Abstract
Key message: WUSCHEL-RELATED HOMEOBOX 11 establishes the acquisition of pluripotencyduring callus formation and accomplishes de novo shoot formation by regulating keytranscription factors in poplar. Abstract: De novo shoot regeneration is a prerequisite for propagation and genetic engineering of elite cultivars in forestry. However, the regulatory mechanism of de novo organogenesis is poorly understood in tree species. We previously showed that WUSCHEL (WUS)-RELATED HOMEOBOX 11 (PtWOX11) of the hybrid poplar clone 84K (Populus alba × P. glandulosa) promotes de novo root formation. In this study, we found that PtWOX11 also regulates de novo shoot regeneration in poplar. The overexpression of PtWOX11 enhanced de novo shoot formation, whereas overexpression of PtWOX11 fused with the transcriptional repressor domain (PtWOX11-SRDX) or reduced expression of PtWOX11 inhibited this process, indicating that PtWOX11 promotes de novo shoot organogenesis. Although PtWOX11 promotes callus formation, overexpression of PtWOX11 and PtWOX11-SRDX also produced increased and decreased numbers of de novo shoots per unit weight, respectively, implying that PtWOX11 promotes de novo shoot organogenesis partially by regulating the intrinsic mechanism of shoot development. RNA-seq and qPCR analysis further revealed that PtWOX11 activates the expression of PLETHORA1 (PtPLT1) and PtPLT2, whose Arabidopsis paralogs establish the acquisition of pluripotency, during incubation on callus-inducing medium. Moreover, PtWOX11 activates the expression of shoot-promoting factors and meristem regulators such as CUP-SHAPED COTYLEDON2 (PtCUC2), PtCUC3, WUS and SHOOT MERISTEMLESS to fulfill shoot regeneration during incubation on shoot-inducing medium. These results suggest that PtWOX11 acts as a central regulator of the expression of key genes to cause de novo shoot formation. Our studies further provide a possible means to genetically engineer economically important tree species for their micropropagation.
| Original language | English |
|---|---|
| Pages (from-to) | 389-406 |
| Number of pages | 18 |
| Journal | Plant Molecular Biology |
| Volume | 98 |
| Issue number | 4-5 |
| DOIs | |
| State | Published - Nov 1 2018 |
Funding
We thank Dr. Lin Xu (Chinese Academy of Sciences, Shanghai) and Momoko Ikeuchi (RIKEN Center for Sustainable Resource Science) for critical comments on this study. This work was supported by the National Natural Science Foundation of China (Grants 31500548 to BL and 31650110478 to YO), Developmental Program for Distinguished Young Scholars of Fujian Province (2017 to BL), Natural Science Foundation of Fujian province, China (Grant 2017J01605 to YO) and by the National Key R&D Program of China (Grants 2016YFD0600106 to LG). The authors declare no conflict of interest. The RNA-seq data are available through the Gene Expression Omnibus (http://www.ncbi.nlm.nih.gov/geo); the accession number is GSE101922. The sequence data obtained in this study can be found in the P. trichocarpa genome database (version 3.0); the accession numbers are provided in Table S5. Acknowledgements We thank Dr. Lin Xu (Chinese Academy of Sciences, Shanghai) and Momoko Ikeuchi (RIKEN Center for Sustainable Resource Science) for critical comments on this study. This work was supported by the National Natural Science Foundation of China (Grants 31500548 to BL and 31650110478 to YO), Developmental Program for Distinguished Young Scholars of Fujian Province (2017 to BL), Natural Science Foundation of Fujian province, China (Grant 2017J01605 to YO) and by the National Key R&D Program of China (Grants 2016YFD0600106 to LG). The authors declare no conflict of interest.
Keywords
- Callus
- De novo shoot organogenesis
- Poplar
- Regeneration
- WUSCHEL-RELATED HOMEOBOX 11