Levels In Leaf Tissue Research Articles

Differential Expression of the Two Subunits of Tomato Polygalacturonase Isoenzyme 1 in Wild-Type and rin Tomato Fruit.

The [beta] subunit of tomato (Lycopersicon esculentum Mill.) fruit polygalacturonase 1 is a cell wall glycoprotein that binds to and apparently regulates the catalytic PG2 polypeptide in vivo. [beta] Subunit and polygalacturonase 2 (PG2) expression have been investigated in both wild-type and ripening inhibitor (rin) mutant fruit. During fruit development and ripening, [beta] subunit expression was unrelated to expression of the catalytic PG2 protein. In wild-type fruit, [beta] subunit mRNA and protein were first detected early in development and increased to maximal levels before PG2 mRNA and protein were detected. At the onset of ripening [beta] subunit mRNA decreased dramatically, but [beta] subunit protein levels remained stable. In rin fruit, which fail to ripen, [beta] subunit expression was similar to that in wild type, although PG2 mRNA and protein were not detected. These data suggest that [beta] subunit expression is ethylene independent and regulated primarily by developmental cues. This conclusion is supported by results from ethylene-treated immature (20 days after pollination) wild-type and rin fruit in which no significant differences were observed in [beta] subunit expression patterns in response to ethylene treatment. Surprisingly, RNA blot analysis indicated that catalytic PG2 mRNA was induced in immature rin fruit after 3 d of exogenous ethylene treatment. In addition, [beta] subunit mRNA and protein were also detected at lower levels in root, leaf, and flower tissues of both genotypes, suggesting a broader functional role for the protein.

Effects of intermittent acidic irrigations on soybean yields and frogeye leaf spot

Acidic irrigations, adjusted to pH 2, were slightly injurious to leaves of Glycine max (L.) Merr., yet concentrations of most chemical elements in leaf tissue, seed yield, seed size (100 seed weight), and plant weight of two southern cultivars (‘Hampton-266A’ and ‘Kirby’) were unaffected by six or seven irrigations in the Georgia piedmont. Sulfur levels in leaf tissue receiving acidic irrigations increased above those levels in plants receiving only ambient rain, but not above those irrigated with well-water containing 10 ppm sulfate at pH 6.8–6.9. There was a suppression of lesions induced by Cercospora sojina K. Hara in acid-irrigated ‘Kirby’ soybean, but development of powdery mildew on ‘Hampton-266A’ soybean was not affected. Hydrogen ion concentrations of current ambient rains in the region probably have little effect on yields. If intermittent ambient precipitation with dramatically lower pH should occur, then frogeye leaf spot on soybean could be less severe.

Differential expression of a gene encoding an acidic dehydrin in chilling sensitive and freezing tolerant gramineae species

We have characterized a new wheat cold-regulated cDNA clone, Wcor410, that accumulates to equivalent levels in root, crown and leaf tissues during cold acclimation. The Wcor410 cDNA contains an ORF encoding a dehydrin-like glutamate-rich protein of 28 kDa with a pI of 5.1. However, the acidic nature, the absence of the glycine-rich repeat and of the conserved N-terminal region, DEYGNP, suggest that Wcor410 belongs to a different subgroup of the D11 protein family. Northern analysis showed that this gene is expressed only in freezing tolerant gramineae, whereas Southern analysis showed that the Wcor410 gene is present in all monocot species tested. The presence of freezing tolerance-associated genes in sensitive species such as rice and corn is interesting. Characterization of the regulatory factors controlling these genes may help to establish an appropriate strategy to improve freezing tolerance.

Relationship of abscisic acid to somatic embryogenesis in Dactylis glomerata

The influence of abscisic acid (ABA) on somatic embryogenesis in orchardgrass ( Dactylis glomerata L.) was studied in one embryogenic (Embryogen-P) and one nonembryogenic (I-39) genotype. Leaf segments from the basal portions of the two innermost leaves were cultured for various lengths of time on SH medium containing 0.01–20.0 μM ABA. Somatic embryogenesis was increased in Embryogen-P by a 3-day exposure to 0.01–10.0 μM ABA; 20 μM was inhibitory. I-39 did not respond to any ABA treatment. Quantification by enzyme-linked immunosorbent assay (ELISA) indicated that exogenous ABA levels in leaf tissues were nearly the same in the two genotypes at the initiation of culture but decreased much more rapidly during the first 7 days in the nonembryogenic than in the embryogenic genotype. They were the same after 14 days of culture. These results suggest that somatic embryogenesis in the embryogenic genotype may be increased by manipulation of concentration and duration of ABA application. Attempts to induce somatic embryogenesis in the nonembryogenic genotype with ABA treatments were not successful.

Changes in abscisic acid levels in bean leaves during the initial stages of host and nonhost reactions to rust fungi

Changes in abscisic acid (ABA) levels were determined in leaf tissues of French bean ( Phaseolus vulgaris) inoculated with Uromyces appendiculatus var. appendiculatus (pathogenic) and U. vignae (nonpathogenic) using an indirect enzyme-linked immunosorbent assay (ELISA) and HPLC. There was a significant decrease in abscisic acid levels both in leaf tissues and intercellular washing fluids of rust-infected bean leaves at 6 h post inoculation. Similar decreases were induced by both fungi. ABA levels remained low until at least 48 h after inoculation. No evidence was found for production of ABA by differentiated urediospore germlings of either U. appendiculatus or U. vignae. The results suggest that the decrease in ABA levels is a nonspecific result of changes brought about by infection, prior to cell penetration, and that this growth regulator is not a determinant of successful fungal invasion.

Regulation of maize root nitrate reductase mRNA levels

The regulation of maize (Zea mays L. cv. W64A x W182E) root nitrate reductase (NR) transcript levels has been investigated. To facilitate this process a partial nitrate reductase cDNA clone has been isolated from a maize root cDNA library. Its derived amino acid sequence was found to be more similar to that of the barley nicotinamide adenine dinucleotide (phosphate)‐reduced from [NAD(P)H] bispecific isoform of NR than to that of the maize leaf NADH:NR. The amount of NR mRNA in maize roots was found to increase very rapidly upon the addition of nitrate, reaching a maximum approximately 30 min after induction in the root tip. The level of NR mRNA was analysed in leaf and root tissue. There was very little cross‐hybridizing mRNA in leaf tissue when the root cDNA clone was used as a probe. Conversely, the leaf NADH:NR cDNA clone hybridized to an mRNA that was present at considerably higher levels in leaf tissue than in root tissue, although there was a clearly detectable level of this transcript present in the roots. Finally, the level of root NR mRNA was analyzed by using the tissue print technique to study its localization at the cellular level. The greatest amount of NR transcript was found in the region just above the root tip. At the cellular level, NR mRNA was found in all root cell types.

N, P, and K Rates and Leaf Tissue Standards for Optimum Anthurium andraeanum Flower Production

The optimum fertilizer levels of N, P, and K for flower production of field-grown Anthurium andraeanum Andre in Hawaii were determined. Applications were at 0, 224, and 448 kg·ha-1·year-1 with all combinations of each nutrient level. Optimum flower production was achieved at 312N-448P-375K kg·ha-l·year-1. Increased N and K application resulted in a linear increase in flower size. Flower stem length also increased with increasing N, P, and K rates. Maximum flower yield occurred when leaf-tissue levels were 1.87% N, 0.17% P, and 2.07% K. Flower stem length and flower size were at their maximum with leaf N at 1.59% and 1.67% and K at 2.20% and 1.86%, respectively. No relationship was observed between leaf percent P, flower size, or stem length. A range of leaf-tissue levels associated with optimum anthurium flower production was determined for Ca, Mg, B, Mn, Fe, Zn, Cu, and Mo).

ELEMENTAL TISSUE LEVELS FOR ANTHURIUM FLOWER PRODUCTION

Critical tissue levels for flower production of field grown Anthurium andraeanum Andre were established. Maximum flower production was obtained when leaf tissue levels were 1.87% N, 0.17% P, and 2.07% K. A range of elemental leaf tissue levels associated with optimum flower production were also determined for Ca, Mg, B, Mn, Fe, Zn, Cu and Mo.

THE EFFECTS OF ABSCISIC ACID ON GROWTH AND DEVELOPMENT OF STAGE III ROOTING ARONIA ARBUTIFOLIA (ROSACEAE)

Stage 2 micropropagules were transferred into woody plant medium supplemented with either 0, 0.1, 1, 10, 100 mg/L ABA (Abscisic acid) and with or without 1 mg/L IBA (Indole-3-butyric acid), Significant decreases in total dry weight and shoot length were observed at 1, 10 and 100 mg/L of ABA regardless of IBA concentration, Leaf area was significantly reduced in all treatments by increasing ABA levels. In the absence of IBA no callus formed but lateral roots developed. Another experiment using ABA levels of 0, 0.1, 0.5 and 0, 1 mg/L IBA was conducted. Total number of roots decreased with increasing ABA levels. Adventitious roots which formed on the stem and roots originating from root primordia were observed in all ABA levels with IBA, Callus did not form in the treatments lacking IBA. Scanning electron microscopy was used to document morphological differences due to ABA, Abscisic acid levels in leaf tissue were assayed using immunological techniques.

COPPER DEFICIENCY IN CALIFORNIA WALNUT

Initial leaf tissue-analysis indicated that the degree of distortion and dieback in a young walnut orchard was correlated with decreasing amounts of Cu in the leaf. Complete correction of Cu deficiency was obtained for two years when high rates of Kocide 101 were used or when low rates were applied repeatedly each year. Soil treatments gave partial correction; soil injected treatments showed continued improvement over time. Tissue analysis for Cu correlated well with the degree of distortion and dieback in the trees. Critical Cu levels in the walnut kernel were 4 ppm and 3 ppm in the leaf. Kernel and leaf tissue levels were highly correlated. Shriveling of the kernels was the main nut quality symptom associated with Cu deficiency. High rates of foliar or a combination of foliar and soil treatments may give the best results in young trees. Once trees are in production, the standard yearly Cu program for walnut blight control should provide adequate Cu deficiency correction.

EUSTOMA GRANDIFLORUM RESPONSE TO pH OF GROWING MEDIA

Symptoms of foliar chlorosis or bleaching, interveinal chlorosis of lower leaves, leaf edge and tip necrosis, stunted growth and delayed flowering of Eustoma increased as pH decreased below 6.5 in various peat-vermiculite based media for all cultivars tested. Symptoms were evident with or without microelement amendments in the media or fertilizer. A 5×5 factorial with pH of media and fertilizer solutions ranging from 5.1 to 7.5 indicated fertilizer pH did not negate plant response to low media pH. Leaf tissue levels of Zn were elevated at low media pH and negatively correlated to plant growth and flowering characteristics, while imbalances in tissue levels of N, P, K, Ca, Mg, Fe, Mn, Cu and B appeared to be less important. Symptomatic plants grown in media with a pH from 5.0 to 5.8 had tissue levels of Zn ranging from 200 to 1200 ppm, and plants without symptoms in media with a higher pH had leaf tissue levels from 40 to 100 ppm Zn.

The relationship between genotype, tissue age and endogenous cytokinin levels on adventitious bud formation on leaves of Lachenalia

The relationship between genotype, tissue age and endogenous cytokinin levels on adventitious bud formation on Lachenalia leaf tissue were investigated. The genotypes studied, showed a variation in bud formation. The hybrid explants responded differently to factorial combinations of BA and NAA. The growth regulators could not substitute for the regeneration potential of the genotype. Tissue age had a pronounced effect on regeneration potential. Young tissue formed the largest number of buds. An interaction between tissue age and genotype was detected. Cytokinin levels in young leaf tissue were higher than in older tissue. In young tissue no relationship was observed between the cytokinin level and the number of buds formed. However, in older tissue it appears as if a relatively low endogenous cytokinin level enhanced bud formation.

Availability and Form of Copper in Three Soils following Eight Annual Applications of Copper‐Enriched Swine Manure

AbstractThe use of high levels of Cu in swine (Sus scrofa domesticus) production to stimulate growth and improve feed efficiency is presently being questioned due to the potential environmental hazard from repeated usage of the resulting Cu‐rich manure in agricultural land. Three field studies were established in 1978 and continued through 1985 to determine the effects of long‐term applications of Cu, as either CuSO4 or Cu‐enriched swine manure, at high rates on corn (Zea mays L.) production. The studies were conducted on Bertie fine sandy loam (Aquic Hapludults), Guernsey silt loam (Aquic Hapludalfs), and Starr‐Dyke clay loam (Fluventic Dystrochrepts‐Typic Rhodudults) in the Coastal Plain, Ridge and Valley, and Piedmont regions of Virginia, respectively. These soils have CEC ranging from 5.0 to 12.3 cmolc kg−1. According to USEPA guidelines, which are based on the CEC values and pH levels ≥6.5, the three soils have a maximum safe Cu loading rate of 280 kg Cu ha−1. After 8 yr, 890.4 t ha−1 of wet Cu‐enriched manure had been applied to these soils. The manure contained up to 1550 mg Cu kg−1 and was produced by pigs fed diets with an average of 251 mg Cu kg−1. Application of 336 kg Cu ha−1 as CuSO4, or up to 264 kg Cu ha−1 as Cu‐enriched manure, from 1978 through 1985 did not decrease corn grain yields on the three soils. The eight annual Cu applications increased Cu concentrations in ear leaf tissue by ≤2.1 mg kg−1, but did not affect the Cu concentrations in the grain. The Cu levels in all plant tissue remained within normal ranges. Diethylenetriaminepentaacetic acid (DTPA)‐extractable Cu was linearly related to the amount of Cu applied to the three soils (r = 0.93−0.98, α = 0.01) and was unrelated to Cu levels in grain or leaf tissue. Small increases, up to 1.6 mg Cu kg−1, in extractable Cu in the B horizons of the Bertie and Starr‐Dyke soils indicated little downward movement of the applied Cu. Larger increases in extractable Cu in the Guernsey subsoil were attributed to downward movement caused by plowing. Copper fractionation data indicated that a substantial portion of the applied Cu has reverted to forms not available to plants.

Effect of turnip mosaic virus infection on the mineral composition of rutabaga

Abstract The effect of Turnip Mosaic Virus (TuMV) infection on the elemental composition of rutabaga (Brassica napus ssp. rapifera (Metzg) Sinsk) at maturity was examined in the greenhouse. TuMV infection markedly reduced dry weight and dry matter percentage of leaves‐plus‐petioles but did not affect storage root development. Virus‐infected plants exhibited higher N, P, Mg and Zn, but lower K levels in leaf tissues. Nitrogen, Ca, Mg and Mn accumulated in storage root tissues as a result of TuMV infection.

Molecular cloning of complementary DNA encoding the lignin-forming peroxidase from tobacco: Molecular analysis and tissue-specific expression

Plant peroxidases play a major role in lignin formation and wound healing and are believed to be involved in auxin catabolism and defense to pathogen attack. The function of the anionic peroxidase isozymes is best understood in tobacco. These isozymes catalyze the formation of the lignin polymer and form rigid cross-links between lignin, cellulose, and extensin in the secondary plant cell wall. We report the purification of the anionic peroxidase isozymes from tobacco and their partial amino acid sequence. An oligonucleotide probe deduced from the amino acid sequence was used to screen a tobacco leaf cDNA library and a 1200-base-pair cDNA clone was isolated and sequenced in its entirety. The predicted amino acid sequence revealed a 22-amino acid signal peptide and a 302-amino acid mature protein (M(r), 32,311). The amino acid sequence was compared to that of the cationic peroxidases from horseradish and turnip and was found to be 52% and 46% homologous, respectively. By RNA blot analysis, the messenger for the tobacco isozyme was found to be abundant in stem tissue while expressed at very low levels in leaf and root tissue. Four distinguishable copies of the gene were found on genomic DNA blots. The gene copy number may reflect the allotetraploid nature of Nicotiana tabacum.

Molecular characterization of the rbcS multi-gene family of Petunia (Mitchell)

The small subunit (RbcS) of ribulose bisphosphate carboxylase (RuBPCase) is encoded by eight genes in Petunia (Mitchell). These genes can be divided into three subfamilies (51, 117 and 71) based upon hybridization to three petunia rbcS cDNA clones. The nucleotide sequence of six of the eight petunia rbcS genes is presented here and the structure of the genes is discussed with respect to their genomic linkage and their expression levels in petunia leaf tissue. The rbcS genes belonging to the same subfamily encode an identical mature RbcS polypeptide, however the different subfamilies encode distinguishable polypeptides. All the genes, except one, contian two introns within the mature subunit coding region; one gene contains one extra intron within the coding region. There are large regions of nucleotide sequence homology within the introns of genes within a subfamily, but significantly less homology between the introns of genes of different subfamilies. A complex pattern of homology within the multiple genes of the 51 subfamily is observed. There are regions within these genes which share high levels of sequence homology; this homology does not extend throughout the whole gene and the regions of homology do not always occur in adjacent genes. Two 3′ rbcS gene fragments which we isolated from the petunia genome show high levels of homology to two of the intact rbcS genes.

ACCUMULATION OF PHOSPHORUS, DRY MATTER AND BETAINE DURING NaCl STRESS OF SPLIT-ROOT CITRUS SEEDLINGS COLONIZED WITH VESICULAR-ARBUSCULAR MYCORRHIZAL FUNGI ON ZERO, ONE OR TWO HALVES.

Sodium chloride tolerance and phosphorus content were examined in split-root Carrizo citrange seedlings [Poncirus trifoliata (L.) Raf. ×Citrus sinensis (L.) Osbeck] colonized with a vesicular-arbuscular mycorrhizal fungus (Glomus intraradices Schenck & Smith) on zero, one or two root halves. Plants were treated with NaCl at 0, 25, 50 or 100 mM, and the degree of stress was measured as reduction of dry matter accumulation and rise in level of leaf proline-betaine (stachydrine). Shoot and root dry weight production during this period decreased with increasing levels of salt. Absolute reductions were similar for plants inoculated on one vs two half-root systems, but percentage decreases were less in the latter due to greater overall growth in all treatments. Betaine levels in leaf tissues were positively related to soil salt levels for each mycorrhizal treatment. Significant differences in betaine levels were also detected in plants with and without mycorrhizal fungi, and mean levels tended to be higher for those colonized on one vs two halves of their root system. In contrast, a half-root system and its fungal symbiont supplied enough phosphorus to allow concentrations of leaf P to equal those of fully infected root systems, yet the two groups did not show equal growth under control conditions or percentage reductions with NaCl stress.

Variability in growth and nutrient accumulation in sorghum grown in waterlogged soils

Abstract Sorghum [Sorghum bicolor (L.) Moench] is a potential crop for use in lowland paddy soils following rice in the Philippines. Little is known about the variability in sorghum germplasm with respect to yield potential in these soils, or the alterations in mineral uptake which might occur if late season rains resulted in waterlogging. Eight sorghum cultivars including the most widely used Philippine cultivar were grown after rice under flooded or non‐flooded conditions. Flooding was initiated 30 days after seeding and terminated when most cultivars were at or near the boot growth stage. Flooding markedly reduced dry matter production, and delayed bloom date on the average of 5.5 days. Grain yield was reduced about 57% over all cultivars. Early maturing cultivars were not reduced in days to bloom as much as the late maturing types, and there was a significant cultivar x treatment interaction for both bloom date and grain yield. Later maturing cultivars outyielded the other cultivars at physiological maturity in both flooded and non‐flooded conditions. Concentrations of the major nutrients N, P, K, Ca, Mg, and S were decreased in foliage at the boot stage due to flooding. The only nutrient to fall below published “critical” levels in leaf tissue, however, was N, and plants growing in these conditions showed classical N deficiency symptoms. Iron and Mn concentrations were significantly higher in foliage at the boot stage with flooding, but not high enough to be considered toxic. Most differences observed at boot still existed at maturity, but of less magnitude. Marked variability existed in the response among cultivars to waterlogging. It would appear that flooding tolerant genotypes could be selected which would improve existing cultivar choices for use in these difficult soils.

Micronutrient, phosphorus and pH influences on growth and leaf tissue nutrient levels of Prosopis alba and Prosopis glandulosa

Nitrogen fixing trees of the genus Prosopis occur on many semiarid lands of the world, where they show potential for food and fuel production. Semiarid soils tend to be alkaline and low in organic matter, N, P and micronutrients. For both native woodlands and plantations, it is important to understand the response of Prosopis to changing fertility regimes and to develop quantitative relationships between leaf tissue mineral nutrient concentrations and productivity. The growth of two contrasting Prosopis species was compared on an inert artificial soil mixture with four lime [Ca(OH) 2] treatments to vary soil pH from 6 to 9 in the greenhouse. At each lime level a factorial design, with and without phosphorus and micronutrient additions, was used. Dry biomass was related to leaf tissue levels of N, P, K, Ca, Na, Mg, Mn, Fe, Zn, Cu and soil pH. Phosphorus was the element most limiting growth. Micronutrient additions produced little change in biomass at the lower lime levels, but at the high lime levels they increased biomass in the P amended plants. At high pH (8.9), zinc appears to play a role in decreasing toxic Na levels. It was the micronutrient most correlated with enhanced biomass production. A significant negative correlation between phosphorus and zinc tissue concentrations occurred and it appears that phosphorus can reduce zinc uptake by Prosopis.

Determination of urea and ammonia in leaf extracts: application to ureide metabolism

Methods are described for the routine determination of urea and ammonia in plant tissues. Ureido compounds such as allantoin and allantoate interfere with the urea assay but can be conveniently removed by ion-exchange chromatography prior to the color reaction with α-isonitrosopropiophenone. This assay was used to examine the effect of the urease inhibitor acetohydroxamate on leaf urea levels. A survey of methods for ammonia determination showed that for plant extracts and assay mixtures containing amides, microdiffusion followed by nesslerization provided a convenient and reliable technique. This procedure was used to determine asparaginase and glutaminase activities as well as ammonia levels in leaf tissue. In a study of detached soybean leaves, 5 mM acetohydroxamate, supplied via the transpiration stream, inhibited the production of ammonia normally observed in the presence of methionine sulfoximine (a glutamine synthetase inhibitor) and caused an accumulation of urea. The data were interpreted as evidence that leaf ammonia can arise from urea metabolism and supported a role for urea, probably derived from ureide breakdown, in the provision of nitrogen for amino acid and protein synthesis.