Search results for "Sporangium"
showing 10 items of 40 documents
The shoot concept of the flower: Still up to date?
2016
Abstract The shoot concept of the flower suggests that flowers correspond to vegetative short-shoots except the fact that their lateral appendages are floral and not vegetative leaves. However, in view of the different properties of vegetative and flower meristems, this concept should be questioned. Differential meristem activity resulting in tubes, hypanthia and inferior ovaries, continuous meristem expansion providing space for stamen fascicles and additional structures and the process of (repeated) fractionation using a given space completely, are characteristics of flower meristems hardly explainable with the shoot concept. Linking instead flower development with recent findings in mole…
First report of brown rot and wilt of fennel caused by Phytophthora megasperma in Italy
2019
Fennel (Foeniculum vulgare Mill. var. azoricum (Mill.) Thell.) in the Apiaceae family is native to southern Europe and southwestern Asia. It is an economically important crop in Italy that produces approximately 85% of all fennel worldwide. The main producing regions are Apulia, Campania, Latium, and Calabria. During the late winter of 2004 in the Crotone Province of the Calabria Region, following heavy rains, patches of fennel plants with symptoms of brown, soft rot of the bulb-like structure formed by the thickened leaf bases, development of yellow leaves, stunting, and wilting of the entire plant were observed in fields. A homothallic Phytophthora sp. was isolated consistently from the …
Morphological and molecular taxonomy ofPythium longisporangiumsp. nov. isolated from the Burgundian region of France
2005
During the course of an investigation on the Pythiaceous oomycetes occurring in the Burgundian vineyards, some species of Pythium possessing mainly hypogynous antheridia were found. These had been classified as oomycetes belonging to the ‘‘Pythium rostratum’’ group for a long time. Three of these isolates, having similar structures and growth, are very closely related to a recently described species, Pythium bifurcatum Paul. A close look at these, however, underlines some fundamental differences with the latter. Not all of them produce zoospores but have very large sporangia. The type specimen is F-1200 (B 76a) which is a medium-slow growing saprophyte. The sequence of the ITS region of the…
Pythium prolatumisolated from soil in the Burgundy region: a new record for Europe
1999
Pythium prolatum Hendrix and Campbell has been isolated from a soil sample taken in the Burgundy region in France. The fungus is easily recognisable by its heavily ornamented oogonia with conical to mammiform spines, elongated sporangia, and its diclinous antheridia forming or originating from a tangled mass of hyphae. Descriptions of the morphological and reproductive aspects of Pythium prolatum, the polymerase chain reaction of the internal transcribed spacer (ITS1) of the ribosomal nuclear DNA as well as the nucleotide sequences of ITS1 coding for 5.8 S rRNA are given.
Pythium segnitiumsp. nov., isolated from the Canary Islands â its taxonomy, ITS region of rDNA, and comparison with related species
2002
Pythium segnitium (CI-44) was isolated from some soil samples taken in the Canary Islands (Spain). This new species is a slow-growing fungus and is perfectly adapted to terrestrial habitat. It belongs to the group of Pythium that have smooth-walled oogonia, mostly hypogynous antheridia, and plerotic oospores. The fungus lacks sporangia, zoospores, and hyphal bodies are rarely formed. Thus the asexual reproduction, which is so common for fungi and especially for the aquatic ones, is completely lacking in this case. However the fungus reproduces sexually by the formation of oogonia, antheridia and oospores plentifully. The taxonomic description of this fungus, the nucleotide sequence of the i…
Callistemon citrinus and Cistus salvifolius, Two New Hosts of Phytophthora taxon niederhauserii in Italy.
2009
Bottlebrush (Callistemon citrinus (Curtis.) Skeels., Myrtaceae) and rock rose (Cistus salvifolius L., Cistaceae) are evergreen shrubs native to Australia and the Mediterranean Region, respectively. In the spring of 2003, approximately 2% of a nursery stock of 12-month-old potted plants of C. citrinus and 8% of a nursery stock of 12-month-old potted plants of Cistus salvifolius grown in the same nursery in Sicily, showed symptoms of leaf chlorosis, defoliation, and wilt associated with root and collar rot. A Phytophthora species was consistently isolated from roots and basal stems on BNPRAH selective medium (2). One isolate from rock rose (IMI 391708) and one from bottlebrush (IMI 391712) w…
Cytology of Thamnidium elegans Link. II. Distribution and behaviour of nuclei in hyphae, sporangiophores and sporangiospores.
1976
The resting nuclei in hyphae, sporangiophores and sporangiospores of sporangia and sporangiola of Thamnidium elegans consist of a large centrals nucleolus and a shell of chromatin surrounding the nucleolus. Division of the nucleus in hyphae and sporangiospores is achieved by elongation and constriction.
First report of root and crown rot of sage caused by Phytophthora cryptogea in Italy
2019
Sages are cultivated as aromatic and ornamental plants in Italy and represent the common name of certain species of Salvia and Phlomis (family Lamiaceae). In Sicily (southern Italy) during the summer of 2001, ≈40% of 1,400 2-year-old landscape plants of S. leucantha Cav. (Mexican bush sage or velvet sage) showed symptoms of stunting, chlorosis, and gradual dieback or sudden wilt, which are associated with root and crown rot. Plants were supplied by a commercial nursery, transplanted from pots in the spring, and irrigated using a trickle system. Phytophthora was isolated consistently from roots and basal stems of symptomatic plants on a BNPRAH medium (2). The species was identified as P. cr…
Wilt and Collapse of Cuphea ignea Caused by Phytophthora tropicalis in Italy.
2006
The genus Cuphea (Lythraceae) includes approximately 250 species of annual, evergreen perennials and short shrubs native to Central and South America. During the springs of 2003 and 2004, 10% of the nursery stock of approximately 12,000 potted cigar-flowers (C. ignea A. DC) grown in a screenhouse at a commercial ornamental nursery near Piedimonte Etneo, Sicily, had symptoms of wilt, defoliation, and rapid collapse of the entire plant. These foliar symptoms were associated with a reduced root system, browning of the collar, and dark brown discolored roots. A Phytophthora species was consistently recovered by plating small pieces of rotted roots of symptomatic plants onto selective medium (3…
Root and Basal Stem Rot of Scotch Broom Caused by Phytophthora citricola and P. drechsleri in Italy.
2005
Scotch broom (Cytisus scoparius (L.) Link, Fabaceae), an evergreen shrub native to Europe, is cultivated as a garden plant. In 2003 and 2004, potted plants with symptoms of leaf chlorosis, defoliation, and eventual wilt and associated with root and collar rot were observed in ornamental nurseries in Sicily. As much as 10% of plants were affected in a single nursery. Two species of Phytophthora were consistently isolated alone or together from the same pot with the selective medium of Masago et al. (2). Pure cultures were obtained by single-hypha transfers and the species were identified as P. citricola Sawada (approximately 40% of isolations) and P. drechsleri Tucker (60% of isolations) on…