Localization of mitochondria in plant cells by vital staining with rhodamine 123

The positively-charged fluorescent dye rhodamine 123 (r-123) specifically stains mitochondria in living plant protoplasts, suspensionculture cells, and root hairs. This dye functions as a vital stain and permits visualization of the localization, distribution and movement of the mitochondria. Dehydration of root hairs caused mitochondria to aggregate into clumps. Mitochondria were either homogenous or heterogeneous and were frequently seen to accumulate in the perinuclear regions of suspension-culture cells but not in those of protoplasts or root-hair cells. Dinitrophenol and high concentrations of ethyleneglycol-bis(-aminoethyl ether)-N,N,N,N-tetraacetic acid and KCl immediately eliminated fluorescence in r-123-stained mitochondria whereas ionomycin enhanced it. Treatment of seedlings with r-123 resulted in differential brightness of fluorescence in different tissues. Meristematic tissues, such as root and shoot tips, exhibited the brightest fluorescence. The cytotoxicity of r-123 in both germinating seedlings and suspension-culture cells was low. The specificity, sensitivity and low toxicity of r-123 should make it a useful tool in experiments designed to examine agents and conditions which affect the location, the physiological status or the viability of mitochondria.Abbreviations EGTA ethyleneglycol-bis-(-aminoethyl ether)N,N,N,N-tetraacetic acid - DAPI 46-diamidino-2-phenylindole - r-123 rhodamine 123     

Mechanism of phosphorus-induced zinc deficiency in cotton. III. Changes in physiological availability of zinc in plants Is mail

The effect of varied supply of P (2.5× 10⁻⁵ to 6× 10⁻⁴ M) and Zn (0 to 10⁻⁶ M) on uptake and concentrations of P and Zn was studied in cotton ( Gossypium hirsutum L. cv. Deltapine 15/21) grown in nutrient solution under controlled environmental conditions. At a given Zn supply, increasing levels of P had no significant effect on the concentrations of total Zn in plants. However, increasing levels of P induced or enhanced visual Zn deficiency symptoms when the Zn concentration in the nutrient solution was low. The concentrations of water-soluble Zn in roots and shoots constituted 60% of the total Zn concentrations for plants grown with low P and 30% for plants grown with high P. The concentration of water-soluble Zn in leaves, but not total Zn, was closely correlated with visual Zn deficiency symptoms, levels of chlorophyll, super oxide dismutase and membrane permeability. The critical deficiency concentration of water-soluble Zn in cotton leaves was in the range of 6 to 7 μg (g dry weight)⁻¹ or about 1.0 μg (g fresh weight)⁻¹. The results show that high P concentrations in plant tissue decrease the physiological availability of Zn. Water-soluble Zn in the tissue appears to be a suitable indicator for Zn nutritional status in general and phosphorus-induced Zn deficiency in particular. Also in field-grown orange trees (Citrus sinensis) visual Zn deficiency symptoms in leaves were closely related to the concentration of water-soluble Zn.     

Evolution des glucides intratissulaires au cours de la néoformation des bourgeons par des explantats racinaires de Cichorium intybus cultivés in vitro

Variation of intratissular carbohydrates during bud formation in root explants of Cichorium intybus cultivated in vitro .
During the cellular activation that begins with excision of root explants from Cichorium intybus L. var. Witloof cv. Zoom cultured in vitro, hydrolysis of fructose polymers, in particular of the polyfructosans (inulin) takes place. The products of degradation are used to cover the energetic needs connected with the increase of the mitotic activity. After day 2 the intracellular carbohydrates (sucrose and reducing sugars) develop differently according to further development of the explants. When growth of unorganized callus is favoured and organ formation inhibited by medium supplemented with auxin, fructose is accumulated; but under bud-forming conditions it is the amount of sucrose that increases. These differences were most notable between days 3 and 10 in culture, the period during which primordia occurred in the shoot-forming callus     

Genetic diversity within and among 11 juvenile populations of green alder (Alnus crispa) in Canada

Germinated seeds from 11 populations of green alder [ Alnus crispa (Ait.) Pursh] sampled in four Canadian provinces were analysed for electrophoretically demonstrable diversity of 10 enzymes encoded by 15 structural loci. Of these, nine were polymorphic, and on average, 52% of the loci per population were polymorphic. Assuming a diploid model of expression, average level of expected heterozygosity was 0.11 with nearly all populations in Hardy-Weinberg equilibrium for the set of polymorphic loci analysed. No significant inbreeding and associated subpopulation structuring were noted. Rates of gene flow appeared high within and among populations. Although little divergence was observed among populations, genetic and geographical distances between populations were related. Discriminant and cluster analyses revealed a pattern of genetic variation associated with geography. Populations from northern Quebec were poorly differentiated, whereas western populations from Alberta exhibited a larger degree of genetic differentiation. Introgresive hybridization with the sympatric species Alnus sinuata (Regel) Rydberg and partial isolation in the West are suggested as an explanation for this larger differentiation. The occurrence and significance of rare alleles is discussed in relation to the importance of geographical distance in the process of population differentiation in this species.     

Diagnosis of iron deficiency in groundnut,Arachis hypogaea L.

Summary Investigations into iron deficiency have been hindered by the lack of a satisfactory diagnostic tissue test, which in turn results from the total iron content of plant tissue commonly being an unreliable index of the iron status. Our measurements of chlorotic and normal leaves of field grown groundnut (Arachis hypogaea L.) showed that total iron was unsatisfactory as the measure of iron status of plant tissue. It was found that iron status was better assessed from an estimate of the ferrous iron content of fresh leaf materials obtained by extraction with o-phenanthroline. Extractable iron content increased with leaf age. Chlorotic buds or the first fully opened leaf always contained less than 6μg extractable-Fe/g fresh tissue. Approved for publication as ICRISAT Journal Article No. 307.     

The effect of lime on phosphorus adsorption and barley growth in three acid soils

For three acid soils from Santa Catarina, Brazil, lime application and time of incubation with lime had little effect on the adsorption of added phosphorus. In two soils with high contents of exchangeable aluminium, solution P and isotopically exchangeable P were decreased by incubating with lime for 1 month: phosphorus was probably adsorbing on freshly precipitated aluminium hydrous oxides. In one soil with less exchangeable aluminium, P in solution was increased by liming. After 23 months lime increased solution and exchangeable P possibly due to crystallization of aluminium hydrous oxides reducing the number of sites for P adsorption. All these changes were however small. In a pot experiment, lime and phosphorus markedly increased barley shoot and root dry matter and P uptake. Although liming reduced P availability measured by solution P, isotopically exchangeable P and resin extractable P, it increased phosphorus uptake by reducing aluminium toxicity and promoting better root growth. The soil aluminium saturation was reduced by liming, but the concentration of aluminium in roots changed only slightly. The roots accumulated aluminium without apparently being damaged.     

Advances in salt tolerance

Summary Advances in and prospects for the development of salt tolerant crops are discussed. The genetic approach to the salinity problem is fairly new, but research has become quite active in a short span of time. Difficulties and opportunities are outlined. Salinity varies spatially, temporally, qualitatively, and quantitatively. In addition, the responses of plants to salt stress vary during their life cycle. Selection and breeding, including the use of wide crosses, are considered the best short-term approaches to the development of salt tolerant crops, but the new biotechnological and molecular biological techniques will make increasingly important contributions. Cooperation is called for among soil and water scientists, agronomists, plant physiologists and biochemists, cytologists, and plant geneticists, breeders, and biotechnologists. Given such cooperation and adequate support for these endeavors, the potential for increasing productivity in salt-affected areas can be realized.     

Prediction of heavy-metal concentrations in mature plants by chemical analysis of seedlings

Five plant species were cultivated on a soil from the Neckar alluvial fan near Heidelberg (FRG) polluted by the emissions of a cement plant. Thallium, cadmium and lead concentrations in seedlings and mature plants were determined by atomic absorption analysis. AdditionallyBrassica napus L.napus was grown on soils containing 5 different concentrations of heavy metals, achieved by mixing two similar soils, from the same area but with different metal concentrations. Thallium and cadmium were shown to be taken up by roots whilst lead which was also absorbed, was deposited mainly on the plant surface. However during cultivation in the winter months, a remarkable deposit of lead via the roots was found. Thallium in the soil from a anthrorogen source was more available to plants than thallium of geological origin. During the lifetime of a plant concentrations of thallium and cadmium were always highest in the seedling. The decrease in metal concentration with maturity depended on the plant species and the element, but was not a function of the metal concentration in the soil.     

The influence of the culture medium on the competitive abilities ofBradyrhizobium japonicum strains

Growth on culture media results in changes in Rhizobium competitivity:Bradyrhizobium japonicum strain G2, when mixed with the strain GMB 1 in the same ratio, formed 85% of the total nodule numbers when the strains were cultured on the YEM medium, whereas, it formed only 55% of the nodules when they were cultured on the MSY medium.     

Induction and floral determination in the terminal bud of Nicotiana tabacum L. cv. Maryland Mammoth,a short-day plant

Floral determination in the terminal bud of the short-day plant Nicotiana tabacum cv. Maryland Mammoth has been investigated. Plants grown continuously in short days flowered after producing 31.4±1.6 (SD) nodes while plants grown continuously in long days did not flower and produced 172.5±9.5 nodes after one year. At various ages, expressed as number of leaves that were at least 1.0 cm in length above the most basal 10-cm leaf, one of three treatments was performed on plants grown from seed in short days: 1) whole plants were shifted from short days to long days, 2) the terminal bud was removed and then rooted and grown in long days, and 3) the terminal bud was removed and then rooted and grown in short days. Whole plants flowered only when shifted from short days to long days at age 15 or later. Only rooted terminal buds from plants at age 15 or older produced plants that flowered when grown in long days. Only terminal buds from plants at age 15 or older that were rooted and grown in short days produced the same number of nodes as they would have produced in their original locations while buds from younger plants produced more nodes than they would have in their original locations. Thus, determination for floral development in the terminal bud, as assayed by rooting, is simultaneous with the commitment to flowering as assayed by shifting whole plants to non-inductive conditions.Abbreviations LD long day(s) - SD short day(s) - DN dayneutral