Elimination of hop latent viroid upon developmental activation of pollen nucleases
Language English Country Germany Media print
Document type Journal Article, Research Support, Non-U.S. Gov't
PubMed
18627315
DOI
10.1515/bc.2008.096
PII: 10.1515/BC.2008.096
Knihovny.cz E-resources
- MeSH
- Enzyme Activation * MeSH
- Humulus genetics growth & development physiology virology MeSH
- Germination MeSH
- Virus Latency MeSH
- Molecular Sequence Data MeSH
- Pollen enzymology growth & development metabolism physiology MeSH
- Gene Expression Regulation, Plant MeSH
- Ribonucleases chemistry genetics metabolism MeSH
- Amino Acid Sequence MeSH
- Base Sequence MeSH
- Substrate Specificity MeSH
- Viroids genetics isolation & purification physiology MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Ribonucleases MeSH
Hop latent viroid (HLVd) is not transmissible through hop generative tissues and seeds. Here we describe the process of HLVd elimination during development of hop pollen. HLVd propagates in uninucleate hop pollen, but is eliminated at stages following first pollen mitosis during pollen vacuolization and maturation. Only traces of HLVd were detected by RT-PCR in mature pollen after anthesis and no viroid was detectable in in vitro germinating pollen, suggesting complete degradation of circular and linear HLVd forms. The majority of the degraded HLVd RNA in immature pollen included discrete products in the range of 230-100 nucleotides and therefore did not correspond to siRNAs. HLVd eradication from pollen correlated with developmental expression of a pollen nuclease and specific RNAses. Activity of the pollen nuclease HBN1 was maximal during the vacuolization step and decreased in mature pollen. Total RNAse activity increased continuously up to the final steps of pollen maturation. HBN1 mRNA, which is abundant at the uninucleate microspore stage, encodes a protein of 300 amino acids (34.1 kDa, isoeletric point 5.1). Sequence comparisons revealed that HBN1 is a homolog of S1-like bifunctional plant endonucleases. The developmentally activated HBN1 and pollen ribonucleases could participate in the mechanism of HLVd recognition and degradation.
References provided by Crossref.org
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