Abstract
Tillering is an important biomass yield component trait in switchgrass (Panicum virgatum L.). Teosinte branched 1 (tb1)/Branched 1 (BRC1) gene is a known regulator for tillering/branching in several plant species; however, its role on tillering in switchgrass remains unknown. Here, we report physiological and molecular characterization of mutants created by CRISPR/Cas9. We successfully obtained nonchimeric Pvtb1a and Pvtb1b mutants from chimeric T0 mutants using nodal culture. The biallelic Pvtb1a-Pvtb1b mutant plants produced significantly more tillers and higher fresh weight biomass than the wild-type plants. The increased tiller number in the mutant plants resulted primarily from hastened outgrowth of lower axillary buds. Increased tillers were also observed in transgene-free BC1 monoallelic mutants for either Pvtb1a-Pvtb1b or Pvtb1b gene alone, suggesting Pvtb1 genes act in a dosage-dependent manner. Transcriptome analysis showed 831 genes were differentially expressed in the Pvtb1a-Pvtb1b double knockdown mutant. Gene Ontology analysis revealed downregulation of Pvtb1 genes affected multiple biological processes, including transcription, flower development, cell differentiation, and stress/defense responses in edited plants. This study demonstrates that Pvtb1 genes play a pivotal role in tiller production as a negative regulator in switchgrass and provides opportunities for further research aiming to elucidate the molecular pathway regulating tillering in switchgrass.
Original language | English |
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Article number | 572193 |
Journal | Frontiers in Plant Science |
Volume | 11 |
DOIs | |
State | Published - Sep 23 2020 |
Externally published | Yes |
Funding
This work was partially supported by the National Institute of Food and Agriculture of the US Department of Agriculture (2013-33522-21091 to BY and S-zF) and the Crop Bioengineering Center of Iowa State University (S-zF). The authors declare no competing financial interests and no conflict-of-interest. The authors also wish to thank Michael Baker at the ISU DNA Facility for his assistance on NGS experiment and Zhaoxia Li and Xianran Li for their valuable suggestions on NGS data analysis. This manuscript has been released as a pre-print at bioRXiv (Liu et al., 2020).
Funders | Funder number |
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Crop Bioengineering Center of Iowa State University | |
Michael Baker | |
US Department of Agriculture | 2013-33522-21091 |
National Institute of Food and Agriculture | |
I-Shou University |
Keywords
- CRISPR/Cas9
- Teosinte branched 1
- gene editing
- micropropagation
- switchgrass
- tillering