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The use of expressed sequence tag-simple sequence repeat (EST-SSR) markers might reflect the better relationship among species or cultivars than markers previously used. The first set of 30 EST-SSR was developed in hop ( Humulus lupulus L.). They represent 25 gene loci with total of 1268 EST sequences. They were used for characterization of 11 hop samples and cross-amplification in Humulus japonicus Sieb. et Zucc. The number of alleles per locus ranged from two to nine. The observed and expected heterozygosities ranged from 0.182 to 0.956 and from 0.233 to 0.775, respectively. We used EST-SSR markers for cluster analysis of hop genotypes. Dendrogram well matched with genealogical and geographical data for hop genotypes. [ABSTRACT FROM AUTHOR]

A complete sequence of chalcone synthase (CHS) gene from hop was cloned. The gene designated chs_H1 consists of two exons and one 187 bp intron. CHS protein predicted from chs_H1 cDNA has 42.5 kDa and retains conserved domains and residues including 26 amino acids at positions identical to those identified by crystallography as characteristic for catalytic domains of alfalfa CHS (EC 2.3.1.74). Cloned CHS_H1 protein shows specific CHS activity with 4-coumaroyl-CoA. Structure modelling revealed clear differences between CHS_H1 and phlorisovalerophenone synthase, the only published CHS-like homologue from hop. Conserved motifs like H, and G boxes characteristic for the light regulated and stress inducible genes were identified within promoter region of chs_H1 gene. Highly specific expression of chs_H1 mRNA was detected by quantitative RT PCR in glandular trichomes during cone maturation. Much lower, but significant levels of chs_H1 mRNA were detected at the stage of hop flowering in petioles (100%), developed flowers (96%), and in stem apexes (78%), while the lowest levels of mRNA were found in the roots (31%) and leaf blades (9%). Southern blot analyses predicted at least five additional chs-like genes related to chs_H1. A genomic arrangement different from phlorisovalerophenone synthase sequences was found for these genes. RFLP analyses using DNA from 15 genotypes revealed several distinct dendrogram clusters, suggesting specific re-arrangements of hop chs-like genes during evolution and/or during the breeding and selection processes. [Copyright &y& Elsevier]

Weed plants characteristic for potato and hop fields have not been considered in the past as potential hosts that could transmit and lead to spreading of potato spindle tuber (PSTVd) and hop stunt (HSVd) viroids, respectively. To gain insight into this problem, we biolistically inoculated these weed plants with viroid populations either as RNA or as cDNA. New potential viroid host species, collected in central Europe, were discovered. From 12 weed species characteristic for potato fields, high viroid levels, detectable by molecular hybridization, were maintained after both RNA and DNA transfers in Chamomilla reculita and Anthemis arvensis. Low viroid levels, detectable by reverse transcription-PCR (RT-PCR) only, were maintained after plant inoculations with cDNA in Veronica argensis and Amaranthus retroflexus. In these two species PSTVd concentrations were 105 and 103 times, respectively, lower than in tomato as estimated by real-time PCR. From 14 weeds characteristic for hop fields, high HSVd levels were detected in Galinsoga ciliata after both RNA and DNA transfers. HSVd was found, however, not to be transmissible by seeds of this weed species. Traces of HSVd were detectable by RT-PCR in HSVd-cDNA-inoculated Amaranthus retroflexus. Characteristic monomeric (+)-circular and linear viroid RNAs were present in extracts from weed species propagating viroids to high levels, indicating regular replication, processing, and circularization of viroid RNA in these weed species. Sequence analyses of PSTVd progenies propagated in C. reculita and A. arvensis showed a wide spectrum of variants related to various strains, from mild to lethal variants; the sequence variants isolated from A. retroflexus and V. argensis exhibited similarity or identity to the superlethal AS1 viroid variant. All HSVd clones from G. ciliata corresponded to a HSVdg variant, which is strongly pathogenic for European hops. [ABSTRACT FROM AUTHOR]