Identification of StBEL5 RNA as a long-distance mobile signal in short-day facilitated tuber formation

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Repository URL:
10.31274/rtd-180813-366; 10.31274/rtd-180816-366
Yu, Yueyue
Iowa State University; Digital Repository @ Iowa State University,
Plant pathology; Molecular; cellular; and developmental biology
thesis / dissertation description
In potato, the BEL1-like transcription factor, StBEL5 and its protein partner POTH1, regulate tuber formation by mediating hormone levels in the stolon tip. Heterografting experiments show that StBEL5 mRNA can move across the graft union to localize in stolon tips and enhance tuber formation. Over-expression of StBEL5 full-length transcripts including the untranslated regions (UTRs) endows transgenic lines with the capacity to overcome the long-day inhibitory effects on tuber formation.;In this study, the precise localization of endogenous StBEL5 mRNA and other gene specific transcripts in the vascular tissues were determined by laser microdissection coupled to laser pressure catapulting (LMPC) and following RT-PCR. The results demonstrate the presence of StBEL5 mRNA in phloem cells which is consistent with its role as a mobile RNA.;StBEL5 full length transcripts exhibited better mobility compared to its UTR-truncated form and StBEL14 transcripts in agroinfiltration experiments. No translation enhancement was observed for full length StBEL5 transcripts compared to its UTR-truncated transcripts by in vitro translation assay. This indicates involvement of StBEL5 UTRs in facilitating its long-distance movement. Further studies of applying EMSA and northwestern blotting to identify StBEL5 mRNA binding proteins may provide pivotal cues to understand the mechanism of phloem delivered StBEL5 RNA in this long-distance signaling pathway during tuber formation.