AUTHOR=Vazquez-Hernandez Maria , Romero Irene , Escribano M. I. , Merodio Carmen , Sanchez-Ballesta M. T. 

TITLE=Deciphering the Role of CBF/DREB Transcription Factors and Dehydrins in Maintaining the Quality of Table Grapes cv. Autumn Royal Treated with High CO2 Levels and Stored at 0°C

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.01591

DOI=10.3389/fpls.2017.01591

ISSN=1664-462X

ABSTRACT=<p>C-repeat/dehydration-responsive element binding factors (CBF/DREB) are transcription factors which play a role in improving plant cold stress resistance and recognize the DRE/CRT element in the promoter of a set of cold regulated genes. Dehydrins (DHNs) are proteins that accumulate in plants in response to cold stress, which present, in some cases, CBF/DREB recognition sequences in their promoters and are activated by members of this transcription factor family. The application of a 3-day gaseous treatment with 20 kPa CO<sub>2</sub> at 0°C to table grapes cv. Autumn Royal maintained the quality of the bunches during postharvest storage at 0°C, reducing weight loss and rachis browning. In order to determine the role of CBF/DREB genes in the beneficial effect of the gaseous treatment by regulating DHNs, we have analyzed the gene expression pattern of three <italic>VviDREBA1s</italic> (<italic>VviDREBA1-1</italic>, <italic>VviDREBA1-6</italic>, and <italic>VviDREBA1-7</italic>) as well as three <italic>VviDHNs</italic> (<italic>VviDHN1a</italic>, <italic>VviDHN2</italic>, and <italic>VviDHN4</italic>), in both alternative splicing forms. Results showed that the differences in <italic>VviDREBA1s</italic> expression were tissue and atmosphere composition dependent, although the application of high levels of CO<sub>2</sub> caused a greater increase of <italic>VviDREBA1-1</italic> in the skin, <italic>VviDREBA1</italic>-<italic>6</italic> in the pulp and <italic>VviDREBA1</italic>-<italic>7</italic> in the skin and pulp. Likewise, the application of high levels of CO<sub>2</sub> regulated the retention of introns in the transcripts of the dehydrins studied in the different tissues analyzed. The DHNs promoter analysis showed that <italic>VviDHN2</italic> presented the <italic>cis</italic>-acting DRE and CRT elements, whereas <italic>VviDHN1a</italic> presented only the DRE motif. Our electrophoretic mobility shift assays (EMSA) showed that VviDREBA1-1 was the only transcription factor that had <italic>in vitro</italic> binding capacity to the CRT element of the <italic>VviDHN2</italic> promoter region, indicating that the transcriptional regulation of <italic>VviDHN1a</italic> and <italic>VviDHN4</italic> would be carried out by activating other independent routes of these transcription factors. Our results suggest that the application of high CO<sub>2</sub> levels to maintain table grape quality during storage at 0°C, leads to an activation of <italic>CBF/DREBs</italic> transcription factors. Among these factors, VviDREBA1-1 seems to participate in the transcriptional activation of <italic>VviDHN2</italic> via CRT binding, with the unspliced form of this <italic>DHN</italic> being activated by high CO<sub>2</sub> levels in all the tissues analyzed.</p>