AWN Vol 41

Institute of Evolution

University of Haifa, Haifa 31905, Israel.

Identification of DNA markers linked to novel yellow rust resistance genes introgressed from Triticum dicoccoides.

T. Fahima, A. Grama¹, A. Korol, T. Turpeinen, and E. Nevo.

¹Institute of Garden and Field Crops A.R.O., The Volcani Center, Bet Dagan 50250, Israel.

The two groups at the University of Haifa and the Volcani Center, during the last 20 years, performed large-scale screening of populations of wild wheat, Triticum dicoccoides, for resistance to various pathogens. About 1,000 genotypes were screened at the Volcani Center for resistance to stripe rust (Puccinia striiformis West.). Several novel resistance genes were identified and introgressed into tetraploid and hexaploid wheat cultivars. One of them was characterized in detail and designated as Yr15. Near-isogenic durum lines, with or without the Yr15 resistance gene, were analyzed with the help of RAPD and RFLP markers. Out of 320 random primers, only 32 showed any polymorphism between backcross lines and the recurrent parent. One RAPD marker seems to be associated with susceptibility to yellow rust. The RFLP analysis confirmed that the resistant lines carry a chromosome segment introgressed from T. dicoccoides.

We plan additional screening of this material with RAPD and RFLP markers, as well as screening of material carrying additional resistance genes that were identified in wild emmer populations from Israel.

RFLP mapping of chlortoluron resistance gene, Su1, in bread wheat Triticum aestivum and the wild wheat Triticum dicoccoides.

T. Krugman, B. Rubin¹, O. Levi¹, J.W. Snape², and E. Nevo.

¹ Faculty of Agriculture, Hebrew University, Rehovot, Israel, and ² John Innes Centre, Cambridge Laboratory, England.

Chlortoluron is a selective herbicide, a member of the phenylurea group, widely used for the control of broadleaf and annual grass weeds in cereal fields. Variation in the tolerance to chlortoluron was found in some cultivars of T. aestivum and in wild emmer T. dicoccoides. The genetical control of tolerance to chlortoluron in bread wheat is determined by a major gene (Su1), located on the short arm of chromosome 6B, but the mode of action or the product of the gene was not determined. Revealing the genetical control of herbicide response in cultivated and wild wheat is crucial for understanding the action and evolution of herbicide resistance in wheat and for further cloning the gene.

We have mapped the Su1 gene in bread and wild wheat using restriction fragment length polymorphism (RFLP) markers. Mapping Su1 in bread wheat was based on 58 F₄ plants of a cross between the susceptible Chinese Spring (CS) and CS(CAP6B), which is a substitution line of the 6B chromosome from the resistant cultivar Cappelle-Desprez. The F₄ plants are single-seed descent lines (SSD), segregating for a single chromosome. Mapping of the resistance gene in wild wheat was based on 37 F₂ plants of a cross between B-7 (resistant) and B-35 (susceptible), both collected in Israel. All plants were scored to chlortoluron response by chlorophyll fluorescence induction kinetics and analyzed by RFLP markers. The mapping populations were analyzed by nine probes, residing on chromosome 6B. In T. aestivum, three of the probes were polymorphic and found to be closely linked to Su1 gene. Recombination percentage (r) between Su1 and each of the markers are: FONT SIZE=2 FACE="WP Greek Century""-Amy1 (r = 9.844-3.46 %); Xpsr371 (r = 5.15-2.52 %) on the long arm, and Nor2 (r = 2.74-1.65 %) on the short arm. The resistance gene of T. dicoccoides was mapped by three RFLP markers, the order of the markers on the chromosomes is Nor2 - Xpsr312 - Su1 - Pgk2, and the genetic distances between the genes are 24.8 cM - 5.3 cM - 6.8 cM, respectively. Only one marker (Nor2) was polymorphic in both crosses, and the genetic distance Su1 - Nor2 was 10 times higher in the wild wheat than in the bread wheat. Along with data obtained from the last published wheat chromosomes map, this indicates that the linear order of the genes on chromosome 6B is identical both in bread wheat and wild emmer wheat.

Publications.

Institute of Evolution, Haifa University, Israel and collaborators (¹).

Nevo E and Beiles A. 1992. Amino-acid resources in the wild progenitor of wheats, Triticum dicoccoides, in Israel: Polymorphisms and predictability by ecology and isozymes. Plant Breed 108:190-201.

Nevo E, Snape¹ JW, Lavie B, and Beiles A. 1992. Herbicide response polymorphisms in wild emmer wheat: ecological and isozyme correlations. Theor Appl Genet 84:209-216.

Nevo E, Ordentlich¹ A, Beiles A, and Raskin¹ I. 1992. Genetic divergence of heat production within and between the wild progenitors of wheat and barley: evolutionary and agronomical implications. Theor Appl Genet 84:958-962.

Kawahara¹ T, Nevo E, and Beiles A. 1993. Frequencies of translocations in Israeli populations of Triticum dicoccoides Koern. XV Inter Bot Cong, August 28 - September 3, 1993. Yokohama, Japan. 8020. (Abstract).

Kawahara¹ T, Yamada¹ T, Nevo E, and Zohary¹ D. 1993. Collection of wild relatives of wheats in Israel. Japanese J Breed, Suppl. 1, 1993. (Abstract).

Nevo E, Krugman T, and Beiles A. 1993. Genetic resources for salt tolerance in the wild progenitors of wheat (Triticum dicoccoides) and barley (Hordeum spontaneum) in Israel. Plant Breed 110:338-341.

Nevo E, Nishikawa¹ K, Furuta¹ Y, Gonokami¹ Y, and Beiles A. 1993. Genetic polymorphisms of alpha and beta amylase isozymes in wild emmer wheat, Triticum dicoccoides, in Israel. Theor Appl Genet 85:1029-1042.

Nevo E, Meyer¹ H, and Piechulla¹ B. 1993. Diurnal rhythms of the chlorophyll a/b binding protein mRNAs in wild emmer wheat and wild barley (Poaceae) in the Fertile Crescent. Pl Syst Evol 185:181-188.

The¹ TT, Nevo E, and McIntosh¹ RA. 1993. Responses of Israeli wild emmers to selected Australian pathotypes of Puccinia spp. Euphytica 71:75-81.

Yamada¹ T, Kawahara¹ T, and Nevo E. 1993. Allozyme diversity of diploid Aegilops species in Israel. Japanese J Breed, Suppl. 1. 1993. (Abstract).

Yamada¹ T, Kawahara¹ T, and Nevo E. 1993 . Clinal changes of allozyme diversity and outcrossing rate along the environmental gradient among populations of Aegilops longissima in Israel. Intern Bot Cong, June 1993, Kyoto, Japan. (Abstract in Japanese).

Krugman T, Rubin¹ B, Levi¹ O, Snape¹ J, and Nevo E. 1994. RFLP mapping of chlortoluron resistance gene (Su1) in cultivated wheat Triticum aestivum, and in wild wheat Triticum dicoccoides. 13th Conf Weed Sci Soc of Israel, January 24-25, 1994. Phytoparasitica (Abstract, in press).

Nevo E, Krugman T, and Beiles A. 1994. Edaphic natural selection of allozyme polymorphisms in Aegilops peregrina at a Galilee microsite in Israel. Heredity 72:109-112.

Poreceddu¹ E, Pagnotta¹ MA, Beiles A, and Nevo E. 1995. Variation for RFLP and PCR markers among and within populations of Triticum dicoccoides in Israel. Eucarpia Symp on "Adaptation in Plant Breeding", 31 July-4 Aug. 1995, Jyvaskyla, Finland. (Abstract, in press).

Nevo E. 1995. Genetic resources of wild emmer, Triticum dicoccoides for wheat improvement: News and Views. Proc 8th Inter Wheat Genet Symp (Li ZS and Xin ZY eds). China Agricultural Scitech Press, Beijing. Pp. 79-88.

Yamada T, Kawahara¹ T, and Nevo E. Allozymic diversity in diploid Aegilops species from Israel (in preparation).

Ongoing projects.

Gutterman¹ Y and E Nevo. Germination patterns in Triticum dicoccoides.

Korol A, T Krugman, T Fahima, and E Nevo. Mapping of Triticum dicoccoides.

Koebner¹ RMD and E Nevo. Salt tolerance in Aegilops species from Israel.

Mail address: | Fax: 972-4-246-554

Institute of Evolution | Bitnet (Earnet): Rabi301@Haifauvm

Haifa University | or Institute.of.Evolution@Haifauvm

Haifa, Mt. Carmel 31905 | Internet: Rabi301@Uvm.Haifa.Ac.IL

Israel | or Institute.of.Evolution@Uvm.Haifa.Ac.IL

ITEMS FROM ITALY

Experimental Institute for Cereal Research

Via Cassia 176, OO191 Rome, Italy.

Preliminary analyses on the black-point disease of durum wheat.

M. Pasquini, N.E. Pogna, S. Pagliaricci, L. Sereni, and F. Casini.

Black-point disease of cereals, generally caused by fungal infection of the wheat florets during grain development, can seriously affect grain quality. A preliminary survey was undertaken in central Italy. Head samples were collected in the field (Montelibretti, Roma) from five durum wheat cultivars (Simeto, Creso, Ofanto, Gardena, and Tavoliere) and included in a block design with three replicates to determine the prevalence of the different fungi infecting the kernels. Sampling and classification were made according to the system of Rossi et al. (1991). Eighteen heads per plot were collected randomly on a diagonal across each plot at the dough stage. The ears were washed in running water for 20 minutes, surface-sterilized by immersion in a calcium-hypochlorite solution (2 % available chlorine) for 5 minutes, rinsed in sterile water, and dried at room temperature. Six seeds per head were sampled: 2 from the basal part, 2 from the center, and 2 from the apical part. The seeds were placed in Petri dishes containing water agar and stored at room temperature for 7 days. Isolates of fungal colonies growing from the seeds then were transferred to PDA medium and incubated at room temperature.

A large portion (90 %) of the kernels were shown to be infected by Alternaria alternata, whereas only 0.2 % were infected by Drechslera sorokiniana. Other species of fungi were isolated sporadically, among them Stemphylium botryosum and Epicoccum nigrum. No relationship was observed between the ear part sampled (apical, center, or basal) and the presence of fungi.

Analyses are being carried out on a 500-kernel sample for each plot to determine the percentage of kernels with black-point and to ascertain a relationship between frequency of A. alternata and kernel discoloration. The classification is being made in accordance to the Huguelet and Kiesling (1973) scale: 1 = healthy kernel with no discoloration, 2 = tip or crease of kernel discolored, 3 = half of kernel discolored, 4 = 3/4 of kernel discolored, and 5 = kernel totally discolored.

Identification of the Gli-B5 locus on the short arm of chromosome 1B in durum wheat (Triticum turgidum spp. durum).

M. Mazza, N.E. Pogna, S. Pagliaricci, M. Pasquini, P. Cacciatori, and A. Iori.

The short arms of chromosomes 1A and 1B in common wheat (T. aestivum L.) have been found to carry the Gli-5 locus that codes for 1-2 FONT SIZE=2 FACE="WP Greek Century"o-gliadin components (Pogna et al. 1993). In particular, the Gli-B5 locus on chromosome 1B was shown to recombine with the Gli-B1 locus at a mean frequency of 1.4 %, and to be distal to this latter locus with respect to the centromere. A PAGE fractionation of gliadins from 279 progeny of two self-pollinated F₅ plants, from the cross between the bread wheat cv. Perzivan-1 and the durum wheat cv. Rodeo, provided evidence that the short arm of chromosome 1B in Rodeo contains a gliadin-coding locus that is tightly linked to Gli-B1 and recombines with it at a mean frequency of 4.7 %. This new locus codes for two FONT SIZE=2 FACE="WP Greek Century"o-gliadins that occur in several durum wheat cultivars of different origins. It lies between Gli-B1 and the glume-colour locus, Rg1, and, therefore, is assumed to correspond to the Gli-B5 locus. Near-isogenic durum wheat lines differing from each other by the presence/absence of the Gli-B5 encoded FONT SIZE=2 FACE="WP Greek Century"o-gliadins currently are being analysed for their gluten viscoelastic properties.