Improving in vitro mineral nutrition for diverse pear germplasm

Mineral nutrition in the media used for growth of in vitro plants is often difficult to optimize due to complex chemical interactions of required nutrients. The response of plant tissue to standard growth media varies widely due to the genetic diversity of the plant species studied. This study was designed as the initial step in determining the optimal mineral nutrient requirements for micropropagation of shoot tips from a collection of genetically diverse pear germplasm. Five mineral nutrient factors were defined from Murashige and Skoog salts: NH₄NO₃, KNO₃, mesos (CaCl₂·2H₂0–KH₂PO₄–MgSO₄), micronutrients (B, Cu, Co, I, Mn, Mo, and Zn), and Fe-EDTA. Each factor was varied over a range of concentrations. Treatment combinations were selected using response surface methods. Five pears in three species (Pyrus communis ‘Horner 51,’ ‘Old Home?×?Farmingdale 87,’ ‘Winter Nelis,’ Pyrus dimorphophylla, and Pyrus ussuriensis ‘Hang Pa Li’) were grown on each treatment combination, responses were measured, and each response was analyzed by analysis of variance. The analyses resulted in the identification of the following factors with the single largest effects on plant response: shoot quality (mesos), leaf spotting/necrosis (mesos), leaf size (mesos), leaf color (mesos, NH₄NO₃, and KNO₃), shoot number (NH₄NO₃ and Fe), nodes (NH₄NO₃ and KNO₃), and shoot length (mesos and Fe). Factors with the largest effects (mesos and Fe) were similar among the genotypes. This approach was very successful for defining the appropriate types and concentrations of mineral nutrients for micropropagation of diverse pear genotypes.     

Iron nutrition and physiological responses to iron stress in Nitrosomonas europaea

Nitrosomonas europaea, as an ammonia-oxidizing bacterium, has a high Fe requirement and has 90 genes dedicated to Fe acquisition. Under Fe-limiting conditions (0.2 μM Fe), N. europaea was able to assimilate up to 70% of the available Fe in the medium even though it is unable to produce siderophores. Addition of exogenous siderophores to Fe-limited medium increased growth (final cell mass). Fe-limited cells had lower heme and cellular Fe contents, reduced membrane layers, and lower NH₃- and NH₂OH-dependent O₂ consumption activities than Fe-replete cells. Fe acquisition-related proteins, such as a number of TonB-dependent Fe-siderophore receptors for ferrichrome and enterobactin and diffusion protein OmpC, were expressed to higher levels under Fe limitation, providing biochemical evidence for adaptation of N. europaea to Fe-limited conditions.     

Mineral nutrition and in vitro growth of Gerbera hybrida (Asteraceae)

The effects of mineral nutrient were examined on in vitro growth of Gerbera hybrida (G. jamesonii?×?G. viridifolia), specifically Gerbera hybrida cv. Pasadena. Four types of experiments were conducted to quantify the effects of mineral nutrients on four in vitro growth responses (quality, shoot number, leaf number, and shoot height) of gerbera and included groups of mineral nutrients (macros/mesos, micros, and Fe), individual salts (CuSO₄·5H₂O, MnSO₄·4H₂O, ZnSO₄·7H₂O, and Fe/EDTA), and the specific ions NO₃ ^?, NH₄ ⁺, and K⁺. Experiments included mixture-amount designs that are essential for separating the effects of proportion and concentration. Highly significant effects were observed in all experiments, but the mineral nutrients with the largest effects varied among the four growth responses. For example, leaf number was strongly affected by the macronutrient group in one experiment and by NH₄ ⁺ and K⁺, which were in the macronutrient group, in the NO₃ ^?/NH₄ ⁺/K⁺ ion-specific experiment, whereas quality was strongly affected by the micronutrients ZnSO₄ and Fe/EDTA. Because mineral nutrient effects varied significantly with the response measured, defining an appropriate formulation requires a clear definition of “optimal” growth.     

Nitrogen nutrition influences some biochemical responses to iron deficiency in tolerant and sensitive genotypes of Vitis

The effects of nitrogen source on iron deficiency responses were investigated in two Vitis genotypes, one tolerant to limestone chlorosis Cabernet Sauvignon (Vitis vinifera cv.) and the other susceptible Gloire de Montpellier (Vitis riparia cv.). Plants were grown with or without Fe(III)-EDTA, and with NO₃⁻ alone or a mixture of NO₃⁻ and NH₄⁺. Changes in pH of the nutrient solution and root ferric chelate reductase (FC-R) activity were monitored over one week. We carried out quantitative metabolic profiling (¹H-NMR) and determined the activity of enzymes involved in organic acid metabolism in root tips. In iron free-solutions, with NO₃⁻ as the sole nitrogen source, the typical Fe-deficiency response reactions as acidification of the growth medium and enhanced FC-R activity in the roots were observed only in the tolerant genotype. Under the same nutritional conditions, organic acid accumulation (mainly citrate and malate) was found for both genotypes. In the presence of NH4⁺, the sensitive genotype displayed some decrease in pH of the growth medium and an increase in FC-R activity. For both genotypes, the presence of NH₄⁺ ions decreased significantly the organic acid content of roots. Both Vitis genotypes were able to take up NH₄⁺ from the nutrient solution, regardless of their sensitivity to iron deficiency. The presence of N-NH₄⁺ modified typical Fe stress responses in tolerant and sensitive Vitis genotypes.     

State influences on ventral medullary surface and physiological responses to sodium cyanide challenges.

Intravenous sodium cyanide (NaCN) administration lowers ventral medullary surface (VMS) activity in anesthetized cats. Sleep states modify spontaneous and blood pressure-evoked VMS activity and may alter VMS responses to chemoreceptor input. We studied VMS activation during peripheral chemoreceptor stimulation by intravenous NaCN using optical procedures in six cats instrumented for recording sleep physiology during sham saline and control site trials. Images of scattered 660-nm light were collected at 50 frames/s with an optical device after 80-100 microg total bolus intravenous NaCN delivery during waking and sleep states. Cyanide elicited an initial ventilatory decline, followed by large inspiratory efforts and an increase in respiratory rate, except in rapid eye movement sleep, in which an initial breathing increase occurred. NaCN evoked a pronounced decrease in VMS activity in all states; control sites and sham injections showed little effect. The activity decline was faster in rapid eye movement sleep, and the activity nadir occurred later in waking. Sleep states alter the time course but not the extent of decline in VMS activity.     

Mineral nutrition and plant morphogenesis

Summary Plant morphogenesis in vitro can be achieved via two pathways, somatic embryogenesis or organogenesis. Relationships between the culture medium and explant leading to morphogenesis are complex and, despite extensive study, remain poorly understood. Primarily the composition and ratio of plant growth regulators are manipulated to optimize the quality and numbers of embryos or organs initiated. However, many species and varieties do not respond to this classical approach and require further optimization by the variation of other chemical or physical factors. Mineral nutrients form a significant component of culture media but are often overlooked as possible morphogenic elicitors. The combination of minerals for a particular plant species and developmental pathway are usually determined by the empirical manipulation of one or a combination of existing published formulations. Often only one medium type is used for the duration of culture even though this formulation may not be optimal for the different stages of explant growth and development. Furthermore, mineral studies have often focused on growth rather than morphogenesis with very little known of the relationships between mineral uptake and morphogenesis. This article examines the present knowledge of the main effects that mineral nutrients have on plant morphogenesis in vitro. In particular, the dynamics of nitrogen, phosphorus, and calcium supply during development are discussed.     

NaCl-induced stress: physiological responses of six halophyte species in in vitro and in vivo culture

Plant Cell, Tissue and Organ Culture (PCTOC) - To investigate the mechanisms underlying salt tolerance, physiological parameters of six halophyte species [Vitex rotundifolia L., Clerodendrum inerme...     

Behavioral influences on the physiological responses of Cancer gracilis, the graceful crab, during hyposaline exposure

The relationship between the behavioral and physiological responses to hyposaline exposure was investigated in Cancer gracilis, the graceful crab. The status of C. gracilis as an osmoconformer was confirmed. Survival decreased with salinity: the LT(50) in 50% seawater (a practical salinity of 16, or 16 per thousand) was 31.5 +/- 22.7 h and in 25% seawater (a salinity of 8) was 8.0 +/- 0.7 h. When exposed to a salinity gradient, most crabs moved towards the highest salinity. However, in the salinity range of 55% to 65% seawater, they became quiescent. This "closure response" was also evident at low salinities: the mouthparts were tightly closed and animals remained motionless for 2 to 2.5 h. During closure, crabs were able to maintain the salinity of water within the branchial chambers at a level that was about 30% higher than that of the surrounding medium. The closure response was closely linked to a short-term decrease in oxygen uptake. During closure, oxygen within the branchial chamber was rapidly depleted, with oxygen uptake returning to pretreatment levels upon the resumption of activity. In addition to the short-term decrease in oxygen uptake, there was a longer-term bradycardia, which may serve to further reduce diffusive ion loss across the gills. By exhibiting a closure response during acute hyposaline exposure and an avoidance reaction during prolonged or severe hyposaline exposure, C. gracilis is able to use behavior to exploit areas prone to frequent episodes of low salinity.     

Hormonal regulation of secondary abscission in pear pedicels in vitro

In vitro cultivated pear, Pyrus communis L. cv. Beurré Hardy, pedicels cut above their primary abscission layer can form a secondary abscission layer, especially under the influence of auxins or cytokinins in the culture medium. The maximum percentage of abscission reached by auxin application was always higher than that by cytokinin. The presence of the flower was of no consequence to the abscission. Characteristic differences in abscission were observed between pear and apple pedicels. In contrast to apple (1) secondary abscission in pear could also be induced by cytokinins, and (2) the site of abscission in pear was dependent on the auxin concentration. At lower auxin concentrations abscission was induced in the basal parts of the pedicels inserted in the medium, whereas at higher auxin concentrations the abscission layer was formed in the terminal parts of the pedicels above the culture medium. A clear effect of gibberellins, ABA and CEPA could not be detected.     

Mineral nutrition of carnivorous plants: A review

Plant carnivory is one of many possible adaptation strategies to unfavorable conditions, mostly low nutrient availability in wet, acid soils. The following issues concerning the mineral nutrition of carnivorous plants are reviewed: the relative importance of carnivory and root nutrition for growth; which nutrients (elements) from prey are of principal importance for growth; the relationship between mineral and organic nutrition based on carnivory; the interactions between carnivory and root mineral nutrition; and the importance of carnivory under natural conditions. Special attention is paid to aquatic carnivorous plants. Studies on mineral nutrition carried out in laboratory and/or greenhouse conditions are discussed separately from those carried out in field conditions. The emphasis of this review is on recapitulation of original data and conclusions of results from a variety of studies that approach carnivorous plants from an ecophysiological point of view.     

水稻纹枯病菌的矿质营养生态位

运用生态位原理与方法,研究了水稻纹枯病菌的矿质元素营养生态位.结果表明,在分蘖盛期、孕穗期、抽穗期和蜡熟期,水稻纹枯病菌矿质营养生态位宽度指数分别为0.2710、0.3865、0.4252和0.4817,即随着水稻的生长而逐渐增大,但各生育期的生态位宽度总体上仍偏小.表明在水稻生长的各时期水稻纹枯病菌只占有了矿质营养类型中的较少部分.水稻纹枯病菌总是优先占有低Mg、低Zn、低Si的营养位,说明Mg、Zn、Si的含量与水稻对纹枯病的抗性紧密相关.     

Mineral nutrition and the water relations of plants

Summary When young tomato plants were transferred from nutrient solution to mineral-free water, reductions in transpiration, water content of the shoots and stomatal aperture were not accompanied by a reduction in the relative water content or an increase in the suction pressure of the leaves. The relative water content of the leaves was increased and the suction pressure was little affected.Following transfer of the plants to mineral-free water, the mineral content of the shoots and the osmotic pressure of expressed leaf sap were reduced. It was concluded that mineral salts were necessary for maintaining the osmotic pressure of the leaf cell sap and that this was achieved, at least in part, by maintaining the mineral concentration of the sap. The amount of water that could be taken up by leaves and their turgor pressure were related to the osmotic pressure of the sap and calculations of turgor pressure showed that it was less in the leaves of plants with their roots in mineral-free water than in the leaves of plants in nutrient solution.Evidence was obtained that in leaflets detached from plants with their roots in mineral-free water, stomatal closure could occur at a higher water content than in leaflets detached from plants in nutrient solution, indicating a further role of minerals in leaf water relations. It is suggested that this role may be related to the properties of the cell walls.     

Mineral nutrition and reduction processes in the rhizosphere of rice

Summary The influence of nitrogen, phosphorus, and potassium on the reduction processes in the rhizosphere of rice grown in solution culture and of rice under lowland conditions was studied. In solution culture the redox potential in the complete nutrient solution was highest, indicating that fully nourished roots have the highest oxidizing power. When the supply of only one element was interrupted, the lack of potassium in the nutrient solution caused the greatest decline in redox potential. Redox potential was further decreased when, besides nitrogen, either phosphorus or potassium was discontinued. Simultaneous deficiencies of nitrogen and potassium lowered redox potential even more severely than did deficiency of all three elements. A long-term nitrogen fertilizer trial under lowland conditions, however, revealed that an abundant supply of nitrogen can decrease redox potential. Redox potential was higher in the soil near plants than in the soil away from plants. In solution culture, at low Eh levels, the increase in iron reducing power of the solution was correlated with the decrease in redox potential. The total number of bacteria and iron reducing bacteria increased almost parallel to the decrease in redox potential and increase in iron reducing power. These relationships show that the nutritional status of the rice plant essentially influences bacterial activity and, thus, oxidation-reduction conditions around the roots. Since sufficient potassium nutrition seems important in maintaining the oxidising power of rice roots, root growth in a potassium deficient soil with K application was compared with root growth without K application. Without potassium the fine lateral roots far from the root base showed black coloration due to ferrous sulfide, indicating a loss of oxidising power. With increasing potassium supply, this phenomenon disappeared and the iron content of the rice plants decreased. re]19751208     

Canopy attachment position influences metabolism and peel constituency of European pear fruit

Background

Inconsistent pear fruit ripening resulting from variable harvest maturity within tree canopies can contribute to postharvest losses through senescence and spoilage that would otherwise be effectively managed using crop protectant and storage regimes. Because those inconsistencies are likely based on metabolic differences, non-targeted metabolic profiling peel of ‘d’Anjou’ pears harvested from the external or internal canopy was used to determine the breadth of difference and link metabolites with canopy position during long-term controlled atmosphere storage.

Results

Differences were widespread, encompassing everything from expected distinctions in flavonol glycoside levels between peel of fruit from external and internal canopy positions to increased aroma volatile production and sucrose hydrolysis with ripening. Some of the most substantial differences were in levels of triterpene and phenolic peel cuticle components among which acyl esters of ursolic acid and fatty acyl esters of p-coumaryl alcohol were higher in the cuticle of fruit from external tree positions, and acyl esters of α-amyrin were elevated in peel of fruit from internal positions. Possibly the most substantial dissimilarities were those that were directly related to fruit quality. Phytosterol conjugates and sesquiterpenes related to elevated superficial scald risk were higher in pears from external positions which were to be potentially rendered unmarketable by superficial scald. Other metabolites associated with fruit aroma and flavor became more prevalent in external fruit peel as ripening progressed and, likewise, with differential soluble solids and ethylene levels, suggesting the final product not only ripens differentially but the final fruit quality following ripening is actually different based on the tree position.

Conclusions

Given the impact tree position appears to have on the most intrinsic aspects of ripening and quality, every supply chain management strategy would likely lead to diverse storage outcomes among fruit from most orchards, especially those with large canopies. Metabolites consistently associated with peel of fruit from a particular canopy position may provide targets for non-destructive pre-storage sorting used to reduce losses contributed by this inconsistency.