Sources of Resistance to Powdery Mildew in Barley Lines Derived from Hordeum spontaneum Collected in Israel

Fourty two barley lines direved from the F₇ of crosses between barley cultivars and different accessions of Hordeum spontaneum collected in Israel and 30 lines or varieties with known genes for resistance to powdery mildew were included m this study. Eleven European and three Israeli powdery mildew cultures, possessing virulence genes corresponding to known resistance genes, were used to make comparisons between the varieties with known resistance genes and H. spontaneum derived lines. The reaction pattern of 39 H. spontaneum derived lines was clearly different from the reaction pattern o; any of the known genes for mildew resistance included in this study. Only two cases were observed in which the reaction pattern of H. spontaneum derived lines agreed with reaction patterns of known genes for mildew resistance viz. Ml-a9 and Ml-p. Trie Mildew resistance of one line apparently traces back to uncontrolled outcrossing with a Ml-a.6+Ml-g resistant cultivar. Since the majority of the 42 host genotypes tested showed distinctive variation in resistant reaction types against different mildew cultures, this study docs not support the assumption that differences in resistant infection types against distinct mildew cultures are sufficient to indicate the presence of supplementary genes for resistance in a given genotype of the host. The results justify the conclusion that the natural population of H. spontaneum in Israel forms a large gene pool for mildew resistance which is not yet used m cultivated barley.     

Identification of New Genes for Mildew Resistance of Barley at the Mia Locus in Lines Derived from Hordeum spontaneum

Genetical studies have been conducted with lines derived from H. spontaneum showing that these lines carry dominant mildew resistance genes located at or near the Mla, locus. The resistance spectra of the lines ‘RS170—10 × Piccolo A’, ‘Diamant × 1B-20’, ‘RS1—8 × Piccolo E’ and ‘Diamant × 1B-151’ obtained from 10 European and Israeli isolates differ from previously-identified Mia alleles. Therefore, it is suggested that these genes should be designated as Mla 25, Mla 26, Mla.27 and Mla 28, respectively. In addition, the RFLP-patterns of these lines and their crossing parents were studied by hybridization with probes MWG 1H036, MWG 1H060 and MWG 1H068, which are very closely linked to the Mia locus. Two double crossover events have been identified. The use of RFLP markers for the identification of mildew resistance genes is discussed.     

Powdery Mildew Resistance Genes in 127 Northwest European Spring Barley Varieties

One hundred and twenty-seven spring barley varieties grown in Denmark since 1979 were characterized for resistance genes using 30 powdery mildew isolates. The resistance genes are traced in the pedigrees to verify the results. Eleven named genes, 12 tentatively named genes/resistances and six unknown resistances were found. Resistance in many varieties was based on combinations of either known genes or of known and new factors. The following five new or relatively new resistance genes more or less effective against the present powdery mildew populations were detected: the ‘Mlo’ resistance conferred by the recessive mlo gene with the characteristic infection type 0/(4), ‘Ricardo’ and ‘Turkish’ sources having gene Mla3 in common and ‘Turkish’ with Ml(Tu2) in addition. In three varieties the new resistance Ml(IM9) was found in combination with different Mia alleles. Variety ‘Jarek’ has two new unidentified resistances.     

Genotypic Composition and Mildew Resistance in a Natural Population of Wild Barley, Hordeum spontaneum

Two sets of accessions were sampled, tram a natural population of Hordeum spontaneum at Shelomi, Israel, viz.: 100 ears along a transect at intervals of 1—1.5 m and 10 ring clusters of 10 ears each, circling each 10th plant of the transect. Single ear progenies were tested for banding patterns of 5 allozyme loci; in addition, hordein sanding; and field reaction against powdery mildew has been determined. 56 allozyme genotypes and 13 hordein patterns were determined. Most of the progenies showed susceptible to moderately susceptible infection types and high frequencies of low infection grade (slow mildewing). For all characters spatial grouping was found in plants derived from neighbouring transect parents. This was even more pronounced in the ring clusters. Reactions to mildew infection appeared to be closely correlated with hordein banding. In addition, accessions showing hypersensitive reactions carried excessive frequencies of a certain allele of the Est-1 locus.     

Multigene Families of Powdery Mildew Resistance Genes in Locus Mla on Barley Chromosome 5

A review of data on powdery mildew resistance genes in the Mla locus of barley reveals that there are at least 12 clusters of genes present, each comprising one Mla gene and one or more closely linked, additional resistance genes. Tentative designations are listed for 16 additional resistance genes. Many sources of powdery mildew resistance in barley appear to harbour multigene families in the Mla region, not single ‘superior’genes.     

Genetic analysis of powdery-mildew (Erysiphe graminis f.sp. hordei) resistance derived from wild barley (Hordeum vulgare ssp. spontaneum)

The inheritance of resistance to powdery mildew was investigated in 20 accessions of Hordeum spontaneum and in 20 F₄ lines derived from crosses between the variety ‘Aramir’ and 13 accessions of H. spontaneum. Two resistance genes were detected in 17 accessions, and three resistance genes in one accession. In two accessions, only one resistance gene was present. The 20 breeding lines showed a large variation in infection type and infection level. The genetic relationship between the resistance genes detected was investigated in the seven most resistant F₄ lines. These F₄ lines were divided into three groups which carried different resistance genes. In two lines, the detected resistance gene was shown to be race-specific.     

Combining Ability and Heterosis for Quantitative Powdery Mildew Resistance in Barley

The estimation of combining abilities and heterosis for quantitative resistance against Erysiphe graminis f. sp. hordei of eight spring barley (Hordeum vulgare) cultivars is presented. Fur this purpose a half diallel cross and its parents were arranged in five Latin rectangles, each inoculated with a current mildew isolate. Significant general combining ability was found whereas specific combining ability was non-significant. A great pan of the general combining ability could be explained by variety effects. Significant variety heterosis was obtained too. Significant average heterosis was obtained but us effect was small. Among those selected for this study, ‘Grit’ and ‘Hora’ were the best parents for further crosses.     

Distorted Segregation for Mildew Resistance in Doubled Haploid Lines of Spring Barley

The mildew reactions of the second generation of doubled haploid (DH) plants, derived from anther culture of crosses among three spring barley lines carrying different Mla mildew resistance alleles and the cv. ‘Pallas’, were analyzed by using a set of three European and one Israeli mildew isolate. The results indicated, (1) a significant level of distortion segregation in favour of resistant DH genotypes, which was possibly due to linkage of mildew resistance genes on chromosome 5 with genes for plant regeneration and (2) various degrees of dominance for the different resistance genes studied as well as the possible action of modifier genes.     

Linkage of Rust Resistance Genes from Wild Barley (Hordeum spontaneum) with Isozyme Markers

Eighty-three third backcross lines which comprise a set of near isogenic lines (NIL's) of the barley cultivar ‘Clipper’ but each carrying a different chromosomal segment from Hordeum spontaneum, marked with a distinct isozyme, were tested for resistance to three races of the barley leaf rust pathogen (Puccmia hordei). Fourteen lines showed resistance to at least one race and three showed resistance to all three races. The resistance in two of these lines was controlled by separate, single partially dominant genes. In one case the resistance gene named Rph1O was on chromosome 3 and linked (r = 0.15 ±0.05) with the isozyme locus Est2. In the second case, the gene (Rph11) was on barley chromosome 6 and linked (r = 0.07±0.02) with the isozyme locus Acp3 and (r = 0.11±0.02) with Dip2.     

Inheritance of the Powdery Mildew Resistance Mlk in Wheat

The inheritance of the Mlk powdery mildew resistance originating from ‘Heine 2174.50’ was analyzed by crossing the Mlk resistant cultivar ‘Ralle’× cv. ‘Amor’ (highly susceptible) and vice versa and by observing the reactions of F₁- and F₂-plants after inoculation with two different Mlk avirulent powdery mildew isolates. In all cases, a 3 (resistant): I (susceptible) segregation was found in F₂. The reactions of the F₂plants against the two powdery mildew isolates were identical in each case. Therefore, it is supposed that one dominant resistant gene is responsible for the resistant reactions against these two isolates. These results support the earlier assumption of Heun and Fischbeck (1987b) that the whole Mlk resistance pattern is controlled by a single gene.     

Effectiveness of Twenty-Four Barley Resistance Genes Against Powdery Mildew (Erysiphe graminis DC f. sp. hordei Em. Marchal) in Spain

Twenty-four near-isogenic barley lines, with a cv.‘Pallas’ background, carrying different mildew resistance genes were subjected in 1987, 1989 and 1990 to natural infection by the pathogen at several different and contrasting Spanish sites in order to study its virulence. The virulence genes proved to be geographically grouped into three regions: western (Valladolid), southern (Sevilla) and northern and northeastern (Navarra, Lleida and Girona). The mildew population of Lleida was more variable when compared with Navarra and Valladolid. Overall, the most effective resistance genes were: Ml-a13 + Ml-(Ru3), mlo and Ml-(1402).     

小麦白粉病抗源材料的有效抗病基因分析

采用携带有不同毒性基因的白粉菌菌株进行苗期接种，通过与已知抗病基因材料抗谱的相似性比较分析，对３０多个小麦抗白粉病材料的有效抗病基因进行了测定，其中１份抗源材料具Ｐｍ２＋６；７份具Ｐｍ４ａ；１０份具Ｐｍ４ｂ；２份具Ｐｍ５；４份与小白冬麦的抗性相同，小白冬麦含有一特定的抗病基因；另外有８份材料的抗谱异于所供试的所有已知基因系，从中可能鉴定出新的抗病类型     

Amino Acid Resources of the Wild Relative of Barley (Hordeum spontaneum) in Israel

Measurements were made on amino acid contents in collection of wild barley (Hordeum spontaneum)., grown in pot conditions, and in some Israeli breeding lines and cultivars of Hordeum vulgare. H. spontaneum was low in lysine content and high in prolilne plus glutamic acid compared to H. vulgare. Lysine content was positively correlated, in H. spontaneum, to all other ammo acids except proline and giutamic acid. Inter-populanon rnean differences for Iv-saie in H. spontaneum were small and lysine variation was obscured due to variation in protein content. The use of H. spomancum in breeding high protein. nutritionally improved barley is discussed.     

Localization of the Laevigatum Resistance Gene MlLa against Powdery Mildew in the Barley Genome by the Use of RFLP Markers

RFLP markers which were previously assigned to chromosome 2 (2H) were found to detect polymorphism between the cv. ‘Pallas’ and a near isogenic line carrying the Laevigatum resistance gene MlLa. Linkage analysis carried out with two sets of DH lines derived from the crosses ‘RisøS’בSultan’ and ‘Alf’בVogelsanger Gold 2’ confirmed three DNA probes closely linked with the MlLa locus.     

若干小麦抗白粉病品系的有效抗病基因的测定

采用具有不同毒性基因的白粉菌菌株进行苗期接种，通过与已知抗病基因材料抗谱的相似性比较，对１７个抗白粉病育种品系的有效抗病基因进行了分析，其中３个阿拉拉特小麦杂种后代品系、４个Ｖ．Ｐ．Ｍ系统的杂种后代品系及另外１个杂交组合的后代品系含主效抗病基因Ｐｍ２；４个具有Ｖ．Ｐ．Ｍ或Ｃ３９血缘的品系及另外１个品系含主效抗病基因Ｐｍ４ ｂ；１个品系含Ｐｍ２＋６；２个普通小麦－黑麦６Ｄ／６Ｒ代换系的抗谱相似，且不     

Use of Isozyme-Marked Segments from Wild Barley (Hordeum spontaneum) in Barley Breeding

Fifty-six accessions of Hordeum spontaneum from various Israeli habitats were hybridized with, and their progeny backcrossed three times to H. vulgare cv. ‘Clipper’. Selected chromosome segments marked by one of 24 isozyme loci were transferred to form 84 backcross lines which were nearly isogenic with ‘Clipper’. Each line was made homozygous for a single isozyme-marked segment. These lines were evaluated in preliminary and advanced field trials. The yield, malt extract percentage and grain size of the lines approached or equalled, and sometimes significantly surpassed, that of ‘Clipper’ and more recent commercial cultivars. Three isozyme-marked segments were combined in pairs and the three resultant doubly-marked lines were compared with the reconstituted parental, singly-marked lines and with the ‘Clipper’ recombinant from the same F²-array. The additive effects of single segments on yield or gram size were not significant, whereas half of the six interactions were significant, but in the unfavorable direction. It was concluded that near-isogenic lines can identify segments of wild barley germplasm that are useful for improving yield, but that pairs of these from different habitats may interact unfavourably.     

Identification of Wheat Powdery Mildew Resistance Genes by Analysing Host-Pathogen Interactions

Fifty-nine winter wheat cultivars and thirteen lines possessing known powdery mildew resistance genes were inoculated with eleven different isolates. By comparing their resistance patterns the responsible major resistance genes of the above-mentioned cultivars have been determined. The so-called “Blaukorn” resistance is conditioned by gent Pm4b. The resistance patterns of Ml-i and Pm5 being similar, the relationship between them has to be analysed by segregating populations.     

Genetic Resources for Salt Tolerance in the Wild Progenitors of Wheat (Triticum dicoccoides) and Barley (Hordeum spontaneum) in Israel

Salt tolerance was tested in the progenitors of cultivated cereals, wild barley (Hordeum spontaneum) and wild emmer wheat (Triticum dicoccoides) from Israel. Plants from five selected populations of H. spontaneum from the Mediterranean Coastal Plain and northern Negev desert, were grown on 250 and 350 mM of NaCl. Likewise, five populations of T. dicoccoides from the eastern Samaria steppes, Mt. Hermon and Mt. Carmel, were grown on 175 and 250 mM of NaCl. Here we report on superior genotypes of H. spontaneum, ripening at 350 mM NaCl (= 60 % sea water), and of T. dicoccoides ripening at 250 mM (— 40 % sea water). We are proceeding now with both genetical and physiological studies aimed at chromosomally-locating salt tolerant genes and unravelling the mechanism(s) of salt resistance in these wild cereals.     

Variation in the Carbohydrate Composition of Wild Barley (Hordeum spontaneum) Grain

The carbohydrate content of Hordeum spotaneum lines collected from 23 diverse environments in Israel was investigated. The range in composition was sucrose: 0.83—1.15%; trisaccharides): 0.48—1.16% total free and combined fructose: 1.2—4.2%; pentosans: 4.2—9.9%; and fl→3), (1→4)-β-glucans: 4.5—13.2%. The high pentosan and β-glucan content in some lines would cause quality problems if found in malting barleys.     

Race Specific Powdery Mildew Resistance in 31 Northwest European Wheat Cultivars

Race specific powdery mildew resistance in 23 winter wheat cultivars, eight spring wheat cultivars, and 14 lines/cultivars possessing known powdery mildew resistance genes, has been studied by analyzing host/pathogen interactions. The cultivars were tested as intact seedlings, and as detached primary leaf segments on water agar; both methods revealed reproducible and concordant results. The 45 cultivars/lines were divided into 24 resistance spectra according to the patterns of reaction to the powdery mildew isolates used. Of the 31 cultivars investigated, eight did not possess any of the resistance genes detected, and the remaining 23 were divided in 16 resistance spectra. The race specific resistance of nine cultivars was conferred by the single resistance genes Pm2, Pm4b, Pm5/Ml-i: or Pm6, while the race specific resistance of 14 cultivars was conferred by 2, 3, 4 or 5 genes in combination.