Authors:Á. Mesterházy, B. Tóth, Á. Szabó-Hevér, J. Varga, and S. Lehoczki-Krsjak
An undescribed symptom caused by
was detected in wheat fields showing masses of orange sporodochia on the node and neighbouring stem tissue. Normally the head above infected nodes dies and only chaff is harvested. This is the first formal description of this type of stem infections caused by
. The economic importance of these disease symptoms need further evaluation.
Virus symptoms were observed on Hedge bindweed (Calystegia sepium) a well known plant in Hungary. In the literature there is no record of virus infection on Hedge bindweed, therefore, investigations were carried out to determine the causal agent. Sap from leaves showing virus-like symptoms was inoculated onto test plants inducing systemic infection on Nicotiana clevelandii, N. benthamiana, local lesions on Chenopodium quinoa and no infection on Datura stramonium and Cucumis sativus. Sap of N. clevelandii was examined by electron microscopy, showed the presence of long flexous particles. The biological and other properties of the virus have also been studied. Properties of particles in sap were as follows: TIP (thermal inactivation point): 78 °C, LIV (longevity in vitro): 26 days and DEP (dilution end point): log 10 minus 5. The size of coat protein is 36 kDa, and the genome consists of 7-8000 nt RNA. Double-stranded cDNA were produced using random hexanucleotide primers, cloned and sequenced. BLAST search of sequence databases revealed nucleotide sequence identity with carlaviruses. Further investigations are needed to decide whether the virus isolated from Hedge bindweed is a new carlavirus or a new strain of an existing carlavirus.
In this review results are summarized
regarding the effect of virus infection on the physiological processes of
weeds. Through several host-virus model relations the biomass and
seed production, seed viability and germination, nutrient uptake,
drought-resistance and photosynthetic pigment content of healthy and virus
infected plants were compared. Because of their broad host range and high
genetic variability viruses cannot be used for biological weed control. It was
concluded that viruses unfavourably can influence physiological processes of
weeds. Therefore, they may contribute indirectly to the reduction of
competitive ability and population of weeds.
Authors:K. Stuper-Szablewska, D. Kurasiak-Popowska, J. Nawracała, and J. Perkowski
The aim of this study was to determine the profile of fungal metabolites and antioxidant substances from plants on a representative population of wheat cultivars grown in Poland. Tests were conducted on grain of 23 wheat cultivars in three experimental variants: natural infection (control), chemical crop protection, and artificial inoculation with the fungi F. graminearum and F. culmorum. Grains were analysed in terms of infection rate, mycotoxin, ergosterol, free and bound phenolic acid content, as well as antioxidant capacity. Calculated Fusarium head blight index (FHB index) ranged from 0% to 24% in the control, from 0% to 95% after inoculation and from 0 to 3% following chemical crop protection treatments. The highest concentration of ergosterol was detected in seeds from inoculated plots, with a mean value of 26.69 mg/kg. The highest mean concentration calculated for total toxin content was recorded after inoculation (7.833 mg/kg). The mean value for ferulic acid for inoculated samples resulted 2574 mg/kg, while for chemically protected samples 1158 mg/kg was obtained.
Based on of discriminant analysis genotypes can be separated for inoculation 100%, for chemical crop protection 95%, and for natural infection 90%. Amongst 12 analysed phenolic acids the highest discrimination power was found for gallic acid, 4-hydroxybenzoic acid and vanillic acid.
Downy mildew, caused by Peronosclerospora sorghi is one of the important diseases affecting maize (Zea mays L.) production worldwide. Several downy mildew resistant maize lines have been identified. However, variability in the degree of resistance among maize genotypes to P. sorghi has been reported. In the present study the molecular basis of resistance of maize to P. sorghi was studied by using differential-display reverse transcription PCR (DDRT-PCR) technique. Maize seedlings of downy mildew resistant (MAI 756) and susceptible (CM 500) cultivars at two-leaf stage were inoculated with P. sorghi and leaf samples were collected at 0, 3 and 5 days after inoculation and analyzed for differentially expressed cDNAs using cDNA-RAPD approach. A total of 17 cDNA fragments corresponding to transcripts that showed alterations during the defence response of maize to P. sorghi were identified. Genes involved in signal transduction and several genes with unknown functions were found to be upregulated in maize after infection by P. sorghi. Among 35 random primers tested, OPD-05 has identified a differentially expressed cDNA coding for serine/threonine kinase protein in resistant maize genotype. Constitutive and high level expression of serine/threonine kinase gene was observed in the uninoculated plants of resistant genotype, whereas no expression of this gene was observed in uninoculated plants of susceptible genotype. However, the transcript level was induced 3 days after inoculation in the susceptible genotype and slightly reduced 5 days after inoculation. This study represents the first identification of maize serine/threonine kinase gene that is upregulated following infection by P. sorghi.
Authors:Anabel Cruz-Romero, Cosme Alvarado-Esquivel, Dora Romero-Salas, Ángel Osvaldo Alvarado-Félix, Sokani Sánchez-Montes, Jesús Hernández-Tinoco, and Luis Francisco Sánchez-Anguiano
, muscular pain, and conjunctival congestion [ 5 ]. Whereas jaundice and hemorrhage are clinical features present in patients with the severe form of leptospirosis [ 5 ]. In animals, the acute phase of the Leptospira infection is mostly sub-clinical, but