Showing papers by "Attila Fehér published in 1992"
TL;DR: The detection of centromeric chromosome fragments and long, poly-constrictional chromosomes in cytological preparations as well as non-parental bands in Southern hybridizations with restriction fragment length polymorphism (RFLP) markers revealed extensive chromosome rearrangements in most of the regenerated clones.
Abstract: Asymmetric somatic hybrids between Solanum tuberosum L. and S. brevidens Phil. have been obtained via the fusion of protoplasts from potato leaves and from cell suspension culture of S. brevidens. The wild Solanum species served as donor after irradiation of its protoplasts with a lethal X-ray dose (200 Gy). Selection of the putative hybrids was based on the kanamycin-resistance marker gene previously introduced into the genome of Solanum brevidens by Agrobacterium-mediated gene transfer. Thirteen out of the 45 selected clones exhibited reduced morphogenic potential. The morphological abnormalities of the regenerated plantlets were gradually eliminated during the extended in vitro culture period. Cytological investigations revealed that the number of chromosomes in the cultured S. brevidens cells used as protoplast source ranged between 28–40 instead of the basic 2n=24 value. There was a high degree of aneuploidy in all of the investigated hybrid clones, and at least 12 extra chromosomes were observed in addition to the potato chromosomes (2n=48). Interand intraclonal variation and segregation during vegetative propagation indicated the genetic instability of the hybrids, which can be ascribed to the pre-existing and X-ray irradiation-induced chromosomal abnormalities in the donor S. brevidens cells. The detection of centromeric chromosome fragments and long, poly-constrictional chromosomes in cytological preparations as well as non-parental bands in Southern hybridizations with restriction fragment length polymorphism (RFLP) markers revealed extensive chromosome rearrangements in most of the regenerated clones. On the basis of the limited number of RFLP probes used, preferential loss of S. brevidens specific markers with a non-random elimination pattern could be detected in hybrid regenerants.
38 citations
TL;DR: The presence of the coat protein gene was proved by Southern hybridization in several transformants and the majority of transformants exhibited reduced accumulation of virus RNA in inoculated leaves.
Abstract: Tuber discs of potato (Solanum tuberosum L.) cultivars Desiree and Gracia were infected by Agrobacterium tumefaciens carrying a binary vector with the coat protein gene of potato virus X controlled by the carrot extensin gene long-transcript promoter. Several transgenic potato plants have been obtained by direct regeneration of shoots on culture medium with kanamycin used for selection. The presence of the coat protein gene was proved by Southern hybridization in several transformants. Its low but detectable expression level was shown by Northern and Western analysis. Ethephon treatment resulted in a five-fold increase in the amounts of the coat protein mRNA. The majority of transformants exhibited reduced accumulation of virus RNA in inoculated leaves. Potentials in the use of an ethylene-inducible promoter in the production of virus-resistant transgenic plants will be discussed.
17 citations