Differential Sources of Resistance from Against Three Races of pathovar (Brown, 1918) Morinière et al. 2020 Causing Bacterial Leaf Spot of Lettuce.

Bacterial leaf spot (BLS) of lettuce ( L.) is caused by the bacterium pv. which is hypothesized to have at least three races of the pathogen present in North America as defined by their differential resistance phenotypes in lettuce cultivars/accessions.

Studying Wild Plant Pathosystems to Understand Crop Plant Pathosystems: Status, Gaps, Challenges, and Perspectives.

Phytopathology is a highly complex scientific discipline. Initially, its focus was on the study of plant-pathogen interactions in agricultural and forestry production systems. Host-pathogen interactions in natural plant communities were generally overlooked until the 1970s when plant pathologists and evolutionary biologists started to take an interest in these interactions, and their dynamics in natural plant populations, communities, and ecosystems.

In-Orbit Performance of the GRACE Follow-on Laser Ranging Interferometer.

The Laser Ranging Interferometer (LRI) instrument on the Gravity Recovery and Climate Experiment (GRACE) Follow-On mission has provided the first laser interferometric range measurements between remote spacecraft, separated by approximately 220 km. Autonomous controls that lock the laser frequency to a cavity reference and establish the 5 degrees of freedom two-way laser link between remote spacecraft succeeded on the first attempt. Active beam pointing based on differential wave front sensing compensates spacecraft attitude fluctuations.

Functional Variation of Plant-Pathogen Interactions: New Concept and Methods for Virulence Data Analyses.

Classical virulence analysis is based on discovering virulence phenotypes of isolates with regard to a composition of resistance genes in a differential set of host genotypes. With such a vision, virulence phenotypes are usually treated in a genetic manner as one of two possible alleles, either virulence or avirulence in a binary locus. Therefore, population genetics metrics and methods have become prevailing tools for analyzing virulence data at multiple loci.

Involvement of S-nitrosothiols modulation by S-nitrosoglutathione reductase in defence responses of lettuce and wild Lactuca spp. to biotrophic mildews.

Resistant Lactuca spp. genotypes can efficiently modulate levels of S-nitrosothiols as reactive nitrogen species derived from nitric oxide in their defence mechanism against invading biotrophic pathogens including lettuce downy mildew. S-Nitrosylation belongs to principal signalling pathways of nitric oxide in plant development and stress responses.

Virulence Structure Within Populations of Pseudoperonospora cubensis in the United States.

Cucurbit downy mildew (CDM), caused by the obligate oomycete Pseudoperonospora cubensis, has resurged around the world during the past three decades. A new pathotype or genetic recombinant of P. cubensis have been suggested as possible reasons for the resurgence of CDM in the United States in 2004.

Unilateral cerebellothalamic tract ablation in essential tremor by MRI-guided focused ultrasound.

Objective: To report results of a prospective trial of unilateral transcranial MRI-guided focused ultrasound (MRIgFUS) ablation of the cerebellothalamic tract in essential tremor (ET).

Methods: This was a prospective, uncontrolled, single-center interventional study. Patients with ET fulfilling criteria for interventional therapy received unilateral ablation of the cerebellothalamic tract (CTT) by MRIgFUS.

Resurgence of Pseudoperonospora cubensis: The Causal Agent of Cucurbit Downy Mildew.

The downy mildew pathogen, Pseudoperonospora cubensis, which infects plant species in the family Cucurbitaceae, has undergone major changes during the last decade. Disease severity and epidemics are far more destructive than previously reported, and new genotypes, races, pathotypes, and mating types of the pathogen have been discovered in populations from around the globe as a result of the resurgence of the disease. Consequently, disease control through host plant resistance and fungicide applications has become more complex.

First Report of Basil Downy Mildew Caused by Peronospora belbahrii in the Czech Republic.

Sweet basil (Ocimum basilicum L.) is an annual aromatic and medicinal plant in the Lamiaceae that is originally native to India but is grown in warm regions all over the world. It is a popular culinary herb used fresh and dried, and is used in traditional folk medicine.

Nitric oxide and reactive oxygen species regulate the accumulation of heat shock proteins in tomato leaves in response to heat shock and pathogen infection.

Heat shock proteins (HSP) are produced in response to various stress stimuli to prevent cell damage. We evaluated the involvement of nitric oxide (NO) and reactive oxygen species (ROS) in the accumulation of Hsp70 proteins in tomato leaves induced by abiotic and biotic stress stimuli. A model system of leaf discs was used with two tomato genotypes, Solanum lycopersicum cv.

The Genetic Structure of Pseudoperonospora cubensis Populations.

Pseudoperonospora cubensis is a destructive foliar pathogen of economically important cucurbitaceous crops in the United States and worldwide. In this study, we investigated the genetic structure of 465 P. cubensis isolates from three continents, 13 countries, 19 states of the United States, and five host species using five nuclear and two mitochondrial loci.

Characterization of polygenic resistance to powdery mildew in tomato at cytological, biochemical and gene expression level.

Extensive research in the area of plant innate immunity has increased considerably our understanding of the molecular mechanisms associated with resistance controlled by a dominant resistance gene. In contrast, little is known about the molecular basis underlying the resistance conferred by quantitative trait loci (QTLs). In this study, using the interaction of tomato (Solanum lycopersicum) with Oidium neolycopersici, we compared the cytological, biochemical and molecular mechanisms involved in both monogenic and polygenic resistances conferred by a dominant gene (Ol-1) and three QTLs (Ol-qtls), respectively.

First Report of Pseudoperonospora cubensis on Cucurbita moschata in the Czech Republic.

Pseudoperonospora cubensis (Berk. & M.A.

Polyploidization facilitates biotechnological in vitro techniques in the genus Cucumis.

Prezygotic interspecific crossability barrier in the genus Cucumis is related to the ploidy level of the species (cucumber (C. sativus), x = 7; muskmelon (C. melo) and wild Cucumis species, x = 12).

Photosynthetic responses of lettuce to downy mildew infection and cytokinin treatment.

Changes in primary metabolism of lettuce, Lactuca sativa L. (cv. Cobham Green), induced by compatible interaction with the biotrophic oomycete pathogen Bremia lactucae Regel (race BL 16), under two intensities of illumination in the presence and absence of exogenous cytokinins were studied by chlorophyll fluorescence imaging.

Recondensation level of repetitive sequences in the plant protoplast nucleus is limited by oxidative stress.

Protoplast cultures are remarkable examples of plant cell dedifferentiation. The state of dedifferentiation is evidenced by changes in cell morphology, genome organization, as well as by the capability of protoplasts to differentiate into multiple types of cells (depending on the type of the stimulus applied). The first change in the genome structure is connected with large-scale chromatin decondensation, affecting chromocentres involving various types of these repetitive sequences.

Local and systemic production of nitric oxide in tomato responses to powdery mildew infection.

Various genetic and physiological aspects of resistance of Lycopersicon spp. to Oidium neolycopersici have been reported, but limited information is available on the molecular background of the plant-pathogen interaction. This article reports the changes in nitric oxide (NO) production in three Lycopersicon spp.

Chromatin structural rearrangement during dedifferentiation of protoplasts of Cucumis sativus L.

This paper reports on the structural rearrangement of satellite DNA type I repeats and heterochromatin during the dedifferentiation and cell cycling of mesophyll protoplasts of cucumber (Cucumis sativus). These repeats were localized in the telomeric heterochromatin of cucumber chromosomes and in the chromocenters of interphase nuclei. The dramatic reduction of heterochromatin involves decondensation of subtelomeric repeats in freshly isolated protoplasts; however, there are not a great many remarkable changes in the expression profile.

Localisation and metabolism of reactive oxygen species during Bremia lactucae pathogenesis in Lactuca sativa and wild Lactuca spp.

A plant's physiology is modified simultaneously with Oomycete pathogen penetration, starting with release and accumulation of reactive oxygen species (ROS). Localisation of superoxide, hydrogen peroxide, peroxidase and variation in their activity, and the isoenzyme profile of antioxidant enzymes peroxidase (1.11.

The biological and chemical variability of yacon.

This paper focuses on the biological and chemical variability of four yacon (Smallanthus sonchifolius) accessions cultivated under field conditions. Significant variations in tuber shape, weight, content of oligofructans, as well as in leaf isozymes, phenolics, and relative DNA contents were found. Accessions 6 and 88 were the most productive (up to 3.

Reactive oxygen species generation and peroxidase activity during Oidium neolycopersici infection on Lycopersicon species.

Histochemical and biochemical study of plant tissue responses were carried out on three Lycopersicon spp. accessions differing in response to Oidium neolycopersici. High production of superoxide anion was observed mainly in infected leaves of highly susceptible Lycopersicon esculentum cv.

[Electronic structure and energetics of transitions in absorption spectra of hypericin].

In half-empirical sigma, pi-valent approximation (PM3) the energetics of tautomer transitions of hypericin and nature of electronic transitions in experimental and calculation absorption spectra is investigated. On the basis of quantum-chemical researches results concerning five tautomer condition of hypericin is established that the most stable is its known structure of a quinone I (7,14-dion-1,3,4,6,8,13-hexahydroxydianthrone). Is determined that longwave characteristic bands in hypericin experimental absorption electronic spectra are connected with its electron- and proton-donor, and acceptor properties, and are caused by modifications of its quinone structure by formation of alcohols, cation- and anion-radicals.

Resistance of green peas to legume viruses.

A total of 16 green pea cultivars (Pisum sativum L.) were screened for resistance to bean yellow mosaic virus (BYMV), pea enation mosaic virus (PEMV), and alfalfa mosaic virus (AMV). Cvs.