Volatile components of sugar beet leaves

Extracts of both young and old sugar beet plants were obtained using a modified Likens and Nickerson apparatus. Constituents were identified by GC/MS, and using selected ion monitoring it was shown that the previously determined phenylacetonitrile was probably not of glucosinolate origin. Some unsaturated aldehydes, alcohols and derivatives (enzymic lipid degradation products) were formed to greater extents by the younger leaves, but otherwise such quantitative differences were relatively few and generally random. An interesting range of chlorinated compounds was obtained only from the older plants; a pesticide origin is suggested.     

Isolation of protoplasts from sugar beet leaves

Isolated protoplasts were prepared from sugar beet leaves by means of the action of a non-specific enzyme xylonase; homologous fusions and total yield were examined.     

Variation in photosynthetic pigments and plastoquinone contents in sugar beet chloroplasts with changes in leaf copper content

The changes in the contents of chlorophyll (Chl) a, Chl b, carotenoid, and plastoquinone in sugar beet (Beta vulgaris) chloroplasts were investigated during Cu deficiency and resupply. With the onset of Cu deficiency, extrachloroplastic Cu decreased more rapidly than chloroplast Cu, which eventually accounted for all of the Cu present in the leaf. The ultrastructure of Cu-deficient chloroplasts did not differ from the control except in very young, severely deficient leaves. During Cu depletion and resupply, Chl a, Chl b, carotenoid, and plastoquinone contents changed concomitantly. Because of the concurrent changes in the contents of terpenoid-containing pigments and plastoquinone with Cu depletion and resupply, we suggest that Cu might be involved in the regulation of the early steps of terpenoid biosynthesis prior to the formation of geranyl-geranyl-pyrophosphate.     

Specific uptake of 6-deoxy-d-glucose and of 2-aminoisobutyric acid by sugar beet leaves and roots

Sugar beet was grown in pots and the transport of 6-deoxy-d-glucose (6-dg) and of 2-aminoisobutyric acid (AIB) into leaf and root tissue segments was examined. The uptake of 6-dg into both tissues displayed two kinetic components, one apparently of diffusional nature, the other saturable (half-saturation constant 0.22 mM in leaves, 0.10 mM in roots; limiting rate 0.37 and 0.10 nmol mg-1 (fresh mass) h-1 for leaves and roots, respectively). It was suppressed by d-glucose and inhibited by diethyl-stilbestrol (DES), suloctidil (SUL) and 2,4-dinitrophenol (DNP), but little by D2O and not at all by sodium vanadate. It showed a temperature optimum at 30 °C and a pH optimum at 6.0 - 6.5 in both tissues. The uptake of AIB was also two-componental but even the specific component had an immeasurably high half-saturation constant although it was inhibited by high concentrations of AIB as well as by DES, SUL, DNP and D2O. However, vanadate stimulated the uptake by as much as 40% in both leaves and roots. The temperature optimum in leaves lay at 30 °C while in the roots no maximum was present; its pH optimum was at 5.5 in leaves and again no maximum was observed in roots. Both transport systems were unaffected by 0.1M NaCl or 0.1 M KCl and by the presence of cytokinin in the incubation vessel. However, spraying with the cytokinin N6-(m-hydroxybenzyl) adenosine decreased both the half-saturation constant and the limiting velocity of 6-dg uptake slightly in the leaves and substantially in the roots. Spraying had an insignificant effect on the uptake of AIB. This revised version was published online in July 2006 with corrections to the Cover Date.     

Estimating photosynthetic rate and annual carbon gain in conifers from specific leaf weight and leaf biomass

Summary Canopy photosynthesis is difficult to measure directly or to predict with complex models demanding knowledge of seasonal variation in environmental and physiological properties of the canopy. Trees in particular offer a challenge with their large, aerodynamically rough and seasonally-changing canopy properties. In this paper we assess the possibility of using specific leaf weight to predict seasonal and annual net photosynthetic rate in deciduous (Larix sp.) and evergreen (Picea abies) conifers.Annual photosynthetic rate and specific leaf weight of different positions of the crown in both species were highly correlated (r ²=0.930). Annual carbon uptake by different segments in a mature P. abies crown was closely related to leaf biomass. The relationship was improved by adjusting the leaf biomass of each segment in regard to its specific leaf weight relative to the maximum found in the canopy. The adjustment accounted for associated differences in photosynthetic activity. This combined structural index (leaf biomassxrelative specific leaf weight) could, when calibrated, predict the total annual carbon uptake by different parts of the crown. If direct measurements of photosynthesis are not available, the combined structural index may still serve as a comparative estimator of annual carbon uptake.     

Effect of surplus glucose on physiological and biochemical characteristics of sugar beet leaves in relation to the age of the leaf and the whole plant

Effect of surplus glucose on physiological and biochemical parameters of leaves of different age was investigated in sugar beet (Beta vulgaris L., subsp. saccharifera) plants in the stages of vegetative growth (SVG). Early and late SVG were differentiated by the ratio between the weights of roots and aboveground organs (0.10 and 0.35, respectively). The excess of Glu was produced by incubation of the disks excised from detached leaves in water or 0.1 M Glu at radiant flux density of 250 μmol/(m² s) with the light regime pattern described as night/day/night/light (8/16/8/3 h). In all the leaf disks incubated in water and glucose solution, the content of Glu and other soluble carbohydrates considerably increased as compared with their content in the leaves they were taken from. After disk incubation in water and glucose solution, the content of chlorophyll (a + b) rose as compared with its level in respective leaves in early SVG; in late SVG, it declined. In early SVG, the rate of the O₂ photosynthetic evolution (Ph) in the ageing leaves under saturating concentration of NaHCO₃ after incubation in water and Glu solution declined more considerably than in young leaves. In late SVG, incubation of leaf disks in water and Glu solution weakly affected P _n. The rate of O₂ dark consumption in the leaf disks of all the types of treatment increased after incubation in water and especially in Glu solution. Activity of soluble carbonic anhydrase (sCA) in the extracts from young leaves in early SVG after their incubation in water and Glu solution was essentially the same, but after the incubation of ageing leaves in Glu solution, it reliably decreased. In late SVG, sCA activity sharply decreased after incubation in water and Glu solution irrespective of the leaf age. In late SVG, activity of Rubisco in the young leaves did not change after their incubation in water but decreased after incubation of the leaves of the three ages in Glu solution. In early SVG, nonphotochemical fluorescence quenching (NPQ) in the young intact leaf was lower than in the ageing leaf, and after leaf incubation in water and Glu solution, it rose. In late SVG, the value of NPQ was greater than in early SVG and, in contrast to the leaves of early SVG, it declined after leaf incubation; in water, this decline was more pronounced than in the Glu solution. In early SVG, efficient quantum yield of photosystem II (PSII) was much greater than in late SVG and it declined in the leaves incubated with Glu. It was concluded that surplus Glu can maintain biosynthetic processes in the young leaves of young sugar beet plants (trophic function). A decline in the level of chlorophyll and the activities of sCA and Rubisco in the course of leaf development and senescence is considered as a symptom of the suppression of biosynthesis of proteins of chlorophyll-protein complexes and the enzymes (Rubisco and sCA).     

Sugar transport in conducting elements of sugar beet leaves

Autoradiography was used to determine the distribution of labeled sugar in conducting elements of the blade and petiole of sugar beet leaves at intervals ranging from 5 sec to 24 hr. The processes of assimilation by the green cells, collection of sugar in the minor veins and export in phloem elements were demonstrated visually. It appears that in minor veins sugar is translocated in companion cells rather than sieve tubes. In major veins translocation occurs in sieve tubes.     

An analysis of leaf growth in sugar beet.

The increase of leaf area index (L) was examined in a series of sugar-beet crops grown on different sites (Broom's Barn, Suffolk and Trefloyne, Dyfed) or with different husbandry treatments (sowing dates and nitrogen rates) between 1978 and 1982. The development of L could be described as a function of thermal time using three parameters; D_E, which was essentially an estimate of the thermal time required for crop establishment, and rH_L and D_L, the thermal rate and duration, respectively, of the increase of L. Variations in D_E between seasons and with sowing date were small, but significant; they were attributed to factors affecting the condition of the seedbed. There were much larger variations in rH_L, especially between seasons, sites and crops given different rates of nitrogen fertiliser, and there was a strong negative relationship between rH_L and D_L. Much of the variation in rH_L was associated with differences in the concentrations of nitrogen in the lamina dry matter. Faster rates for rH_L at Trefloyne than at Broom's Barn, and in the crop grown in 1982 as compared with other years, were also partly attributable to particularly warm conditions during the early development of some of the larger, faster-growing leaves within the canopy. The wider application of the relationships established from these experiments was tested with data from a series of crops grown on other sites between 1960 and 1962. The relationships held particularly well for beet grown on soils with high water-holding capacity but not for those on soils of low water-holding capacity.     

An analysis of leaf growth in sugar beet.

The responses of leaf appearance and expansion to temperature in sugar beet were measured under controlled conditions, using ruler and auxanometers, to establish a basis for a subsequent analysis of leaf growth in field crops. The studies showed that leaf appearance rate responded linearly to temperature above 1°C, that leaf expansion rate responded likewise above 3°C and that both rates were zero below these base temperatures. Auxanometer measurements of leaf extension showed that daily rates of expansion of leaf area increased linearly with the daily integral of temperature. However, hourly rates of extension in length alternated with those in width during each 24 h cycle in patterns that were not clearly related to hourly changes of temperature or to the day/night sequence.     

Diurnal changes in adenylates and nicotinamide nucleotides in sugar beet leaves

Sugar beets (Beta vulgaris L. cv. F58-554H1) were cultured hydroponically in growth chambers at 25°C, with a photon flux density of 500 mol m^-2s^-1. Measurements were made of net CO₂ exchange, leaf adenylates (ATP, ADP and AMP), and leaf nicotinamide nucleotides (NAD⁺, NADP⁺, NADH, NADPH), over the diurnal period (16h light/8 h dark) and during photosynthetic induction. All the measurements were carried out on recently expanded leaves from 5-week-old plants. When the lights were switched on in the growth chamber, the rate of photosynthetic CO₂ uptake, and the levels of leaf ATP and NADPH increased to a maximum in 30 min and remained there throughout the light period. The increase in ATP over the first few minutes of illumination was associated with the phosphorylation of ADP to ATP and the increase in NADPH with the reduction of NADP⁺; subsequently, the increase in ATP was associated with an increase in total adenylates while the increase in NADPH was associated with an accumulation of NADP⁺ and NADPH due to the light-driven phosphorylation of NAD⁺ to NADP⁺. On return to darkness, ATP and NADPH values decreased much more slowly, requiring 2 to 4 hours to reach minimum values. From these results we suggest that (i) the total adenylate and NADPH and NADP⁺ (but not NAD⁺ and NADH) pools increase following exposure to light; (ii) the increase in pool size is not accompanied by any large change in the energy or redox states of the system; and (iii) the measured ratios of ATP/ADP and NADPH/NADP⁺ for intact leaves are low and constant during steady-state illumination.Abbreviations AEC adenylate energy charge - DHAP dihydroxyacetone phosphate - MTT 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide - PES phenazine ethosulfate - PEP phosphoenolpyruvate - PGA 3-phosphoglycerate - PFD photon flux density - Ru5P ribulose-5-phosphate - Rubisco ribulose 1,5-bisphosphate carboxylase/oxygenase     

Characterization of sterol uptake in leaf tissues of sugar beet

The uptake of cholesterol has been characterized in leaf discs from mature leaves of sugar beet (Beta vulgaris L.). This transport system exhibited a simple saturable phase with an apparent Michaelis constant ranging from 30 to 190 M depending on the sample. When present at 10 M excess, other sterols were able to inhibit cholesterol uptake. Moreover, binding assays demonstrated the presence of high-affinity binding sites for cholesterol in purified plasma membrane vesicles. In the range 1–60 M, cholesterol uptake showed an active component evidenced by action of the protonophore carbonyl cyanide m-chlorophenylhydrazone. Energy was required as shown by the inhibition of uptake induced by respiration inhibitors (NaN₃), darkness and photosynthesis inhibitors [3-(3,4-dichlorophenyl)-1,1-dimethylurea, methyl viologen]. Moreover, the process was strongly dependent on the experimental temperature. Uptake was optimal at acidic pH (4.0), sensitive to ATPase modulators, inhibited by thiol reagents (N-ethylmaleimide, p-chloromercuribenzenesulfonic acid, Mersalyl) and by the histidyl-group reagent diethyl pyrocarbonate. The addition of cholesterol did not modify H⁺ flux from tissues, indicating that H⁺-co-transport was unlikely to be involved. MgATP did not increase the uptake, arguing against involvement of an ABC cassette-type transporter. By contrast, cryptogein, a sterol carrier protein from the Oomycete Phytophtora cryptogea, greatly increased absorption. Taken together, the results reported in this work suggest that plant cells contain a specific plasma membrane transport system for sterols.Abbreviations CCCP carbonyl cyanide m-chlorophenylhydrazone - PCMBS p-chloromercuribenzenesulfonic acid - PMV plasma membrane vesicle - TLC thin-layer chromatography     

黄土高原甜菜叶片生长特性及其对块根产量、含糖量的影响

通过对旱地甜菜叶片生长特性及摘除不同叶组对块根产量,含糖量,显微结构的影响研究,结果表明：甜菜第10-20片叶的叶龄最长,积温最高,是甜菜的主要功能叶;甜菜从第20片叶期起进入块根,糖份增长期,从第55叶期起进入糖份积累期;摘除不同叶组的叶片对甜菜块根产量,含糖量及显微结构均有不同程度降低作用,摘除前期叶组对甜菜块根产量,产糖量,根径减幅较大,摘除后期叶组对块根含糖量,维管束环数,维管束环密度减幅较大;摘除第1-30片叶对甜菜影响最大。     

Proteome analysis of sugar beet leaves under drought stress

Drought is one of the major factors limiting the yield of sugar beet (Beta vulgaris L.). The identification of candidate genes for marker-assisted selection (MAS) could greatly improve the efficiency of breeding for increased drought tolerance. Drought-induced changes in the proteome could highlight important genes. Two genotypes of sugar beet (7112 and 7219-P.69) differing in genetic background were cultivated in the field. A line-source sprinkler irrigation system was used to apply irrigated and water deficit treatments beginning at the four-leaf stage. At 157 days after sowing, leaf samples were collected from well-watered and drought-stressed plants for protein extraction and to measure shoot biomass and leaf relative water content. Changes induced in leaf proteins were studied by two-dimensional gel electrophoresis and quantitatively analyzed using image analysis software. Out of more than 500 protein spots reproducibly detected and analyzed, 79 spots showed significant changes under drought. Some proteins showed genotype-specific patterns of up- or downregulation in response to drought. Twenty protein spots were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), leading to identification of Rubisco and 11 other proteins involved in redox regulation, oxidative stress, signal transduction, and chaperone activities. Some of these proteins could contribute a physiological advantage under drought, making them potential targets for MAS.     

Variations in photosynthetic rate and associated parameters with age of oil palm leaves under irrigation

Net photosynthetic rate (P _N), transpiration rate (E), and stomatal conductance (g _s) in an adult oil palm (Elaeis guineensis) canopy were highest in the 9^th leaf and progressively declined with leaf age. Larger leaf area (LA) and leaf dry mass (LDM) were recorded in middle leaves. P _N showed a significant positive correlation with g _s and a negative relationship with leaf mass per area (ALM). The oil palm leaf remains photosynthetically active for a longer time in the canopy which contributes significantly to larger dry matter production in general and greater fresh fruit bunch yields in particular.     

Specific leaf mass, fresh: dry weight ratio, sugar and protein contents in species of Lamiaceae from different light environments

Samples from eleven species of Lamiaceae were collected from different light environments in Venezuela for laboratory analysis. The studied species were: Plectranthus scutellarioides (Ps), Scutellaria purpurascens (Sp), Hyptis pectinata (Hp)), H. sinuata (Hs). Leonorus japonicus (Lj), Plecthranthus amboinicus (Pa) Ocimum hasilicum (Ocb), O. campechianum (Occ) Origanum majorana (Orm), Rosmarinus officinali, (Ro) and Salvia officinalis (So). Protein and soluble sugar contents per unit of area were measured, Specific Leaf Mass (SLM) and fresh:dry weight (FW/DW) ratios were calculated. The higher values for soluble sugars contents were present in sun species: Lj, Pa, Ocb, Occ, Orm, Ro and So; the lower values were obtained in low light species: Ps, Sp, Hp, Hs. The values of protein content do not show any clear trend or difference between sun and shade environments. The lowest values for the fresh weight: dry weight ratio are observed in sun species with the exception of Lj and Pa, while the highest value is observed in Pa, a succulent plant. The higher values of specific leaf mass (SLM) (Kg DMm(-2)) are observed in sun plants. The two way ANOVA revealed that there were significant differences among species and between sun and low light environments for sugar content and FW:DW ratio. while SLM was significant for environments but no significant for species, and not significant for protein for both species and environments. The soluble sugar content, FW:DW ratio and SLM values obtained in this work, show a clear separation between sun and shade plants. The sugar content and FW:DW ratio are distinctive within the species, and the light environment affected sugar content. FW:DW ratio and SLM. These species may he shade-tolerant and able to survive in sunny environments. Perhaps these species originated in shaded environments and have been adapting to sunny habitats.     

Photosynthetic capacity,irradiance and sequential senescence of sugar beet leaves

In field-grown sugar beet plants (Beta vulgaris L. cv. Dobrovická A), each of66 successive leaves produoed in the course of the vegetation period was different with respect to its photosynthetic capaoity (P_c), life span, duration of leaf area expansion, and longevity after its maximum leaf area (A_max) has developed. The proportionality between the seasonal changes in these characteristics was not the same if the sequential senescence of leaves was taken into account. With aging of individual leaves, P_c increased with the leaf area expansion having attained the peak value between 75% to 100% of A_max The rate of ontogenetic changes in P_c of each leaf was specified by the rate of its growth and development so that even at comparable ages the successive leaves constituted a series of different physiological units. The seasonal changes in quantum irradiance (PAR) were found to be responsible for differences in the growth characteristics between the successive leaves: Leaf expansion period was related with daily integrals of the incoming PAR (Io), while leaf longevity, after the A_max had been attained, was closely linked with PAR intercepted by the canopy (I). P_c expressed per the total leaf area of the plant was significantly correlated withI, while P_c calculated per unit leaf area of the plant was related toI _o Leaf potential to adapt P_c correspondingly to changes in PAR was greatest during leaf blade expansion; after the leaf had ceased to expand, changes in P_c were independent of differences in leaf irradiance. The results stress, at least for field conditions, the inadmissibility of the extrapolation of attributes from one leaf to the other ones sequentially senescing on the plant.