A simple and efficient cryopreservation of in vitro-grown shoot tips of `Troyer' citrange [Poncirus trifoliata (L.) Raf. × Citrus sinensis (L.) Osbeck.] by encapsulation-vitrification

Wheat of two strong high-protein and two weak low-protein cultivars from New Zealand and Australia were milled to commercial specifications. All millstreams were tested for α-amylase, β-amylase, falling number, protein, starch, damaged starch, amylose, amylopectin, pentosan and ash. The distribution of β-amylase in millstream flours was more variable among cultivars than α-amylase. Generally, both enzymes had lowest activity in sizing and early reduction flours. α-Amylase was very high in the bran, pollard and germ fractions, in which ash content was very high, whereas β-amylase was low in these fractions. These observations, together with the moderate correlation of α-amylase and poor correlation of β-amylase to ash content, suggest that most α-amylasein flour derives from contamination with bran, pollard and germ, whereas most β-amylase derives from the endosperm. Falling numbers varied between the cultivars, but variation amongst millstreams for each cultivar was low, except for cv. Frame, which had particularly high falling number values (834 and 1197) in second and third break flours. These two flours had some of the highest α-amylase levels and lowest starch levels. However, they also had very high protein content (22 and 26%) and very low starch damage (3.2 and 4.5%), which may contribute to the high falling numbers. When endogenous α-amylase in the flour with the highest falling number was supplemented with high levels of barleyα-amylase, the flour withstood the detrimental effects of α-amylasein baking (sticky crumb, poor crumb texture and loaf volume) better than flours of lower falling number, but did not withstand the effects ofα-amylase on falling number. This revised version was published online in August 2006 with corrections to the Cover Date.     

Evaluation of plant-based water status indicators in mature apple trees under field conditions

The performance of different indicators of plant water status as a tool for irrigation management was evaluated in mature field grown ‘Golden Delicious’ apple trees during the late summer of 1998. Control (C) and stress (S) treatments were studied. In the C treatment trees were irrigated daily at 100% ET_c whereas in the S treatment water was withheld during 31 days (DOY’s 236–266). Predawn water potential (Ψ_pd) and midday stem water potential (Ψ_stem) were measured several times a week during the experimental period. Three daily measurements of stomatal conductance (g_s) and stem water potential were made during five consecutive days in mid-September. Trunk diameter changes (TDC) were recorded by LVDT sensors, and from these measurements, maximum daily shrinkage (MDS), daily growth (DG), and cumulative growth (CG) were calculated. Midday Ψ_stem showed the best ratio between the response to moderate water stress and tree variability (“signal/noise” ratio) among the indicators studied here, followed closely by Ψ_pd. On the other hand, the poorest water status indicator was g_s. Due to the low trunk growth rate of the trees, and its high variability, DG and CG were not adequate indicators. MDS showed a lower sensitivity to water stress and a higher variability (CV = 0.19) than midday Ψ_stem (CV = 0.08) and Ψ_pd (CV = 0.10). However, MDS correlated well with ET₀ and with midday Ψ_stem (R ² = 0.79) thus, making this parameter an interesting and promising tool for irrigation management in apple orchards. More research needs to be done in order to define reference values for MDS and plant water potential indicators, in relation to evaporative conditions and in different phenological periods, and to quantify the relationship between water status indicators values and apple tree yield and fruit quality.     

Structural changes in plasma circulating fibrinogen after moderate beer consumption as determined by electrophoresis and spectroscopy

The effects of short-term moderate beer consumption (MBC) on plasma circulating fibrinogen (PCF) in patients suffering from coronary atherosclerosis were investigated by use of 2-dimensional electrophoresis (2-DE), circular dichroism (CD), and Fourier transform infrared spectroscopy (FT-IR). Forty-eight volunteers after coronary bypass surgery were divided into experimental (EG) and control (CG) groups, each of 24. Patients of the EG group consumed 330 mL of beer/day (about 20 g of alcohol) for 30 consecutive days, and CG volunteers drank mineral water instead of beer. Blood samples were collected before and after the experiment. In 21 out of 24 patients after beer consumption the plasma circulating fibrinogen was compromised: changes in its secondary structure were found. These changes were expressed in relatively low electrophoretic mobility and charge heterogeneity, decrease in alpha-helix and increase in beta-sheet, and in slight shift of amide I and II bands. Our findings indicate that one of the positive benefits of moderate beer consumption is to diminish the production of fibrinogen and its stability, which reduces the potential risk exerted by this protein. Thus, in most of beer-consuming patients some qualitative structural changes in plasma circulating fibrinogen were detected.     

Post infection application of DL-3-amino-butyric acid (BABA) induces multiple forms of resistance against <Emphasis Type="Italic">Bremia lactucae</Emphasis> in lettuce

DL-3-amino-butyric acid (BABA) induces local and systemic resistance against disease in numerous plant species. In a recent study we showed that preventive application of BABA to lettuce (Lactuca sativa) plants induced resistance against downy mildew caused by the oomycete Bremia lactucae by callose encasement of the primary infection structures of the pathogen. Now we show that post-infection application of BABA to the foliage or the roots, even at progressive stages of disease development, is highly protective against B. lactucae. Resistance induced by BABA is manifested in multiple microscopic forms, depending on the time of its application. When applied at 1 day post inoculation (dpi) BABA induced HR in penetrated epidermal cells; at 2 dpi it caused massive encasement with callose of the primary haustoria; and, at 3 or 4 dpi it enhanced the accumulation of H₂O₂ in the developing mycelia runners and altered their colour to red. The pronounced change in the colour of the mycelium was visually apparent to the naked eye. In all cases the pathogen failed to sporulate on the treated plants. This is the first indication that an immunizing compound may be protective at advanced stages of disease development.     

Effect of Cadmium and Iron on Rice (Oryza Sativa L.) Plant in Chelator-Buffered Nutrient Solution

ABSTRACT

To better understand the mechanisms responsible for differences in uptake and distribution of cadmium (Cd), nutrient-solution experiments were conducted with different varieties of rice (Oryza sativa), ‘Khitish’ and ‘CNRH3’. The plants were grown in a complete nutrient solution with different levels of pCd (-log free Cd⁺² activity) and pFe [-log free iron (Fe⁺²) activity]. The required concentrations of chelating agent and metals were determined using a computerized chemical equilibrium model such as Geochem-PC. Experimental treatments included a combination of four pCd activity levels (0, 7.9, 8.2, and 8.5) applied as Cd (NO₃)₂ 4H₂O, and two pFe activity levels (17.0 and 17.8) applied as FeCl₃. The application of both Cd and Fe in solution culture significantly affected plant growth, yield, and Cd accumulation in plant tissue. In general, yield of rice was decreased by an increase in amount of solution Cd; however, yield response varied among the cultivars. At the 7.9 pCd level, yields of rice cultivars ‘Khitish’ and ‘CNRH3’ were reduced to 69% and 65%, respectively, compared with control plants. Root Cd concentrations ranged from 2.6 mg kg^?1 (control plants) to 505.7 mg kg^?1 and were directly related to solution Cd concentrations. In rice plants, Cd toxicity symptoms resembled Fe chlorosis. Differential tolerance of varieties to phytotoxicity was not readily visible, but a significant interaction of substrate Cd and variety was obtained from dry-matter yields. Significant interactions indicated that response of tissue Cd concentration, plant Cd uptake, and translocation of Cd to the aerial parts were dependent on variety as well as substrate Cd. Uptake of Cd by roots was significantly higher than by shoots. Higher Cd uptake by rice plants decreased the uptake of other beneficial metals.

The effect of Cd and Fe on the rate of phytometallophore release was also studied in the nutrient solution. Among the rice genotypes, ‘Khitish’ was the most sensitive to Cd toxicity. In both genotypes, with the onset of visual Cd-toxicity symptoms, the release of phytometallophore (PM) was enhanced. Among the rice varieties, ‘Khitish’ had the highest rate of PM release. Treatments with the metal ions studied produced a decrease in chlorophyll and enzyme activity. A decrease in concentrations of chlorophyll pigments in the third leaf was observed due to the highest activity level of Cd (pCd 7.9). Activities of enzymes such as peroxidase (POD) and superoxide dismutase (SOD) are altered by toxic amounts of Cd. Changes in enzyme activities occurred at the lowest activity of Cd (pCd 8.5) in solution. Peroxidase activity increased in the third leaf. Results showed that in contrast with growth parameters, the measurements of enzyme activities may be included as early biomarkers in a plant bioassay to assess the phytotoxicity of Cd-contaminated solution on rice plants. Evidence that Cd uptake and translocation are genetically controlled warrants the selection of varieties that assimilate the least Cd and that translocate the least metal to the plant part to be used for human and animal consumption.     

Aspects of the benthic life cycle of Penaeus (Melicertus) japonicus Bate (Crustacea Decapoda) along the south-eastern coast of the Mediterranean

Recruitment, migration, growth, longevity and reproduction of Penaeus (Melicertus) japonicus Bate along the south-east coast of the Mediterranean were investigated.Relative population density, measured by catch per unit effort and average body length of the population were used in studying the recruitment, migration and growth of the various age groups.The reproductive state of the females was examined using three parameters: (1) gonado somatic index (ovary weight/total weight); (2) average diameter of ova; (3) morphological appearance of the ova according to a three stage scale.The results showed that P. japonicus migrates from inshore waters to the open sea during its benthic life cycle.Penaeus japonicus is distributed only on sandy substrate. It is suggested that the width of the longshore sandy strip determines the duration of the migration and hence the longevity and maximal growth of the individuals. Rate of migration might be accelerated by increasing density of young age groups near the shore. The estimated life span of each age group is 28–29 months. The maximal average body length of the population is 17 cm for males and 20 cm for females.Penaeus japonicus reproduce from April to November. This period corresponds to the appearance of a new age group about one kilometer offshore.The morphological appearance of the ova, average ovum diameter in each ovary and the female gonado-somatic index (GSI) are related to each other and can serve as a maturation index.Mature females are characterized by body length > 14 cm, GSI > 0.085 and average ovum diameter > 296 μ.     

A novel method for Citrus propagation: Seed grafting

Summary

We have developed a novel technique for grafting citrus seeds onto citrus rootstock plants that resulted in successful graft-take with normal vascular connections between the emerging seedling stem tissues and the rootstock plant. The method was found to be suitable for producing grafted plants from seeds of six cultivars and hybrids of Citrus and the citrus relative Murraya paniculata, using four common Citrus rootstocks. Plants produced by this method developed normally and were established in the field more rapidly than those produced by the common practice of grafting the rootstocks with budwood derived from seedlings prepared from seed in soil-based media. Seed grafting is expected to find a range of uses in breeding programmes; for example, by reducing the time required for the evaluation of hybrid seedlings, in cases where the female parent is mono-embryonic, for testing for vertical transmission of pathogens, and for screening for pathogen resistance among hybrid and mutagenised seed sources.