RESUMEN
In vitro culture was used to study morphogenetic aspects of the tuberization process under controlled conditions in potato (Solanum tuberosum L.) plants. This paper accurately defines four stages of tuber development and their correlation to external morphological characteristics and histological structures. Protein kinase activity, assayed in each stage using Historic HAS as substrate, was differentially expressed during the tuberization process. Phosphorylation was maximum in the first stages of tuber formation. The incorporation of [32PO4 -1] to endogenous peptides containing serine/threonine amino acidic residues followed the same pattern that the protein kinase activity did.
RESUMEN
The complete cDNA sequence corresponding to the genomic RNA of a South American strain of potato virus X (PVXc) is reported. The sequence (6432 nucleotides) contains five open reading frames coding for polypeptides with molecular weights of 165.3, 24.3, 12.3, 7.6 and 25.0 and displays an overall homology of 77.4% with those previously reported for two European isolates. Comparison of amino acid sequences shows an average homology of 87%. Two major domains of variability, located between amino acids 476-615 of ORF 1 and 64-100 of ORF 5, are identified. Sequence similarities between RNA stretches lying upstream of ORFs 2, 4 and 5, and at the 3'-non coding regions of PVX and other plus-strand RNA viruses are described.
Asunto(s)
Genes Virales , Virus de Plantas/genética , ARN Viral , Secuencia de Aminoácidos , Secuencia de Bases , Clonación Molecular , ADN Viral , Europa (Continente) , Datos de Secuencia Molecular , ARN Viral/aislamiento & purificación , Homología de Secuencia de Ácido Nucleico , Solanum tuberosum/microbiología , América del SurRESUMEN
cDNA libraries, representative of potato viruses X (PVXc strain) and Y (PVY degrees strain) genomes were obtained. A PVX cDNA cloned fragment was sequenced and biotinylated to be used as hybridization probe for the detection of purified virus or nucleic acid extracts of infected plants. Dot hybridization assay was sensitive to detect 4 ng of viral particles, corresponding to about 200 pg of viral RNA. The level of detection in infected plant extracts was as effective as that obtained with the ELISA. The presence of biotinylated PVY cDNA in the hybridization mixture did not affect sensitivity of the PVX detection assay, suggesting that a single diagnostic assay for several potato viruses and virus-related pathogens could be developed.