Latifa Nuraini1, Yukiko Ando2, Kentaro Kawai2, Fumi Tatsuzawa3, Kotomi Tanaka4, Masaki Ochiai1,5, Katsumi Suzuki1,2,4,6, Verónica Aragonés7, José-Antonio Daròs7, Takashi Nakatsuka8,9,10,11. 1. The United Graduate School of Agricultural Science, Gifu University, 1-1 Yanagido, Gifu-shi, Gifu, 501-1193, Japan. 2. Graduate School of Integrated Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan. 3. Faculty of Agriculture, Iwate University, 3-18-8 Ueda, Morioka, 020-8550, Japan. 4. Faculty of Agriculture, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan. 5. Faculty of Applied Biological Sciences, Gifu University, Yanagido 1-1, Gifu, 501-1193, Japan. 6. College of Agriculture, Academic Institute, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan. 7. Instituto de Biología Molecular y Celular de Plantas (Consejo Superior de Investigaciones Científicas-Universitat Politècnica de València), 46022, Valencia, Spain. 8. The United Graduate School of Agricultural Science, Gifu University, 1-1 Yanagido, Gifu-shi, Gifu, 501-1193, Japan. nakatsuka.takashi@shizuoka.ac.jp. 9. Graduate School of Integrated Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan. nakatsuka.takashi@shizuoka.ac.jp. 10. Faculty of Agriculture, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan. nakatsuka.takashi@shizuoka.ac.jp. 11. College of Agriculture, Academic Institute, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529, Japan. nakatsuka.takashi@shizuoka.ac.jp.
Abstract
MAIN CONCLUSION: MiMYB1 and MibHLH2 play key roles in anthocyanin biosynthesis in Matthiola incana flowers. We established a transient expression system using Turnip mosaic virus vector in M. incana. Garden stock (Matthiola incana (L.) R. Br.) is a popular flowering plant observed from winter to spring in Japan. Here we observed that anthocyanin accumulation in 'Vintage Lavender' increased with flower development, whereas flavonol accumulation remained constant throughout flower development. We obtained five transcription factor genes, MiMYB1, MibHLH1, MibHLH2, MiWDR1, and MiWDR2, from M. incana floral cDNA contigs. Yeast two-hybrid analyses revealed that MiMYB1 interacted with MibHLH1, MibHLH2, and MiWDR1, but MiWDR2 did not interact with any transcription factor. Expression levels of MiMYB1 and MibHLH2 increased in petals during floral bud development. Their expression profiles correlated well with the temporal profiles of MiF3'H, MiDFR, MiANS, and Mi3GT transcripts and anthocyanin accumulation profile. On the other hand, MibHLH1 was expressed weakly in all organs of 'Vintage Lavender'. However, high expression levels of MibHLH1 were detected in petals of other cultivars with higher levels of anthocyanin accumulation than 'Vintage Lavender'. MiWDR1 and MiWDR2 maintained constant expression levels in petals during flower development and vegetative organs. Transient MiMYB1 expression in 1-month-old M. incana seedlings using a Turnip mosaic virus vector activated transcription of the endogenous anthocyanin biosynthetic genes MiF3'H, MiDFR, and MiANS and induced ectopic anthocyanin accumulation in leaves. Therefore, MiMYB1 possibly interacts with MibHLH2 and MiWDR1, and this trimeric protein complex activates the transcription of anthocyanin biosynthetic genes in M. incana flowers. Moreover, MibHLH1 acts as an enhancer of anthocyanin biosynthesis with the MiMYB1-MibHLH2-MiWDR1 complex. This study revealed the molecular mechanism involved in the regulation of anthocyanin accumulation levels in M. incana flowers.
MAIN CONCLUSION: MiMYB1 and MibHLH2 play key roles in anthocyanin biosynthesis in Matthiola incana flowers. We established a transient expression system using Turnip mosaic virus vector in M. incana. Garden stock (Matthiola incana (L.) R. Br.) is a popular flowering plant observed from winter to spring in Japan. Here we observed that anthocyanin accumulation in 'Vintage Lavender' increased with flower development, whereas flavonol accumulation remained constant throughout flower development. We obtained five transcription factor genes, MiMYB1, MibHLH1, MibHLH2, MiWDR1, and MiWDR2, from M. incana floral cDNA contigs. Yeast two-hybrid analyses revealed that MiMYB1 interacted with MibHLH1, MibHLH2, and MiWDR1, but MiWDR2 did not interact with any transcription factor. Expression levels of MiMYB1 and MibHLH2 increased in petals during floral bud development. Their expression profiles correlated well with the temporal profiles of MiF3'H, MiDFR, MiANS, and Mi3GT transcripts and anthocyanin accumulation profile. On the other hand, MibHLH1 was expressed weakly in all organs of 'Vintage Lavender'. However, high expression levels of MibHLH1 were detected in petals of other cultivars with higher levels of anthocyanin accumulation than 'Vintage Lavender'. MiWDR1 and MiWDR2 maintained constant expression levels in petals during flower development and vegetative organs. Transient MiMYB1 expression in 1-month-old M. incana seedlings using a Turnip mosaic virus vector activated transcription of the endogenous anthocyanin biosynthetic genes MiF3'H, MiDFR, and MiANS and induced ectopic anthocyanin accumulation in leaves. Therefore, MiMYB1 possibly interacts with MibHLH2 and MiWDR1, and this trimeric protein complex activates the transcription of anthocyanin biosynthetic genes in M. incana flowers. Moreover, MibHLH1 acts as an enhancer of anthocyanin biosynthesis with the MiMYB1-MibHLH2-MiWDR1 complex. This study revealed the molecular mechanism involved in the regulation of anthocyanin accumulation levels in M. incana flowers.
Authors: Christine Bernhardt; Myeong Min Lee; Antonio Gonzalez; Fan Zhang; Alan Lloyd; John Schiefelbein Journal: Development Date: 2003-11-19 Impact factor: 6.868