On the specific difference in the local necrotic response to infection by tobacco mosaic and cabbage black ringspot viruses in tobaccos

Dědi?ně faktory podmiňující v rostlině schopnost reagovat na infekci virem mozaiky tabáku (Nicotiana virus 1) a virem ?erné krou?kovitosti zeli (Brassica virus 1) lokálními nekrotickými lézemi, resp. systémovoù infekcí, jsou u těchto dvou vir? Jen zdánlivě v inversní závislosti. Nicotiana tabacum var. Xanthi-nc, který získal nekrotický faktor z N. glutinosa, má je?tě nekrotický faktor pro infekci virem ?erné krou?kovitosti zelí.     

First report of epiphytic dinoflagellate Coolia malayensis (Dinophyceae) in the southeastern Pacific Ocean

Coolia species are epiphytic and benthic dinoflagellates with a cosmopolitan distribution in tropical and subtropical areas. In the austral summer of 2016, during a survey in Bahía Calderilla, a dinoflagellate of the genus Coolia was detected in macroalgae samples, and a clonal culture was established. Subsequently, the cultured cells were observed by scanning electron microscopy (SEM) and identified as C. malayensis based on their morphological characteristics. Phylogenetic analyses based on the LSU rDNA D1/D2 regions confirmed that strain D005-1 corresponded to C. malayensis and clustered with strains isolated from New Zealand, Mexico, and Asia Pacific countries. Although the strain D005-1 culture did not contain yessotoxin (YTX), cooliatoxin, 44-methyl gambierone, or its analogs in detectable amounts by LC–MS/MS, more research is needed to evaluate its toxicity and to determine the possible impact of C. malayensis in northern Chilean waters.     

Preservative effect of saccharose solution on some plant viruses

Konzervaci vir? jsme prováděli v oddělených listech infek?ních rostlin, které byly pono?eny do roztoku sacharózy. Nejlep?ího výsledku jsme dosáhli s 3molálním roztokem. Takto byly úspě?ně konzervovány: oby?ejný a nekrotický kmen Y viru bramboru, X virus bramboru, 2 zelené kmeny viru mozaiky okurky, virus ?erné krou?kovitosti zelí, komplex viru mozaiky okurky a viru ?erné krou?kovitosti zelí, virus mozaiky ?epy a virus nekrotické kade?avosti tabáku. Pr?měrná doba ulo?ení list? v roztoku sacharózy byla 7 - 8 měsíc?. Tímto zp?sobem se v?ak nepoda?ilo konzervovat ?lutý kmen viru mozaiky okurky.     

Nitrogen regulation of fatty acids and avermectins biosynthesis in Streptomyces avermitilis

Fatty acid composition was analysed in the producer of avermectins, Streptomyces avermitilis C-18 grown in chemically defined medium with different nitrogen sources. Significant differences in nitrogen regulation of fatty acid biosynthesis were found in this strain in comparison with other streptomycetes studied so far. This finding could be explained at the level of regulation of branched-chain amino acid metabolism.     

Colonization by endophytic Ochrobactrum anthropi?Mn1 promotes growth of Jerusalem artichoke

The Ochrobactrum anthropi Mn1 strain, taxonomically identified using 16S ribosomal DNA sequence, was isolated from roots of Jerusalem artichoke. Its endophytic colonization was investigated microscopically using green fluorescent protein introduced by vector pHC60. The strain entered Jerusalem artichoke tissues through the root, and was localized in the roots and stems. The plant growth-promoting (PGP) effects of O. anthropi Mn1 were assessed in greenhouse as well as field trials with different nitrogen supplies. Only under moderate to ample nitrogen supply, could O. anthropi Mn1 promoted growth of host plant. The PGP effects of the strain were symbiotic nitrogen fixation, root morphological optimization and enhanced nutrient uptake. We hypothesize that the symbiotic interspecies interaction might be quorum sensing related.     

Uptake and distribution of 65Zn and 54Mn in wheat grown at sufficient and deficient levels of Zn and Mn II. During grain development

We investigated the uptake and distribution of Zn and Mn inwheat during grain development. Plants were grown in a chelate-bufferednutrient solution with one of the following treatments: control,low Zn or low Mn. Plants were dual-labelled with ⁶⁵Zn and ⁵⁴Mnat 2 and 8 wk post-anthesis for 5 and 24 h, respectively. Afterlabelling, the plants were separated into individual componentsfor analysis. In the plants harvested at 8 wk after anthesis,spikelets were separated into individual structures and analysedfor radioactivity. Little or no root-supplied ⁵⁴Mn was distributed to the leavesof both the controls and low-Mn plants during the grain developmentstages studied here. More ⁵⁴Mn was distributed to the head at8 wk than at 2 wk post-anthesis. In contrast, root-supplied⁶⁵Zn was transported to the leaves at 2 and 8 wk post-anthesis.More⁶⁵Zn was distributed to the leaves of the low-Zn plants thanthe controls during grain development.More esZn was detectedin the head towards grain maturity. Relatively larger amountsof ⁵⁴Mn than ⁶⁵Zn were found in different parts of the florets.Labelled Mn was found in relatively large quantities in thepalea, lemma and in the glumes, even though most ⁵⁴Mn was foundin the grain. A large percentage of the grain MMn was in theouter pericarp. During grain development leaves may still require Zn but notMn, which may be due to the requirement of Zn in maintainingmembrane structure and function. Distribution of Zn and Mn withinthe spikelets suggests that Zn may enter the grain via the phloemwhile Mnmay enter the grain via the xylem. Key words: Zinc, manganese, nutrient transport, grain development, wheat, Triticum aestivum