A search for transcripts producing differential splice variants in spikelets of apomictic and sexual Paspalum notatum.

COLONO C; SIENA L; ORTIZ JPA; LEBLANC O; PESSINO SC

Foz de Iguazú

Congreso; 11th International Congress Plant Molecular Biology 2015 (IPMB 2015); 2015

International Plant Molecular Biology

PNTGS1 encodes a PIMT/TGS1-like methyltransferase involved in sn(o)RNA biogenesis and coactivation of PPAR-regulated gene expression. PIMT/TGS1 catalyzes the post-transcriptional conversion of 7-methylguanosine caps (m7G) into 2,2,7-trimethylguanosine (m3G). In eukaryotic non-plant model systems, the abolishment of PIMT/TGS1 function causes a wide range of phenotypic alterations, including cold-sensitive splicing defects, growth delay at low temperatures, loss of nucleolar structural organization, pre-rRNA processing deficiency and meiotic failure after aberrant splicing of key regulators. In prior work we reported that PNTGS1 expression displays positive correlation with the degree of sexuality in ovules of facultative apomictic Paspalum notatum plants. Moreover, mutations in the arabidopsis putative ortholog revealed a significant proportion of seed abortion. We hypothesized that apomicts show defective RNA splicing in ovules associated with PIMT down-regulation. In order to put this hypothesis to the test, our first objective was to identify transcripts represented by contrasting splice variants in sexual and apomictic Paspalum notatum. Total RNA was extracted from an equitative mix of spikelets at different developmental stages. Two libraries (sexual and apomictic) were sequenced by using 454 GS FLX+ Roche, which produced 1,367,227 and 1,378,523 reads with an average size of 470.21 and 494.88, respectively. All sequences (sexual and apomictic) were assembled together and annotated with TRINOTATE. This general file was substracted with sequences originated from either sexual or apomictic libraries. Filtered assemblies were compared to identify transcripts showing splice variants. In further work, the splicing of the identified candidates will be examined in arabidopsis wild-type plants and tgs1 mutants.