PdMYB118, isolated from a red leaf mutant of Populus deltoids, is a new transcription factor regulating anthocyanin biosynthesis in poplar
A new anthocyanin biosynthesis transcription factor PdMYB118, which could be used for the genetic engineering of colorful tree species, was indentified from a red leaf mutant of Populus deltoids.
In higher plants, the biosynthesis of anthocyanins is regulated by several classes of transcription factors (TFs), including R2R3-MYB, bHLH and WD-repeat proteins. In this work, we isolated an MYB gene regulating anthocyanin biosynthesis from a red leaf mutant of Populus deltoids, which accumulated more anthocyanins in the leaves and showed higher expression levels of anthocyanin biosynthesis genes than did the wild type. Gene expression analyses of all TFs regulating anthocyanin biosynthesis demonstrated that only a MYB118 homologous gene, PdMYB118, was up-regulated in the mutant compared with the wide type. Subcellular localization analyses in poplar leaf mesophyll protoplasts showed that PdMYB118-YFP fusion protein was specifically located in nucleus. When transiently expressed in poplar leaf protoplasts, PdMYB118 specifically promoted the expression of anthocyanidin biosynthesis genes. Dual-luciferase assays revealed that PdMYB118 can directly activate the promoters of these genes. When overexpressed in Shanxin Yang (P. davidiana × P. bolleana), a hybrid clone commercially grown for landscaping in the northern part of China, transgenic plants overexpressing PdMYB118 produced more anthocyanins in the leaves and turned their color into redness when grown in both greenhouse and field. Consistently, transcripts of some important anthocyanidin biosynthesis genes were significantly increased in the leaves of transgenic plants. All these results indicate that PdMYB118 functions as an essential transcription factor regulating anthocyanin biosynthesis in poplar and could be used for the genetic engineering of colorful tree species.
KeywordsAnthocyanins PdMYB118 Poplar Red leaf Transcription factor
We thank Prof. Gui-Feng Liu (Northeast Forestry University, China) for kindly providing us the Shanxin yang (P. davidiana × P. bolleana) clone.
Author contributions statement
HW, XW, SW, YJ, CJ and CW performed the experiments and analyzed the data. HW and HZ conceived the study. HW, YB, BL, and HZ wrote the manuscript. All authors read and agreed at the last version of the manuscript.
This work was supported by the following grants: the National Key Program on Transgenic Research (2018ZX08020002-003-004); the Forestry Science and Technology Innovation Project of Shandong province of China (LYCX03-2018-18); the National Key R & D Program of China (2016YFD0600106); the National Major Project of GMO New Species Cultivation (2016ZX08004-002-006); The Modern Agricultural Industry Technology System Innovation Team of Shandong Province of China (SDAIT-02-05); Comprehensive Surveys on Saline Lake Lithium and other New Energy Resources in the North Tibetan Plateau (DD20160025); the National Natural Science Foundation of China (31870576, 31871625).
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Conflict of interest
We declare that we do not have any commercial or associative interest that represents a conflict of interest in connection with the work submitted.
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