First Report of Cylindrocladium Black Rot (C. parasiticum) on Partridgepea and Sicklepod.

Partridgepea (Cassia fasciculata Michx.) is grown in the southeastern U.S. in food plots for game birds. In 1997, numerous dead plants were observed in a commercial planting for seed production. Perithecia of Calonectria ilicicola Boedijin & Reitsma (imperfect stage: Cylindrocladium parasiticum Crous, Wingfield & Alfenas), a serious pathogen of peanut (Arachis hypogaea L.), were found on the crown of diseased plants. Two isolates each from partridgepea and peanut were grown on potato dextrose agar for 5 weeks. Microsclerotia produced were added to a 2:1 mixture of pasteurized field soil and Pro-mix potting medium (25 microsclerotia per g of mix). Both infested and noninfested potting mixes were put in Super Cell Cone-Tainers (Stuewe & Sons, Corvallis, OR) in the greenhouse and planted to one pre-germinated seed each of either peanut or partridgepea (10 replications). Soil moisture was kept at field capacity and after 7 weeks root rot severity (0 to 4 scale with 4 = dead plant) and fresh weight of whole plants and roots were determined. Mean disease ratings for peanut were 2.1 and 2.5 with the peanut and partridgepea isolates, respectively, and 0.1 for the controls. Mean disease ratings for partridgepea were 3.2 and 3.2 with the peanut and partridgepea isolates, respectively, and 1.0 for the controls. Peanut and partridgepea plant weights were reduced by 50 and 68%, respectively, compared with controls. Reductions in root weights were similar to those for whole plants. The pathogen was consistently recovered from diseased roots. In summary, all four isolates were pathogenic to both hosts, but partridgepea was more susceptible (P ≤ 0.05) than peanut to C. parasiticum. Sicklepod (Senna obtusifolia (L.) H. Irwin & Barneby), one of the most troublesome weeds in the southeastern U.S., was previously observed to have black rot symptoms and perithecia of C. ilicicola on the crowns of diseased plants. Plants grown in soil infested with an isolate of the fungus from sicklepod exhibited typical symptoms and the pathogen was reisolated from diseased tissue. Rotation with soybean (Glycine max L.) traditionally has been the major concern for peanut production in fields with a history of Cylindrocladium black rot; however, these additional hosts also should be considered.

Cytoplasmic genetic effects and growth of hybrid mice.

Variation in cellular biochemical functions controlled by cytoplasmic genes was studied in relation to phenotypic differences between progeny of reciprocal hybrid female mice. Least squares procedures were used to test for differences in mitochondrial respiratory metabolism and in capacity for ATP synthesis, and differences in growth of progeny of hybrid dams. Under identical nuclear influences, mitochondria of A/J and C57BL/6J cytoplasms differed (P less than .10 to P less than .01) from those of BALB/cJ cytoplasm in energy conservation. No differences were detected in mitochondrial efficiency between BALB/cJ cytoplasm evaluated in different nuclear environments. Three-way cross progeny of C57BL/6J x BALB/cJ reciprocal hybrid females mated to DBA/2J males differed (P less than .05) in litter weight at weaning and 1 wk and 2 wk postweaning. The F2 progeny of reciprocal C57BL/6J x BALB/cJ dams and F2 and three-way cross progeny of reciprocal A/J x BALB/cJ dams did not differ in weight at any age measured. Across all genotypes of dam, rank correlations of mitochondrial traits with F2 litter weights were nonsignificant. Observed variation in mitochondrial functions partially controlled by cytoplasmic genes did not limit mouse growth under these experimental conditions.

Phosphate Starvation Inducible Metabolism in Lycopersicon esculentum: I. Excretion of Acid Phosphatase by Tomato Plants and Suspension-Cultured Cells.

Both tomato (Lycopersicon esculentum cv VF 36) plants and suspension cultured cells show phosphate starvation inducible (psi) excretion of acid phosphatase (Apase). Apase excretion in vitro was proportional to the level of exogenous orthophosphate (Pi). Intracellular Apase activity remained the same in both Pi-starved and sufficient cells, while Apase excreted by the starved cells increased by as much as six times over unstressed control cells on a dry weight basis. At peak induction, 50% of total Apase was excreted. Ten day old tomato seedlings grown without Pi showed slight growth reduction versus unstressed control plants. The Pi-depleted roots showed psi enhancement of Apase activity. Severely starved seedlings (17 days) reached only one-third of the biomass of unstressed control plants but, because of a combination of psi Apase excretion by roots and a shift in biomass to this organ, they excreted 5.5 times the Apase activity of the unstressed control. Observed psi Apase excretion may be part of a phosphate starvation rescue system in plants. The utility of the visible indicator dye 5-bromo-4-chloro-3-indolyl-phosphate-p-toluidine as a phenotypic marker for plant Apase excretion is demonstrated.

Phosphate Starvation Inducible Metabolism in Lycopersicon esculentum: II. Characterization of the Phosphate Starvation Inducible-Excreted Acid Phosphatase.

Three-day-old suspension cultured cells of Lycopersicon esculentum transferred to a Pi-depleted medium had 2.7 times the excreted acid phosphatase (Apase) activity of cells transferred to a Pi-sufficient medium. Cell growth during this time period was identical for the two treatments. Excreted Apase activity was resolved into two fractions on a Sephadex G-150 column. Most of the phosphate starvation inducible (psi) enhancement in activity was in the lower molecular weight fraction. These two fractions exhibited different substrate versus pH activity profiles. With a native polyacrylamide gel electrophoresis assay, the lower molecular weight fraction resolved into two bands of activity. Both column fractions resolved into the same single band of activity with sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The apparent molecular weight of this enzyme was 57 kilodalton. These data indicate that L. esculentum has at least two isozymes of the psi-excreted Apase and that these isozymes may associate to form high molecular weight aggregates. Labeling studies using [(35)S]methionine show that the psi response in tomato cells is complex and involves changes in the steady state levels of several excreted proteins.

Mitochondrial respiratory metabolism and performance of cattle.

Two groups of cows were sampled to study variation of mitochondrial metabolism. The first group included 10 lactating and five gestating Holstein cows, representing available phenotypic extremes for milk yield. The second group included 13 Angus, 13 Brangus and 13 Hereford cows, representing available extremes within breeds for growth breeding value ratios. Consistently poor mitochondrial samples were obtained from gestating cows; these were excluded from analyses. Linear correlations of Holstein mitochondrial respiratory activities with sire-predicted difference for milk and milk fat ranged from -.35 to .15. Correlations of dam and cow indices and cow yields for milk with acceptor-stimulated mitochondrial respiration, oxidative phosphorylation efficiency (adenosine diphosphate:oxygen ratio [ADP:O ratio]) and adenosine triphosphate (ATP) synthesis rate were .25 to .48, consistently higher than for milk fat, -.06 to .17. No differences among beef breeds in mitochondrial respiration rates, coupling of respiration to phosphorylation, ADP:O ratio or ATP synthesis rate were detected by repeated measures analyses of variance. No patterns were evident among correlations of the mitochondrial characteristics and growth and milk traits in beef cattle. These initial findings indicate that variability in the mitochondrial respiratory activities measured has less relation to weaning and yearling growth traits of beef cattle than to milk yield of Holstein cattle.

Molecular divergence of alfalfa somaclones.

Plantlets were regenerated from alfalfa callus following passage through a tissue culture medium which contained gibberellic acid. A proportion of these plantlets showed obvious morphological variations. Leaflet, stem and petiole tissue of these plants were extracted to yield a soluble protein homogenate which was characterized by polyacrylamide gel electrophoresis. Over 18 individual protein bands were resolved and visualized by staining with coomassie blue G250. Electrophoretic gels from regenerated plantlets and from the parent plant were scanned spectrophotometrically and analyzed. The relative quantity of each of the proteins resolved from plants was correlated with proteins of other plants via the Pearson's product-moment correlation. Cluster analysis was then performed using these correlation coefficients to judge relatedness among somaclones and the parent plant. Two of 22 somaclones (9.1%) differed significantly from the parent and from the other somaclones judged by quantitative protein pattern variations. Three distinctive lineages through tissue culture produced plantlets. Using a discriminant analysis strategy somaclones could be grouped according to lineage with 80.8% accuracy based upon distinctions between protein electrophoretic patterns. Two of the somaclone lineage groupings showed no overlap with the parental grouping which indicated significant molecular divergence of these plantlets as judged by quantitative protein differences.

Hepatic mitochondrial activity in two breeds of chicken.

Respiration rates and efficiencies of oxidative phosphorylation of hepatic mitochondria from mature Hubbard White Mountain Cross broiler and White Leghorn layer hens were compared. Broiler hen mitochondria consistently tended to exhibit higher succinate-supported State 3 respiration rate, respiratory control ratio, and ratio of adenosine diphosphate to oxygen, although breed differences were not statistically significant. Within-breed variation in mitochondrial activity was not associated with body weight or egg production. Hepatic tissue of broiler hens yielded significantly more protein in the mitochondrial fraction than tissue of layer hens. In vitro mitochondrial mixtures representing equal wet tissue weights from each breed showed mitochondrial activity intermediate between the two breeds.

Heterosis for H1 histone content in aging Drosophila hybrids.

Temporal changes in electrophoretically separated histones were investigated in a heterotic and a non-heterotic Drosophila melanogaster F1 hybrid and in their respective inbred parents. Histones were acid-extracted from isolated nuclei of larvae and of adult flies at selected age intervals. Five major histone fractions were identified, and distinct quantitative differences in H1 histones were found between early third instar larvae and adults. Age-related quantitative histone differences were also apparent when hybrids were compared with parents. Heterotic hybrids maintained a significantly higher proportion of H1 histone fractions with aging than did all parents or non-heterotic hybrids. Relative H1 histone quantity in non-heterotic hybrids paralleled the decline observed in parents. These data suggest a relation between the manifestation of hybrid vigor and the maintenance of chromatin structure during the aging process.

Cyanide-insensitive and Cyanide-sensitive O(2) Uptake in Wheat: II. GRADIENT-PURIFIED MITOCHONDRIA LACK CYANIDE-INSENSITIVE RESPIRATION.

Enriched mitochondrial fractions isolated from durum wheat seedlings via differential centrifugation exhibited classical cyanide- or antimycin A-insensitive O(2) uptake which was inhibited by either salicylhydroxamic acid or propyl gallate. Further purification of this fraction using Percoll density gradients resulted in two discrete bands which were essentially homogeneous mitochondrial populations, as verified by electron microscopy. Respiratory O(2) uptake in these two fractions was completely inhibited by cyanide or antimycin A. Addition of linoleic acid to a third-step gradient band, which was shown to contain virtually no mitochondria, resulted in demonstrable cyanide-insensitive O(2) uptake. This O(2) consumption was completely inhibited by propyl gallate or salicylhydroxamic acid, two known lipoxygenase inhibitors. In contrast, addition of linoleic acid to the two purified mitochondrial fractions did not stimulate O(2) uptake. These data indicate that lipoxygenase oxygenation, the enzyme physically separable from the mitochondria, is responsible for the cyanide-insensitive component of O(2) uptake that was observed in subcellular fractions isolated from etiolated wheat seedlings.

Effects of protectants on the activity of wheat mitochondria.

A mitochondrial fraction was isolated from durum wheat seedlings via differential centrifugation using three different tissue grinding buffers. One buffer contained bovine serum albumin (BSA), a protein proven effective in protecting mitochondria from damage during isolation. The other two buffers contained either polyethyleneglycol of M.W. 20,000D (PEG-20), a phenolic binding compound or PEG-20 plus XAD-2, a non-ionic adsorbent material. Organelles isolated with the BSA exhibited an average ADP/O ratio of 2.3 and an average respiratory control ratio of 5.1, substantially higher than those obtained with the other media. Addition of the XAD-2 to a buffer containing PEG-20 resulted in an increase in the respiratory control ratio to an average value of 3.7 vs 2.7 for organelles isolated with PEG-20 alone without causing a concomitant rise in the ADP/O ratio which remained an average of 1.9. Protein values for the mitochondrial fraction isolated with BSA ranged from 2.5 to 3 times greater than those obtained from the PEG-20 preparations. This difference in organelle protein is discussed in relation to the accurate measurement of mitochondrial respiration.

Cyanide-insensitive and Cyanide-sensitive O(2) Uptake in Wheat: I. GRADIENT-PURIFIED MITOCHONDRIA.

The mitochondrial fraction isolated from durum wheat seedlings by differential centrifugation demonstrated antimycin A- or cyanide-insensitive O(2) uptake. Further purification of this initial mitochondrial pellet using a linear Percoll (Pharmacia) density gradient separated the mitochondria into two bands of physiologically distinct activity. Based on the usual mitochondrial respiratory criteria of ADP/O and respiratory control values, these fractions were qualitatively similar to the crude pellet. However, we observed no antimycin A-insensitive O(2) uptake in either gradient band. Antimycin A-insensitive O(2) consumption could be restored to the upper gradient band of mitochondria by the addition of linoleic acid. This activity was inhibited either by salicylhydroxamic acid or propyl gallate, a known lipoxygenase inhibitor. Likewise, addition of linoleic acid to the crude mitochondrial pellet elicited a 4- to 5-fold increase in O(2) uptake. This O(2) consumption was insensitive to antimycin A and cyanide but was inhibited by either propyl gallate or salicylhydroxamic acid. Electron microscopic examination revealed that only the lower gradient band contained contamination-free mitochondria, which, in turn, lacked ability to oxidize linoleic acid. Antimycin A-insensitive O(2) consumption in the differential centrifugation fraction from germinating durum wheat seedlings decreased over 64 hours of development.

Histones and histone-DNA ratios in diploid and polyploid cottons.

Histones are nuclear proteins which repress gene transcription and modify chromosome structure. They are remarkably conservative in structure throughout a wide evolutionary array of plants and animals; however, quantitative histone differences have been detected by cytological means in species having extra chromosomes. The purpose of this study was to: 1) isolate and characterize the histones of several Gossypium species and 2) relate differences to known differences in vigor, ploidy level, and genome constitution or size. Histones extracted from isolated nuclei of leaf tissues were characterized by electrophoresis on polyacrylamide gels into 14 subfractions of the five major histone classes. The subfractions were identified by various means including co-electrophoresis with known histone standards. Densitometric analysis revealed only slight quantitative differences in subfraction ratios between species. Histone-DNA ratios were significantly higher in the pentaploid species. This observed increase is considered a result of genome imbalance. These data support the premise that histones may function as generalized gene deactivators in plant species having multiple genomes.

Comparison of Light-dependent Oxygen Uptake, Protochlorophyll(ide)-650 Photoconversion, and Chlorophyll Disappearance in Wheat Etioplasts.

Red light exposures given to dark-grown wheat seedlings (Triticum aestivum L.) prior to etioplast isolation reduced the ability of these organelles to consume O(2). The same preharvest red light exposures also decreased protochlorophyll(ide) content of etioplasts. In addition, regeneration of both O(2) uptake rates as well as protochlorophyll(ide) levels followed a parallel time course. These similarities suggested that photoconversion of protochlorophyll(ide)-650 to chlorophyll(ide) may mediate some process with O(2) as the electron acceptor. This process appears to involve photooxidation of nonphotoconvertible protochlorophyll(ide) as well as of newly formed chlorophyll(ide). This hypothesis is further supported by the observations that: (a) the in vitro light induced O(2) uptake phenomenon was observed in solubilized protochlorophyll(ide) holochrome preparations; and (b) photoinduced O(2) uptake was reduced to zero rate by light exposure time equivalent to that required for chlorophyll(ide) and nonphotoconvertible protochlorophyll(ide) destruction.

Light-mediated Oxygen Uptake Measured in Wheat Etioplasts.

An in vitro O(2) assay was used to measure early response of wheat (Triticum aestivum L.) etioplasts to light. A transient photoinducible O(2) uptake occurred when dark-grown etioplasts were initially exposed to light. The rate of inducible O(2) consumption was dependent on both the intensity of light and the quantity of organelle protein present. Higher light intensities resulted in greater O(2) utilization per minute, and a greater quantity of organelle protein in the sample resulted in an increased rate of O(2) uptake under the same light intensity conditions. Experiments with various plant tissues as well as with mitochondrial respiratory inhibitors indicated that etioplasts are the organelles responsible for the photoinduced O(2) uptake phenomenon. A preliminary action spectrum study revealed that wavelengths 640 to 680 nm resulted in maximum O(2) uptake. This indicated the presence of an etioplast red light receptor pigment which induces O(2) uptake in etioplasts.