scholarly journals Photosynthetic properties and biochemical metabolism of Cucurbita moschata genotypes following infection with powdery mildew

2020 ◽  
Vol 102 (4) ◽  
pp. 1021-1027
Author(s):  
Bi-Hua Chen ◽  
Wei-Li Guo ◽  
He-Lian Yang ◽  
Qing-Fei Li ◽  
Jun-Guo Zhou ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Stomatal Closure ◽  
Fungal Growth ◽  
Photosynthetic Performance ◽  
Cucurbita Moschata ◽  
Physiological Mechanisms ◽  
Resistant Genotype ◽  
Related Enzyme ◽  
Photosynthetic Properties ◽  
Shed Light

Abstract Powdery mildew (PM) is one of the most important fungal diseases in Cucurbita moschata (pumpkin) cultivation. This experiment was conducted to shed light on the physiological mechanisms of PM resistance in pumpkin cultivars. PM pathogen was inoculated on pumpkin seedlings, PM-susceptible genotype (JJJD) and PM-resistant genotype (inbred line 112–2) to study the PM-fungal growth, plant photosynthetic and biochemical parameters with different intervals of time. The disease index and pathogen growth observed for the PM-infected 112–2 seedlings were milder than those observed for the JJJD seedlings. The net photosynthetic rate (Pn), stomatal conductance (gs) and transpiration rate (Tr) were reduced for both the PM-infected genotypes, while the internal CO2 concentration (Ci) increased in comparison with the non-infected controls. PM pathogen inoculation impaired the photosynthetic performance in seedlings of both genotypes and this was largely associated with stomatal closure. In comparison with the non-infected controls, the superoxide dismutase (SOD) and β-1,3-glucanase activities were reduced for both the PM-infected genotypes, while the peroxidase (POD) and phenylalanine ammonia lyase (PAL) activities were increased. The catalase (CAT) activity was reduced in the 112–2 genotype and increased in the JJJD genotype after PM pathogen inoculation. Together, our data show that PM resistance in pumpkin seedlings is associated with the maintenance of photosynthetic performance and the regulation of defense-related enzyme activities .

scholarly journals The Landscape of microRNAs in βCell: Between Phenotype Maintenance and Protection

2021 ◽  
Vol 22 (2) ◽  
pp. 803
Author(s):  
Giuseppina Emanuela Grieco ◽  
Noemi Brusco ◽  
Giada Licata ◽  
Daniela Fignani ◽  
Caterina Formichi ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Metabolic Disorders ◽  
Molecular Mechanisms ◽  
Β Cell ◽  
Physiological Mechanisms ◽  
Effective Strategies ◽  
Chronic Hyperglycaemia ◽  
Shed Light

Diabetes mellitus is a group of heterogeneous metabolic disorders characterized by chronic hyperglycaemia mainly due to pancreatic β cell death and/or dysfunction, caused by several types of stress such as glucotoxicity, lipotoxicity and inflammation. Different patho-physiological mechanisms driving β cell response to these stresses are tightly regulated by microRNAs (miRNAs), a class of negative regulators of gene expression, involved in pathogenic mechanisms occurring in diabetes and in its complications. In this review, we aim to shed light on the most important miRNAs regulating the maintenance and the robustness of β cell identity, as well as on those miRNAs involved in the pathogenesis of the two main forms of diabetes mellitus, i.e., type 1 and type 2 diabetes. Additionally, we acknowledge that the understanding of miRNAs-regulated molecular mechanisms is fundamental in order to develop specific and effective strategies based on miRNAs as therapeutic targets, employing innovative molecules.

scholarly journals Hormonal and Hydroxycinnamic Acids Profiles in Banana Leaves in Response to Various Periods of Water Stress

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Jalel Mahouachi ◽  
María F. López-Climent ◽  
Aurelio Gómez-Cadenas
Keyword(s):  
Water Stress ◽  
Leaf Gas Exchange ◽  
Stomatal Closure ◽  
Photosynthetic Performance ◽  
Hydroxycinnamic Acids ◽  
Cinnamic Acids ◽  
Gas Exchange Parameters ◽  
Banana Leaves ◽  
Indole 3 Acetic Acid

The pattern of change in the endogenous levels of several plant hormones and hydroxycinnamic acids in addition to growth and photosynthetic performance was investigated in banana plants (Musa acuminatacv. “Grand Nain”) subjected to various cycles of drought. Water stress was imposed by withholding irrigation for six periods with subsequent rehydration. Data showed an increase in abscisic acid (ABA) and indole-3-acetic acid (IAA) levels, a transient increase in salicylic acid (SA) concentration, and no changes in jasmonic acid (JA) after each period of drought. Moreover, the levels of ferulic (FA) and cinnamic acids (CA) were increased, and plant growth and leaf gas exchange parameters were decreased by drought conditions. Overall, data suggest an involvement of hormones and hydroxycinnamic acids in plant avoidance of tissue dehydration. The increase in IAA concentration might alleviate the senescence of survival leaves and maintained cell elongation, and the accumulation of FA and CA could play a key role as a mechanism of photoprotection through leaf folding, contributing to the effect of ABA on inducing stomatal closure. Data also suggest that the role of SA similarly to JA might be limited to a transient and rapid increase at the onset of the first period of stress.

scholarly journals Breaking and Flowering: The Budding Story of Macadamia

Proceedings ◽  
2020 ◽  
Vol 36 (1) ◽  
pp. 166
Author(s):  
Francois Barbier ◽  
Ye Gong ◽  
Carola Parfitt ◽  
Craig Hardner ◽  
John Wilkie ◽  
...  
Keyword(s):  
Gene Expression ◽  
Marker Gene ◽  
Axillary Buds ◽  
Bud Break ◽  
Physiological Mechanisms ◽  
Promoter Sequences ◽  
Model Plant Arabidopsis Thaliana ◽  
Peach Trees ◽  
Mobile Protein ◽  
Shed Light

Macadamia is the only Australian native crop tree. Unlike some model crop trees like apple or peach trees, the understanding of the physiological mechanisms regulating bud break and flowering in macadamia has never been investigated. We have recently attempted to fill this gap by improving the genetic resources available for macadamia. We identified several components involved in flowering and bud break, including the FLOWERING LOCUS T (FT). FT is a mobile protein, synthesized in the leaves which triggers flowering in terminal and axillary buds. In macadamia, we found two FT-related genes, FTa and FTb namely. FTa and FTb are differentially regulated; FTa being more abundant in axillary buds than leaves, which is unexpected based on the studies performed in model plants. Analysis of the promoter sequences of FTa and FTb, revealed that the FTa regulation may be closer to FT regulation in the model plant Arabidopsis thaliana. Gene expression in buds revealed that the expression of TERMINAL FLOWER1 (TFL1), a gene previously reported to inhibit flowering, was induced prior to bud break and flowering. The patterns of marker gene expression in buds highlighted that the bud dormancy decreased before May, after which flowering induction occurs. Altogether these results shed light on the regulation of bud break and flowering in macadamia and demonstrate that some regulatory mechanisms may be different from other models.

scholarly journals Development and Evaluation of Laboratory Bioassays to Study Powdery Mildew Pathogens of Phlox In Vitro

Plant Disease ◽  
2019 ◽  
Vol 103 (7) ◽  
pp. 1536-1543 ◽  
Author(s):  
Coralie Farinas ◽  
Pablo Jourdan ◽  
Pierce A. Paul ◽  
Francesca Peduto Hand
Keyword(s):  
Powdery Mildew ◽  
Ornamental Plants ◽  
Fungal Growth ◽  
Ms Medium ◽  
Adaxial Side ◽  
Single Spore ◽  
Experimental Conditions ◽  
Inoculation Techniques ◽  
Biotrophic Fungi

The genus Phlox consists of approximately 65 species that include some of the most prevalent ornamental plants in the temperate zone. These popular ornamentals are extremely susceptible to powdery mildew (PM) caused by the biotrophic fungi Golovinomyces magnicellulatus and Podosphaera sp. In this study, we used Phlox paniculata and P. glaberrima to develop a set of laboratory tools to study these pathogens in vitro, including a detached leaf and a micropropagated plantlet bioassay. We assessed pathogen growth under different experimental conditions, which included the use of four different media variations (1/2 MS medium amended with benzimidazole and tetracycline), three ages of pathogen culture (14, 18, and 22 days), three phenological stages of the host tissue (1st, 3rd, and 5th node leaves), placement of inoculum on both leaf surfaces (abaxial and adaxial), and three different inoculation techniques (single spore transfer, colony tapping, colony brushing). Detached P. paniculata leaves were successfully maintained on benzimidazole-amended 1/2 MS medium for up to 3 weeks. For both pathogens, the use of 18-day-old cultures resulted in a higher number of larger, higher sporulating colonies compared with 1-4 and 22-day-old cultures. The adaxial side of 3rd node leaves supported statistically significant more fungal growth compared with the adaxial side of 1st and 5th node leaves. Both pathogens also successfully infected micropropagated plantlets of P. glaberrima. These newly developed tools should facilitate in vitro studies on PM of Phlox and possibly be applicable to other ornamental species attacked by the same fungi.

scholarly journals Breeding for Powdery Mildew Resistant Varieties in Cucurbita moschata

2005 ◽  
Vol 11 (2) ◽  
pp. 106-114 ◽  
Author(s):  
Myeong-Cheoul Cho ◽  
Young-Hyun Om ◽  
Dae-Hyun Kim ◽  
Yun-Chan Heo ◽  
Jeong-Su Kim ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Cucurbita Moschata ◽  
Resistant Varieties

scholarly journals First Report of Powdery Mildew Caused by Sphaerotheca fusca on Tomatillo in California

Plant Disease ◽  
1998 ◽  
Vol 82 (6) ◽  
pp. 711-711 ◽  
Author(s):  
S. T. Koike ◽  
R. F. Smith
Keyword(s):  
Powdery Mildew ◽  
Fungal Growth ◽  
Premature Senescence ◽  
First Report ◽  
Powdery Mildew Disease ◽  
Salinas Valley ◽  
Germ Tubes ◽  
Husk Tomato ◽  
Sphaerotheca Fusca ◽  
Commercial Field

Tomatillo or husk tomato (Physalis ixocarpa Brot.) is an annual Solanaceous bush grown for its fruit, which are harvested when the fruit fill the enlarged calyx and are used primarily in Hispanic cooking. In the summer of 1997, commercial field-grown tomatillo in the Salinas Valley (Monterey County) was severely affected by a powdery mildew disease. Fungal growth was found on leaves, petioles, and calyces and resulted in twisting, desiccation, and premature senescence of the tissues. The mycelium was white to gray, ectophytic, amphigenous, and effuse. Mycelial appressoria were indistinct. Conidiophore foot cells were straight, cylindric, measured 36.1 to 61.1 µm (mean 47.0) × 11.1 to 13.9 µm (mean 11.7), and were followed by 1 to 3 shorter cells. Doliform conidia were formed in chains and measured 25.0 to 50.0 µm (mean 32.5) × 11.1 to 22.2 µm (mean 17.7). The length-to-width ratios of conidia generally were less than 2.0, and fibrosin bodies were present. Germ tubes usually were laterally inserted, lacked conspicuous appressoria, and were of the pannosa-type. Cleistothecia were not observed. Based on these characters, the fungus was identified as Sphaerotheca fusca (Fr.) Blumer, Beitr. Krypt.-Fl. Schweiz (1). Pathogenicity was confirmed by gently pressing infected leaves onto leaves of potted tomatillo. Inoculated plants were kept in a chamber at 100% humidity for 48 h, and then maintained in a greenhouse. Powdery mildew developed on inoculated plants after 12 to 14 days, while uninoculated plants did not develop disease. The experiment was conducted a second time and the results were the same. This is the first report of a powdery mildew disease of tomatillo in California. Reference: (1) U. Braun. Nova Hedwigia 89:1, 1987.

scholarly journals Photosynthetic performance in cyanobacteria with increased sulphide tolerance: an analysis comparing wild-type and experimentally derived strains

2021 ◽  
Author(s):  
Elena Martín-Clemente ◽  
Ignacio J. Melero-Jiménez ◽  
Elena Bañares-España ◽  
Antonio Flores-Moya ◽  
María J. García-Sánchez
Keyword(s):  
Resistance Mechanisms ◽  
Photosynthetic Performance ◽  
Oxygenic Photosynthesis ◽  
Wild Type ◽  
Sensitive Species ◽  
Anoxygenic Photosynthesis ◽  
In The Wild ◽  
Photosynthetic Machinery ◽  
Type Strains ◽  
Shed Light

AbstractSulphide is proposed to have influenced the evolution of primary stages of oxygenic photosynthesis in cyanobacteria. However, sulphide is toxic to most of the species of this phylum, except for some sulphide-tolerant species showing various sulphide-resistance mechanisms. In a previous study, we found that this tolerance can be induced by environmental sulphidic conditions, in which two experimentally derived strains with an enhanced tolerance to sulphide were obtained from Microcystis aeruginosa, a sensitive species, and Oscillatoria, a sulphide-tolerant genus. We have now analysed the photosynthetic performance of the wild-type and derived strains in the presence of sulphide to shed light on the characteristics underlying the increased tolerance. We checked whether the sulphide tolerance was a result of higher PSII sulphide resistance and/or the induction of sulphide-dependent anoxygenic photosynthesis. We observed that growth, maximum quantum yield, maximum electron transport rate and photosynthetic efficiency in the presence of sulphide were less affected in the derived strains compared to their wild-type counterparts. Nevertheless, in 14C photoincoporation assays, neither Oscillatoria nor M. aeruginosa exhibited anoxygenic photosynthesis using sulphide as an electron donor. On the other hand, the content of photosynthetic pigments in the derived strains was different to that observed in the wild-type strains. Thus, an enhanced PSII sulphide resistance appears to be behind the increased sulphide tolerance displayed by the experimentally derived strains, as observed in most natural sulphide-tolerant cyanobacterial strains. However, other changes in the photosynthetic machinery cannot be excluded.

scholarly journals First Report of Powdery Mildew Caused by Golovinomyces biocellatus on Peppermint in California

Plant Disease ◽  
2010 ◽  
Vol 94 (2) ◽  
pp. 276-276 ◽  
Author(s):  
D. B. Marcum ◽  
K. Perez ◽  
R. M. Davis
Keyword(s):  
Powdery Mildew ◽  
Fungal Growth ◽  
Universal Primers ◽  
Mentha Piperita ◽  
Exact Match ◽  
First Report ◽  
Plastic Bag ◽  
The One ◽  
Shasta County ◽  
Disease Free

In August of 2009, powdery mildew was observed on peppermint (Mentha piperita L.) in several commercial fields in the Fall River Valley of eastern Shasta County, California. Plant growth was apparently reduced by the disease, but its impact on yield was unknown. White fungal growth was restricted to the adaxial surfaces, where colonies were thin and effused. Heavily infected leaves developed a reddish tint as growth prematurely ceased. Doliform conidia ([26.6-] 29.2 [-31.7] × [13.2-] 15.6 [-16.8] μm) were produced in chains of approximately six conidia. Foot cells were cylindrical ([41.3-] 55.2 [-75.0] × [11.2-] 12.0 [-12.8] μm). Immature chasmothecia were yellowish brown and approximately 100.0 μm in diameter with flexuous, mycelium-like appendages up to 200 μm long. All these features were consistent with those of Golovinomyces biocellatus. Asci were not observed. To confirm the identity of the fungus, nuclear rDNA internal transcribed spacer (ITS) regions were amplified by PCR with universal primers ITS4 and ITS5. The sequence (537 bp) was an exact match for several submissions of G. biocellatus in GenBank (e.g., Accession No. EU035602, a sequence of the fungus from mint in Australia [1]). Pathogenicity was confirmed by brushing spores from naturally infected leaves onto three rooted cuttings of M. piperita ‘Black Mitchum’. After the plants were covered with a plastic bag for 36 h to maintain high humidity, they were kept on a greenhouse bench at 23 to 28°C. Three noninoculated plants, which served as controls, were placed in another greenhouse in similar conditions. The experiment was repeated once. All inoculated plants developed signs of powdery mildew within 7 days of inoculation whereas noninoculated plants remained disease free. The fungus on inoculated leaves was morphologically indistinguishable from the one used to inoculate the plants. To our knowledge, this is the first report of G. biocellatus on peppermint in California. References: (1) J. R. Liberato and J. H. Cunnington. Australas, Plant Dis. Notes 2:38, 2007.

scholarly journals First Occurrence of Cucurbit Powdery Mildew Caused by Race 3-5 of Podosphaera fusca in Spain

Plant Disease ◽  
2009 ◽  
Vol 93 (10) ◽  
pp. 1073-1073 ◽  
Author(s):  
J. A. Torés ◽  
J. M. Sánchez-Pulido ◽  
F. López-Ruiz ◽  
A. de Vicente ◽  
A. Pérez-García
Keyword(s):  
Powdery Mildew ◽  
Citrullus Lanatus ◽  
Morphological Characteristics ◽  
Fungal Growth ◽  
Powdery Mildew Fungus ◽  
First Occurrence ◽  
New Race ◽  
First Time ◽  
Cucurbit Powdery Mildew ◽  
Podosphaera Fusca

A new race of cucurbit powdery mildew was observed for the first time on melon (Cucumis melo) in three research greenhouses in the Axarquia area of southern Spain during the spring of 2008. Fungal growth appeared as white powdery colonies initially restricted to the upper leaf surfaces. Morphological characteristics of colonies, conidiophores, conidia, germ tubes, and appressoria indicated that the powdery mildew fungus was Podosphaera fusca (also known as P. xanthii) (3), a fungal pathogen extensively reported in the area (1). However, the fungus developed on plants of melon cv. PMR 6, which is resistant to races 1 and 2 of P. fusca, suggesting that the fungus could belong to race 3, a race of P. fusca not yet reported in Spain. Race determination was carried out by inoculating the third true leaf of a set of differential melon genotypes that were maintained in a greenhouse. Symptoms and colonization observed on cvs. Rochet, PMR 45, PMR 6, and Edisto 47 indicated that the isolates belonged to race 3-5 of P. fusca. Fungal strains of races 1, 2, and 5 of P. fusca (all present in Spain) were used as controls. Pathotype designation was determined by inoculating different cucurbit genera and species (2). In addition to melon, the isolates were pathogenic on zucchini (Cucurbita pepo) cv. Diamant F1, but failed to infect cucumber (C. sativus) cv. Marketer and watermelon (Citrullus lanatus) cv. Sugar Baby; therefore, the isolates were pathotype BC (2). Races 1, 2, 4, and 5 of P. fusca have been previously reported in the area (1). The occurrence of race 3-5 represents another challenge in the management of cucurbit powdery mildew in Spain. References: (1) D. del Pino et al. Phytoparasitica 30:459, 2002. (2) E. Křístková et al. Sci. Hortic. 99:257, 2004. (3) A. Pérez-García et al. Mol. Plant Pathol. 10:153, 2009.

scholarly journals First Report of Powdery Mildew of Parsley Caused by Erysiphe heraclei in Florida

Plant Disease ◽  
2007 ◽  
Vol 91 (4) ◽  
pp. 461-461 ◽  
Author(s):  
R. Raid ◽  
C. Miller ◽  
K. Pernezny
Keyword(s):  
Powdery Mildew ◽  
Fungal Pathogens ◽  
Fungal Growth ◽  
Leaf Tissue ◽  
Signs And Symptoms ◽  
Climatic Conditions ◽  
Petroselinum Crispum ◽  
First Report ◽  
Dark Green ◽  
Vegetable Farm

Parsley (Petroselinum crispum (Mill.) Nym. ex A.W. Hill) is an important leaf crop in the Everglades Agricultural Area of southern Florida. During the spring of 2005 and 2006, disease signs and symptoms resembling those incited by powdery mildew were observed on parsley at a commercial vegetable farm located 15 km east of Belle Glade. Symptoms consisted of leaf chlorosis, particularly in the dense lower canopy, and desiccation of affected tissue. A dense, white-to-light gray fungal growth was visible macroscopically on the surface of affected leaf tissue. Microscopic examinations revealed ectophytic hyphae with lobed appressoria and hyaline, straight conidiophores bearing single conidia. Conidia were short-cylindrical to cylindrical, measured 33 to 44 μm long and 13 to 16 μm wide, and lacked fibrosin bodies. Conidiophore foot cells were also cylindrical, straight, and measured 27 to 37 × 9 to 10 μm. Ascocarps of the teleomorph were not observed. The fungus closely matched the description of Erysiphe heraclei DC, a pathogen previously reported as attacking parsley on the U.S. West Coast (1,2). Pathogenicity was verified by inoculating adaxial leaf surfaces of 12 plants (cv. Dark Green Italian) with conidia collected from infected tissue by using a small brush. Inoculated plants and 12 noninoculated plants were lightly misted, held in a moist chamber for 48 h (22°C), and then incubated in a growth chamber for 4 weeks at 22°C with a photoperiod of 16 h. Symptoms that developed on inoculated plants were similar to those observed in the field, with no symptoms evident on the controls treated in a similar manner. To our knowledge, this is the first report of powdery mildew on parsley in Florida, even though parsley has been grown in the area for at least six decades. Noted as being somewhat unique among fungal pathogens because it favors dry rather than moist climatic conditions, it is probably no coincidence that powdery mildew was observed both years during the month of April, the height of Florida's dry season. The fact that monthly rainfall totals of 22 and 35 mm were recorded during April of 2004 and 2005, respectfully, well below the historical average of 72 mm, may have been a contributing influence. Glawe et al. (1), in issuing a first report of E. heraclei on carrots and parsley in the state of Washington and observing ascocarps on carrot tissue, mentioned the prospect of contaminated seed serving as a potential source of dissemination. Although they did not observe the teleomorph on parsley, prospects for its occurrence seem likely. With the bulk of parsley seed planted in Florida being produced in Washington, Oregon, or California, the observations reported herein may provide credence to such a hypothesis. References: (1) D. A. Glawe et al. Online publication. doi:10.1094/PHP-2005-0114-01-HN. Plant Health Progress, 2005. (2) S. T. Koike and G. S. Saenz. Plant Dis. 78:1219, 1994.

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