Suppression of RICE TELOMERE BINDING PROTEIN1 Results in Severe and Gradual Developmental Defects Accompanied by Genome Instability in Rice

Abstract

Although several potential telomere binding proteins have been identified in higher plants, their in vivo functions are still unknown at the plant level. Both knockout and antisense mutants of RICE TELOMERE BINDING PROTEIN1 (RTBP1) exhibited markedly longer telomeres relative to those of the wild type, indicating that the amount of functional RTBP1 is inversely correlated with telomere length. rtbp1 plants displayed progressive and severe developmental abnormalities in both germination and postgermination growth of vegetative organs over four generations (G1 to G4). Reproductive organ formation, including panicles, stamens, and spikelets, was also gradually and severely impaired in G1 to G4 mutants. Up to 11.4, 17.2, and 26.7% of anaphases in G2, G3, and G4 mutant pollen mother cells, respectively, exhibited one or more chromosomal fusions, and this progressively increasing aberrant morphology was correlated with an increased frequency of anaphase bridges containing telomeric repeat DNA. Furthermore, 35S:anti-RTBP1 plants expressing lower levels of RTBP1 mRNA exhibited developmental phenotypes intermediate between the wild type and mutants in all aspects examined, including telomere length, vegetative and reproductive growth, and degree of genomic anomaly. These results suggest that RTBP1 plays dual roles in rice (Oryza sativa), as both a negative regulator of telomere length and one of positive and functional components for proper architecture of telomeres.

Protection of Telomeres 1 Is Required for Telomere Integrity in the Moss Physcomitrella patens

“…A similar phenotype is associated with POT1 deletion in chicken cells (Churikov et al, 2006), implying that some aspects of Pp POT1 function are more similar to vertebrate POT1 than to the S. pombe POT1. It is also possible that P. patens POT1 functions redundantly with another telomere protection factor, such as a homolog of the putative Arabidopsis double-stranded telomere binding protein TBP1 (Hong et al, 2007) or the newly identified plant CST complex (Surovtseva et al, 2009). …”

Evolution of CST function in telomere maintenance

“…Arabidopsis encodes multiple TRF-like proteins, which bind ds telomeric DNA in vitro and negatively regulate telomere length in vivo 32,33 ( Fig. 5A).…”

Telomerase-Dependent 3′ G-Strand Overhang Maintenance Facilitates GTBP1-Mediated Telomere Protection from Misplaced Homologous Recombination

“…PCR reactions consisted of 22 cycles of 30 s at 95°C, 1 min at 55°C, and 2 min at 72°C. Telomeres and amplified DNA-tag were visualized using FISH analysis with Alexa Fluor 488 (Invitrogen) conjugated to dUTP-labeled DNA-tag probes and Texas Red-dUTP-labeled telomere (TTTAGGG) 70 probes, respectively, as described (Hong et al, 2007).…”