scholarly journals What Could Arrest an Eriophyoid Mite on a Plant? The Case of Aculops allotrichus from the Black Locust Tree

Insects ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1031
Author(s):  
Katarzyna Michalska ◽  
Marcin Studnicki
Keyword(s):  
Black Locust ◽  
Leaf Disc ◽  
Leaf Discs ◽  
Eriophyoid Mite

Aculops allotrichus is a vagrant eriophyoid that lives gregariously on the leaves of the black locust tree. This study demonstrated that conspecifics can have a significant impact on A. allotrichus females on unprofitable, old black locust leaves and can arrest them on those leaves. The effect was more pronounced in females that were exposed to artificially injured individuals than to intact ones. They not only prolonged their sojourn on leaf discs with pierced conspecifics, but also preferred the leaf disc halves with damaged individuals to clean ones. Aculops allotrichus is the first described herbivore in which artificially injured conspecifics, instead of causing alarm, keep the foraging individuals within a risky patch. Other objects, such as artificially injured or intact heterospecifics, pollen or sand, were irrelevant to the eriophyoid females on old leaf patches. In tests with old leaves of maple, magnolia and hard kiwi vine, the females postponed their movement from non-host leaf discs, which suggests that they may need more time to recognise and evaluate unfamiliar plants than familiar ones.

Resistance of Solanaceous and non-Solanaceous species to Peronospora tabacina as shown by necrotrophic reactions

1971 ◽  
Vol 11 (48) ◽  
pp. 94 ◽  
Author(s):  
M Mandryk
Keyword(s):  
Leaf Disc ◽  
Peronospora Tabacina ◽  
Nicotiana Species ◽  
Leaf Discs ◽  
Solanaceous Species ◽  
Wide Range ◽  
Disc Area ◽  
Susceptibility Status

A necrotrophic reaction in leaf discs of a wide range of Nicotiana and other Solanaceous and non-Solanaceous species following infection by Peronospora tabacina Adam is described.With a few exceptions, species resistant to the pathogen developed water-soaking or gave no reaction, whereas susceptible species showed necroses affecting 60-100% of the leaf disc area. The degree if necrotrophic reaction is related to the resistance-susceptibility status of Nicotiana species, and it may be extended to detect susceptibility to the pathogen in Petunia, Capsicum, Lycopersicon, Hyoscyamus, Schizanthus, and other genera related ti Nicotiana.

scholarly journals Effect of Detergent on the Quantification of Grapevine Downy Mildew Sporangia from Leaf Discs

HortScience ◽  
2015 ◽  
Vol 50 (5) ◽  
pp. 656-660 ◽  
Author(s):  
Atsushi Kono ◽  
Akihiko Sato ◽  
Bruce Reisch ◽  
Lance Cadle-Davidson
Keyword(s):  
Downy Mildew ◽  
Leaf Disc ◽  
Plasmopara Viticola ◽  
Inhibitory Effect ◽  
Tween 20 ◽  
Infected Leaf ◽  
Grapevine Downy Mildew ◽  
Visual Rating ◽  
Leaf Discs ◽  
Highly Correlated

Grapevine downy mildew (DM), caused by the oomycete Plasmopara viticola (Berk. & Curt.) Berlese & de Toni, is a major disease, especially in humid viticultural areas. Development of resistant cultivars is an important objective for grapevine breeding. To establish a reliable and inexpensive quantitative method to aid in breeding for DM resistance, we improved the method for counting the number of sporangia on leaf discs, and developed a method for counting the number of sporangia in solution. To prevent the loss of DM sporangia from adhesion onto plastic ware, we found as little as 0.01% Tween 20 was effective. On the other hand, this detergent was shown to have a severe inhibitory effect upon DM infection of leaves. We developed a sporangia counting method using dried droplets of DM suspensions, and the method was highly correlated with counting by hemacytometer (R2 > 0.96). The nonparametric Spearman’s rank correlations between visual rating and the number of the sporangia were as high as ρ = 0.82 to 0.91, suggesting that evaluation by the visual rating could provide a good estimate of the sporangia numbers on leaf discs. We established a high-throughput and inexpensive method with acceptable accuracy for DM resistance evaluation based on a leaf disc assay, and our results suggested that visual ratings of infected leaf discs provide a good estimate of sporangia numbers.

Assessment of two nondestructive assays for detecting glyphosate resistance in horseweed (Conyza canadensis)

Weed Science ◽  
2005 ◽  
Vol 53 (4) ◽  
pp. 438-445 ◽  
Author(s):  
Clifford H. Koger ◽  
Dale L. Shaner ◽  
W. Brien Henry ◽  
Talia Nadler-Hassar ◽  
Walter E. Thomas ◽  
...  
Keyword(s):  
Leaf Disc ◽  
Glyphosate Resistance ◽  
Conyza Canadensis ◽  
Dependent Manner ◽  
Leaf Discs ◽  
Plant Sensitivity ◽  
Soybean Plants ◽  
Nondestructive Assays ◽  
Dose Dependent

Two rapid, nondestructive assays were developed and tested for their potential in differentiating glyphosate-resistant from glyphosate-susceptible biotypes of horseweed. In one assay, leaves of glyphosate-resistant and -susceptible corn, cotton, and soybean plants, as well as glyphosate-resistant and -susceptible horseweed plants, were dipped in solutions of 0, 300, 600, and 1,200 mg ae L−1glyphosate for 3 d, and subsequent injury was evaluated. In the second assay, plant sensitivity to glyphosate was evaluated in vivo by incubating excised leaf disc tissue from the same plants used in the first assay in 0.7, 1.3, 2.6, 5.3, 10.6, 21.1, 42.3, and 84.5 mg ae L−1glyphosate solutions for 16 h and measuring shikimate levels with a spectrophotometer. The leaf dip assay differentiated between glyphosate-resistant and -susceptible crops and horseweed biotypes. The 600 mg L−1rate of glyphosate was more consistent in differentiating resistant and susceptible plants compared with the 300 and 1,200 mg L−1rates. The in vivo assay detected significant differences between susceptible and glyphosate-resistant plants of all species. Shikimate accumulated in a glyphosate dose–dependent manner in leaf discs from susceptible crops, but shikimate did not accumulate in leaf discs from resistant crops, and levels were similar to nontreated leaf discs. Shikimate accumulated at high (≥ 21.1 mg ae L−1) concentrations of glyphosate in leaf discs from all horseweed biotypes. Shikimate accumulated at low glyphosate concentrations (≤ 10.6 mg L−1) in leaf discs from susceptible horseweed biotypes but not in resistant biotypes. Both assays were able to differentiate resistant from susceptible biotypes of horseweed and could have utility for screening other weed populations for resistance to glyphosate.

COMPARISON OF LEAF DISC AND PETRI DISH ASSAYS FOR THE ASSESSMENT OF DICOFOL RESISTANCE IN POPULATIONS OF EUROPEAN RED MITE FROM SOUTHERN ONTARIO

1989 ◽  
Vol 121 (9) ◽  
pp. 771-776 ◽  
Author(s):  
D.J. Pree ◽  
K.J. Cole ◽  
P.A. Fisher
Keyword(s):  
Leaf Disc ◽  
Petri Dish ◽  
Wild Populations ◽  
Low Frequencies ◽  
Southern Ontario ◽  
Leaf Discs ◽  
Field Type ◽  
European Red Mite ◽  
Petri Dishes

AbstractTwo bioassay methods using leaf discs and Petri dishes as the treated medium were compared. Resistance levels were approximately 11-fold with the leaf disc method and 7-fold using the Petri dish assay. Comparisons of the two methods on six wild populations indicated that the Petri dish assay was more sensitive in identifying low frequencies of resistance. Advantages of the Petri dish assay over the previously used leaf disc method for rapid, field-type surveys are discussed.Surveys of populations from the Simcoe and Niagara areas, using the Petri dish assay, indicated resistance to dicofol in 11 of 22 samples. Resistance was generally correlated with sites where dicofol had been used at least once a year for 2–3 consecutive years. The data indicate a resurgence of dicofol resistance since 1984 when resistance was detected at 4% of the surveyed sites.

scholarly journals Development of Agrobacterium-mediated Transformation System in Pear Cultivars with Low-regeneration Frequency

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 755C-755
Author(s):  
Narumi Matsuda* ◽  
Kanji Isuzugawa ◽  
Mei Gao ◽  
Tadashi Takashina ◽  
Koichi Nishimura
Keyword(s):  
Leaf Disc ◽  
Multiple Shoots ◽  
Transformation Method ◽  
Shoot Meristem ◽  
Axillary Shoot ◽  
Transformation System ◽  
Regeneration Frequency ◽  
Leaf Discs ◽  
Subculture Period

The transformation of pears such as `Conference', `Doyenne du Comice' and `Passe-Crassane' has been attributed to the high regeneration frequency from leaf discs (71% to 97%; Leblay et al. 1991). However, it has been difficult to transfer desirable genes into cultivars with low-regeneration frequency such as `Silver bell' (35.4%) and `La France' (10.7%), which are the two major pear cultivars in Japan. In this study, we developed an Agrobacterium-mediated transformation system for `Silver bell' and `La France'. For `Silver bell', leaf discs derived from in vitro shoots were used as explants. The antibiotics for selection of transformants and elimination of Agrobacteria were investigated. In the most optimum condition, which is 30 mg·L-1 Kanamycin and 500 mg·L-1 Sulbenicillin, a 3.2 % transformation efficiency was obtained. However, no success was recorded in an effort to transform `La France' using leaf disc explants because of very poor regeneration frequency. Therefore, axillary shoot meristems were used as explants for transformation of `La France'. The conditions for antibiotic selection and elimination of Agrobacteria were also investigated. In 5 mg·L-1 Kanamycin and 375 mg·L-1 Carbenicillin, transformed shoots were produced at 4.8% efficiency. No chimera was observed in the transgenic shoots during a 2-year subculture period. Since the inoculated explants developed into multiple shoots during selection, it was thought that the problem of chimera might have been overcome. Therefore, this transformation method using axillary shoot meristem may be applicable to pear cultivars recalcitrant to regeneration from leaf disc. To the best of our knowledge, this is the first report of a transformation system in pear cultivars with low regeneration efficiency.

scholarly journals Oviposition by the vagrant eriophyoid mite Aculops allotrichus on leaves of black locust tree, Robinia pseudoacacia

2019 ◽  
Vol 79 (1) ◽  
pp. 1-19
Author(s):  
Katarzyna Michalska ◽  
Anna Tomczyk ◽  
Barbara Łotocka ◽  
Sławomir Orzechowski ◽  
Marcin Studnicki
Keyword(s):  
Cell Walls ◽  
Black Locust ◽  
Robinia Pseudoacacia ◽  
Leaf Age ◽  
Leaf Tissue ◽  
Adaxial Side ◽  
Abaxial Side ◽  
Production And Distribution ◽  
Young Leaves ◽  
Eriophyoid Mite

Abstract Leaf-dwelling mites often prefer to feed on young leaves and also are more likely to inhabit the abaxial leaf side. The aim of our study was to examine whether leaf age may affect production and distribution of eggs on black locust leaves by females of Aculops allotrichus. The eriophyoids were tested for 2.5 days on ‘trimmed’ compound leaves (with only two opposite leaflets left), which were maintained in vials filled with water. For the experiments we used leaves of three categories: (1) the ‘youngest’, in which both halves of the adaxial side of leaflets still adhered to each other (and usually remained folded for the next few hours), (2) ‘young’ with already unfolded leaflets, and (3) ‘mature’ with fully expanded leaflets. The tested females laid significantly more eggs on developing leaves than on ‘mature’ ones, although they deposited the highest number of eggs on the ‘young’ leaves. The distribution of eggs on adaxial or abaxial leaf sides also depended on leaf age. On the ‘youngest’ leaves, eriophyoids placed similar numbers of eggs on both sides of a blade. However, the older the leaf, the more willingly females deposited eggs on the abaxial side. Our biochemical and morphometrical analyses of black locust leaves indicated significant changes in the contents of nutrients and phenols within leaf tissue, and in the density of trichomes and thickness of the outer epidermal cell walls, correlated with leaf age. Their possible effects on the production and distribution of eggs on leaves by A. allotrichus are discussed.

scholarly journals Reprotoxic effects of the systemic insecticide fipronil on the butterfly Pieris brassicae

2020 ◽  
Vol 287 (1922) ◽  
pp. 20192665
Author(s):  
Rieta Gols ◽  
Michiel F. WallisDeVries ◽  
Joop J. A. van Loon
Keyword(s):  
Egg Production ◽  
Sublethal Effects ◽  
Limit Of Detection ◽  
Degradation Products ◽  
Leaf Disc ◽  
Dry Mass ◽  
Pieris Brassicae ◽  
Effective Dosage ◽  
Leaf Discs ◽  
Whole Plant

In addition to controlling pest organisms, the systemic neurotoxic pesticide fipronil can also have adverse effects on beneficial insects and other non-target organisms. Here, we report on the sublethal effects of fipronil on the farmland butterfly Pieris brassicae . Caterpillars were reared on plants that had been grown from seeds coated with fipronil or on leaf discs topically treated with a range of fipronil dosages (1–32 µg kg −1 on dry mass basis). Females that had developed on fipronil plants laid ca half the number of eggs than females that had developed on control plants. In the bioassay with leaf discs, longevity and lifetime egg production declined with increasing fipronil dosage. Remarkably, exposure to fipronil during larval development primarily affected the adult stage. Chemical analyses of leaf tissues collected from seed-treated plants revealed concentrations of fipronil and its degradation products close to the analytical limit of detection (less than or equal to 1 µg kg −1 ). The effective dosage was fivefold higher in the leaf-disc than in the whole-plant experiment. In the whole plant, degradation of fipronil to products that are more toxic than fipronil may explain this discrepancy. Neurotoxicity of insecticides at the level of detection decreases the probability of pinpointing insecticides as the causal agent of harmful effects on non-target organisms.

scholarly journals A Leaf Disc Assay for Evaluating the Response of Tea (Camellia sinensis) to PEG-Induced Osmotic Stress and Protective Effects of Azoxystrobin against Drought

Plants ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 546
Author(s):  
Yu-Chieh Chiu ◽  
Bo-Jen Chen ◽  
Yen-Shuo Su ◽  
Wen-Dar Huang ◽  
Chang-Chang Chen
Keyword(s):  
Osmotic Stress ◽  
Radical Scavenging ◽  
Leaf Disc ◽  
Reducing Power ◽  
Tea Plant ◽  
Leaf Discs ◽  
Scavenging Capacity ◽  
Tea Plants ◽  
Dpph Radical Scavenging ◽  
Disc Assay

Tea (Camellia sinensis), a globally cultivated beverage crop, is sensitive to drought, which can have an adverse effect on the yield and quality of tea. Azoxystrobin (AZ) is one kind of fungicide considered as an agent to relieve damage caused by stress. Initially, the response of tea plant to osmotic-gradient stress was evaluated using leaf disc assays with PEG-induced osmotic stress. The decline of the maximum quantum yield of PSII (Fv/Fm), actual photosynthetic efficiency of PS II (Y(II)), total chlorophylls, carotenoids, DPPH radical scavenging capacity, reducing power, total phenols, and the increase in MDA was observed in leaf discs treated with a gradient of PEG solutions (22.8, 33.2, 41.1% PEG, and blank). These results revealed that efficiency of photosystem II (PSII), photosynthetic pigments, and antioxidant ability in leaf discs were inhibited with an aggravated lipid peroxidation under PEG-induced osmotic stress, and indicated leaf disc assay with moderate PEG iso-osmotic condition would reflect a portion of tea plant response to drought stress. Therefore, the protective effect of AZ (0.125 and 1.25 g a.i. L−1) on tea plants suffering from drought was evaluated using leaf disc assays with 22.8% PEG iso-osmotic condition. Pretreatment of AZ (0.125 a.i. g L−1) reversed Fv/Fm, Y(II), DPPH radical scavenging capacity, and reducing power with reduced MDA in PEG-treated leaf discs, but photosynthetic pigments, total phenols, and ascorbate peroxidase activity were irresponsive to AZ. An Alleviated physiological damage in tea leaf with AZ applying was preliminarily revealed in this study. A Rapid screening of agents for tea plants against drought was developed to assist in the selection of protective agents.

scholarly journals First Report of Pseudoperonospora cubensis Causing Downy Mildew of Trichosanthes cucumerina in Malaysia

Plant Disease ◽  
2010 ◽  
Vol 94 (5) ◽  
pp. 642-642 ◽  
Author(s):  
M. Salati ◽  
M. Y. Wong ◽  
M. Sariah ◽  
H. Nik Masdek
Keyword(s):  
Downy Mildew ◽  
Average Length ◽  
Leaf Disc ◽  
Its Region ◽  
Pseudoperonospora Cubensis ◽  
Abaxial Surface ◽  
First Report ◽  
Leaf Discs ◽  
Morphological Criteria ◽  
Field Samples

In December 2008, infected leaves of Trichosanthes cucumerina were observed on commercial cucurbit farms located in Pontian, Johor (south of West Malaysia). Bright yellow and small necrotic lesions were observed on the adaxial surface of the leaves, whereas sporangiophores were observed on pale yellowish brown-to-brown lesions on the abaxial surface. The length and width of the sporangia ranged from 19 to 36 μm (28.6) and 11 to 23 μm (17.6), respectively. The length of the sporangiophores ranged from 310 to 450 μm, with an average length of 380 μm. The pathogen was identified as Pseudoperonospora cubensis on the basis of the morphological criteria described by Palti and Cohen (2). To confirm the morphological findings, DNA was extracted from symptomatic tissue and the internal transcribed spacer (ITS) region was PCR amplified using primers ITS5-P2 and ITS4 (3). The appropriate-sized amplicon was gel excised and column purified and then submitted for direct sequencing. The resulting 802 bp amplified ITS region was 100% identical to published P. cubensis sequences (GenBank Accession Nos. EU876603, EU876584, and AY198306). This sequence was deposited with NCBI GenBank under the Accession No. GU233293. In this study, pathogenicity tests were conducted using detached leaf disc assays (1) and a P. cubensis isolate obtained from T. cucumerina. For this purpose, leaf discs were excised from 6- to 8-week-old leaves of T. cucumerina using a 20-mm cork borer. Five leaf discs were placed with their abaxial surface facing upward on moist filter paper in petri dishes. Each of four leaf discs was inoculated with four 10-μl droplets of a 1 × 105 per ml sporangial suspension, whereas the fifth disc was inoculated with water droplets and served as a control. Three replications were completed. The leaf discs were placed in darkness at 14 ± 2°C for 24 h and subsequently incubated with a 12-h photoperiod. After 10 days, sporulation was observed on the sporangia-inoculated leaf discs with similar morphological features to the initial field samples. To our knowledge, this is the first report of P. cubensis causing downy mildew of T. cucumerina in Malaysia. References: (1) A. Lebeda and M. P. Widrlechner. J. Plant Dis. Prot. 110:337, 2003. (2) J. Palti and Y. Cohen. Phytoparasitica 8:109, 1980. (3) H. Voglmayr and O. Constantinescu. Mycol. Res. 112:487, 2008.

scholarly journals The response of leaves to heat stress in tomato plants with source-sink modulated by growth regulators

2014 ◽  
Vol 58 (3) ◽  
pp. 355-373
Author(s):  
Zofia Starck ◽  
Barbara Witek-Czcpryńska ◽  
Dorota Blancard
Keyword(s):  
Heat Stress ◽  
High Temperature ◽  
Starch Content ◽  
Control Plant ◽  
Leaf Disc ◽  
Optimal Temperature ◽  
Leaf Discs ◽  
Growth Activation ◽  
Sink Demand ◽  
Source Sink

The response to heat stress was investigated in heat-sensitive, Roma V. F. and heat-tolerant, Robin, cultivars whose fruit growth was stimulated by NOA + GA<sub>3</sub> , or NOA + GA<sub>3</sub> + zeatin. The treated plants were compared with untreated control plant. In each of these series half of the plants were subjected to one or three cycles of heat stress. A single cycle of 38°/25°C day and night did not significantly affect either the respiration rate or chlorophyll content. In PGR-untreated intact cv. Roma, heat stress inhibited starch formation during the day and strongly depressed night export from the blades. High temperature depressed the night transport less in plants having a higher sink demand of fruits in plant treated with PGR. In this case the amount of substances available for export was much higher and both sugars and starch were more intensively remobilized at night. In intact Robin plants, PGR and heat stress much less affected sugar and starch content. High temperature diminished noctural starch remobilization only in the NOA + GA<sub>3</sub> series. Leaf disc growth was evaluated as a measure of response to heat stress after elimination of the direct effect of fruit demands. One cycle of high temperature did not negatively affect the growth of leaf discs; it even caused thermal low growth activation in both cultivars. Three cycles of heat stress depressed leaf disc growth after short-term stimulation, especially in Roma plants. Immediately after 3-day heat stress, there was no response of discs to GA<sub>3</sub> or zeatin added to the solution on which the discs were floated. Leaf disc growth of Robin control and NOA + GA<sub>3</sub> series was very similar in plants from optimal temperature conditions. High temperature inhibited only disc growth of the NOA + GA<sub>3</sub> series owing to depression of starch break-down, diminishing the pool of sugars. In contrast, leaf discs of Roma cv. excided from NOA + GA<sub>3</sub> treated plants from the optimal temperature series, grew more intensively as compared with control plants, owing to a higher content of sugar available for growth.

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