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Fusarium equiseti (Corda) Saccardo is a soil saprophyte and a weak pathogen, associated with several diseases of fruit and other crops in subtropical and tropical areas, but also in countries with temperate climate. A wide range of secondary metabolites has been identified among natural F. equiseti populations, with zearalenone (ZEA), fusarochromanone and fusarenon-X being the most common. In present study, the genetic diversity of strains from two populations (from Italy and Poland) was evaluated by analysing the translation elongation factor 1? (tef-1?) sequences, two polyketide synthases from the ZEA biosynthetic pathway (PKS13 and PKS4) and the TRI5 gene from the trichothecene biosynthetic pathway. ZEA was produced in rice cultures by 20 of the 27 tested isolates in concentrations ranging from 1.34 ng/g to 34,000 ng/g). The ability to produce enniatins and trichothecenes was evaluated in all strains by identifying esyn1, TRI13 and TRI4 genes. The presence of PKS4 and PKS13 genes was confirmed by polymerase chain reaction (PCR) in only some ZEA-producing isolates. Similarly, the TRI5 gene was found in 14 of the 27 isolates tested. This is likely to have been caused by the divergence of those genes between F. equiseti and F. graminearum (the latter species was used for the primers design) and can be exploited in phylogenetic studies. The analysis of the mycotoxin biosynthetic gene sequences can be used to differentiate the studied genotypes even more precisely than the analysis of the non-coding regions (like tef-1alpha).
Winter wheat cultivars were significantly infected by Puccinia triticina causing leaf rust in seasons 2000-2002 in southern and also central regions of Poland. Resistance genes Lr9, Lr19 and Lr24 were found to be effective against dominating populations of the pathogen and typical isolates of P. triticina. Mentioned three resistance genes as well as genes Lr10 and Lr37 were identified using STS (Sequence Tagged Site) DNA - PCR markers in cultivars and resistance sources. Mentioned markers were found very useful in resistance breeding of wheat.
Genotyping of 98 wheat cultivars/lines was carried out with molecular markers that are linked to the Pm1 locus: two bi-allelic (dominant) markers: the sequence-tagged site Xsts638-7A and the amplified fragment length polymorphism XE39M58-77-7A; and the multi-allelic simple sequence repeat marker Xgwm344-7A. Employing segregation data recorded in the population Chinese Spring x Virest (Pm1e), genetic mapping revealed that Xgwm344-7A and XE39M58-77-7A were distally linked to Pm1e in the repulsion phase with respective linkage distances of 0.9 cM and 4.8 cM, while Xsts638-7A was found to co-segregate with Pm1e in the coupling phase. The genotyping results of Xsts638-7A and XE39M58-77-7A confirmed disease scoring, except for the accessions of cultivars Omega, Remus and Weihenstephan Stamm M1N. The SSR marker Xgwm344 amplified 15 different fragments ranging from 102 bp to 147 bp, with 15 entries being null-allelic at the 7A and 7B homoeoloci. It was found that wheat lines having resistance alleles at the Pm1 locus mainly show the null allele at the Xgwm344-7A locus. Due to their fast-evolving nature, the use of multi-allelic SSRs for genotype determination may be complicated. However, the combined use of multiple linked marker alleles seems to be a promising approach for genotyping a broad range of plant materials.
Three Fusarium species: F. graminearum, F. culmorum and F. cerealis were identified in laboratory cultures and in sporodochia from spikelets of scabby wheat. SCAR (sequence characterized amplified region) primers were used to identify Fusarium species and nivalenol (NIV) and deoxynivalenol (DON) chemotypes within species in laboratory cultures and field collected heads harvested in 2006. Results from PCR analyses confirmed preliminary identifications of species on the basis of examination of macroconidia under a light microscope and identification of cultures on agar media. NIV and DON (3Ac-DON and 15Ac-DON) chemotypes were identified using PCR assay. Among samples and isolates of F. graminearum, the 15Ac-DON chemotype dominated, and among those where F. culmorum was identified, the 3Ac-DON chemotype prevailed. Only 5 of the 41 isolates of F. graminearum tested, displayed the NIV chemotype. An increase in the frequency of F. graminearum and a decrease in the frequency of F. culmorum were found during 1998 to 2006.
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