Chloroplast 16S rRNA sequences from different Triticum species

The wheats (Triticum spp.) form a polyploid series with diploid, tetraploid and hexaploid forms. The wild allotetraploid emmer wheat T. turgidum ssp. dicoccoides (AABB) arose by amphyploidy between the wild diploid wheat T. urartu (AA) and a diploid member of the Aegilops genus (BB). The origin of B genome is still a matter of debate. Hexaploid wheats (AABBDD) may have evolved by hybridisation between the AABB tetraploid as cytoplasm donor and the D genome diploid Ae. taushii. The source of the genomes in hexaploid wheats has been thoroughly investigated. Small subunit rRNAs are widely used for the evaluation of genetic diversity or relatedness between different species. In this work small subunit 16S rDNA sequences from chloroplasts of hexaploid T. aestivum possible ancestors were examined. Sequences of 16S rDNAs in the plastids of Ae. taushii (DD), Ae. speltoides (BB) and T. dicoccum (AABB) were determined. They share complete identity in their 16S rDNA sequence and differ from 16S rDNA of T. aestivum by a single position of the gene

FLC-like factors in wheat (cv. Mv15) and Conyza sp.

Plants have evolved multiple pathwaysto regulate flowering time. The repressor pathway maintains the vegetative phase until the promotion pathways initiate reproductive development. The promotion pathways include the long-day, autonomous and vernalization pathways of flowering. A MADS-box protein encoded by FLOWERING LOCUS C (FLC) may be a major repressor of flowering in vernalization pathway since the transcript level of FLC is negatively regulated by vernalization. Special primer pairs were constructed here to identify the FLC genes in a monocotiledonous plant with strong requirement for vernalization and in a weed. This study describes the first example for the presence of FLC-like factors in winter wheat Triticum aestivum L. cv. MV15 and in the horseweed Conyza canadensis L. (Cronq.)

Studies on chloroplast and nuclear rDNA in hexaploid bread wheat and its relatives

Though allohexaploid bread wheat (Triticum aestivum) is grown on more acreage than any other cereal crop, its evolutionary history and origin of its three genomes have not been cleared up in every detail. The wheats form a polyploid series with diploid, tetraploid and hexaploid forms. Hexaploid wheats (AABBDD) may have evolved by hybridization between the AABB tetraploid as cytoplasm donor and the D genome diploid Aegilops tauschii. The origin of B genome is still a matter of debate. In the present study sequences of chloroplast and nuclear rDNA regions were used for giving new data to contribute to our knowledge on evolution of wheat. Analysis of cloned nrITS sequences of T. aestivum showed that 1) more than one ITS sequence type can be derived from the same sample, 2) a rye chromosome element formerly introgressed into wheat genome can be detected and 3) a partial segment of ITS similar to that of einkorn wheats (AA genome) can be identified. These results give evidences for ancient and recent introgressions and could help us to identify all of the three genomes of hexaploid bread wheat

S-methylmethionine alters gene expression of candidate genes in Maize dwarf mosaic virus infected and drought stressed maize plants

In the present work we investigated the potential beneficial effects of the exogenous application of S-methylmethionine (SMM) that plays an important role in the plants’ sulphur metabolism and contributes to the production of certain defence compounds. The possible beneficial effects were challenged against Maize dwarf mosaic virus infection and drought stress. We studied the expression changes of GF14-6 and SAMS during viral infection and DREB2A and DBP2 during drought stress. The product of GF14-6 recognise the viral coat protein and contributes to RNA-silencing, while the product of SAMS plays a central role in the plant sulphur metabolism and contributes to the production of several defence compounds. The products of DREB2A and DBP2 contribute to better plant defence against drought stress and increase the efficiency of water uptake. According to our results, SMM pretreatment has a considerable change on the investigated genes’ expression. It significantly decreases the gene expression of GF14-6, while infection results in a higher expression level. On the other hand, a more prolonged and long lasting increase is measured in SAMS expression as a result to SMM pretreatment followed by infection. SMM lessens the gene expression of DREB2A, while no changes were observed in DBP2 compared to drought stressed plants

Aspects of in situ, in vitro germination and mycorrhizal partners of Liparis loeselii

Our present work investigated asymbiotic in vitro and symbiotic in situ germination of the rare and protected terrestrial orchid, Liparis loeselii (L.) Rich. as one of the possibilities for its conservation. Asymbiotic germination array was tested on four different asymbiotic media (different macroelement and organic nitrogen levels) in dark and light. Additionally the effect of cold-treatment was also investigated. In situ germination rate was moderate, protocorms was observed only in the close surroundings of adult L. loeselii individuals. The fungal partners of L. loeselii were identified by sequence analysis of the internal transcribed spacer (ITS) of nuclear ribosomal DNA (nrDNA). The ‘root segment technique’ was effective for isolation of only one species, Tulasnella (Epulorhiza), whereas using ‘in situ bating’ yielded isolates of both Tulasnella and Ceratobasidium (Rhizoctonia) species

Changes in physiology, gene expression and ethylene biosynthesis in MDMV-infected sweet corn primed by small RNA pre-treatment

The physiological condition of plants is significantly affected by viral infections. Viral proliferation occurs at the expense of the energy and protein stores in infected plant cells. At the same time, plants invest much of their remaining resources in the fight against infection, making them even less capable of normal growth processes. Thus, the slowdown in the development and growth processes of plants leads to a large-scale decrease in plant biomass and yields, which may be a perceptible problem even at the level of the national economy. One form of protection against viral infections is treatment with small interfering RNA (siRNA) molecules, which can directly reduce the amount of virus that multiplies in plant cells by enhancing the process of highly conserved RNA interference in plants. The present work demonstrated how pre-treatment with siRNA may provide protection against MDMV (Maize dwarf mosaic virus) infection in sweet corn (Zea mays cv. saccharata var. Honey Koern). In addition to monitoring the physiological condition of the maize plants, the accumulation of the virus in young leaves was examined, parallel, with changes in the plant RNA interference system and the ethylene (ET) biosynthetic pathway. The siRNA pre-treatment activated the plant antiviral defence system, thus significantly reducing viral RNA and coat protein levels in the youngest leaves of the plants. The lower initial amount of virus meant a weaker stress load, which allowed the plants to devote more energy to their growth and development. In contrast, small RNA pre-treatment did not initially have a significant effect on the ET biosynthetic pathway, but later a significant decrease was observed both in the level of transcription of genes responsible for ET production and, in the amount of ACC (1-aminocyclopropane-1-carboxylic acid) metabolite. The significantly better physiological condition, enhanced RNAi response and lower quantity of virus particles in siRNA pretreated plants, suggested that siRNA pre-treatment stimulated the antiviral defence mechanisms in MDMV infected plants. In addition, the consistently lower ACC content of the plants pre-treated with siRNA suggest that ET does not significantly contribute to the successful defence in this maize hybrid type against MDMV

The effects of putrescine are partly overlapping with osmotic stress processes in wheat

Polyamine metabolism is in relation with several metabolic pathways and linked with plant hormones or signalling molecules; in addition polyamines may modulate the up- or down-regulation of gene expression. However the precise mechanism by which polyamines act at the transcription level is still unclear. In the present study the modifying effect of putrescine pre-treatment has been investigated using the microarray transcriptome profile analysis under the conditions where exogenous putrescine alleviated osmotic stress in wheat plants. Pre-treatment with putrescine induced the unique expression of various general stress-related genes. Although there were obvious differences between the effects of putrescine and polyethylene glycol treatments, there was also a remarkable overlap between the effects of putrescine and osmotic stress responses in wheat plants, suggesting that putrescine has already induced defence processes under control conditions. The fatty acid composition in certain lipid fractions and the antioxidant enzyme activities have also been specifically changed under osmotic stress conditions or after treatment with putrescine

Protective role of S-methylmethionine-salicylate in maize plants infected with Maize dwarf mosaic virus

This study aimed to detect the harmful effects of Maize dwarf mosaic virus (MDMV) infection, and to demonstrate the potential benefits of S-methylmethionine-salicylate (MMS) pretreatment in infected maize (Zea mays L.) plants. The results of chlorophyll a fluorescence measurements showed that in MDMV-infected plants additional quenchers of fluorescence appear, probably as the result of associations between the virus coat protein and thylakoid membranes. It is important to note that when infected plants were pretreated with MMS, such associations were not formed. MDMV infection and MMS pretreatment resulted in a decrease in ascorbate peroxidase (APX) activity in maize leaves, while infection contributed to an increase in activity in the roots. Infection raised the guaiacol peroxidase (GPX) enzyme activity level, which was reduced by MMS pretreatment. MMS contributed to a decrease in both the RNA and coat protein content of MDMV, to an equal extent in maize leaves and roots. The results showed that MMS pretreatment enhanced the stress response reactions against MDMV infection in maize plants and retarded the spreading of infection

Természetes vegyület, az S-metilmetionin hatásának vizsgálata a paradicsom és a kukorica fiziológiai sajátságaira, biotikus és abiotikus stressztoleranciájára = Effect of the natural compound S-methylmethionine on the physiological characteristics, biotic and abiotic stress tolerance of tomato and maize

Az S-metilmetionin (SMM) stresszvédelemben betöltött szerepét vizsgáltuk. Megállapítottuk, hogy ez a természetes, nem proteinogén aminosav jelentős szerepet játszik a vizsgált növények abiotikus és biotikus stresszorokkal szembeni védekezőképességének kialakításában, a stressztolerancia növelésében. Közvetlenül szerepel a kénanyagcsere alapvető folyamataiban, befolyásolja poliaminok bioszintézisét, mint az S-adenozilmetionin prekurzora és mint aminopropil-donor vegyület membránvédő, stabilizáló hatású. Transzkripció szinten elősegíti a hidegstressz elleni védelemben központi szabályozóként működő, számos gén kifejeződését együtt szabályozó CBF transzkripciós faktorok expresszióját. Növeli az ugyancsak sokoldalú szabályozó és stresszvédő poliaminok, valamint az általános stresszvédelemben jelentős fenilpropanoidok (fenoloidok, antociánok) szintéziséért felelős gének expresszióját. Mindezek következményeként a metabolomikai szinten bekövetkező változások jelentős fiziológiai választ eredményeznek. Fontos szerepe van egy- és kétszikű növények vírusok elleni védelmében is, csökkentve a víruskoncentrációt, lassítva a vírusok terjedését és szaporodását a gazdanövényekben, amihez hozzájárulhat, hogy fokozza a hormonok és a stresszvédő kénvegyületek képzésében fontos szerepet betöltő S-adenozilmetionin szintéziséért felelős gén expresszióját. Az SMM hatására jellemző a priming hatás, ami előkészíti a növényt a stresszre és lehetővé teszi a gyorsabb és hatékonyabb stresszválaszt. | The present work aimed to reveal the multiple role of SMM in protection against biotic and abiotic stressors. We proved that this non–proteinogenic amino acid has an important function in the development of defence potential and in the improvement of stress and disease tolerance of examined plants. At the level of transcription SMM exerts its effect via central regulatory factor CBF, which influences the expression of number of genes during cold stress as a coordinator. The effect of SMM is chiefly manifested in its influence on the expression of CBFs that act as central coordinator in the regulation of number of genes during cold stress. In addition, SMM enhances the expression of regulatory and stress protecting polyamines and the expression of genes coding for proteins with beneficial influence in defence compound phenolics, for instance anthocyanins. The changes of gene expression result in changes of metabolomic and physiological processes of plants. SMM has an important role in biotic stress protection against both of TSWV virus of tomato and the MDMV virus of maize, decreasing the virus concentrations and moderating their replication in plant. This beneficial influence may be due to its effect in increasing the expression of gene responsible for S-adenosylmethionine synthesis, which is important in the synthesis of stress protecting compounds. We found that SMM characteristically affects due to a priming effect, resulting in faster and improved stress response