Wenwen Liu1,2,3, Renkun Tang1,2,3, Yuyu Zhang1,2,3, Xianju Liu1,2,3, Yingying Gao1,2,3, Zhanwu Dai1,3, Shaohua Li1,2,3, Benhong Wu4,5, Lijun Wang6,7. 1. Beijing Key Laboratory of Grape Science and Enology, and Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, People's Republic of China. 2. University of Chinese Academy of Sciences, Beijing, 100093, People's Republic of China. 3. LIA INNOGRAPE International Associated Laboratory, Beijing, 100093, People's Republic of China. 4. Beijing Key Laboratory of Grape Science and Enology, and Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, People's Republic of China. bhwu@ibcas.ac.cn. 5. LIA INNOGRAPE International Associated Laboratory, Beijing, 100093, People's Republic of China. bhwu@ibcas.ac.cn. 6. Beijing Key Laboratory of Grape Science and Enology, and Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, People's Republic of China. ljwang@ibcas.ac.cn. 7. LIA INNOGRAPE International Associated Laboratory, Beijing, 100093, People's Republic of China. ljwang@ibcas.ac.cn.
Abstract
MAIN CONCLUSION: Genome-wide identification, analysis and functional characterization of an unreported VvBBX gene showed a response to light and positive correlation with anthocyanin content, but also inhibition of light-induced anthocyanin synthesis. B-box (BBX) proteins are a class of zinc (Zn) finger transcription factors or regulators characterized by the presence of one or two BBX domains and play important roles in plant growth and development. However, the BBX genes' potential functions are insufficiently characterized in grape, a globally popular berry with high economic value. Here, 25 BBX family genes including a novel member (assigned VvBBX44) were identified genome widely in grape. The expression level of these VvBBXs were analyzed in 'Cabernet Sauvignon' (V. vinifera) stem, flower, leaf, tendril, petiole, and developing berries. The expression of VvBBX44 increased in developing 'Cabernet Sauvignon' berries. Its expression was inhibited in 'Jingxiu' and 'Muscat Hamburg' berry skin without sunlight. Furthermore, overexpression of VvBBX44 decreased the expression of LONG HYPOCOTYL 5 (VvHY5) and UDP-glucose flavonoid 3-O-glucosyltransferase (VvUFGT), and reduced the anthocyanin content in grape calli. Our results suggest that VvBBX44 may play an important role in grape berry coloring by directly repressing VvHY5 expression. This study provides new insights into the potential role of VvBBXs in berry development and light response and contributes to the understanding on the regulation mechanism of VvBBX44 in anthocyanin biosynthesis.
MAIN CONCLUSION: Genome-wide identification, analysis and functional characterization of an unreported VvBBX gene showed a response to light and positive correlation with anthocyanin content, but also inhibition of light-induced anthocyanin synthesis. B-box (BBX) proteins are a class of zinc (Zn) finger transcription factors or regulators characterized by the presence of one or two BBX domains and play important roles in plant growth and development. However, the BBX genes' potential functions are insufficiently characterized in grape, a globally popular berry with high economic value. Here, 25 BBX family genes including a novel member (assigned VvBBX44) were identified genome widely in grape. The expression level of these VvBBXs were analyzed in 'Cabernet Sauvignon' (V. vinifera) stem, flower, leaf, tendril, petiole, and developing berries. The expression of VvBBX44 increased in developing 'Cabernet Sauvignon' berries. Its expression was inhibited in 'Jingxiu' and 'Muscat Hamburg' berry skin without sunlight. Furthermore, overexpression of VvBBX44 decreased the expression of LONG HYPOCOTYL 5 (VvHY5) and UDP-glucose flavonoid 3-O-glucosyltransferase (VvUFGT), and reduced the anthocyanin content in grape calli. Our results suggest that VvBBX44 may play an important role in grape berry coloring by directly repressing VvHY5 expression. This study provides new insights into the potential role of VvBBXs in berry development and light response and contributes to the understanding on the regulation mechanism of VvBBX44 in anthocyanin biosynthesis.