The mobilization of copper in sheep by chelating agents.

D-penicillamine and 2,3-dimercapto-propane-l-sulphonate (DMPS) were administered orally and disodium-calcium-ethylene-diamine-tetraacetate (Ca-EDTA) subcutaneously into copper loaded sheep. The results showed that D-penicillamine has a copper mobilizing effect, while DMPS and Ca-EDTA do not seem to have this effect to any significant degree. Penicillamine, 52 mg/kg of body weight daily for 6 days, increased the urinary excretion of copper by a factor of 10 to 20. The same dosage (on weight basis) of DMPS increased the excretion of copper in urine by 2 fold. Following Ca-EDTA treatment no increase in urinary excretion of copper was observed. Penicillamine could be used in prophylactic treatment of copper toxicosis in sheep, but it is still too expensive for practical use.     

Evidence for common genetic mechanisms controlling the tolerance of sudden salt stress in the tribe Triticeae

Previous studies in several Triticeae species have suggested that salt tolerance is a polygenic trait, but that genes on some chromosomes confer better tolerance to salt stress than others. This suggests an intriguing possibility that there may be a similar basis for salt tolerance in the species of the tribe Triticeae. In this study, chromosomal control of the tolerance to sudden salt stress, measured as the mean rate of leaf elongation in solution cultures with a single increment of 200 mM NaCl, was investigated in the genomes of cultivated barley (Hordeum vulgare L.), rye (Secale cereale L.), and Dasypyrum villosum (L.) Can-dargy by using disomic addition lines of individual pairs of chromosomes or chromosome arms of each of the three species in the ‘Chinese Spring’ wheat genetic background. It was observed that the chromosomes of homoeologous groups 3, 4, and 5 in barley, 5 and 7 in rye, and 4 and 6 in D. villosum carry loci with significant positive effects on salt tolerance. Increased doses of chromosomes of group 2, however, reduce or do not increase the tolerance to salt stress. These results are in agreement with a previous study of the tolerance of this salt stress regime in wheat and wheatgrass Lophopyrum elongatum. A ranking analysis of the chromosomal effects within each genome of the five Triticeae species investigated in this and previous studies revealed that the chromosomes of homoeologous groups 3 and 5 consistently confer large positive effects on the tolerance of sudden salt stress, while the chromosomes of homoeologous group 2 in increased dose have no or negative effects on the tolerance. This strongly suggests that species of the tribe Triticeae share some common genetic mechanisms of tolerance of sudden salt stress. The findings in this study give credence to the proposal that wild relatives can be exploited in the development of wheat cultivars with greater tolerance to salt stress.     

Chemical induction of sterility in wheat

Euphytica - Foliar application of two spring wheat varieties, Anza and Yecora 70, with RH-531 several days before meiosis in a field experiment almost completely prevented seed development. A...     

Distribution of the cis-sabinene hydrate acetate-chemotype in accessions of marjoram (Origanum majorana L.)

The bicyclic monoterpenes cis-sabinene hydrate and cis-sabinene hydrate acetate are considered to be responsible for the special flavor of marjoram (Origanum majorana L.). Analysis of single plants of different marjoram accessions revealed the presence of a chemotype that divided the samples into two groups, with cis-sabinene hydrate acetate present either at high amounts of above 19% or at low amounts below 2%. Additionally, an arrow negative correlation of the concentration of cis-sabinene hydrate to its acetate was observed (R² = 0.92).Since no trans-sabinene hydrate acetate could be found in the analyzed samples, the formation of cis-sabinene hydrate acetate seems to be a result of a specific enzymatic conversion in marjoram. Among 20 accessions ofmarjoram studied, 17 were heterogeneous for the cis-sabinene hydrate acetate chemotype with frequencies of the low cis-sabinene hydrate acetate type between10% and 50%. If further sensorial studies can give leads as to which of the two compounds contributes to the preferred flavor, the variation observed in this study among natural populations could be used in breeding towards an optimized quality of marjoram. The analytical technique applied in this study can be used to screen high sample numbers with a reasonable effort and time. This revised version was published online in August 2006 with corrections to the Cover Date.     

Inheritance of resistance to sunflower downy mildew races 1, 2 and 3 in cultivated sunflower

Sunflower downy mildew (SDM) caused by Plasmopara halstedii, is a major disease of sunflower. Eleven resistance genes have been identified, but allelic relationships among these genes are not clear. This study examined the inheritance and allelic relationships of genes conferring resistance to SDM races 1, 2 and 3 (virulence phenotypes 100, 300 and 700, respectively) and confirmed a twelfth resistance gene. Three USDA Plant Introductions, AMES 3235, PI 497250, and PI 497938, and three released lines, RHA 266, RHA 274 and DM‐2 were studied. RHA 266 has only the Pl₁ gene for race 1 resistance. Digenic inheritance of resistance was found in AMES 3235, PI 497250, and RHA 274. These lines have the Pl₁ and Pl₁₂ genes, conferring resistance to race 1, and the Pl₂ and Pl₁₁ genes, conferring resistance to race 2. DM‐2 and PI 497938 have Pl₁₂ (but not Pl₁ for resistance to race 1, the Pl₁₂ gene (but not the Pl₂) for resistance to race 2, and Pl₅ for resistance to race 3. These resistance genes will serve as a foundation for future gene designations and genetic diversity studies of resistance to SDM.     

Life history studies of the leafminer Liriomyza trifolii on susceptible and resistant cultivars of Dendranthema grandiflora

Summary The feeding, fecundity, mortality and rate of development of Liriomyza trifolii (Burgess) on 12 cultivars of Dendranthema grandiflora (Tzvel.) (Syn. Chrysanthemum morifolium (Ramat.)) were determined in no choice experiments. Number of feeding punctures, number of eggs laid and total number of larvae varied between cultivars but these characters were not strongly associated with leafminer population increase. Good indicators of host plant resistance were larval mortality, number of pupae and duration of the larval period. Of these three, larval mortality which could be as high as 98% was most suitable.Based on life history data it was predicted that Liriomyza trifolii cannot survive on the resistant cultivar Penny Lane. This prediction was verified experimentally.     

Plant tissue culture of Secale: A review

Summary Plant tissue culture of rye employs different parts of plant bodies originating from various stages of rye ontogenesis. For the culture initiation mainly diploid and after that tetraploid forms were used, however, haploids and triploids were subject of investigation. The development of plant regeneration via somatic embryogenesis or organogenesis required the using of numerous basal media with various plant growth hormones. Haploidization appeared to be the most difficult problem and only interspecies hybridization helped to overcome this problem. Wide sexual intergenera and interspecies hybridization in cereals require the development of proembryo and immature embryo culture system. Using the nurse culture basing on immature endosperm resulted in getting fully formed rye plants. There is no progress in somatic cell genetic manipulation of rye because of lack of plant regeneration system in mesophyll green leaf and suspension protoplast cultures.Abbreviations 2, 4, 5, Cl₃POP... 2, 4, 5-Cl₃-phenoxypropionic acid, dicamba...-3, 6-dichloroasinic acid - GA₃... gibberellic acid - BA... benzyladenine - IBA... 3-indolebutric acid - IAA... indoleacetic acid - NAA... 1-naphtylacetic acid - 2, 4-D... 2, 4-dichlorophenoxyacetic acid - 2, 4, 5-T... 2, 4, 5-trichloroacetic acid - p-CPA... parachlorophenoxyacetic acid - CM... coconut milk - CW... deproteined coconut milk - Kin Kinetin     

Selection of Al-resistant plants from a sensitive rice cultivar, using somaclonal variation, in vitro and hydroponic cultures

A selection procedure is described that isolated Al-resistant individuals from a sensitive rice (Oryza sativa L.) genotype. Somaclonal variation was used as the only source of variability and selection pressures were applied at both callus and regenerated plant levels. When 10 week-old, embryo-derived calli were submitted to different Al stresses for a period of 20 weeks. After this in vitro stress period, selected calli were grown during 18 weeks, without selection pressure, on regeneration media. Selection pressures were applied on regenerated plants (R0), and 9 R0 plants which produced seeds were selected. The transmission of the Al-resistant character to the R1, R2, R3 and R4 generations was then investigated, and three plant lines which had an increased percentage of Al-resistant plants till the fourth generation of self-pollination, were identified. One was from a callus maintained on an Al-free medium. The efficiency of in vitro selection pressures was therefore debated. This revised version was published online in July 2006 with corrections to the Cover Date.