Search results for "Zoospore"

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.

Influence of leaf age on induced resistance in grapevine against Plasmopara viticola

2012

International audience; Sulfated laminarin (PS3) has previously been shown to induce resistance of grapevine leaves against the oomycete Plasmopara viticola, the causal agent of grape downy mildew. Here, we observed that the level of PS3-induced resistance (PS3-IR) was higher in the adult leaf (in position P3) than in the younger, not fully expanded leaf (in position P1, located above P3). By investigating grapevine defense reactions upon PS3 treatment and inoculation, we found that the production of H2O2, of phytoalexins, and the deposition of phenolics were more abundant in P3 than in P1 leaves. In addition, PS3 significantly reduced stomatal colonization by zoospores only in P3 leaves. T…

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…

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)…

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

1982

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…

Pythium campanulatumsp. nov., isolated from the rhizosphere of maize, its taxonomy, ITS region of rDNA, and comparison with related species

2003

Pythium campanulatum sp. nov. was isolated from some soil samples taken in the rhizosphere of maize (Zea mays) in north-eastern India. This species is characterized by the absence of zoospores and sporangia, antheridial branches wrapping around the oogonia leaving one to two campanulate antheridial cells after fertilization, and aplerotic oospores. The ITS region of its rDNA is comprised of 922 bases. This oomycete is closely related to Pythium orthogonon, Pythium nunn and Pythium toruloides. However, it has its own characteristic features and is completely devoid of zoospores. Taxonomic description of this new species and its comparison with related oomycetes, together with the sequence of…