Lysenko Affair and Polish Botany

This article describes the slight impact of Lysenkoism upon Polish botany. I begin with an account of the development of plant genetics in Poland, as well as the attitude of scientists and the Polish intelligentsia toward Marxist philosophy prior to the World War II. Next I provide a short history of the introduction and demise of Lysenkoism in Polish science, with a focus on events in botany, in context with key events in Polish science from 1939 to 1958. The article outlines the little effects of Lysenkoism upon botanists and their research, as well as how botanists for the most part rejected what was often termed the “new biology.” My paper shows that though Lysenko’s theories received political support, and were actively promoted by a small circle of scientists and Communist party activists, they were never accepted by most botanists. Once the political climate in Poland altered after the events of 1956, Lysenko’s theories were immediately abandoned.     

Occurrence of Polysiphonia Epiphytes in Kappaphycus Farms at Calaguas Is., Camarines Norte, Phillippines

This paper describes the occurrence of an epiphyte infestation of Kappaphycus farms in Calaguas Is. Camarines Norte, Philippines. In particular, percentage cover of ‘goose bump’-Polysiphonia and ‘ice-ice’ disease, and some environmental parameters that influence the thallus condition of Kappaphycus alvarezii in Calaguas Is. were assessed during 3 separate visits and are discussed.Commercial cultivation of Kappaphycus at Calaguas Is. began in the early 1990s. After five years of farming, the stock was destroyed by a strong typhoon. The area was re-planted the following year and production increased annually and reached its peak in 1998–1999. However, the following year, the first occurrence of a Polysiphonia epiphyte infestation occurred concurrently with an ‘ice-ice’ disease. Consequently, annual production and the number of seaweed planters declined rapidly, and this situation persists to the present time. This paper highlights the etiological factors and their consequences.Results show that farm-site selection is critical for the success of Kappaphycus production. Characteristics of water movement and light intensity in farming areas contributed to the occurrence and detrimental effect of the phenomenon described as ‘goose bumps’: a morphological distortion of the host seaweed due to the presence of a Polysiphonia sp. epiphyte. A strong inverse correlation was observed between the occurrence of Polysiphonia and water movement: areas with low water motion registered a higher % cover (65%) of Polysiphonia than those in more exposed areas (17%). Although ‘goose bump’-Polysiphonia infestation and ‘ice-ice’ disease pose a tremendous problem to the seaweed farmers, the results of this limited assessment provide a useful baseline for future work.     

Effects of NaCl stress on germination, antioxidant responses, and proline content in two rice cultivars

We investigated the physiological and biochemical bases for salt tolerance in two rice (Oryza sativa L.) cultivars — relatively salt-tolerant ‘Dongjin’ and salt-sensitive ‘Kumnam’. Salinized hydroponic cultures were studied at the germination and seedling stages. NaCI inhibited germination more severely in ‘Kumnam’ than in ‘Dongjin’. Increasing the salt concentration also deterred growth to a larger extent in the former. Moreover, the leaves of ‘Kumnam’ exhibited greater increases in lipid peroxidation and Na⁺ accumulation than those of ‘Dongjin’ under stress. The activities of constitutive and salt-induced superoxide dismutase (SOD, EC 1.15.1.1) and ascorbate peroxidase (AP, EC 1.11.1.11) were also higher in ‘Kumnam’, while only catalase (CAT, EC 1.11.1.6) activity was slightly higher in stressed plants of ‘Dongjin’. The positive correlation between leaf proline levels and NaCI concentration was more evident in ‘Kumnam’. However, ‘Dongjin’ seeds, which had higher germinability in the presence of NaCI, also contained more proline. These results suggest that the higher salt tolerance in ‘Dongjin’ seedlings could be ascribed to their lower NaCI accumulations in the leaves. This presumably is due to reductions in the uptake or transport rates of saline ions to the shoots from the roots. Finally, we believe that the higher germination rate by ‘Dongjin’ is caused by its higher seed proline content.     

Bacteria of muds colonized bySpartina townsendii and their possible role in Spartina die-back

Summary A study of the bacterial microflora of muds colonized bySpartina townsendii agg. in healthy and ‘die-back’ sites in the Lymington estuary was made. No important qualitative differences were found between the microfloras of the two types of site. Fewer species, however, were present in the die-back sites. It is suggested that under anaerobic conditions, such as occur in a ‘die-back’ site, the bacteria will utilise such oxygen as is present, and will then engage in anaerobic metabolic processes, producing reduced ions which will reduce the oxidation-reduction potential still further. The occurrence of abundant sulphate reducers in the ‘die-back’ sites may be particularly significant in this respect. No evidence was obtained of any more direct relationship between bacterial flora and the development of ‘die-back’.     

Small plot mating disruption trials for tufted apple bud moth,Platynota idaeusalis, in Pennsylvania apple orchards

Mating disruption treatments for the tufted apple bud moth (TABM),Platynota idaeusalis (Walker), were tested in small plot trials in apple orchards in Pennsylvania. Treatments were evaluated by fruit injury and by capture of male TABM in traps baited with synthetic pheromone sources or virgin females. The TABM pheromone is a two component isomeric blend ofE-11-tetradecen-1-ol (E11-14:OH) andE-11-tetradecenyl acetate (E11-14:Ac). A 50∶50 ratio of these two components was used in standard monitoring septa and in mating disruption treatments released from either hollow fibers (‘fiber’) or PVC tubes (‘PVC’). Other pheromone blends tested included a 90∶10 ratio of E11-14: Ac and E11-14:OH (‘EAc’) and its reverse (‘EOH’), mixture ‘EAc’ with 30% of the Z-isomers (‘low AEc’), and a blend similar to the preceding with 2% Z9-12:Ac (‘generic’). These other blends were released from multi tube tape (‘tape’) or Shin-Etsu type rope (‘rope’) dispensers. Seasonal dispenser release rate in mg ha⁻¹ h⁻¹ was ca. 30 for the ‘rope’ dispensers, 14 for ‘PVC’ and 6 for ‘fiber’. ‘EAc-tape’ and ‘EOH-tape’ were equally effective in reducing catches of males in traps baited with synthetic lures and in traps baited with virgin females. Both treatments also reduced fruit injury. ‘EAc-rope’, ‘fiber’ and ‘PVC’ also were generally effective; whereas, the ‘low EAc’ and ‘generic’ treatments reduced trap capture less than 90% and did not reduce fruit injury. Dispenser density was positively correlated with reduction in trap capture for the ‘low EAc-rope’ and ‘genericrope’ treatments. Traps loaded with ‘fiber’ dispensers captured more male TABM than the other treatments in non-pheromone permeated environments. Trap capture of other tortricids was reduced in pheromone treatments. ‘EAc-rope’ and the ‘TABM’ treatments provided mean (s.e.) percent reduction in trap catch of 99.5 (0.4) and 42.9 (10.1), respectively, for the redbanded leafroller,Argyrotaenia velutinana (Walker), and 90.4 (6.8) and 90.4 (1.3), respectively, for the obliquebanded leafroller,Choristoneura rosaceana (Harris).     

Genetic control theory of developmental events

An earlier theory of cell differentiation and morphogenesis (Wassermann, 1972, 1973, 1978) is combined with the genetic control model of Davidson and Britten (e.g. 1979). The resulting new theory suggests how, bysystematic process algorithms, specifically enumerated combinations of batteries of structural genes can become switched on in particularly enumerated cells, via battery-specific enumerable regulator genes. The systematization is idealized. Up to a certain stage of development in each mitotically arising cell a unique cell-specific combination of structural genes called ‘marker genes’ is active. Marker genes are assumed to code for cell-specifying marker proteins (CSMPs) which permit cells carrying related markers to recognize each other, thus permitting specific cell sorting.Batteries of marker genes could ensure great developmental precision and can safeguard—via redundancies of CSMP types—against accidental loss or detrimental mutational modification of CSMPs or marker genes, respectively. This paper is much concerned with cell lineage in relation to ‘microdifferentiation’, where ‘microdifferentiation’ of a cell refers to a cell's active marker genes and its syntheses of CSMPs. A drastic distinction is made between ‘microdifferentiation’ and ‘gross’ differentiation of a cell, where the same ‘gross’ differentiation may be shared by a large number of cells that could each be uniquely ‘microdifferentiated’. Typical ‘gross’ differentiation could manifest itself in tissue specificity, whereas, up to certain stages of development, all cells of the same gross differentiation type (say tissue specificity) could each be uniquely ‘microdifferentiated’. The theory also assumes that at certain stages of the developmental process some (or in some organisms all) of the previously uniquely specified cells could give rise to small (or occasionally large) clones of equispecified cells, some of which might form clusters that represent complete ‘morphogenetic fields’ Tentative implementation mechanisms are proposed which suggest how the theory could operate in molecular biological terms. In particular, CSMPs could endow cell surface membranes with a highly specific protein network, and an associated equally specific cell surface coat. It is suggested how these highly specified cell surface coats and other systems could provide an ‘extracellular guidance network’ which could help to direct cells to attain energetically optimal locations relative to each other based on the matching of their surface specificities. In numerous experimental situations, where normally present optimal matching of cells is excluded, ‘alternative matching’ based on experiment-specific suboptimal matching could explain many data, notably in experimental development neurobiology (Wassermann, 1978).     

Modification of competence for in vitro response to Fusarium oxysporum in tomato cells. III. PR-protein gene expression and ethylene evolution in tomato cell lines transgenic for phytohormone-related bacterial genes

 Previous work carried out in our laboratory has shown that, in tomato, the alteration of endogenous phytohormone equilibria through the integration of Agrobacterium tumefaciens genes for auxin and cytokinin synthesis can modify the active defense response to Fusarium oxysporum f. sp. lycopersici. The susceptible cv ‘Red River’ acquires a stable competence for active defense, particularly when the phytohormone equilibrium is altered in favour of cytokinins. Here, we analyse the expression of genes involved in the defense response against pathogens, i.e. pathogenesis-related (PR)-protein genes, in the susceptible ‘Red River’ and resistant ‘Davis’ cultivars transgenic for the aforementioned genes. Fungal cell-wall components, glutathione, salicylic acid and the ethylene-forming ethephon are used as “probes” for the induction of defense processes, including ethylene production. The data obtained show that the extracellular PR-proteins (acidic chitinase and PR-1 protein) that were inducible in the control tissue of the resistant ‘Davis’ cultivar and not expressed in the susceptible ‘Red River’ cultivar became constitutive in the transgenic tissues of both. On the other hand, expression of the intracellular PR-proteins (basic chitinase and β-1,3-glucanase) was found to be constitutive in all cases, both in the control and in the transgenic cell lines of the resistant and the susceptible tomato cultivars. Ethylene production was higher in ‘Davis’ than in ‘Red River’, and significantly increased in the transgenic cell lines, particularly when cytokinin synthesis was altered. Received: 25 February 1998 / Accepted: 7 April 1998     

Localization of the rice stripe disease resistance gene, Stv-bi, by graphical genotyping and linkage analyses with molecular markers

 We used graphical genotyping and linkage analyses with molecular markers to determine the chromosomal location of the rice stripe disease resistance gene, Stv-b ⁱ . The stripe resistance gene from the indica rice (Oryza sativa) cv ‘Modan’ was introgressed into several Japanese rice varieties. We found 4 RFLP markers in ‘Modan’, five susceptible parental rice varieties (‘Norin No. 8’, ‘Sachihikari’, ‘Kanto No. 98’, ‘Hokuriku No.103’ and ‘Koganebare’) and four resistant progeny varieties (‘St. No. 1’, ‘Aichi No. 6’, ‘Aoisora’ and ‘Asanohikari’). Graphical genotyping of the resistant progeny revealed a chromosomal segment ascribable to ‘Modan’ and associated with stripe resistance. The chromosomal segment from ‘Modan’ was located at 35.85 cM on chromosome 11. Linkage analysis using 120 F₂ individuals from a cross between ‘Koshihikari’ (susceptible) and ‘Asanohikari’ (resistant) revealed another 8 RFLP markers in the same chromosome. We performed a bioassay for rice stripe resistance in F₃ lines of the F₂ individuals using infective small brown planthoppers and identified an 1.8-cM segment harboring the rice stripe disease resistance gene, Stv-b ⁱ , between XNpb220 and XNpb257/ XNpb254. Furthermore, Stv-b ⁱ was linked by 0.0 cM to a RFLP marker, ST10, which was developed on the basis of the results of RAPD analysis. These DNA markers near the Stv-b ⁱ locus may be useful in marker-assisted selection and map-based cloning of the Stv-b ⁱ gene. Received: 26 September 1997 / Accepted: 4 November 1997     

Osmoregulation and osmoprotection in the leaf cells of two olive cultivars subjected to severe water deficit

In this study, we compared the efficacy of defense mechanisms against severe water deficit in the leaves of two olive (Olea europaea L.) cultivars, ‘Chemlali’ and ‘Meski’, reputed drought resistant and drought sensitive, respectively. Two-year old plants growing in sand filled 10-dm³ pots were not watered for 2 months. Changes in chlorophyll fluorescence parameters and malondialdehyde content as leaf relative water content (RWC) decreased showed that ‘Chemlali’ was able to maintain functional and structural cell integrity longer than ‘Meski’. Mannitol started to accumulate later in the leaves of ‘Chemlali’ but reached higher levels than in the leaves of ‘Meski’. The latter accumulated several soluble sugars at lower dehydration. ‘Chemlali’ leaves also accumulated larger quantities of phenolic compounds which can improve its antioxidant response. Furthermore, the activity of three antioxidant enzymes catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX) increased as leaf RWC decreased. However, differences were observed between the two cultivars for CAT and POD but not for APX. The activity of the first two enzymes increased earlier in ‘Meski’, but reached higher levels in ‘Chemlali’. At low leaf hydration levels, ‘Chemlali’ leaves accumulated mannitol and phenolic compounds and had increased CAT and POD activities. These observations suggest that ‘Chemlali’ was more capable of maintaining its leaf cell integrity under severe water stress because of more efficient osmoprotection and antioxidation mechanisms.     

Stieltjes integration and differential geometry: A model for enzyme recognition,discrimination, and catalysis

A model for enzymic catalysis is presented using the mathematical theories of differential geometry and Stieltjes integration. The Stieltjesintegrator is a complex-valued function of bounded variation which represents the curvature and torsion, hence the conformation, of the backbone of an enzyme molecule. Theintegrand is a complex-valued continuous function which describes the shape of the surface of a substrate molecule. We postulate that enzyme-substrate interactions correspond to evaluations of Stieltjes integrals, and that observables of enzymic catalysis correspond to projections. Results from the mathematical theory of the Stieltjes integral are discussed together with their biological interpretations. We contrast the difference between structural and functional proteins, and construct analogues of enzyme cofactors, modifications, and regulation. Various techniques of locating the active site on enzymes are also given. We construct a total variation metric, which is particularly useful for detecting similarities among proteins. An examination on the many different modes of convergence of mathematical functions representing biological molecules leads to a mathematical statement of the fundamental dogma of molecular biology, that ‘structure implies function’. Similar arguments also result in the converse statement ‘function dictates structure’, which is a basic premise of relational biology. Stepped-helical approximations of the backbone space curves of enzymes provide a concrete computational tool with which to calculate the Stieltjes integrals that model enzymic catalysis, by replacing the integral with a finite series. The duality between enzymes and substrates (that they aremeters ‘observing’ one another) is shown to be a consequence of the mathematical duality of Banach spaces. The Stieltjes integrals of enzyme-substrate interactions are hence shown to be bounded bilinear functionals. The mechanism of enzymic catalysis, the transformation from substrate to product, is also formulated in the Stieltjes integration context via the mathematical theory of adjoints. The paper closes with suggestions for generalizations, prospects for future studies, and a review of the correspondence between mathematical and biological concepts.     

‘Chillum’ jar,a better technique for screening of rhizobia under summer conditions

Summary In the present investigations ‘Chillum’ jar assembly was found to provide more favourable environmental conditions for rhizobia to nodulate leguminous plants particularly under summer conditions than the usual Leonard jar assembly. When thirty pigeon pea rhizobia isolates were tested for their nodulation efficiency in both Leonard jars as well as ‘Chillum’ jars, it was noticed that there was no nodulation in any of the isolates under Leonard jars whereas all isolates were nodulating well under ‘Chillum’ jars conditions. This was probably due to lowering of temperature in ‘Chillum’ jar caused by rapid evaporation from the outer surface of ‘Chillum’ jar assembly. The maximum temperature recorded in ‘Chillum’ jar was 34°C whereas in Leonard jars it was 46.5°C.     

In vitro assay of native Iranian almond species (<Emphasis Type="Italic">Prunus</Emphasis> L. spp.) for drought tolerance

Eight native Iranian almond species from three sections, ‘Euamygdalus’ (Prunus communis; Prunus eleagnifolia and Prunus orientalis); ‘Lycioides’ (Prunus lycioides and Prunus reuteri) and ‘Spartioides’ (Prunus arabica, Prunus glauca and Prunus scoparia) were in vitro screened for drought tolerance using sorbitol and polyethylene glycol (PEG) as an osmoticum. Different levels of water stress were induced using five concentrations of either sorbitol or polyethylene glycol in Woody Plant Medium (WPM). Water potential of various media ranged from −0.80 to −2.05 MPa and water stress in culture medium adversely affected plantlet growth. Wild species from ‘Spartioides’ were less affected than ‘Lycioides’ and ‘Euamygdalus’. At the same level of water potential, sorbitol had lower adverse effects than PEG; the latter being severe. Prunus × sorbitol and Prunus × PEG interactions were significant. At 0.2 M sorbitol and 0.003 M PEG, ‘Spartioides’ produced significantly more roots with higher total root length and root volume, as well as root-dry weight than those of ‘Lycioides’ and ‘Euamygdalus.’ It is concluded that in vitro screening of native Iranian almond species under specific and limited water-stress conditions may provide a system for effectively differentiating the wild species of almond for their expected root mass production under field conditions.     

Impact of sulfur on density of <Emphasis Type="Italic">Tetranychus pacificus</Emphasis> (Acari: Tetranychidae) and <Emphasis Type="Italic">Galendromus occidentalis</Emphasis> (Acari: Phytoseiidae) in a central California vineyard

Sulfur is the oldest and most widely used fungicide in the vineyards of California, where it is used for control of powdery mildew (Uncinula necator [Schw.] Burr). For decades, sulfur use has been associated with outbreaks of Tetranychus pacificus McGregor (Acari: Tetranychidae) on cultivated grapes in the San Joaquin Valley. I undertook large-scale field studies to test this association, to evaluate the impact of sulfur on Galendromus occidentalis (Nesbit) (Acari: Phytoseiidae), a major predator of T. pacificus, and to determine if timing of sulfur applications with respect to grape bloom has an impact on T. pacificus density. The studies took place in a 32 ha vineyard in Fresno County, and all fungicide applications were made with commercial-scale equipment. In 1998 a ‘high sulfur’ treatment, a combination of wettable sulfur and sulfur dust, was compared to ‘low sulfur,’ in which demethylation inhibitor (DMI) fungicides partially substituted for sulfur. In 1999 treatments were ‘sulfur,’ ‘DMI,’ ‘sulfur pre-bloom’ (here sulfur was applied prior to grape bloom, in late May, and then DMIs were applied until mid-season) and ‘sulfur post-bloom’ (the reverse of ‘sulfur pre-bloom’). In each year, the T. pacificus population increase came after the end of fungicide applications, and results clearly show a relationship between sulfur use and T. pacificus density. In 1998, mean T. pacificus density was 2.7 times higher and mean G. occidentalis density 2.5 times higher in ‘high sulfur’ compared to ‘low sulfur.’ In 1999, the highest T. pacificus counts were in the ‘sulfur’ and ‘sulfur pre-bloom’ treatments, 4.8 times higher than ‘sulfur post-bloom’ and 2 times higher than ‘DMIs.’ Density of G. occidentalis was 2.3 times as high in ‘sulfur’ or ‘sulfur pre-bloom’ than ‘DMIs.’ The predator/prey ratio was not significantly different among treatments in 1998, but in 1999 it was highest in the ‘sulfur pre-bloom’ treatment. In 1999, density of Homeopronematus anconai (Baker) (Acari: Tydeidae) was 2.7 times higher in ‘sulfur pre-bloom’ compared to ‘sulfur,’ and higher by 2.7 times in ‘DMI’ compared to ‘sulfur post-bloom,’ suggesting a negative effect of sulfur on this tydeid. These results do not support the hypotheses that the cause of the increase in T. pacificus density is due to negative effects of sulfur on phytoseiids or tydeids. Rather, it appears that a plant-based explanation is likely, first, because of the differences in pre-bloom versus post-bloom sulfuring, and second, because of the long lag time between the end of the sulfur applications and the corresponding increase in spider mite density.     

Oud-leerling versus ancien élève: A Comparative Study of Adjectives Grammaticalizing into Prefixes in Dutch and French

This article analyzes the grammaticalization of adjectives into prefixes in Dutch and French. In the first part, the notion of ‘affixoids’, hybrid elements that combine properties of free lexemes and bound morphemes, will be defined and illustrated. It will be claimed that affixoids can be seen as a result of a grammaticalization process for which we will advance phonological, morphological, semantic and distributional parameters applying to the evolution of adjectives into prefixes. The second part will be devoted to a specific case study in which these grammaticalization parameters will be applied to the Dutch adjectives oud ‘old’ and nieuw ‘new’ and their French counterparts ancien ‘old’ and nouveau ‘new’ when used in word-formation. More particularly, we will examine whether these adjectives may develop prefix-like properties when embedded in a compound structure and determine their degree of grammaticalization. Kristel Van Goethem is a Postdoctoral fellow of the Research Foundation-Flanders (FWO)     

Hybrid origin of some ornamentals of Allium subgenus Melanocrommyum verified with GISH and RAPD

 Random amplified polymorphic DNA (RAPD) and genomic in situ hybridization (GISH) methods have been used to verify the hybridogenic origin and to identify the parental species of some ornamental cultivars in the subgenus Melanocrommyum of the genus Allium. The cultivars had been selected from seed obtained after uncontrolled pollination in breeders’ fields. The combination of GISH analysis with RAPD markers is very suitable for testing the hybridogenic origin of plants and to ascertain the parental species of the hybrids in such cases. As suspected, A. macleanii and A. cristophii are the parental species of ‘Globemaster’. The parental species of cultivar ‘Globus’ are A. karataviense and A. stipitatum, and not A. cristophii and A. giganteum as has been assumed on morphological grounds. Cultivars ‘Lucy Ball’ and ‘Gladiator’ are of hybrid origin, though only one of the parental species, A. hollandicum, could be confirmed. The cultivars ‘Purple Sensation’, ‘Mount Everest’, ‘White Giant’, ‘Michael H. Hoog’ and ‘Mars’ are not hybrids since neither GISH nor RAPD suggest the presence of a second genome. ‘Purple Sensation’ belongs to A. hollandicum, ‘Mount Everest’, ‘White Giant’ and ‘Mars’ to A. stipitatum,‘Michael H. Hoog’ to A. rosenorum. Received: 3 July 1997 / Accepted: 9 October 1997     

Subtle ‘boom and bust’ response of <Emphasis Type="Italic">Macquaria ambigua</Emphasis> to flooding in an Australian dryland river

The ecology of dryland rivers is driven by their highly variable hydrology, particularly flooding regimes, whereby intermittent floods typically generate ‘booms’ of primary and secondary productivity, including massive fish production. We tested these concepts in the Moonie River, Australia, using the percichthyid, Macquaria ambigua, a dryland river species known to display pronounced ‘boom and bust’ abundance patterns in response to floodplain inundation followed by extended periods of low to no channel flow. We expected that body condition (as measured by whole body lipid content) and biomass of M. ambigua would be related to prey biomass, and that these factors would all ‘spike’ following widespread flooding. Instead we found more subtle responses. There were ‘booms’ in biomass of Macrobrachium and zooplankton, two important food items, whereas M. ambigua maintained relatively low but sustained lipid and biomass levels following flooding. It appears that instead of a ‘boom’ in fish biomass, abundant invertebrate food resources and sustained lipid levels contributed to high survivorship of this species during the ‘bust’ period over cool dry months.     

Response of durum wheat cultivars to immature embryo culture,callus induction and in vitro salt stress

Response of twenty eight cultivars of durum wheat (Triticum turgidum var. durum) to immature embryo culture, callus production and in vitro salt tolerance was evaluated. For assessment of cultivars to salt tolerance, growing morphogenic calli were exposed to different concentrations of NaCl (0, 0.3, 0.6, 0.9, 1.2, 1.5, 1.8 and 2.1% w/v) added to the culture medium during two subsequent subcultures (4 weeks each). Comparison of cultivars for callus induction from immature embryo was based on callus induction frequency and fresh weight growth of callus (FWG). While, for salt tolerance, the relative fresh weight growth (RFWG) and necrosis percent of callus were used. There were significant differences among cultivars for potential of regeneration from immature embryo, and ‘Shahivandi’ a native durum wheat cultivar originating from western Iran was superior among the cultivars tested. The FWG distinguished cultivars more than callus induction frequency did for callus induction evaluation. Hence, a range of FWG from 1.23 to 14.65 g was observed in ‘Mexical-75’ and ‘Omrabi-5’ cultivars, respectively. Growing calli derived from cultivars ‘PI 40100’ and ‘Dipper-6’ showed superiority for tolerating salinity under in vitro conditions. This revised version was published online in June 2006 with corrections to the Cover Date.     

Contributions of apoplasmic cadmium accumulation,antioxidative enzymes and induction of phytochelatins in cadmium tolerance of the cadmium-accumulating cultivar of black oat (<Emphasis Type="Italic">Avena strigosa</Emphasis> Schreb.)

The contributions of cadmium (Cd) accumulation in cell walls, antioxidative enzymes and induction of phytochelatins (PCs) to Cd tolerance were investigated in two distinctive genotypes of black oat (Avena strigosa Schreb.). One cultivar of black oat ‘New oat’ accumulated Cd in the leaves at the highest concentration compared to another black oat cultivar ‘Soil saver’ and other major graminaceous crops. The shoot:root Cd ratio also demonstrated that ‘New oat’ was the high Cd-accumulating cultivar, whereas ‘Soil saver’ was the low Cd-accumulating cultivar. Varied levels of Cd exposure demonstrated the strong Cd tolerance of ‘New oat’. By contrast, low Cd-accumulating cultivar ‘Soil saver’ suffered Cd toxicity such as growth defects and increased lipid peroxidation, even though it accumulated less Cd in shoots than ‘New oat’. Higher activities of ascorbate peroxidase (EC 1.11.1.11) and superoxide dismutase (EC 1. 15. 1. 1) were observed in the leaves of ‘New oat’ than in ‘Soil saver’. No advantage of ‘New oat’ in PCs induction was observed in comparison to Cd-sensitive cultivar ‘Soil saver’, although Cd exposure increased the concentration of total PCs in both cultivars. Higher and increased Cd accumulation in cell wall fraction was observed in shoots of ‘New oat’. On the other hand, in ‘Soil saver’, apoplasmic Cd accumulation showed saturation under higher Cd exposure. Overall, the present results suggest that cell wall Cd accumulation and antioxidative activities function in the tolerance against Cd stress possibly in combination with vacuolar Cd compartmentation.     

Induction of embryogenic mango cultures as affected by genotype,explanting, 2,4-D and embryogenic nurse culture

The nucellus was removed from immature seeds of 4 mango genotypes, andcultured under different induction conditions. The mango genotypes includedpolyembryonic ‘Hindi’ and ‘Nam Doc Mai’ and monoembryonic ‘Lippens’ and’Tommy Atkins‘. Nucellar explants were cultured on modified B5 basal mediumunder the following inductive conditions: 1) 4.52 μM 2,4-D; 2) nogrowth regulator (control); 3) 4.52 μM 2,4-D + embryogenic ‘Parris‘nurse culture; 4) no growth regulator + embryogenic ‘Parris’ nurse culture.Induction of embryogenic competence was mediated by 4 factors: genotype,explanting, 2,4-D and the presence of a highly embryogenic nurse culture,although there was considerable difference in genotype response. ‘Hindi’ hadthe greatest embryogenic potential, followed by ‘Lippens’, ‘Tommy Atkins‘and ‘Nam Doc Mai’, respectively. Induction of embryogenic cultures of allgenotypes at low frequency occurred as a result of explanting excisednucellus onto control medium. The most effective treatment for inducingembryogenic cultures was 2,4-D + embryogenic ‘Parris’ nurse culture with’Hindi’, ‘Lippens’ and ‘Nam doc Mai’, with the exception of ‘Tommy Atkins’,in which the treatment with 2,4-D alone was most effective. This revised version was published online in June 2006 with corrections to the Cover Date.     

The productivity of pine plantations in relation to previous land use

Summary Differences in the productivity of establishedP. radiata plantations on pasture and forest soils were found to be reproducible withP. radiata seedlings in a glasshouse environment. The growth of seedlings on pasture soil exceeded that of seedlings on native forest soil (the ‘primary pasture effect’). After a history of pine on both native and pasture soils a residual effect of pasture on seedling growth was evident (the ‘secondary pasture effect’). However, the effect of a history of pine plantation (the ‘pine effect’) was to decrease the productivity of both native and pasture soil as assessed by seedling growth. These effects were not related to changes due to land management in mycorrhizal infection or in soil structure. The analysis of seedling growth leads to the conclusion that soil fertility, particularly the availability of nitrogen and phosphorus, has changed.