bHLHTT8 Transcription Factor from Sorghum Restores Brown Seed Coat in tt8 Arabidopsis Mutants

SALEZ, AGUSTINA; RODRIGUEZ, MARÍA VICTORIA; FALCONE FERREYRA, M.L.; CASATI, P.; RIUS, S.P.

Paraná

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

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Sorghum [Sorghum bicolor (L) Moench.] is one of the most important cereals cultivated in the world. One of the limiting factors of its production is the pre-harvest sprouting, due to an inadequate establishment or maintenance of seed dormancy. Numerous evidence suggests that the levels of flavonoids accumulated in the seed coat could be involved in the establishment and maintenance of dormancy. Thus, the focus of our research was to elucidate the biological role of the putative bHLH-SbTT8 transcription factor from sorghum and its relationship with the flavonoid pathway. To do this, we generate transgenic plants expressed this transcription factor was under CaMV35S in tt8 A. thaliana plants (transparent testa 8, mutants in the orthologue gene of SbTT8). These transgenic plants restored partially the brownish color due to the accumulation of flavonoids in the seed coat. By vanillin assay, the presence of proanthocyanidins from immature stages of transgenic seeds was confirmed. The degree of dormancy was measured by the germination index (GI) and mean germination time, transgenic lines expressing SbTT8 show an intermediate behavior between tt8 mutants and the wild type.Also, in root tips of plants expressing 35S:GFP-SbTT8, GFP fluorescence was observed primarily in the nucleus, although faint fluorescence was also detected in the cytoplasm, these data indicate the fusion protein was mainly targeted to the nucleus, consistent with its predicted role as a transcription factor.