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.     

A core collection of common bean from the Iberian peninsula

Characterization of crop germplasm from specific regions helps understand the patterns of genetic variation that facilitates further germplasm collection, characterization, management and their more efficient utilization in genetics, breeding and other studies. Common bean (Phaseolus vulgaris L.) is a traditional crop in the Iberian Peninsula (Spain and Portugal) where subsistence farmers have been growing and maintaining their own cultivars since their introductions from the Americas in the sixteenth century. Our objectives were to: (i) characterize diversity in the landraces collected from the Iberian Peninsula and (ii) form a core collection. Of 388 landraces from the major production regions characterized for 34quantitative and 13 qualitative characters, including morphological, agronomic and biochemical traits, 74.7% had an Andean origin, 16.8% a Mesoamerican origin and 8.4% had seed mixtures or were recombinants between the two gene pools. Landraces of indeterminate climbing growth habit Type IV(47.2%) and bush determinate Type I(26.4%) with large (52.9%) and medium(27.4%) seeds of white (38.8%) and cream(25.9%) colour were predominant. Similarly, the ‘T’ phaseolin pattern and common bean race Nueva Granada were the most frequent(51%). Some exceptionally large-seeded landraces of Andean (e.g., PHA-0917 with119 g 100-seed weight^-1) and Mesoamerican (e.g., PHA-0399 with 66 g100-seed weight^-1) were found. These and other possible recombinants between the two gene pools merit further investigation. Fifty two landraces (13%) were chosen to form a core collection representing the genetic diversity in the Iberian Peninsula. This revised version was published online in July 2006 with corrections to the Cover Date.     

Characterization of resistance to the wheat stem sawfly in spring wheat landrace accessions from targeted geographic regions of the world

Plant landraces have long been recognized as potential gene pools for biotic and abiotic stress-related genes. This research used spring wheat landrace accessions to identify new sources of resistance to the wheat stem sawfly (WSS) (Cephus cinctus Norton), an important insect pest of wheat in the northern Great Plains of North America. Screening efforts targeted 1409 accessions from six geographical areas of the world where other species of grain sawflies are endemic or where a high frequency of accessions possesses the resistance characteristic of solid stems. Resistance was observed in approximately 14% of accessions. Half of the lines displayed both antixenosis and antibiosis types of resistance. Among the resistant accessions, 41% had solid or semi-solid stems. Molecular genetic screening for haplotypes at the solid stem QTL, Qss.msub.3BL, showed that 15% of lines shared the haplotype derived from ‘S-615’, the original donor of the solid stem trait to North American germplasm. Other haplotypes associated with solid stems were also observed. Haplotype diversity was greater in the center of origin of wheat. Evaluation of a representative set of resistant landrace accessions in replicated field trials at four locations over a three year period identified accessions with potential genes for reduced WSS infestation, increased WSS mortality, and increased indirect defense via parasitoids. Exploitation of distinct types of plant defense will expand the genetic diversity for WSS resistance currently present in elite breeding lines.     

Penetrance of creeping-rootedness in clonal progenies of lucerne and observations on underground morphology of plants differing for this character

Elaeis oleifera or ‘caiaué’, a close relative of oil palm (E. guineensis), has some agronomic traits of great interest for the oil palm genetic breeding such as slow growth, oil quality (mostly unsaturated) and disease resistance. An analysis of a Brazilian oil palm germplasm collection was carried out using RAPD (Random Amplified Polymorphic DNA) markers with the objective of understanding the genetic variation of ‘caiaué’ accessions collected in the Amazon Forest in the last two decades. A sample of 175 accessions obtained along the Amazon River Basin was analyzed and compared to 17 accessions of oil palm from Africa. Ninety-six RAPD markers were used in the analysis, of which fourteen were shown to be specific to oil palm, while twelve were specific to ‘caiaué’. Results showed that the Brazilian ‘caiaué’ accessions studied have moderate levels of genetic diversity as compared to oil palm accessions. The data allowed the establishment of similarity groups for ‘caiaué’ accessions, which is useful for selecting parental plants for population breeding. Cluster analysis showed that, in general, genetic similarities are not correlated to geographical distances, but consistent with geographical dispersal along the Amazon River network. AMOVA showed that most of the genetic variation is found within populations, as expected for anallogamous and long-lived perennial species. The study provides important information to define strategies for future collection expeditions, for germplasm conservation and for the use of E. oleifera in breeding programs. This revised version was published online in August 2006 with corrections to the Cover Date.     

Geographical differentiation and diallel analysis of seed dormancy in barley

Seed dormancy is one of the most important parameters affecting the malting process and pre-harvest sprouting in barley (Hordeum vulgare L.). Variation of seed dormancy in 4365 cultivated and 177 wild barley (ssp. spontaneum) accessions derived from different regions of the world was investigated in Okayama University, Kurashiki, Japan. Seed dormancy of each accession was estimated from their germination percentages at 0, 5, 10 and 15 weeks post-harvest after-ripening periods. All of the wild barley accessions showed less than 10% germination at 0 week after-ripening period. Level of seed dormancy in 4365 cultivated barley accessions showed a clear geographical differentiation. Seventy seven percent of Ethiopian accessions showed high germination percentages, while 86% of Japanese, Turkish and North African accessions showed low germination percentages at 0 week after-ripening period. A half diallel cross using eleven barley accessions with different level of dormancy revealed that seed dormancy was predominately controlled by additive gene effects. These results suggest that large genetic diversity for seed dormancy in barley is explained as different levels of additive accumulation of genetic factors. Barley varieties showing appropriate dormancy could be developed by crossing among barley germplasm accessions used in the present study.     

The drought response of landraces of wheat from the northern Negev Desert in Israel

Summary Diverse landraces of wheat, collected from the semi-arid (150 to 250 mm of total annual rainfall) Northern Negev desert in Israel were considered as a potential genetic resource of drought resistance for wheat breeding. These materials were therefore evaluated for their reponses to drought stress in agronomical and physiological terms. Up to 68 landraces, comprising of Triticum durum, T. aestivum, and T. compactum were tested in two field drought environments, in one favourable field environment, under post-anthesis chemical plant desiccation which revealed the capacity for grain filling from mobilized stem reserves, under a controlled drought stress in a rainout shelter and in the growth chamber under polyethylene glycol (PEG)-induced water stress. Biomass, grain yield and its components, harvest index, plant phenology, canopy temperatures, kernel weight loss by chemical plant desiccation, growth reduction by PEG-induced drought stress and osmotic adjustment were evaluated in the various experiments.Landraces varied significantly for all parameters of drought response as measured in the different experiments, which was in accordance to their documented large morphological diversity. Variation in grain yield among landraces under an increasing drought stress after tillering was largely affected by spike number per unit area. Kernel weight contributed very little to yield variation among landraces under stress, probably because these tall (average of 131 cm) landraces generally excelled in their capacity to support kernel growth by stem reserve mobilization under stress. Yield under stress was reduced with a longer growth duration of landraces only under early planting but not under late planting. Landraces were generally late flowering but they were still considered well adapted phenologically to their native region where they were always planted late.Landraces differed significantly in canopy temperature under drought stress. Canopy temperature under stress in the rainout shelter was negatively correlated across landraces with grain yield (r=0.67^**) and biomass (r=0.64^**) under stress. Canopy temperature under stress in the rainout shelter was also positively correlated across landraces (r=0.50^**) with canopy temperature in one stress field environment. Osmotic adjustment in PEG-stressed plants was negatively correlated (r=–0.60^**) with percent growth reduction by PEG-induced water stress. It was not correlated with yield under stress in any of the experiments. In terms of yield under stress, canopy temperatures and stem reserve utilization for grain filling, the most drought resistant landrace was the Juljuli population of T.durum.     

Genetic diversity in mung bean germplasm revealed by RAPD markers

Knowledge of the genetic relationships among landraces is useful to gene bank managers because it permits a better organization of the crop's gene pool management, more efficient sampling of the available germplasm resources and better access to useful genetic variation for breeders. Genetic diversity of 19 landraces of the cultivated mung bean, Vigna radiate, and three weedy and wild relatives including Vigna mungo, Vigna luteola and Vigna radiate var. sublobata, was investigated at the DNA level with the random amplified polymorphic DNA (RAPD) procedure. Sixty random decamer primers were employed in amplification reactions; 28 of these were informative and yielded 246 bands, of which 229 were polymorphic with a mean of 8.2 bands per primer. A genetic distance matrix based on Nei and Li coefficient was converted to a dendrogram and a two-dimensional plot using multidimensional scaling (MDS). The accessions studied were separated into three main clusters, which included V. radiate landraces, V. mungo and V. luteola, respectively. The variation of this cluster supports the view that the genetic distance of V. mungo and V. luteola varies considerably from the accession VO2955 (V. radiata). The multidimensional scaling plot confirmed that V. mungo, V. luteola and most of the accessions of V. radiata formed distinct clusters with no overlap, and two mung bean accessions (PI177493 and VO4134–1 from Turkey and India, respectively) were genetically distant from other V. radiata landraces. V. radiata and V. mungo are positioned in separate botanical species and V. radiata var. sublobata is classified within other V. radiata landraces. Based on the limited range of accessions tested, the approach holds promise for the classification of mung bean germplasm, identification of mung bean landraces and applications of molecular markers to mung bean breeding.     

Comparison of molecular markers and coefficients of parentage for the analysis of genetic diversity among spring bread wheat accessions

The comparison of different methods of estimating genetic diversity could define their usefulness in plant breeding and genetic improvement programs. This study evaluates and compares the genetic diversity of 70 spring wheat accessions representing a broad genetic pool based on molecular markers and parentage relationships. The sample was composed of 32 accessions from the International Maize and Wheat Improvement Center (CIMMYT) and 38 from other breeding programs worldwide. Eight AFLP-primer combinations and 37 pairs of SSR primers were used to characterize the accessions and the Coefficients of Parentage (COP) were calculated from registered pedigrees. The average genealogical (COP) similarity (0.09 with a range of 0.0–1.0) was low in comparison to similarity calculated using SSR markers (0.41 with a range of 0.15–0.88) and AFLP markers (0.70 with a range of 0.33–0.98). Correlation between the genealogical similarity matrix (excluding accessions with COPs = 0) and the matrices of genetic similarity based on molecular markers was 0.34≤r≤0.46 (p <0.05). It is concluded that AFLP and SSR markers are generally in agreement with estimates of diversity measured using COPs, especially when complete pedigree data are available. However, markers may provide a more correct estimate due to some unrealistic assumptions made when calculating COPs, such as absence of selection. Furthermore, both COP and marker distances indicate that CIMMYT accessions are different from the worldwide group of accessions. This revised version was published online in July 2006 with corrections to the Cover Date.     

Crossability percentages of bread wheat collections from Tibet,China with rye

Summary The crossability percentages of 282 accessions of wheat (Triticum aestivum L.) collected in Tibet, China with rye (Secale cereale L.) have been tested. Five collections have a similar to and 277 accessions have a lower crossability percentage than Chinese Spring or are non-crossable with rye. The accessions with high crossability percentage occur along the highway near Lhasa. No landraces with higher crossability than Chinese Spring and rare landraces with similar crossability to Chinese Spring indicated that the landraces in Tibet region are different from those in Sichuan, Shaanxi and Henan provinces in the distribution frequency of high crossability, and there is no distribution of recessive kr4 alleles.     

Optimization of DNA amplification fingerprinting techniques to study genetic relationships of white lupin germplasm

DNA amplification fingerprinting (DAF) techniques were used to evaluate genetic relationships among 24 randomly selected white lupin (Lupinus albus L.) accessions originating from four endemic regions. Parameters affecting DAF were optimized to obtain high resolution and reproducible banding patterns. DNA amplification was tolerant to a wide range of both template and primer concentrations but sensitive to Mg²⁺ concentration, and annealing temperature and time. Pure template DNA was found to be essential for obtaining reproducible banding patterns. Primer annealing occurred at multiple sites, permitting detection of polymorphism using only a single primer. Of 56 octamer primers tested, 22 yielded highly polymorphic DAF bands that could be used to distinguish closely related accessions. Genetic similarity coefficients were calculated and a dendrogram, using the unweighted pair group method with arithmetic average (UPGMA), was constructed. A high level of genome diversity was found among the accessions, but several from the Middle East and West Africa tended to cluster together. The results support the future use of DAF markers for the characterization and identification of white lupin germplasm.     

Comparative analysis of diversity based on morpho-agronomic traits and microsatellite markers in common bean

Morpho-agronomic traits and microsatellite markers were used to survey genetic diversity in 115 common bean genotypes that included 70 Indian landraces, 24 released varieties and 21 exotic accessions. Twelve morpho-agronomic traits, namely, days to 50% flowering, leaflet length, leaflet width, pod length, pod width, number of pods per plant, days to maturity, seed length, seed width, number of seeds per pod, 100 seed weight and seed yield per plant were studied. Field data of two consecutive years were subjected to multivariate analysis as proposed by Mahalanobis’s D²-statistics, Tochers method of clustering and combined analysis of variance. Seventeen microsatellite markers were also used to examine genetic diversity at molecular level that showed polymorphic information content (PIC) in the range of 0.00–0.684. Dendrograms based on Euclidean distances and UPGMA analysis showed the presence of majority of released varieties into single cluster, which pointed toward their low genetic base in comparison to indigenous landraces and exotic germplasm. Significant correlation existed between morphological genetic distance and microsatellite genetic distance tested by Mantel test (r = 0.876).     

Partial resistance to a Fusarium root disease in Egyptian white lupin landraces

A Fusarium sp. root pathogen of lupin is the causal agent of the most important disease that affects the cultivation of white lupin (Lupinus albus L.) in Egypt. The aim of our research was to investigate whether host resistance to Fusariumroot disease was available in Egyptian landraces ofLupinus albus. Five Fusarium isolates collected from white lupin samples in Egypt were tested with an Egyptian landrace and a French cultivar. The most aggressive isolate was used to screen an additional 15 Egyptian landraces, two cultivars released in Egypt after selection among landraces, one Polish cultivar, and two French cultivars. The assessment of host response to Fusarium was performed in a field, and under controlled conditions in a greenhouse pot experiment. Most landraces and the two Egyptian cultivars showed better resistance with good accordance between field and pot experiment. This experiment showed that Egyptian genetic resources of white lupin possess partial resistance to Fusarium root rot. Egyptian germplasm may be an alternative genetic source for incorporating partial resistance to Fusarium root rot into the breeding pools. This revised version was published online in July 2006 with corrections to the Cover Date.     

Diversity in selected wild and cultivated species of pigeonpea using RFLP of mtDNA

Diversity in 28 accessions representing 12 species of the genus, Cajanus arranged in 6 sections including 5 accessions of the cultivated species, C. cajan, and 4 species of the genus Rhyncosia available in the germplasm collection at ICRISAT was assessed using RFLP with maize mtDNA probes. Cluster analysis of the Southern blot hybridization data with 3 restriction enzymes – 3 probe combinations placed the genus Rhyncosia in a major group well separated from all the species belonging to the genus Cajanus. Within the genus Cajanus, the 4 accessions of C. platycarpus belonging to section Rhynchosoides formed a separate group in contrast to those in other sections of pigeonpea. In the section, Cajanus all the 5 accessions of C. cajan were grouped together and C. cajanifolius belonging to the same section was in a subgroup by itself closer to the main group. The four accessions of C. scarabaeoides, were together and the other species belonging to section Cantharospermum were in different subgroups. The intra-specific variation was seen even within accessions of certain pigeonpea wild species such as C. scarabaeoides, C. platycarpus, C. acutifolius, and even the cultivated species of C. cajan. This study suggests that RFLP of mtDNA can be used for the diversity analysis of pigeonpea and it gives some indications on the maternal lineage among the species. The variations in the mitochondrial DNA hybridization patterns also suggest the extensive rearrangement of the organelle genome among the Cajanus species. This revised version was published online in July 2006 with corrections to the Cover Date.     

Unique gliadin patterns in Chinese winter wheat cultivars

Cultivated Chinese wheat germplasm has been a valuable genetic resource in international plant breeding. Patterns of gliadin among cultivated Chinese accessions are unknown, despite the proven value and potential novelty. The objective of this work was to analyse the diversity within improved Chinese wheat germplasm. The electrophoretic banding patterns of gliadin in winter wheat cultivars and advanced lines were determined by acid-polyacrylamide gel electrophoresis. For 148 leading commercial cultivars and promising advanced lines used in this study, 48 patterns were identified, 29 corresponding to ω -gliadin, nine to γ -gliadin, five to β -gliadin and five to α -gliadin. The most frequent patterns were A6 in ω ; B in γ ; B in β and A in the region of α . A total of 116 band types appeared in the 148 samples: 94 accessions had unique gliadin types, and 22 gliadin, types while not unique, were found in 54 accessions. The gliadin patterns of Chinese wheat cultivars and lines greatly differed from the patterns of wheat lines from other countries. Three patterns, E, J, H, M, N and O in the ω -zone had not been reported previously. Three wheat zones of China, the Northern Winter Wheat Region, the Yellow and Huai Valley River valleys Winter Wheat Region and the Southwestern Winter Wheat Region, showed different frequencies in their gliadin patterns. This information can be used to monitor genetic diversity with Chinese wheat germplasm.     

Random amplified polymorphic DNA (RAPD) variation in Fagopyrum tataricum Gaertn. accessions from China and the Himalayan region

The diversity among 52 landraces and cultivars of tartary buckwheat (Fagopyrum tataricum Gaertn.) and one accession of its wild ancestor, F. tataricum ssp. potanini Batalin, from diverse geographic origins was examined using random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) markers. Eighteen primers produced a total of 240 fragments, of which 153 (63.75%) were monomorphic and 87 (36.25%) polymorphic bands. UPGMA-based pairwise Jaccard’s coefficient of similarity was used to deduce the relationships among 53 genetically diverse accessions. The similarity between cultivated tartary buckwheat accessions ranged from 0.61 to 1.00. Four distinct clusters were formed which corresponded well with the geographic distribution of the tartary buckwheat. Nepalese accessions showed maximum diversity followed by Chinese accessions. Tartary buckwheat accessions from the Himalayan region of northwestern India revealed a narrow gene pool. The wild buckwheat accession did not group with any of the three cultivated tartary buckwheat groups, and formed its own single-entry group. Genetic similarity (0.59) of Chinese buckwheat accessions with the wild ancestor reaffirmed that cultivated tartary buckwheat originated in the Yunnan province of northwestern China. Consistent with some earlier reports, our study demonstrated the usefulness of the RAPD technique for the characterization of plant genetic resources and assessment of diversity between species. This revised version was published online in August 2006 with corrections to the Cover Date.     

Diversity in the wild potato species Solanum chacoense Bitt.

Summary The morphological and isozyme variation was studied in 22 accessions of Solanum chacoense from Paraguay and Argentina. Clear geographic groups were identified through the use of multivariate analyses. S. chacoense from mountain sites in Argentina could be readily distinguished from plains forms from Paraguay, on the basis of several correlated morphological characters. Three isozyme systems, namely phosphoglucose isomerase (PGI), glutamate-oxaloacetate transaminase (GOT) and peroxidase (PRX) were studied using starch gel electrophoresis. The banding patterns indicated that for each isozyme there were several loci, which were polymorphic. A genetic interpretation of one of the PGI loci was made, and indices of genetic diversity and genetic identity calculated. Principal components analysis, cluster analysis and genetic diversity indicated a close relationship between the geographical groups. These results are discussed in the context of in situ genetic conservation.     

Phenotypic variation in a core collection of common bean (Phaseolus vulgaris L.) in the Netherlands

Forty accessions, forming a core collection of mainly bush type of the common bean (Phaseolus vulgaris L.) germplasm in the Netherlands, were evaluated for 14 qualitative and quantitative traits at the Agricultural University, Wageningen (WAU), the Netherlands in 1992. These and an additional 117 Dutch accessions, mainly collected in private home gardens, were also evaluated for phaseolin seed protein pattern, and morphological and agronomic traits at the International Center for Tropical Agriculture (CIAT, Spanish acronym), Cali, Columbia between 1987 and 1997. Multivariate and principal component analyses at both WAU and CIAT indicated existence of one large group with no discernable patterns among Dutch common bean collections of landraces, garden forms and cultivars. However, when phaseolin, an evolutionary, biochemical marker, was used as an initial classification criterion followed by use of morphological markers, the two major gene pools; Andean and Middle American with two races in each (Chile and Nueva Granada in Andean, and Durango and Mesoamerica in Middle American) were identified. The Andean gene pool was predominant (136 of 157 accessions), especially the race Nueva Granada (126 accessions) characterized by the bush determinate growth habit type I and T phaseolin. The new core collection comprised 31 accessions. Bean races Chile, Durango, and Mesoamerica were represented by 10, 7, and 14 accessions, respectively. Of the 9 French or snap bean accessions six possessed characteristics of race Mesoamerica and three belonged to Durango race. Occurrence of these and a large number of other recombinants strongly suggested considerable hybridization and gene exchange between Andean and Middle American gene pools, thus blurring the natural boundaries and forming a large single group of common bean germplasm in the Netherlands. The inter-gene-pool recombinants of both dry and French beans should be of special interest to breeders for use as bridging-parents for development of broad-based populations. This revised version was published online in July 2006 with corrections to the Cover Date.