, Lr22a, and Lr35 that condition adult plant resistance, were effective against the natural pathogen populations present in all the locations.

Genes Lr1, Lr2a, Lr15, Lr17, Lr26, and Lr28 were effective in controlling the disease in central and southern Italy but not in the north. Wheat lines with the resistance genes Lr3, Lr3ka, and Lr23 were susceptible in northern and central Italy but not in the south. The resistance genes Lr14b, Lr21, Lr32, Lr38, and Lr44 were most effective in central and southern Italy.

In 1997, we confirmed that the leaf rust population present in northern Italy appears more complex and different from that present in south, as previously observed, and is probably due to the selection pressure provided by the wheat species and varieties cultivated in these areas.

Durum wheat: identification of genes for resistance to fungal diseases from local or alternative sources.

M. Pasquini, L. Sereni, F. Casini, and P. Cacciatori.

The present work aims to broaden the genetic variability of cultivated durum wheats in order to protect the crop population from pathogens with minimal environmental impact and for a more effective use of energy. The detection and valorization of local germplasm from Mediterranean regions and the utilization of alien sources (T. dicoccoides) of resistance genes have been considered.

Thirty-seven durum wheat genotypes from different Mediterranean countries were analyzed for their resistance to Blumeria graminis isolates, widespread on wheat in Italy. Some of these lines had moderate resistance to powdery mildew. The genotypes Sert 217/1, Cham 3, Duramba, FG17980, Gerardo 518, Jordan Col.86-172, M33, Roqueno, Sabil 1, and TE8304 (kindly supplied by ICARDA) were the most resistant. We are now making pathological, agronomical, and genetical analyses on this material.

A systematic and careful screening for resistance to different fungal diseases has been made inT. dicoccoides accessions from different areas in Israel. This species seems to be a good source of resistance genes especially to powdery mildew, other fungal diseases and abiotic stress and has interesting agronomic and qualitative characters. New wheat selections were obtained by crossing some of these T. dicoccoides accessions with Italian durum wheat genotypes. The most interesting lines from these crosses were grown in replicated plots and tested for their phytopathological, biochemical, and agronomical traits. Selection was made in order to identify improved types with combined resistance to both mildew and stem rust (derived from the durum wheats parents), good agronomic traits, and good quality characteristics. The most promising lines were backcrossed to their durum parent. During the selection process, the transfer of the high grain protein content present in the T. dicoccoides accessions also is being monitored.

Publications.

Acquistucci R, D'Egidio MG, and Vallega V. 1995. Amino acid composition of selected strains of diploid wheat, Triticum monococcum L. Cereal Chem 72:213-216.

Cantone F, Perenzin M, Minoia C, Redaelli R, Sbidaro M, Padovan S, Frattini F, Delogu G, Concari L, Poli M, Porfiri O, Biancolatte E, Pasquini M, Galterio G, De Ninno G, Boggini G, Bianchi M, and Borghi B. 1997. Le nuove varietà di cereali vernini iscritte al registro varietale nel 1996. Sementi Elette n. 3-4:17-29.

Casulli F, Pasquini M, and Pancaldi D. 1997. Wheat leaf rust in Italy: virulence and host resistance during the last five years. In: Approaches to improving disease resistance to meet future needs: Airborne pathogens of wheat and barley, Conf Proc. Praga 11-13 November, 1997. pp. 106-107.

Clarke JM, McCaig TN, Vallega V, De Pauw RM, Mc Leod JG, and Thiessen LL. 1995. Registration of seven pairs of durum wheat genetic stocks near-isogenic for glaucousness. Crop Sci 35:1241.

Frisoni M, Vallega V, D'Egidio MG, Corazza GR, and Gasbarrini G. 1995. In vitro toxicity of gluten of three wheat species on the intestinal mucosa of coeliac patients. In: Book of Abstracts ICC Jubilee Conference, May 1995, Vienna, Austria. Pp. 8.

Pasquini M, Sereni L, Casulli F, Siniscalco A, Mameli L, Gallo G, Monti M, Lo Re L, Coppolino F, Padovan S, Arduini MG, and Minoia C. 1997. Comportamento di frumenti duri e teneri verso alcune malattie fungine. L'Informatore Agrario 36:41-49.

Vallega V. 1996. The quality of Triticum monococcum L. in perspective. In: Hulled wheats: promotion of conservation and use of valuable and underutilized species, Proc. First Intern. Workshop on hulled wheats (Padulosi S, Hammer K, and Heller J, eds.). July, 1995, Castelvecchio Pascoli, Italy. Pp. 213-221.

Vallega V. 1996. Registration of partially free-threshing diploid wheat germplasm. Crop Sci 36:1717.

Vallega V, Rubies-Autonell C, Ratti C, and Turina M. 1997. Reactions of 36 common wheat cultivars grown in Italy to soilborne wheat mosaic virus during 1995-1996. In: Proc 10th Cong Mediterranean Phytopathological Union, June, 1997m, Montpellier, France. Pp. 627-631.

Vitellozzi F, Basili F, Zhang XY, Forte P, Delre V, Bitti A, Pasquini M, and Ceoloni C. 1997. Ricombinanti frumento duro-Agropyron elongatum contenenti i geni Lr19+Yp. Atti XLI Conv.Annuale SIGA: 142.

INSTITUTE OF PHYTOPATHOLOGY, COLLEGE OF AGRICULTURE

Via Filippo Re 8, 40126 Bologna.

Reactions of cultivars of common wheat to wheat soilborne mosaic virus.

C. Rubies-Autonell, V. Vallega, M. Turina, C. Ratti, and S. Contoli.

WSBMV is widespread in Italy, especially in the northern and central regions of the country. Yield losses of about 50 % have been recorded on susceptible common wheat cultivars. The only economically viable means of controlling this virus is growing WSBMV-resistant genotypes, yet little is known about the reactions of the common wheat cultivars presently grown in Italy. During 1995-96, we grew 36 such cultivars in a severely WSBMV-infested field near Bologna. Each cultivar was grown in 10 m2 plots distributed in the field according to a randomized block design with three replicates. Resistance to WSBMV was evaluated on the basis of DAS-ELISA readings, symptom severity (on a 0-4 scale) and agronomic performance. Symptom severity (mean score = 0.7; range = 0.0-2.3) and ELISA values (mean = 0.882) were relatively low, especially if compared to those observed on 33 durum wheats grown in an adjacent field. Nine of the common wheat cultivars analyzed remained asymptomatic throughout the entire season, and four of these (Francia, Mol, Santerno, and Tremie) also were devoid of the causal agent, at least according to the ELISA and ISEM tests performed. Simple correlation coefficients among agronomic data, ELISA values, and symptom scores were significant in most cases (Table 1). Regression analysis indicated that the common wheat cultivars presenting the highest ELISA values and / or the highest disease scores suffered grain losses attributable to WSBMV between 29 and 36 %, and that in such cultivars mean kernel weight was reduced by about 25 %.

Reactions of cultivars of durum wheat to wheat soilborne mosaic virus.

C. Rubies-Autonell, V. Vallega, M. Turina, C. Ratti, and L. Concari.

In Italy, WSBMV causes severe economic losses on both common and durum wheat crops. Yield losses of about 70 % have been recorded on susceptible durum wheat cultivars. During 1995-96, we assayed the reactions to WSBMV of 33 durum wheat cultivars in a severely WSBMV-infested field situated near Bologna. Each cultivar was grown in a 10 m2 plot distributed in the field according to a randomized block design with three replicates. Resistance to WSBMV was evaluated on the basis of DAS-ELISA readings, symptom severity (on a 0-4 scale), and agronomic performance. Symptom severity (mean score = 1.3; range = 0.0-3.8) and ELISA values (mean = 1.207) were moderately high. The highest grain yields were recorded for the cultivar Ares. This cultivar remained asymptomatic throughout the entire season and also devoid of the causal agent, at least according to the ELISA and ISEM tests performed. Simple correlation coefficients among agronomic data, ELISA values, and symptom scores were relatively high and statistically significant (Table 2). Regression analysis indicated that the cultivars presenting the highest disease scores (i.e., Granizo, Cirillo, Agridur, etc.) suffered grain losses attributable to WSBMV of about 45 %. In these cultivars, test weight was reduced by about 5 kg/hl, mean kernel weight by about 25 %, and plant height by about 20 cm.