The Inheritance of Morphological and Biochemical Traits Introgressed into Common Wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) from <Emphasis Type="Italic">Aegilops speltoides</Emphasis> Tausch

The genetic control of morphological characters and gliadin composition was studied in two bread wheat lines with introgressed segments from Aegilops speltoides Tausch. It was found that the transferred trait of leaf hairiness is controlled by one dominant gene, non-allelic to the known gene, Hl1. It was localized in 7B chromosome. Whole plant non-glaucousness is under the control of an inhibitor gene, allelic to the gene W1^I of wheat located on chromosome 2B. This gene was found to be epistatic to the gene controlling spike waxlessness. The introgressed gene for spike glume color was found to be allelic to the Rg1 gene located on 1BS of common wheat, but it was linked with another allele of the gliadin locus Gli-B1.     

Gliadin Electrophoretic Analysis of the Genetic Integrity of Wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) Accessions After Frequent Seed Reproductions

A standard electrophoretic method for wheat cultivar identification was used on single seeds to analyse the genetic integrity of 11 wheat (Triticum aestivum L.) accessions after up to 24 seed reproductions in the Gatersleben genebank. It was clearly demonstrated that the gliadin pattern of single seeds can be used to analyse the genotype composition of wheat accessions. Stability of electrophoretic banding patterns was detected in eight accessions. Very week genetic drift was observed in three accessions. Our investigations confirm experiences of the successful utilisation of protein markers for cultivar verification and genetic integrity testing and demonstrate the high standard of wheat accessions maintenance in the Gatersleben genebank.     

Genetic diversity of HMW glutenin subunit in Chinese common wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) landraces from Hubei province

The high molecular weight (HMW) glutenin subunit composition of 111 common landraces of bread wheat collected from Hubei province, China has been determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Ninety six of the accessions were homogeneous for HMW glutenin subunit composition and 15 were heterogeneous. For the Glu-1 loci, 16 alleles were detected, 3 at the Glu-A1locus, 9 at the Glu-B1and 4 at the Glu-D1. Three novel alleles were identified, two at the Glu-B1 and one at the Glu-D1locus. Combination of these 16 alleles resulted in 14 different HMW subunit patterns. The distribution of HMW glutenin subunit alleles in a subset of 105 of the 111 accessions representing six populations was assessed both at the individual population and whole population levels. The results demonstrated that the distribution of allelic patterns varied among populations. Taken together, 62.5% of the alleles detected were considered to be rare alleles while the Glu-A1c (null), Glu-B1b (1Bx7 + 1By8) and Glu-D1a (1Dx2 + 1Dy12) alleles were found most frequently in the six populations. The subset exhibited relatively high genetic diversity (A = 5.33, P = 1.00, Ae = 1.352 and He = 0.238) with 81.5% of the diversity being within populations and 18.5% between populations.     

Genetic variability in bread wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) of Pakistan based on polymorphism for high molecular weight glutenin subunits

Variation in bread wheat including pre and post green revolutions varieties of Pakistan along with landraces was investigated for high molecular weight Glutenin subunits (HMW Gs) encoded at three genes (Glu-A1, Glu-B1, Glu-D1) with SDS-PAGE. The germplasm was diverse and unique on the basis of HMW Gs compositions and out of 14 alleles detected at all the Glu-1 loci, three belonged to Glu-A1, nine to Glu-B1 and two to Glu-D1 locus. High variation was observed in the landraces and higher gene diversity was observed between the populations as compared to the gene diversity within populations, whereas a reverse pattern of gene diversity was observed when populations were pooled across the region (higher within the regions than between the regions). A lack of relationship between the HMW Gs diversity and the altitude of collection site was observed. A data base has been generated in this study which could be expanded/exploited for cultivar development or management of gene bank.     

Genetic diversity of the D-genome in <Emphasis Type="Italic">T. aestivum</Emphasis> and <Emphasis Type="Italic">Aegilops</Emphasis> species using SSR markers

Simple sequence repeats (SSRs), highly dispersed nucleotide sequences in genomes, were used for germplasm analysis and estimation of the genetic relationship of the D-genome among 52 accessions of T. aestivum (AABBDD), Ae. tauschii (D^tD^t), Ae. cylindrica (CCD^cD^c) and Ae. crassa (MMD^cr1D^cr1), collected from 13 different sites in Iran. A set of 21 microsatellite primers, from various locations on the seven D-genome chromosomes, revealed a high level of polymorphism. A total of 273 alleles were detected across all four species and the number of alleles per each microsatellite marker varied from 3 to 27. The highest genetic diversity occurred in Ae. tauschii followed by Ae. crassa, and the genetic distance was the smallest between Ae. tauschii and Ae. cylindrica. Data obtained in this study supports the view that genetic variability in the D-genome of hexaploid wheat is less than in Ae. tauschii. The highest number of unique alleles was observed within Ae. crassa accessions, indicating this species as a great potential source of novel genes for bread wheat improvement. Knowledge of genetic diversity in Aegilops species provides different levels of information which is important in the management of germplasm resources.     

Proline accumulation as a response to salt stress in 30 wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) cultivars differing in salt tolerance

The effects of NaCl salt (EC = 16 dS m⁻¹) on water potential, and accumulation of proline, Na⁺ and K⁺ in leaves on the main stem of 30 wheat cultivars (Triticum aestivum L.) at awn appearance and 20 days after anthesis (20 DAA) were evaluated in a greenhouse experiment. Plants were arranged in a according to a randomized complete block design with factorial treatments in three replications. Proline accumulation at 20 DAA increased with increasing salt stress. This increase was 27.4-fold with the salt-sensitive cultivar “Ghods,” while the mean was 5.2-fold for 19 salt-resistant cultivars. Positive correlations between proline, and K⁺ + Na⁺ concentrations associated with higher sensitivity to salt stress indicated that proline may not have a protecting role against salt stress. No correlation was observed between leaf proline and water potential. Almost no contribution to the osmotic adjustment seems to be made by proline. The contribution made by proline to the osmotic adjustment of plants at 20 DAA was 0.69 bar, whereas that made by K⁺ and Na⁺ was 2.11 and 4.48 bar, respectively. The 30 wheat CV_s used in this experiment showed different performances regarding the traits observed. Eleven of them showing the higher stress sensitivity indices had the highest level of proline and Na⁺ concentrations. They were considered to be salt-sensitive cultivars. Among the others, nine cultivars showed salt tolerance with almost the same Na⁺ and proline concentrations, but a higher K⁺/Na⁺ selectivity of ions from leaf to grains. In 10 of the cultivars, Na⁺ and proline concentrations were low, indicating the presence of a salt avoiding mechanism.     

Identification of <Emphasis Type="Italic">Aegilops</Emphasis> L. species and <Emphasis Type="Italic">Triticum aestivum</Emphasis> L. based on chloroplast DNA

The genus Aegilops L. is a very important genetic resource for the breeding of bread wheat Triticum aestivum. Therefore, an accurate and easy identification of Aegilops species is required. Traditionally, identification of Aegilops species has relied heavily on morphological characters. These characters, however, are either not variable enough among Aegilops species or too plastic to be used for identification at the species level. Molecular markers that are more stable within species, therefore, could be the alternative strategy towards an accurate identification. Since the chloroplast DNA has a lower level of evolution compared to the nuclear genome, an attempt was made in this study to investigate polymorphism in the chloroplast DNA among 21 Aegilops species (including Ae. mutica that is now known as Amblyopyrum muticum) and between the latter and T. aestivum to generate markers for the diagnosis of all targeted species. Cleaved amplified polymorphic sequence (CAPS) applied on 22 coding and non-coding chloroplast regions using 80 endonucleases and sequencing of two of those regions revealed little polymorphism between T. aestivum and the various Aegilops species examined and to a less extent was the variation among Aegilops species. Polymorphism observed among species analysed allowed the discrimination of T. aestivum and 12 Aegilops species.     

Evaluating landraces of bread wheat <Emphasis Type="Italic">Triticum aestivum</Emphasis> L. for tolerance to aluminium under low pH conditions

Bread wheat (Triticum aestivum L.) landraces held within ex situ collections offer a valuable and largely unexplored genetic resource for wheat improvement programs. To maximise full utilisation of such collections the evaluation of landrace accessions for traits of interest is required. In this study, 250 accessions from 21 countries were screened sequentially for tolerance to aluminium (Al) using haematoxylin staining of root tips and by root regrowth measurement. The staining test indicated tolerance in 35 accessions, with an intermediate response to Al exhibited in a further 21 accessions. Of the 35 accessions classified as tolerant, 33 also exhibited increased root length following exposure to Al. The tolerant genotypes originated from Bulgaria, Croatia, India, Italy, Nepal, Spain, Tunisia, and Turkey. AFLP analysis of the 35 tolerant accessions indicated that these represent diverse genetic backgrounds. These accessions form a valuable set of germplasm for the study of Al tolerance and may be of benefit to breeding programs for expanding the diversity of the gene pool from which tolerant cultivars are developed.     

Assessing genetic diversity of Polish wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis>) varieties using microsatellite markers

Fifty-three wheat cultivars have been genotyped using 24 SSR (simple sequence repeat) markers in order to evaluate genetic similarities among Polish wheats, i.e. 53 spring and winter cultivars; ‘Chinese Spring’ was taken as reference. ll but one SSR marker allowed to identify DNA polymorphisms, giving in total 166 alleles (including nulls), from 3 to 13 alleles per marker with mean of 7.22. Based on marker data, genetic similarities were calculated and a dendrogram was created. ‘Spring’ cultivars were less diverse than winter ones, showing the biggest similarity to ‘Chinese Spring’. Four sister cultivars (Nutka, Tonacja, Zyta and Sukces), formed a cluster of very similar materials, of which Zyta and Sukces had the highest similarity indices. Parental lines Jubilatka and SMH 2182 were more distant from each other (genetic similarity of 0.227). It was possible to differentiate all the wheats using only four SSR markers: Xgwm186, Xgwm389, Xgwm459 and Xgwm577.     

<Emphasis Type="Italic">Calamintha nepeta</Emphasis> (L.) Savi and <Emphasis Type="Italic">Micromeria thymifolia</Emphasis> (Scop.) Fritsch cultivated in Italy

Calamintha nepeta and Micromeria thymifolia have been traditionally used in the Mediterranean area as condiments and medicinal plants for a long time. Whereas in parts of Italy C. nepeta (special recipes have been developed in Lazio and Tuscany) is also an established garden plant showing different evolutionary products and their interaction among each other and the wild progenitor, M. thymifolia is being developed into a new crop plant. Both plants and their uses are described with regard to Italy. There is a marked tendency to broaden the use of condiments and spices which results in new crop plants which have to be documented and elaborated in further studies. Many species of Labiatae are predisposed to use by man and new items can be found even in areas which have to be considered as well studied.     

<Emphasis Type="Italic">Rhizobium</Emphasis>,<Emphasis Type="Italic"> Bradyrhizobium</Emphasis> and<Emphasis Type="Italic"> Agrobacterium</Emphasis> strains isolated from cultivated legumes

The present study was conducted to isolate and characterize rhizobial strains from root nodules of cultivated legumes, i.e. chickpea, mungbean, pea and siratro. Preliminary characterization of these isolates was done on the basis of plant infectivity test, acetylene reduction assay, C-source utilization, phosphate solubilization, phytohormones and polysaccharide production. The plant infectivity test and acetylene reduction assay showed effective root nodule formation by all the isolates on their respective hosts, except for chickpea isolate Ca-18 that failed to infect its original host. All strains showed homology to a typical Rhizobium strain on the basis of growth pattern, C-source utilization and polysaccharide production. The strain Ca-18 was characterized by its phosphate solubilization and indole acetic acid (IAA) production. The genetic relationship of the six rhizobial strains was carried out by random amplified polymorphic DNA (RAPD) including a reference strain of Bradyrhizobium japonicum TAL-102. Analysis conducted with 60 primers discriminated between the strains of Rhizobium and Bradyrhizobium in two different clusters. One of the primers, OPB-5, yielded a unique RAPD pattern for the six strains and well discriminated the non-nodulating chickpea isolate Ca-18 from all the other nodulating rhizobial strains. Isolate Ca-18 showed the least homology of 15% and 18% with Rhizobium and Bradyrhizobium, respectively, and was probably not a (Brady)rhizobium strain. Partial 16S rRNA gene sequence analysis for MN-S, TAL-102 and Ca-18 strains showed 97% homology between MN-S and TAL-102 strains, supporting the view that they were strains of B. japonicum species. The non-infective isolate Ca-18 was 67% different from the other two strains and probably was an Agrobacterium strain.     

<Emphasis Type="Italic">Ziziphus </Emphasis><Emphasis Type="Italic">spina-christi</Emphasis> (L.) Willd.: a multipurpose fruit tree

Neglected and underutilized species often play a vital role in securing food and livestock feed, income generation and energy needs of rural populations. In spite of their great potential little attention has been given to these species. This increases the possibility of genetic erosion which would further restrict the survival strategies of people in rural areas. Ziziphus spina-christi is a plant species that has edible fruits and a number of other beneficial applications that include the use of leaves as fodder, branches for fencing, wood as fuel, for construction and furniture making, and the utilization of different parts e.g. Fruits, leaves, roots and bark in folk medicine. Moreover, the plant is adapted to dry and hot climates which make it suitable for cultivation in an environment characterized by increasing degradation of land and water resources. Lack of research in Z. spina-christi hinders its successful improvement and promotion. Therefore, studies are needed to fully exploit this species. This article aims at summarizing information on different aspects of Z. spina-christi to stimulate interest in this crop which is of importance in Sudan and other countries of the semi-arid tropics.

Genetic diversity of landraces of wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) from hilly areas of Uttaranchal,India

Seed samples of 27 landraces of wheat were collected from farmers’ fields of hilly areas of Himalaya in Uttaranchal state of India during April 2004. Genetic diversity among 41 genotypes (cultivars and landraces of wheat) was studied using morphological traits, microsatellite markers and SDS-PAGE of HMW-GS. The dendrogram and PCA (Principal Component Analysis) based on morphological data clearly separated landraces of wheat from cultivars. In the dendrogram based on microsatellite markers data all the wheat cultivars released after the introduction of high yielding dwarf wheat varieties from CIMMYT, used in this study, were grouped separately with the exception of NP4. The pre-green revolution indigenous varieties grouped with landraces suggesting that the same had been probably developed through selection among landraces in India. The landraces had higher diversity for HMW-glutenin subunits coded by Glu-B1, with distinct subunit combinations 6 + 8, 7 + 9, 13 + 16, than within the wheat cultivars analyzed. Most of the landraces except IITR10 and IITR14 are clearly distinct from the indigenous and modern wheat cultivars released in India in the 20th century. More than half of the landraces were heterogeneous mixture of plants with different glume color, awnness, grain color and HMW-GS profile and hence need purification through single plant selection. Some of the landraces with resistance to yellow rust and powdery mildew and distinct HMW-GS subunits can be used in appropriate breeding programs. It will be desirable to conserve and protect the landraces as geographical indications of Uttaranchal.     

Salt tolerance in <Emphasis Type="Italic">Zea mays</Emphasis> (L). following inoculation with <Emphasis Type="Italic">Rhizobium</Emphasis> and <Emphasis Type="Italic">Pseudomonas</Emphasis>

This study aimed to investigate the effect of inoculation with plant growth-promoting Rhizobium and Pseudomonas species on NaCl-affected maize. Two cultivars of maize (cv. Agaiti 2002 and cv. Av 4001) selected on the basis of their yield potential were grown in pots outdoors under natural conditions during July. Microorganisms were applied at seedling stage and salt stress was induced 21 days after sowing and maintained up to 50% flowering after 120 days of stress. The salt treatment caused a detrimental effect on growth and development of plants. Co-inoculation resulted in some positive adaptative responses of maize plants under salinity. The salt tolerance from inoculation was generally mediated by decreases in electrolyte leakage and in osmotic potential, an increase in osmoregulant (proline) production, maintenance of relative water content of leaves, and selective uptake of K ions. Generally, the microbial strain acted synergistically. However, under unstressed conditions, Rhizobium was more effective than Pseudomonas but under salt stress the favorable effect was observed even if some exceptions were also observed. The maize cv. Agaiti 2002 appeared to be more responsive to inoculation and was relatively less tolerant to salt compared to that of cv. Av 4001.     

A haplotype specific to North European wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

A previous study indicated decreased DNA content of chromosome 4A in the wheat (Triticum aestivum L. cv. Tähti) compared to cvs. Chinese Spring and Rennan. Here we show that the lower 4A DNA content is associated with a specific haplotype in the distal part of 4AL. In 41 cultivars of bread wheat (T. aestivum L.), including cv. Tähti, a common haplotype was identified in the linkage disequilibrium region on the long arm of chromosome 4A (4AL). The haplotype (haplotype A) is characterized by 7 SSR and 5 EST marker alleles, including five zero-alleles. Haplotype A was found in 46 % of the Swedish/Finnish/Estonian spring wheat genotypes, while only one of the modern wheat accessions from Germany carried the same haplotype. Fluorescent cytometry analysis linked haplotype A to diminished DNA content of chromosome 4A. The haplotype was introduced into the Canadian and US breeding programs at the beginning of the twentieth century (cvs. Marquis, Thatcher, Ruby) from the common progenitor, the Polish landrace Fife, and it is still found in modern wheat germplasm in these countries. Zero-alleles characteristic for haplotype A were also detected in several accessions of European spelt (Triticum spelta L.), and in two accessions of tetraploid Triticum timopheevii Zhuk. The presence of haplotype A in European spelt indicates the considerable antiquity of the haplotype, as it must have been inherited from the hexaploid or tetraploid parent of spelt in at least one hybridization event.     

Comparison of the genetic diversity between <Emphasis Type="Italic">Triticum aestivum</Emphasis> ssp. <Emphasis Type="Italic">tibetanum</Emphasis> Shao and Tibetan wheat landraces (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) by using intron-splice junction primers

In order to evaluate and compare the germplasm resources of wheat in Tibet, we analyzed the genetic diversity of 136 Triticum aestivum ssp. tibetanum Shao and 119 Tibetan wheat landraces (Triticum aestivum L.) by using Intron-Splice Junction (ISJ) primers. The results showed that polymorphism of PCR products were obtained by 33 primer combinations, which accounted for 11% of the 300 primer combinations produced by 26 ISJ primers. A total of 333 stable bands can be amplified from the T. aestivum ssp. tibetanum Shao and 243 bands were polymorphic, which accounted for 72.9% of the total bands. Tibetan wheat Landraces produced 316 stable bands, of which 197 bands were polymorphic. The polymorphic bands accounted for 62.34% of the total bands produced from Tibetan wheat landraces. The genetic diversity of T. aestivum ssp. tibetanum Shao was higher than that of Tibetan wheat landraces in Tibet, suggesting that T. aestivum ssp. tibetanum Shao can be used as important genetic resource for the breeding and genetic improvement of wheat in Tibet. Matrix (1, 0) was generated according to the presence or absence of the bands produced from a particular wheat accession. Clustering and principle coordinates analysis showed that T. aestivum ssp. tibetanum Shao and Tibetan wheat landraces were divided into two groups. We conclude that high polymorphisms produced by ISJ primers can reflect the genetic diversity between T. aestivum ssp. tibetanum Shao and Tibetan wheat landraces.     

Joint toxicity of three plant protection products to <Emphasis Type="Italic">Triticum aestivum</Emphasis> (L.) and <Emphasis Type="Italic">Brassica rapa</Emphasis> (L.)

Purpose  

Few studies have been conducted to evaluate the effects of mixtures of chemicals in terrestrial environment. Thus, it seems important to evaluate if the combined application of pesticides currently used in agricultural fields may pose a risk to terrestrial plants.     

Mitigation of salt stress in wheat seedlings by a <Emphasis Type="Italic">gfp</Emphasis>-tagged <Emphasis Type="Italic">Azospirillum lipoferum</Emphasis>

Root colonization and mitigation of NaCl stress on wheat seedlings were studied by inoculating seeds with Azospirillum lipoferum JA4ngfp15 tagged with the green fluorescent protein gene (gfp). Colonization of wheat roots under 80 and 160 mM NaCl stress was similar to root colonization with this bacterial species under non-saline conditions, that is, single cells and small aggregates were mainly located in the root hair zone. These salt concentrations had significant inhibitory effects on development of seedlings, but not on growth in culture of gfp-A. lipoferum JA4ngfp15. Reduced plant growth (height and dry weight of leaves and roots) under continuous irrigation with 160 mM NaCl was ameliorated by bacterial inoculation with gfp-A. lipoferum JA4ngfp15. Inoculation of plants subjected to continuous irrigation with 80 mM NaCl or to a single application of either NaCl concentration (80 or 160 mM NaCl) did not mitigate salt stress. This study indicates that, under high NaCl concentration, inoculation with modified A. lipoferum reduced the deleterious effects of NaCl; colonization patterns on roots were unaffected and the genetic marker did not induce undesirable effects on the interaction between the bacterium and the plants.     

<Emphasis Type="Italic">Achromobacter insolitus</Emphasis> and <Emphasis Type="Italic">Zoogloea ramigera</Emphasis> associated with wheat plants (<Emphasis Type="Italic">Triticum aestivum</Emphasis>)

This study reports for the first time the presence of diazotrophic bacteria belonging to the genera Achromobacter and Zoogloea associated with wheat plants. These bacterial strains were identified by the analysis of 16S rDNA sequences. The bacterium IAC-AT-8 was identified as Azospirillum brasiliense, whereas isolates IAC-HT-11 and IAC-HT-12 were identified as Achromobacter insolitus and Zoogloea ramigera, respectively. A greenhouse experiment involving a non-sterilized soil was carried out with the aim to study the endophytic feature of these strains. After 40 days from inoculation, all the strains were in the inner of roots, but they were not detected in soil. In order to assess the location inside wheat plants, an experiment was conducted under axenic conditions. Fifteen days after inoculation, preparations of inoculated plants were observed by the scanning electron microscope, using the cryofracture technique, and by the transmission electron microscope. It was observed that all isolates were present on the external part of the roots and in the inner part at the elongation region, in cortex cells, but not in the endodermis or in the vascular bundle region. No colonizing bacterial cells were observed in wheat leaves.     

Phosphate solubilization by <Emphasis Type="Italic">Penicillium</Emphasis> spp. closely associated with wheat roots

In this study we found that Penicillium spp. exhibiting P-solubilizing activity are common both on and in the roots of wheat plants grown in southern Australian agricultural soils. From 2,500 segments of washed and surface-disinfested root pieces, 608 and 223 fungi were isolated on a selective medium, respectively. All isolates were screened for P solubilization on solid medium containing hydroxyapatite (HA); 47 isolates (5.7%) solubilized HA and were identified as isolates of Penicillium or its teleomorphs. These isolates were evaluated for solubilization of Idaho rock phosphate (RP) in liquid culture. Penicillium bilaiae strain RS7B-SD1 was the most effective, mobilizing 101.7 mg P l^–1 after 7 days. Other effective isolates included Penicillium simplicissimum (58.8 mg P l^–1), five strains of Penicillium griseofulvum (56.1–47.6 mg P l^–1), Talaromyces flavus (48.6 mg P l^–1) and two unidentified Penicillium spp. (50.7 and 50 mg P l^–1). A newly isolated strain of Penicillium radicum (KC1-SD1) mobilized 43.3 mg P l^–1. RP solubilization, biomass production and solution pH for P. bilaiae RS7B-SD1, P. radicum FRR4718 or Penicillium sp. 1 KC6-W2 was determined over time. P. bilaiae RS7B-SD1 solubilized the greatest amount of RP (112.7 mg P l^–1) and had the highest RP-solubilizing activity per unit of biomass produced (up to 603.2 g P l^–1 mg biomass^–1 at 7 days growth). This study has identified new isolates of Penicillium fungi with high mineral phosphate solubilizing activity. These fungi are being investigated for the ability to increase crop production on strong P-retaining soils in Australia.