Growth and chlorophyll production in plant callus tissues grown in vitro

Summary Growth, nutrition and chlorophyll development were studied in chlorophyllous callus tissues isolated from the following edible angiospermous plants: carrot root, crown gall of tomato, endive embryo, leaf petiole and stem of lettuce, leaf petiole of parsley, pea stem and rose stem. Growth patterns of these tissues in vitro were sigmoid. Synthetic media produced less growth, in terms of fresh weight increase, than media containing coconut milk, a highly complex and little understood natural substance. Murashige and Skoog's synthetic medium proved useful for satisfactory growth and chlorophyll production in a number of tissues. Its usefulness was further increased by additional amounts of copper sulphate, potassium nitrate and monobasic ammonium phosphate. Increased levels of iron and magnesium inhibited growth. Incorporation of yeast extract in the tobacco-high-salts-medium produced the highest amount of growth and chlorophyll formation in endive tissue. Presence of exogenous sucrose was essential for the continued good growth of the above callus tissues in vitro. Highest amount of growth took place either in white light or in the dark. Different tissues had different responses to high or low intensities of light. Endive and carrot tissues produced in vitro were palatable to human taste. Endive tissue was particularly good as it also differentiated many small rosettes of leaves, shoots and had a mild aromatic flavor typical of the endive plants grown in nature.     

Methods for Observing Microbial Biofilms Directly on Leaf Surfaces and Recovering Them for Isolation of Culturable Microorganisms

Epifluorescence microscopy, scanning electron microscopy, and confocal laser scanning microscopy were used to observe microbial biofilms directly on leaf surfaces. Biofilms were observed on leaves of all species sampled (spinach, lettuce, Chinese cabbage, celery, leeks, basil, parsley, and broad-leaved endive), although the epifluorescent images were clearest when pale green tissue or cuticle pieces were used. With these techniques, biofilms were observed that were about 20 (mu)m in depth and up to 1 mm in length and that contained copious exopolymeric matrices, diverse morphotypes of microorganisms, and debris. The epifluorescence techniques described here can be used to rapidly determine the abundance and localization of biofilms on leaves. An additional technique was developed to recover individual biofilms or portions of single biofilms from leaves and to disintegrate them for isolation of the culturable microorganisms they contained. Nineteen biofilms from broad-leaved endive, spinach, parsley, and olive leaves were thus isolated and characterized to illustrate the applications of this technique.     

In vitro culture of unfertilized ovules in carrot (<Emphasis Type="Italic">Daucus carota</Emphasis> L.)

To induce development of isolated carrot ovules, flowers were pollinated with pollen from different species. Effects of pollen origin, medium composition, and light conditions were evaluated for 13 carrot cultivars. The highest efficiency of development was recorded following pollination of carrot flowers with parsley pollen. The highest frequency of embryo formation (0.84%) was obtained for cv. ‘Flamanka’; whereas the highest frequency of callus formation (1.56%) was obtained for cv. ‘Karlena’. Medium supplemented with indole-3-acetic acid (IAA) promoted embryo development (0.63%), while supplementation with 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzyladenine (BA) promoted callus development (1.34%). Placement of isolated ovules in the dark stimulated embryo development. Embryos and calli thus obtained were regenerated into plants. Flow cytometry revealed that 97.7% regenerants were diploid. Based on a phosphoglucoisomerase (PGI) isozyme assay, 45.9% diploid regenerants were homozygous. Pollen tube growth of parsley, parsnip, celery, and cabbage in carrot pistils were studied using the aniline blue fluorescent method. The pollen tube growth was inhibited in transmitting tissues of the pistils.     

Development of a toxic bait for control of eastern lubber grasshopper (Orthoptera: Acrididae)

This study assessed baits for eastern lubber grasshopper, Romalea guttata (Houttuyn). When offered a choice among several grain-based baits (rolled oats, wheat bran, oat bran, yeast, corn meal, cornflakes) and vegetable oils (canola, corn, peanut, soybean), eastern lubber grasshopper adults preferred bait consisting of wheat bran carrier with corn oil as an added phagostimulant. Other carriers were accepted but consumed less frequently. Discrimination by eastern lubber grasshoppers among oils was poor. Similarly, addition of flavorings (peppermint, anise, lemon, banana) resulted in few significant effects. The carbaryl, wheat bran, and oil bait developed in this study was effective at causing eastern lubber grasshopper mortality in field-cage studies. Significant mortality occurred even though grasshoppers had to locate dishes of bait in a large cage, and could feed on daylilies, or grass growing through the bottom of the cage, rather than on the bran flakes. Consumption of as little as a single carbaryl-treated bran flake could induce mortality, although individuals varied greatly in their susceptibility. The bait matrix developed in this study was readily consumed when in the presence of some plant species. We expect that wheat bran and corn oil bait would be most effective as protection for less preferred plants (tomato, pepper, eggplant, leek, parsley, fennel, daylily, lily of the Nile, and canna lily) because baits were readily consumed in the presence of these plants. Plants that are readily consumed in the presence of bait (preferred plants) included butter crunch lettuce, carrot, yellow squash, cauliflower, collards, green onion, chive, cucumber, cabbage, cantalope, endive, red leaf lettuce, society garlic, caladium, and amaryllis. Baits are likely to be less effective in the presence of such plants. On average, vegetables in Solanaceae (i.e., tomato, pepper, and eggplant) and Apiaceae (i.e., fennel and parsley) elicited high levels of bait-feeding activity, indicating that these vegetables were not highly preferred. The plants tested from Liliaceae, Cucurbitaceae, Asteraceae, and Brassicaceae elicited an intermediate-to-low level of bait feeding.     

Pseudomonads associated with midrib rot and soft rot of butterhead lettuce and endive

During the past ten years, bacterial soft rot and midrib rot of glasshouse-grown butterhead lettuce (Lactuca sativa L. var. capitata) and field-grown endive (Cichorium endivia L.) has become increasingly common in the region of Flanders, Belgium. Severe losses and reduced market quality caused by bacterial rot represent an important economical threat for the production sector. Symptoms of midrib rot are a brownish rot along the midrib of one or more inner leaves, often accompanied by soft rot of the leaf blade. Twenty-five symptomatic lettuce and endive samples were collected from commercial growers at different locations in Flanders. Isolations of dominant bacterial colony types on dilution plates from macerated diseased tissue extracts yielded 282 isolates. All isolates were characterized by colony morphology and fluorescence on pseudomonas agar F medium, oxidase reaction, and soft rot ability on detached chicory leaves. Whole-cell fatty acid methyl esters profile analyses identified the majority of isolates (85%) as belonging to the Gammaproteobacteria, which included members of the family Enterobacteriaceae (14%) and of the genera Pseudomonas (73%), Stenotrophomonas (9%), and Acinetobacter (3%). Predominant bacteria were a diverse group of fluorescent Pseudomonas species. They were further differentiated based on the non-host hypersensitive reaction on tobacco and the ability to rot potato slices into 4 phenotypic groups: HR-/P- (57 isolates), HR-/P+ (54 isolates), HR+/P (16 isolates) and HR+/P+ (35 isolates). Artificial inoculation of suspensions of HR-, pectolytic fluorescent pseudomonads in the leaf midrib of lettuce plants produced various symptoms of soft rot, but they did not readily cause symptoms upon spray inoculation. Fluorescent pseudomonads with phenotype HR+ were consistently isolated from typical dark midrib rot symptoms, and selected isolates reproduced the typical midrib rot symptoms when spray-inoculated onto healthy lettuce plants.     

Temperature Control and Metabolic Drifts in Ageing Disks of Storage Tissue

The respiratory drifts of ageing disks of sugar-beet, red beet,carrot, swede, and potato maintained at different temperatureshave been determined mano-metrically. The general pattern ofthe respiratory time-drift exhibited by all tissues is thatof a hyperbolic curve but its exact form is largely determinedby the temperature of pretreatment, higher temperatures causinga telescoping effect. Different respiratory time-drifts obtainedby earlier workers from the same tissue are shown to be explicablein terms of the temperature of pretreatment. Except in swededisks, estimations of total and reducing sugar content of thedisks throughout the experimental period revealed a very considerableconversion of sucrose (or starch in potato) to reducing sugars.In sugar-beet, red beet, carrot, and potato the concentrationof reducing sugar is positively correlated with the rate ofrespiration. The character of the respiratory time-drift inthe disks is discussed in relation to substrate concentrationand other possible determinants.     

Plant-parasitic nematodes associated with semi-temperate vegetables in the highlands of Benguet Province,Philippines

Thirteen genera (Aphelenchoides, Criconemella, Ditylenchus, Globodera, Helicotylenchus, Hoplolaimus, Meloidogyne, Longidorus, Paratrichodorus, Pratylenchus, Trichodorus, Tylenchus and Xiphinema) of plant-parasitic nematodes were found associated with 15 semi-temperate vegetable crops in Benguet Province, Philippines. Among these taxa, Helicotylenchus, Meloidogyne and Pratylenchus were the most predominant. Four taxa that can vector plant viruses were also found: Trichodorus, Paratrichodorus, Longidorus and Xiphinema. The taxa Paratrichodorus, Longidorus and Xiphinema have not been reported previously on semi-temperate vegetable crops in the Philippines. The most predominant nematode species were H. dihystera, P. penetrans and Meloidogyne spp. These nematodes were found abundantly in five out of the nine municipalities surveyed: Atok, Bakun, Buguias, Kibungan and Mankayan. The incidence of Criconemella sp., G. rostochiensis, Hoplolaimus sp., Longidorus sp., Trichodorus sp. and Tylenchus sp. was also recorded in at least one municipality. The predominant nematode species were also found on every vegetable crop examined. More particularly, H. dihystera was highly abundant on cucumber, cauliflower, Chinese cabbage, sweet pepper, snap bean and onion; P. penetrans was highly abundant on carrot, celery, garden pea, broccoli, cabbage, Chinese cabbage, Chinese mustard, onion, potato, radish and lettuce; Meloidogyne spp. were highly abundant on celery, cucumber, Chinese mustard, carrot, sweet pepper and potato. According to the formula by Fortuner and Merny (1973 Fortuner, R and Merny, G. 1973. Les nématodes parasites des racines associés au riz en Basse Casamance (Senegal) et en Gambie, Cahiers de l'Orstom. Série Biologique, 21: 3–20.  [Google Scholar]) for identifying the potential plant pathogens, these predominant nematode species were classified as potential pathogens with the ability to cause economic loss which shows that they are probably important active pathogens of these semi-temperate vegetables. The incidence of other nematode species in the rhizosphere included G. rostochiensis on sweet pepper, garden pea and potato; D. dipsaci on onion; Tylenchus sp. on lettuce, onion and broccoli; A. fragariae on carrot, lettuce, broccoli and onion; Criconemella sp. on cucumber and cauliflower; Longidorus sp. on carrot, celery, cucumber, broccoli, cabbage, cauliflower, Chinese mustard, snap beans, onion, potato and radish; X. americanum on lettuce, broccoli and onion; Paratrichodorus sp. on carrot, lettuce, onion and potato; and Trichodorus sp. on snap bean, potato and radish.     

Use of monoclonal antibody to potato leafroll virus for detecting groundnut rosette assistor virus by ELISA*

Three of 10 monoclonal antibodies (MAbs) produced to potato leafroll luteovirus (PLRV) were found to react in triple antibody sandwich ELISA (TAS-ELISA) with groundnut rosette assistor luteovirus (GRAV), though none reacted with four other luteoviruses (barley yellow dwarf, bean leaf roll, beet western yellows or carrot red leaf)- The most effective PLRV MAb, SCR 6, was used in TAS-ELISA to detect isolates of GRAV from groundnut plants with chlorotic, green and mosaic forms of rosette from Nigeria and Malawi. The test also detected GRAV in extracts of single Aphis craccivora.     

Beet leafhopper (Hemiptera: Cicadellidae) settling behavior, survival, and reproduction on selected host plants

Experiments were conducted to determine the settling behavior, survival, and reproduction of the beet leafhopper, Circulifer tenellus (Baker), when maintained on selected host plants. This leafhopper was recently identified in the Columbia Basin of Washington and Oregon as the probable vector of the beet leafhopper-transmitted virescence agent phytoplasma, causal agent of several vegetable crop diseases, including potato purple top. Plants selected for study were sugar beet, Beta vulgaris L.; radish, Raphanus sativus L.; dry bean, Phaseolus vulgaris L.; potato, Solanum tuberosum L.; carrot, Daucus carota L.; and tomato, Lycopersicon esculentum Mill. Leafhopper adults were confined on caged plants, and settling behavior was observed during a 72-h period and survival was monitored for 40 d. Also, oviposition and nymphal production were investigated by maintaining leafhoppers for approximately 90 d on each of the selected plants. Sixty to 100% of leafhoppers settled on all studied plants during the first 5 h, but settling on bean and tomato declined sharply thereafter. Leafhopper mortality was very high on bean and tomato, with 95 and 65% of the leafhoppers, respectively, dying in about a week. In contrast, 77, 90, and 95% of leafhoppers maintained on potato, sugar beet, and radish, respectively, survived until the end of the 40-d experimental period. Beet leafhopper oviposition and nymphal production and development only occurred on sugar beet, radish, and potato; reproduction was lower on potato.     

A Comparative Study of Chlorophyll Production in Cotyledons

Chlorophyll production was studied in four species with cotyledonsdiffering widely in photosynthetic potential. When cotyledons were detached from dark-grown seedlings at intervalsduring germination and exposed to light for 24–48 h, maximumchlorophyll production was found after 8 days of dark-germinationin french bean, runner bean, and lupin, and after 5 days inmustard. Chlorophyll formation was reduced when the cotyledonswere detached earlier or later than this time, and during thefirst 1–2 days of germination the cotyledons producedvery little chlorophyll. With later times of excision the abilityto accumulate chlorophyll increased, rapidly in lupin and mustardand more slowly in the beans. A comparison of chlorophyll accumulation by attached cotyledonsand those excised during the first 24 h of germination showeda fourfold enhancement of chlorophyll content in detached french-beancotyledons and a fourfold reduction in chlorophyll content indetached mustard cotyledons, whilst chlorophyll accumulationwas similar in both the attached and detached cotyledons oflupin. The results are discussed in relation to the possible promotiveand inhibitory influence of the seedling axis on greening ofcotyledons differing in their potential for expansion and inthe amount of reserve material stored.     

Methods of Inoculation of Faba Bean Plants with Sclerotinia sclerotiorum

Different organic materials colonized by the fungus were applied, as an energy-rich inoculum, on faba bean plants cv. Polycarpe in growth chamber experiments. The organic materials used were colonized pieces of celery stems, faba bean petioles, and carrot root, blocks of cultures on potato dextrose agar and pieces of sclerotia. The inoculum was left attached to the plant stems for 48 h. After removal of the inoculum the plants were scored for disease incidence and severity. It was found that colonized pieces of carrot root produced the most uniform disease incidence and severity.     

The effects of actinomycin D on the greening of etiolated bean leaves

The effects of actinomycin D on chlorophyll formation in beanleaves were studied. Chlorophyll formation was inhibited inilluminated bean leaves. In etiolated leaves and actinomycinD-treated illuminated leaves, we observed the accumulating ofRNA components, probable precursors of ribosomal RNA. (Received August 14, 1971; )     

Inhibition of succinate oxidation by the herbicide UKJ72J

The inhibitory activity of the herbicide UKJ72J on succinate oxidation in mitochondria from various plant species was studied. In monocotyledons (Gramineae: wheat, oat, maize; Liliaceae: onion, leek) succinate oxidation was affected only at high concentrations. Among dicotyledons widely differing sensitivities were found: in Solanaceae (tomato, potato, tobacco), Leguminosae (mung bean, soybean) and Compositae (sunflower) I₅₀ concentrations for UKJ72J inhibition were below 55 μM. In Cruciferae (turnip, cauliflowers Chenopodiaceae (lambsquarter, beetroot) and Compositae (endive) I₅₀ were between 100 and 250 μM, whereas in Rosaceae (apple, pear) and Umbelliferae (carrot, fennel) I₅₀ were near (apple) or higher than 500 μM. No correlation could be found between the sensitivity to UKJ72J of mitochondrial succinate oxidation in these families and their location in the presently accepted flowering plant classification.     

Fate of Listeria monocytogenes on four types of minimally processed green salads

The fate of Listeria monocytogenes on green leafy vegetables (broad-leaved endive, curly-leaved endive, butterhead lettuce and lamb's lettuce) was studied. Populations of L. monocytogenes increased by 1.5 log in 7 d at 10°C on broad-leaved endives and butterhead lettuce, by 0.5 log on curly-leaved endives and decreased by 1 log on lamb's lettuce. Growth patterns of the epiphytic microflora were similar among the four salad types.     

Effectiveness of some substances in the control of carrot and parsley roots against fungal diseases

Field experiments were carried out in the years 2005 and 2006 on carrot cv. 'Koral' and 'Perfekcja', and parsley cv. 'Berlinska' and 'Cukrowa'. Effectiveness of substances: Biochikol 020 PC (biologically active substances BAS--chitosan 20 g/dm3), Bioczos BR (extract of garlic 10 g/1 brick) and Biosept 33 SL (extract of grapefruit 33%) on seedling roots of carrot and parsley was studied. As the standard fungicide Zaprawa Funaben T (carbendazim 20% + tiuram 45%) was used. Roots of carrot and parsley were treated one of tested substances spring immediately before planting seedling roots. During vegetation period the growth of seedling shoots and setting of seeds, and their infestation by fungal and bacterial pathogens was noticed. Among substances used for spring dressing of carrot and also parsley seedling roots, the best efficacy exhibited Zaprawa Funaben T in both years of observation. The highest yield of carrot seeds had combination roots cv. 'Koral' and parsley seeds roots cvs 'Berlińska' and 'Cukrowa' dressed Zaprawa Funaben T. Effectiveness of biopreparates Biochikol and Biosept was lower in comparison with the standard fungicide, but their protective effect was significantly higher than in control. Bioczos had the lowest control efficacy.     

农作物钾离子通道基因的生物信息学分析

以AtAKT1所编码的氨基酸序列为检索序列,通过对GenBank NR数据库以及EMBL、DDBJ、PDB数据库进行检索,发现水稻、小麦、大麦、玉米、烟草等作物中具有cds全长的34个疑似K~+通道基因.其中:水稻7个,玉米6个,烟草4个,马铃薯、胡萝卜、大麦各3个,葡萄、番茄各2个,蚕豆、小麦、油菜、甜瓜等各1个;有25个基因经过功能验证确定为K~+通道基因.利用比较基因组学,将剩余的9个基因确定为K~+通道基因.对34个K~+基因进化关系的分析表明,与AtAKT1的同源性较高的K~+通道基因为马铃薯的SKT1(相似性71%)、番茄的LKT1(相似性71%)、胡萝卜的DKT1(相似性69%)、烟草的NKT1(相似性62%).     

The Adsorption of a Polygalacturonase Isoenzyme of Botryodiplodia theobromae on Plant Tissues and the Implication on the Pathogenicity of the Fungus

The polygalacturonase isoeazyme (PG 3) of Botryodiplodia theobromae extracted from rotted sweet potato was adsorbed by sweet potato, potato, carrot, bean stem and tomato fruit to various degrees. Adsorption was greater with sweet potato and tomato fruit tissues. Carrots, bean stem and potato absorbed the enzyme to more or less the same degree. The enzyme was not adsorbed on tomato stem. A spore/mycelial suspension of B. theobromae infected the test tissues to various degrees. The enzyme completely macerated sweet potato roots, potato tubers and tomato fruits within 5 h while the bean stem and onion tissues were little affected by the enzyme. The tomato stem was neither infected by the fungus nor macerated by the enzyme.     

The effect of sugars on inverse relation between the growth and chlorophy11 synthesis in tobacco tissue

Cytokinin-dependent and cytokinin-autonomous strains of tobacco callus tissue (Nicotiana tabacum L. cv. ‘Wisconsin 38’) were grown on media containing sucrose, glucose and fructose, respectively. The tissues were kept 14 days in darkness and then transferred for 9 days to continuous light after which time the fresh weight and chlorophyll content were estimated. The highest chlorophyll concentration was recorded at sugar levels which were either suboptimal (sucrose in the case of cytokinin-dependent strain) or supraoptimal (all other sugars for both strains and sucrose for the cytokinin-autonomous strain) for tissue growth. The chlorophyll concentration was increased when the tissue was cultured on media containing glucose or fructose,i.e. sugars whioh did not support the growth as well as sucrose. Chlorophyll synthesis in the cytokinin-autonomous strain is significantly lower than in the cytokinin-dependent strain. This difference was independent of either sugar source or concentration. These results support the observed inverse relationship between tissue growth and plastid development and the limited metabolic activity of plastids in cytokinin-autonomous tissues.     

Expression of early and late-emerging phenotypes in both diapausing and non-diapausing Delia radicum L. pupae

Feeding preferences of nymphs of a predatory stink bug, Eocanthecona furcellata, to Spodoptera litura larvae fed with various food items were examined. Bugs preferred larvae fed with spinach leaves to those feeding on bean sprouts. Solvent extracts of S. litura larvae given spinach or lettuce leaves contained a large amount of (E)-phytol which was found to elicit the proboscis-protruding behavior of this bug. (E)-Phytol was not detected in similar extracts of larvae fed with bean sprouts containing no (E)-phytol. When S. litura larvae fed with artificial diets containing various amounts of chlorophyll, the (E)-phytol contents in those larvae and their feces increased in proportion to the dietary chlorophyll contents, indicating that (E)-phytol was derived from the chlorophyll ingested through hydrolysis. Bugs showed the proboscis-protruding behavior in response to extracts of larvae fed with spinach and lettuce leaves or a kidney-bean artificial diet, and their response depended on (E)-phytol contents. On the other hand, extracts of larvae fed with bean sprouts were not effective. When a larva fed with bean sprouts was treated with (E)-phytol and presented together with a larva fed with spinach leaves, bugs failed to distinguish between the two. These results indicate that (E)-phytol originating from chlorophyll in the prey diet serves as an important cue in the prey-locating behavior of E. furcellata.     

Study of the aggressiveness of Rhizoctonia solani isolates

This paper presents an in vitro test to screen the pathogenicity of different Rhizoctonia solani isolates on a host range. The level of aggressivity of the different isolates was different for several host plants tested. There were significant differences between the crops and the isolates tested. In general, the disease level was higher on beans, lettuce and cabbage. In carrot and rye grass the level of infection was lower for the isolates of R. solani tested. The potato isolates of R. solani were less aggressive than the isolates coming from maize, fodder beet and sugar beet. The R. solani isolates were also biochemically characterized by pectic zymograms: the isolates Rs0401 (from maize) and Rs0504 (from sugar beet) belong both to the anastomosis group AG2-2.