Genetic resources of wild cereals in Israel and vicinity. II. Phenotypic variation within and between populations of wild barley,Hordeum spontaneum

Summary Populations of wild barley, Hordeum spontaneum, in Israel, originating from diverse habitats, and tested earlier for allozyme (Nevo et al., 1979a) and disease resistance polymorphisms (Moseman et al., 1984; Nevo et al., 1984a), were compared and contrasted for performance in agronomically important phenotypic traits. The traits compared involved 10 variables comparing germination, earliness, numerical and weight variables of biomass and yield. The field experiments were conducted in 1980, 1981 and 1982 in two relatively standardized and contrasting environments: mesic (Mount Carmel, Haifa) and xeric Avedat farm, and Sede Boqer (both in the northen Negev desert). The experimental design involved 26 population quadrangles at Avedat farm (1980), and rows of randomized plants of 11 populations in both Haifa and Sede Boqer (1981 and 1982).The results indicate that the characters studied are partly genetically determined. Striking genetic variation was found between and within populations in each site, whereas remarkable environmental variation including genetic environmental interaction was found between the mesic and the xeric sites, as well as between populations and years. We conclude that natural populations of wild barley in Israel vary not only in genetic polymorphisms of allozymes and disease resistance, but also in quantitative traits of agronomie importance. These traits are economically significant and should be conserved and utilized in barley crop improvement.     

Genetics of morphological traits in wild wheat,Triticum turgidum var.dicoccoides

Summary The mode of inheritance, linkage groups, and chromosomal location of 23 morphological and 4 biochemical traits were characterized in the wild tetraploid emmer wheat,Triticum turgidum var.dicoccoides. These traits were described and their mode of inheritance was determined by their segregation in four F₂ populations derived from crosses between four var.dicoccoides accessions and a tetraploiddurum cultivar. Linkage groups among the genes encoding for these traits were determined or postulated, and their chromosomal location was deduced by linkage to previously located genes. The genetic control of the following traits was characterized and is first reported here: black keel; hairy leaf sheath; hairy auricles; hairy rachilla; hairy kernel brush; obtuse flag leaf; and curved neck/peduncle. The linkage data indicated that developmentally-related genes tended to occur in clusters.     

A valuable source of yellow rust resistance in Israeli populations of wild emmer,Triticum dicoccoides Koern.

Summary An extensive collection of wild emmer was screened for yellow rust resistance in a joint project by research institutes in Israel and The Netherlands. In inoculation experiments performed both in seedling stage and at maturity, the wild emmer accessions displayed a diversity of responses to yellow rust infection, ranging from immunity to complete susceptibility.SelectionTriticum dicoccoides var.aaronsohni G-25 was most promising proving highly resistant to all 21 races and field races used. Selection G-7, which was also very resistant in the trials, differed slightly from G-25 in infection types produced on inoculation with one of the isolates; this may be an indication that the genetic factors controlling resistance in these two selections are not identical.It is concluded that the diversified populations of wild emmer indigenous to Israel possess genes which confer high resistance to a very wide spectrum of yellow rust races, including all common races in Western Europe and the Middle East. As resistance factors can be transferred easily fromT. dicoccoides to durum and common wheat, this source may be utilized in producing varieties of cultivated wheat with improved yellow rust resistance.Joint contribution from the Volcani Institute of Agricultural Research, Bet Dagan, Israel, 1969 Series, No. 1594-E, and the Institute of Phytopathological Research, Wageningen, The Netherlands.     

Resistance to powdery mildew in wild emmer (Triticum dicoccoides Körn.)

Summary Wild emmer from 73 collection sites, including 107 accessions from Israel, two from Lebanon and one from Turkey, were evaluated for resistance to powdery mildew in field nurseries in Israel and the Netherlands.The wild emmer entries displayed a diversity of responses to powdery mildew infection, ranging from high resistance to complete susceptibility. Most entries were resistant in at least one of the nurseries; several entries proved to be resistant in all the tests.Comparing the reactions of 47 wild emmer accessions tested in six nurseries, 11 markedly different patterns were discerned, indicating the probable presence of several different resistance genes.Genes for resistance to powdery mildew appear to be very common in wild emmer indigenous to Israel. Resistance was found in accessions from most collection sites, in all the geographic regions represented in the collection.The common occurrence of resistance and the apparent diversity of genotypes makes wild emmer a rich gene-pool for resistance to powdery mildew. Since genes for resistance to wheat pathogens can be quite readily transferred to cultivated wheat, wild emmer may be utilized as a valuable source of powdery mildew resistance in wheat breeding.     

Resistance of wild emmer wheat to stem rust: Ecological,pathological and allozyme associations

Summary Seedling resistance to wheat stem rust was determined in populations of wild emmer wheat, Triticum dicoccoides, and characterized by means of ecological factors and allozyme genotypes. Reactions to wheat stem rust were studied in 102 single plant accessions of T. dicoccoides from ten populations by inoculation with Puccinia graminis tritici race 14, isolate GSR-739. Six populations displayed different degrees of response polymorphism with reactions ranging from high resistance to complete susceptibility, whereas four populations contained only susceptible plants. In some of the accession, unexplained intrasib variation in resistance and intraplant variation of infection-types were found. Resistance to stem rust was negatively correlated with two ecological factors, altitude and number of Sharav (hot-dry) days which are unfavorable to disease development. Variation in stem rust response was shown to exist in ecogeographic regions where climatic variables enhanced the development of the fungus, conceivably maintained by natural selection. Likewise, allozyme genotypes, single or in multiple loci combinations, appeared to be associated with resistance or susceptibility to rust. Such association need to be verified by genetic studies in order to become established as useful markers.     

Agronomic and qualitative traits of T. turgidum ssp. dicoccum genotypes cultivated in Italy

Summary The increasing popularity of organic agriculture and health food products has led to a renewed interest in hulled wheat species such as emmer (Triticum turgidum ssp. dicoccumSchubler). Knowledge on agronomic and quality traits is required for effective and efficient use of germplasm collections in breeding programs. The objective of this study was to estimate agronomic and grain quality traits of emmer wheat cultivated in Italy. A total of 20 emmer accessions consisting of landraces, breeding lines or cultivars selected from landraces and modern cultivars were examined under low input conditions. The study was conducted for three successive years (2002–2004) at one location of Southern Italy (Foggia). The entries were characterized for agronomic and qualitative traits [grain yield (t ha⁻¹), thousand grain weight (g), test weight (kg hl⁻¹), grain protein content (%), HMWG composition, dry gluten content (%), gluten index and yellow index, alveograph indices and Total Organic Matter (TOM) on cooked pasta]. The results showed a large genetic variability for most of the traits measured and, even if most of the accessions showed inferior bread- and pasta-making performance, modern cultivars exhibited improved quality traits with some potential to perform healthy and tasty food.     

Postulation of resistance genes to yellow rust in wild emmer wheat derivatives and advanced wheat lines from Nepal

Summary Seedlings of 38 wild emmer derivatives, and a total of 53 advanced wheat varieties/lines introduced from the International Maize and Wheat Improvement Centre (CIMMYT) or other sources, Nepalese breeding lines and local cultivars were inoculated with 18 different yellow rust isolates to postulate yellow rust resistance genes (Yr). Many wild emmer wheat derivatives used were resistant to all isolates indicating the presence of undescribed genes. Some derivatives carried Yr9, Yr6 and/or YrSU. Genes Yr1, Yr2, Yr6, Yr7, Yr8, Yr15, YrSU and YrA+ are no longer effective in Nepal; Yr4, Yr5, Yr9, Yr10, YrSP and YrSD are still effective; the effectiveness of Yr3 remains unclear. This study shows that stripe rust resistance in seedling stage of most Nepalese cultivars and advanced materials is based on Yr9 with combinations of Yr2, Yr6, Yr7, and YrA+, of which only Yr9 is still effective in Nepal. In many countries Yr9 has lost its effectiveness. Therefore the introduction of new Yr-genes from wild emmer wheat in Nepalese cultivars is highly important.     

Race-specificity of temperature-sensitive genes for resistance to Puccinia striiformis in Triticum dicoccoides

Summary Twenty-four entries of wild emmer possessing temperature-sensitive genes for resistance to yellow rust were studied in the seedling stage, at two temperature-profiles, with 15 pathogenic races from 11 countries in South America, Africa, Asia and Europe. It was shown that the majority of the resistance genes in these wild emmer entries were race-specific. In most of these entries a more resistant reaction was displayed at the higher temperature-profile; however in three entries a shift in reaction towards resistance was observed with certain races but towards susceptibility with some of the other races, suggesting that two different kinds of temperature-sensitive genes were involved in each of these entries. The similarity of temperature-sensitive genes occurring in wild emmer and in cultivated wheat is discussed.     

The evaluation of arabica coffee cultivars for resistance to coffee berry disease: Some comments

Summary The preselection test as used in the Kenya arabica coffee breeding program was critically examined prior to use in a similar program in Uganda, since the criticism by Van der Graaff (1982) of the an der Vossen et al., scaling technique for measurement of seedling resistance to Colletotrichum coffeanum may alter the interpretation of results.The published data were re-analysed using non-parametric statistical techniques and it is concluded that, despite the criticism, the method appears to give satisfactory results. It is suggested however, that the mode of the distribution obtained by the selection test be considered as a suitable alternative to the mean in the interpretation of results.     

Performance of Avena sativa L./Avena fatua L. Backcross lines

Summary Although wild oats (Avena fatua L.) have been considered a potential source of genes for cultivated oat (Avena sativa L.) improvement, most progenies of A. sativa/A. fatua crosses have weak straw and are very susceptible to crown rust (Puccinia coronata CDA. var. avenae Fraser and Led.). Backcrossing to A. sativa has been suggested as a method of improving progeny lines while introducing new genes from wild oats to cultivated oats. In this study, A. sativa/A. fatua F₁ hybrids were backcrossed twice to A. sativa, and lines from three backcross populations were selected on the basis of agronomic performance in segregating generations. The A. sativa recurrent parents were Dal (tall and late) and Stout (short and early).Backcross lines and recurrent parents were evaluated in five performance trails from 1983 through 1985. There was significant variation among backcross lines for most traits, but most backcross lines did not produce higher grain and straw yields than their A. sativa parent. Several backcross lines were higher than their recurrent parent in test weight and groat percentage. A line derived from Stout, 175BC2-6, was considered the most promising backcross line in the study. This line produced more grain, had heavier kernels, and headed 3.3 days earlier than Stout. Although 175BC2-6 does not have sufficient straw strength and crown rust resistance to be released as a cultivar, it is considered to be a new source of high grain yield, high test weight and earliness for oat breeding.     

Wild emmer: genetic resources,gene mapping and potential for wheat improvement

Wild emmer, Triticum dicoccoides, the progenitor of cultivated wheat, harbors rich genetic resources for wheat improvement. They include many agronomic traits such as abiotic stress tolerances (salt, drought and heat), biotic stress tolerances (powdery mildew, rusts, and Fusarium head blight), grain protein quality and quantity, and micronutrient concentrations (Zn, Fe, and Mn). In this review, we summarize (1) traits and controlling genes identified and mapped in T. dicoccoides; and (2) the genes transferred to cultivated wheat from T. dicoccoides. These genes, controlling important agronomic traits such as disease resistance, high protein and micronutrient content, should contribute to wheat production and food nutrition. However, most of the rich genetic reservoir in wild emmer remains untapped, highlighting the need for further exploration and utilization for long-term wheat breeding programs.     

The inheritance and chromosomal location of morphological traits in wild wheat, Triticum turgidum L. ssp. dicoccoides

The homoeologous groups of chromosomes carrying the genes for some morphological traits in wild wheat Triticum turgidum L. ssp. dicoccoides (T. dicoccoides) were determined, but not the actual chromosomes carrying them. The objectives of this study were to investigate the modes of inheritance, and determine the chromosomes carrying some morphological traits in wild emmer (2n = 28; AABB), the progenitor of most cultivated wheats. To investigate the inheritance of morphological traits, crosses were made between T. turgidum L. ssp. durum (T. durum cultivar Chartokhmi (IR10) and T. dicoccoides accessions TA1150 and TA1131. F₂ seeds from each cross were grown in the field and six qualitative characters were investigated. Purple coleoptile, purple auricle, purple culm, hairy auricle, hairy rachilla, and fragility of spike were controlled by single dominant genes. To determine the chromosomal locations, accession TA1131 was crossed with the complete set of LDN D-genome disomic substitution lines. Assessments of F₂ populations showed that chromosomes 7A, 6A, 7B, 5B, 5A and 3B carried genes for purple coleoptile, purple auricle, purple culm, hairy auricle, hairy rachilla and brittle rachis, respectively.     

Grain yield and grain protein percentage of common wheat lines with wild emmer chromosome-arm substitutions

Wild emmer wheat, Triticum turgidum subsp. dicoccoides, (2n = 4× = 28; genome BBAA), the progenitor of domesticated wheat, is genetically closely related to durum and common wheat. This wild taxon has characteristics that would be valuable if transferred to domesticated wheat. A series of chromosome-arm substitution lines (CASLs) of wild emmer wheat were produced in the background of an Israeli common wheat cultivar. These CASLs were evaluated in a pot experiment and in field trials in Israel and California for their grain yield (GY) and its components and for grain protein percentage. In addition, the extent of genetic interactions (epistatic effects) between “wild” and “domesticated” alleles, within and between homoeologous groups 1 and 7 as expressed in grain and protein yields and other quantitative traits, were determined. The research has shown that wild emmer wheat harbors genetic variability for quantitative traits and that the “wild” genes interact among themselves in a non-additive way in the common genetic background. Several chromosome arms improve GY and protein percentage in common wheat, but their effects will be presumably enhanced when combination of genes from several “wild” arms are integrated into a single “domesticated” genotype. Hence, the interaction between these genes and those in the recipient common wheat must be accounted for when higher yield or protein content is desired. The results of this study indicate on the potential of this material for breeding and genetic analysis, and support the idea of pyramiding genes from a wild species.     

Acceleration of generation advancement in spring wheat

Summary The results indicated that acceleration of generation time in wheat was practical. The method developed by Mukade et al. (1973) was improved by extending the hydrogen peroxide treatment at low temperature.     

A re-examination of apparent selection in Globodera pallida on Solanum vernei hybrids

Summary This paper re-examines the data in support of recent findings by Turner et al. (1984), that selection for virulence in Globodera pallida takes place on Solanum vernei hybrids. It is concluded that there are a number of factors that must be taken into account and that these data must be interpreted with caution.     

Identification and polymorphism of cultivars and wild ecotypes of safflower based on isozyme patterns

Summary Acid phosphatase and cathodal peroxidase isozyme patterns were used to identify nine introduced and five local cultivars of common safflower (Carthamus tinctorius L.) and seven ecotypes of wild safflower (C. oxyacantha Bieb.). Nineteen and nine bands, respectively, were readily observed for the phosphatase and peroxidase systems in the extracts from seedling shoots. Results indicated that both systems could be used jointly for complete identification of all the 21 seed sources used.Band frequencies and polymorphic indices (PI) were determined from acid phosphatase patterns using at least 92 individual seedlings of five introduced and five local cultivars and three wild ecotypes. Band frequencies ranged from complete absence in some to total presence in other populations. The mean PI for the introduced, local and wild safflowers were found to be 0.069, 0.052 and 0.058, respectively.The banding patterns of either enzyme system were similar in some instances for the cultivated and wild safflowers and there was as much variation between two cultivars as between a cultivar and a wild ecotype, indicating close genetic relationships between C. oxyacantha and C. tinctorius.     

Use of the gene pools of Triticum turgidum ssp. dicoccoides and Aegilops squarrosa for the breeding of common wheat (T. aestivum), through chromosome-doubled hybrids

Summary Triticum turgidum ssp. dicoccoides (wild emmer wheat, AABB, 2n=28) and Aegilops squarrosa (goat grass, DD, 2n=14) comprise a rich reservoir of valuable genetic material, which could be useful for the breeding of common wheat (T. aestivum, AABBDD, 2n=42). Many accessions of both wild species, most of them selected for resistance to stripe rust, were used to make amphiploids. Two strategies were applied: (1) the production of autopolyploid cytotypes of the wild species, followed by hybridisation, and (2) the production of allotriploid interspecific hybrids, followed by doubling of the number of chromosomes. The first route was unsuccessful because of failure of the crosses between the autopolyploid cytotypes, possibly due to incongruity between the two species and to reduced fertility in the autopolyploid cytotypes. The second route yielded the desired synthetic hexaploids. However, the rate of success of the crosses was low and there were great differences between years, and within years between crosses. Embryo rescue was applied to obtain the primary hybrids (2n=21), which were highly sterile and had on average 0.3 bivalents and 20.4 univalents per pollen mother cell. Various abnormalities were recorded. Doubling of the number of chromosomes sometimes occurred spontaneously or was brought about by colchicine treatment. The large scale of the interspecific hybridisation programme ensured that one-third of the female and one-sixth of the male accessions were represented in the synthetic hexaploids.     

Single cell origin of adventitious buds

Summary Objections are raised against the view of Norris et al. (Science 220, 1983), that adventitious buds from African violet leaf explants are of multicellular origin.The experimental results of these authors can be interpreted differently and may therefore support as well the opposite standpoint that the adventitious buds are (ultimately) of single-cell origin.     

Location of genes for high grain protein percentage and other quantitative traits in wild wheat Triticum turgidum var. dicoccoides

Summary The genetic control of grain protein percentage (GPP) in the wild tetraploid wheat, Triticum turgidum var. dicoccoides, was determined by crossing four accessions of this taxonomic variety with durum cultivar Inbar, and analyzing the parents, F₁ and F₂ populations. Reciprocal crosses indicated no cytoplasmic effect on GPP. The F₂ variation was continuous in all crosses, showing no transgressive segregation. However, crosses between different accessions of var. dicoccoides showed transgressive segregation indicating the presence of different genes for high GPP in these accessions. Grain protein percentage was mostly codominant with high GPP, showing either no dominance, or a weak dominance. Heritability coefficients (broad sense) ranged from 0.30 to 0.53. Correlation coefficients between GPP and yield components were usually significantly negative, with the exception of the number of spikelets per spike, and in some crosses, grain weight.The number and chromosomal location of genes coding for high GPP were determined by the association between GPP and 27 markers (23 morphological and 4 biochemical markers). For this purpose, the genetic control of these markers, their linkage groups and chromosomal location were studied. At least four loci for high GPP that segregated in the F₂ populations are suggested: one on chromosome arm 1AS, marked by the black glume gene (Bg); one on 1BS, marked by the HMW gliadin locus Gli-B1; one on group 5, marked by the genes for beaked glume (Bkg) and toothed palea (Tp); and one on group 7, marked by the kinky neck gene (Kn). The relationship between GPP and several yield components was studied in a similar manner. In general, loci of markers that correlated positively with high GPP were not correlated with a decrease in yield components. Moreover, several loci of var. dicoccoides were associated with an increase in yield components.The utilization of markers for chromosomal location of genes coding for quantitative traits is compared to the technique of aneuploid analysis, commonly used in wheat. The significance of the above findings for breeding is discussed.     

Phylogenetic differentiation of cultivated rice,XXIII. Potentiality of wild progenitors to evolve the Indica and Japonica types of rice cultivars

Summary Studies of intermediate wild-cultivated plants suggested that the Indica-Japonica differentiation of cultivars of Oryza sativa L. has taken place with the domestication of wild plants. The wild progenitor, which is considered to be the Asian form of O. perennis Moench, shows no trace of differentiation into two such types as the Indica and Japonica. To elucidate the potentiality of the wild progenitor to evolve the two types when domesticated, the selfed progenies from an Indica × wild and a japonica × wild cross were examined with regard to three characters known to be useful for distinguishing between the two types. The data showed that Japonica-like plants were derived from the Indica × wild cross and Indica-like plants from the Japonica × wild cross. The Indica-Japonica differentiation was considered to have resulted from selection of incipient domesticates having such potentiality under different climatic conditions; the dynamics was discussed.