Search results for "Oospore"

Pythium stipitatumsp. nov. isolated from soil and plant debris taken in France, Tunisia, Turkey, and India

2009

Pythium stipitatum is a slow-growing oomycete and has been isolated from soil samples and plant materials from France, Tunisia, Turkey and India. Its morphological characteristics are reminiscent of those of Pythium ramificatum, discovered in Algeria by the corresponding author. Unfortunately, the Algerian isolate was not deposited in any culture collection and ultimately got lost. Those were the days when molecular description of fungi was not a fashion; hence, no molecular characteristics of the Algerian isolates were deposited to the GenBank. Moreover, its coralloid antheridial branches made it an easy prey to be considered as synonymous to Pythium minus. Because there are no living stra…

Antimicrobial Activity of Resveratrol Analogues

2014

Stilbenes, especially resveratrol and its derivatives, have become famous for their positive effects on a wide range of medical disorders, as indicated by a huge number of published studies. A less investigated area of research is their antimicrobial properties. A series of 13 trans-resveratrol analogues was synthesized via Wittig or Heck reactions, and their antimicrobial activity assessed on two different grapevine pathogens responsible for severe diseases in the vineyard. The entire series, together with resveratrol, was first evaluated on the zoospore mobility and sporulation level of Plasmopara viticola (the oomycete responsible for downy mildew). Stilbenes displayed a spectrum of acti…

ITS1 region of the rDNA of Pythium megacarpum sp. nov., its taxonomy, and its comparison with related species.

2000

Pythium megacarpum sp. nov., was isolated from a soil sample taken from a wheat field in Lille in northern France. It was mistakenly described as Pythium ostracodes Drechsler [Paul, B (1994) Cryptogam. -Mycol. 15,263-271]. Despite morphological resemblance, the comparison between the internal transcribed spacer (ITS)1 regions of the rDNA of the two fungi, leaves no doubt of their different identities. This species is unique because of its large oogonia and plerotic, thick walled oospores, its monoclinous antheridia with large antheridial cells and its lack of zoospores. The character combination of P. megacarpum and the ITS1 sequence of its rDNA, justifies the creation of a new species with…

Saprolegnia bulbosa sp. nov. isolated from an Argentine stream: taxonomy and comparison with related species

2007

Saprolegnia bulbosa sp. nov. was isolated from floating and decaying twigs and leaves in El Gato stream, Partido de La Plata, Buenos Aires Province, Argentina. The distinctive characteristics of S. bulbosa are the product of smooth oogonia and predominantly contorted monoclinous, androgynous and diclinous antheridia. The oogonial stalks are usually bent, curved or once coiled; oospores are subcentric, (1) 2–15 (45) per oogonium and are variable in size. Taxonomical description of this new species, its comparison with related oomycetes of the genus and the nucleotide sequences of the internal transcribed region (spacers ITS1, ITS2 and the gene 5.8S) of its rRNA gene are given here.

First Report of Bud Rot of Canary Island Date Palm Caused by Phytophthora palmivora in Italy.

2007

Canary Island date palm (Phoenix canariensis hort. ex Chabaud) is planted as an ornamental in Mediterranean climatic regions of the world. From 2004 to 2006, withering of the spear leaf was observed on screenhouse-grown potted plants of this palm in Sicily (Italy). The first symptom was a dark brown rot that extended from the petiole base of the spear to the adjacent youngest leaves and killed the bud. Dissection of plants revealed a foul-smelling internal rot. After the bud died, external older leaves remained green for months. As much as 10% of plants in a single nursery were affected. A Phytophthora species was consistently isolated from symptomatic plants on BNPRAH selective medium (4)…

A new species ofPythiumisolated from burgundian vineyards and its antagonism towardsBotrytis cinerea, the causative agent of the grey mould disease

2004

During the course of an investigation on the pythiaceous fungi occurring in burgundian vineyards, three isolates of Pythium were found, all of which were characterised by spherical to lemoniform, proliferating sporangia. Only one out of these three isolates produced sexual characters (S-12) after prolonged incubation, but their asexual structures, temperature growth relationship and molecular characteristics were identical. Saprolegnia-type internal proliferation of the sporangia, and Phytophthora-type lemoniform, papillate sporangia were characteristic of all the three isolates. The type specimen is S-12 which is a medium slow growing saprophyte. The sequence of its ITS region of the rDNA …

The development of sporangia of Phytophthora infestans

1995

The dynamics of sporulation and zoosporogenesis of Phytophthora infestans in a naturally infected crop of potato cv. Maris Bard and on potted plants of the same cultivar infected artificially with the same fungus are described. Development of sporangiophores and sporangia was synchronous after induction. Migration of several nuclei from the sporangiophore into the sporangium initial was followed by nuclear division, then by degeneration of a proportion of the nuclei. Sporangia then became deciduous, developed papillae and became able to release zoospores in rapid succession. When infected leaves were detached and transferred from the field to moist Petri dishes, sporulation was at first syn…

Duplication cycle in nuclei of germinating zoospores of Phytophthora drechsleri as revealed by DAPI staining

1982

Characterisation of Pythium paroecandrum and its antagonism towards Botrytis cinerea, the causative agent of grey mould disease of grape.

2004

Pythium paroecandrum (B-30), an oomycete, was isolated from soil samples taken from a wheat field in Genlis in the Burgundy region of France and was found to check the growth and development of Botrytis cinerea, a serious grapevine pathogen. The oomycete is a fast-growing organism, living on vegetable debris, and can be recognised by its catenulate hyphal swellings, catenulate oogonia, and monoclinous antheridia. When grown together with B. cinerea, the causal agent of the grey mould disease of the grapevine, P. paroecandrum shows a pronounced antagonism and suppresses its growth and its aptitude to provoke the grey mould symptoms. Morphological features of this oomycete, its antagonism to …

The life cicle of Plasmopara viticola

2000

Plasmopara viticola (Berk. & M. A. Curtis) Bed. & De Toni is an obligate biotrophic oomycetous organism which causes downy mildew of grape vine. An understanding of its life-cycle is essential in relation to the pathology and epidemiology, and for the development of better control of the disease. It overwinters as oospores within fallen leaves.