bHLH-TT8 TRANSCRIPTION FACTOR FROM Sorghum RESTORES BROWN SEED COAT IN TT8 Arabidopsis MUTANTS

SALEZ, A.; RODRIGUEZ, MV; FALCONE FERREYRA, M.L.; CASATI, P.; RIUS, S.P.

Parana, Entre Rios

Congreso; 54th Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2018

Sorghum [Sorghum bicolor (L) Moench.] is one of the most important cereals cultivated in the world. The pre-harvest sprouting, due to an inadequate establishment or maintenance of seed dormancy, is responsible for high yield losses. Flavonoids are secondary metabolites with wide biological functions described in plants. Different evidences suggest that their accumulation in the seed coat could be involved in the establishment and maintenance of dormancy. Thus, this research aims to elucidate the biological roles of the putative bHLH-SbTT8 transcription factor (TF) from sorghum and its contribution in the flavonoid biosynthesis. We generated Arabidopsis transgenic plants expressing this transcription factor under the control of CaMV35S in the background tt8 (mutants in transparent testa 8, the orthologous gene of SbTT8, 35Spro:SbTT8). SbTT8 TF partially complemented the flavonoid deficiency of tt8 mutants in seed coats. By vanillin assay, transgenic plants showed proanthocyanidins accumulation in immature stages of transgenic seeds. Moreover, when dormancy was studied by calculating the germination index and the mean germination time, 35Spro:SbTT8 plants exhibited an intermediate behavior between tt8 mutants and the Wild Type Col-0 (higher levels than tt8 mutants, but lower than WT plants). In addition, in root tips of Arabidopsis plants expressing SbTT8 fused to GFP, SbTT8 localized primarily in the nucleus, although faint fluorescence was also detected in the cytoplasm, consistent with its predicted role as a transcription factor.