Accumulation of viroid-specific small RNAs and increase in nucleolytic activities linked to viroid-caused pathogenesis.
Strong viroid-caused pathogenesis was achieved in tomato cv. Rutgers by biolistic transfer of severe or lethal potato spindle tuber viroid (PSTVd) strains, while other tomato genotypes (e.g., Moneymaker) were tolerant. With reciprocal hybrids between sensitive and tolerant genotypes, we show that plant depression dominates over tolerance. Biolistic transfer of the most pathogenic PSTVd strain AS1 to Nicotiana benthamiana, which is considered to be a symptomless PSTVd host, led to a strong pathogenesis reaction and stunting, suggesting the presence of specific viroid pathogenesis-promoting target(s) in this plant species. Total levels of small siRNA-like PSTVd-specific RNAs were enhanced in strongly symptomatic tomato and N. benthamiana plants after biolistic infection with AS1 in comparison to the mild QFA strain. This indicates association of elevated levels of viroid-specific small RNA with production of strong symptoms. In symptom-bearing tomato leaves in comparison to controls, an RNase of approximately 18 kDa was induced and the activity of a nuclease of 34 kDa was elevated by a factor of seven in the vascular system. Sequence analysis of the nuclease cDNA designated TBN1 showed high homology with plant apoptotic endonucleases. The vascular-specific pathogenesis action is supported by light microscopic observations demonstrating a certain lack of xylem tissue and an arrest of the establishment of new vascular bundles in collapsed plants.
Matousek
Jaroslav
J
Department of Molecular Genetics, Biological Centre of the Czech Academy of Sciences, Institute of Plant Molecular Biology, Branisovská 31, CZ-37005 Ceské Budĕjovice, Czech Republic.
Kozlová
Petra
P
Orctová
Lidmila
L
Schmitz
Axel
A
Pesina
Karel
K
Bannach
Oliver
O
Diermann
Natalie
N
Steger
Gerhard
G
Riesner
Detlev
D
D000595:Amino Acid Sequence; D001483:Base Sequence; D019470:Biolistics / Q000379:methods; D015152:Blotting, Northern; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004720:Endonucleases / Q000235:genetics / Q000378:metabolism*; D005838:Genotype; D018551:Solanum lycopersicum / Q000235:genetics* / Q000378:metabolism / Q000821:virology; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010935:Plant Diseases / Q000235:genetics / Q000821:virology; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000821:virology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D010942:Plant Viruses / Q000235:genetics / Q000472:pathogenicity; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism*; D012367:RNA, Viral / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D011198:Solanum tuberosum / Q000235:genetics / Q000378:metabolism / Q000821:virology; D014772:Viroids / Q000235:genetics* / Q000472:pathogenicity
D018076:DNA, Complementary; D010940:Plant Proteins; D034741:RNA, Small Interfering; D012367:RNA, Viral; D004720:Endonucleases