Rostaniha
Year:2003 | Volume:4 | Issue:1-2|Papers Count:7

The structural differences between dormant and nondormant seeds of wild oats (Avena ludoviciana Durieu) were studied by light and transmission electron microscopy. Radial elongation of scutellum epithelial cells was observed in nondormant seeds after imbibition, compared with dormant seeds in which cells were completely compressed. Ultrastructural differences for example, dilution of cytoplasm, digestion of lipid and aleurone grains, enlarged endoplasmic reticulum, increase and assembly of polysomes and mitochondria, presence of a big vacuole were observed in nondormant seeds. Electron microscopy did not reveal such changes in dormant seeds. Nevertheless a lot of spherosomes, aleurone grains and some small vacuole were observed in the cytoplasm.

Biodiversity of the genus Medicago in Iran was studied. Distribution of two perennial species M. sativa and M. lupulina mainly conforms to the mountainous regions of Iran. Among the other annual species of this genus, M rigidula has the most similar distribution to the distribution of perrenial species in mountainous regions. Most species of Medicago (apart from M. sativa and M lupulina) are distributed in regions with Mediterranean climates. One major and two minor variation centers for the genus Medicago in Iran were identified. The most possible route for species to enter Iran is from the West via North Iraq.

Five species of Puccinia and two of Uromyces making 7 rust-host combinations are reported from Iran. Puccinia leveillei on Geranium sylvaticum, P. libanotidis on Libanotis transcaucasica, P. podospermi on Scorzonera laciniata and Uromyces scrophulariae on Scrophularia umbrosa are reported as new to the flora of Iran. For other three species viz. P. campanulae and P. gaubae on Campanula spp. and U. bupleuri on Bupleurum exaltatum, new morphological features, new hosts and new localities are also reported.

Effect of various NaCI treatments (0, 50, 100, 200 and 300 mM) at different growth and development stages (tillering, boot swollen, flowering and anthesis) of two wheat cultivars on the kinetic activity and PAGE electrophoretic pattern of leaf malate dehydrogenase was studied under greenhouse conditions. Ghods was salt-sensitive and Boolani was salt-tolerant. In general, in response to salintiy treatments, the increase in malate dehydrogenase was only significant during tillering and boot swollen and there was no significant difference between these cultivars. In addition, the electrophoretic patterns of leaf malate dehydrogenase showed significant changes during tillering and booting and these differences were not significant between Ghods and Boolani. Thus, it seemed that salt stress could induce significant changes in the kinetic activity and PAGE electrophoretic pattern of leaf malate dehydrogenase only during early growth stages in these cultivars.

Molecular approaches were used to re-evaluate the morphological criteria used to identify plant-associated Verticillium species. ITS-RFLPs divided the 31 studied strains of seven Verticillium species, (including the type species V. luteo-album) into four clusters. Cluster one comprised strains of the type species, V.oleo-album, cluster two V albo-atrum, V. dahliae, V. nubilum and I! tricorpus; cluster three comprised strains of V. theobromae and cluster four comprised strains of V nigrescens. b-tubulin gene RFLPs offered a higher degree of resolution, distinguishing all seven species from each other. The highest degree of resolution was obtained from mitochondrial DNA-RFLPs that divided strains of V theobromae and V. nigrescens into infraspecific groups. The  b- tubulin gene digested by Hae III offers a reliable way to separate the two economically important and controversial species V. albo-atrum and V dahliae.

Macro-fungi from different places of   Mazandaran and Tehran provinces, collected since 1982-2000, identified. An account of 16 Coprinus species, namely, Coprinus picaceus, C. cinereus, C. lagopus, C. lagopides, C. macrocephalus, C. brunneofibrillosus, C. subimpatiens, C. angulatus, C. niveus, C. ephemeroides, C. comatus, C. flocculosus, C. scobicola, C. disseminatus, C. plicatilis and C. patouillardii, were collected around Noor, Babulsar and Tehran and identified. Nine species, namely, Coprinus lagopus, C. comatus, C. flocculosus, C. scobicola, C. disseminatus, C. plicatilis, C. picaceus, C. macrocephalus and C. niveus, were previously recorded from Iran but other 7 species, namely, C. lagopides, C. macrocephalus, C. brunneofibrillosus, C. subimpatiens, C. angulatus, C. ephemeroides and C. cinereus are new to Iran along with C. lagopus, C. niveus, C. picaceus and C. macrocephalus are described and illustrated in detail.