Genetic Modification of KNAT7 Transcription Factor Expression Enhances Saccharification and Reduces Recalcitrance of Woody Biomass in Poplars
The precise role of KNAT7 transcription factors (TFs) in regulating secondary cell wall (SCW) biosynthesis in poplars has remained unknown, while our understanding of KNAT7 functions in other plants is continuously evolving. To study the impact of genetic modifications of homologous and heterologous...
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Frontiers Media S.A.
2021-10-01
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| Series: | Frontiers in Plant Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fpls.2021.762067/full |
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| author | Yogesh Kumar Ahlawat Yogesh Kumar Ahlawat Akula Nookaraju Anne E. Harman-Ware Crissa Doeppke Ajaya K. Biswal Ajaya K. Biswal Chandrashekhar P. Joshi |
| author_facet | Yogesh Kumar Ahlawat Yogesh Kumar Ahlawat Akula Nookaraju Anne E. Harman-Ware Crissa Doeppke Ajaya K. Biswal Ajaya K. Biswal Chandrashekhar P. Joshi |
| author_sort | Yogesh Kumar Ahlawat |
| collection | DOAJ |
| description | The precise role of KNAT7 transcription factors (TFs) in regulating secondary cell wall (SCW) biosynthesis in poplars has remained unknown, while our understanding of KNAT7 functions in other plants is continuously evolving. To study the impact of genetic modifications of homologous and heterologous KNAT7 gene expression on SCW formation in transgenic poplars, we prepared poplar KNAT7 (PtKNAT7) overexpression (PtKNAT7-OE) and antisense suppression (PtKNAT7-AS) vector constructs for the generation of transgenic poplar lines via Agrobacterium-mediated transformation. Since the overexpression of homologous genes can sometimes result in co-suppression, we also overexpressed Arabidopsis KNAT7 (AtKNAT7-OE) in transgenic poplars. In all these constructs, the expression of KNAT7 transgenes was driven by developing xylem (DX)-specific promoter, DX15. Compared to wild-type (WT) controls, many SCW biosynthesis genes downstream of KNAT7 were highly expressed in poplar PtKNAT7-OE and AtKNAT7-OE lines. Yet, no significant increase in lignin content of woody biomass of these transgenic lines was observed. PtKNAT7-AS lines, however, showed reduced expression of many SCW biosynthesis genes downstream of KNAT7 accompanied by a reduction in lignin content of wood compared to WT controls. Syringyl to Guaiacyl lignin (S/G) ratios were significantly increased in all three KNAT7 knockdown and overexpression transgenic lines than WT controls. These transgenic lines were essentially indistinguishable from WT controls in terms of their growth phenotype. Saccharification efficiency of woody biomass was significantly increased in all transgenic lines than WT controls. Overall, our results demonstrated that developing xylem-specific alteration of KNAT7 expression affects the expression of SCW biosynthesis genes, impacting at least the lignification process and improving saccharification efficiency, hence providing one of the powerful tools for improving bioethanol production from woody biomass of bioenergy crops and trees. |
| first_indexed | 2024-12-22T05:29:05Z |
| format | Article |
| id | doaj.art-52907ddfa82a4fbaaf1e34f34fa0951d |
| institution | Directory Open Access Journal |
| issn | 1664-462X |
| language | English |
| last_indexed | 2024-12-22T05:29:05Z |
| publishDate | 2021-10-01 |
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| series | Frontiers in Plant Science |
| spelling | doaj.art-52907ddfa82a4fbaaf1e34f34fa0951d2022-12-21T18:37:29ZengFrontiers Media S.A.Frontiers in Plant Science1664-462X2021-10-011210.3389/fpls.2021.762067762067Genetic Modification of KNAT7 Transcription Factor Expression Enhances Saccharification and Reduces Recalcitrance of Woody Biomass in PoplarsYogesh Kumar Ahlawat0Yogesh Kumar Ahlawat1Akula Nookaraju2Anne E. Harman-Ware3Crissa Doeppke4Ajaya K. Biswal5Ajaya K. Biswal6Chandrashekhar P. Joshi7Department of Biological Sciences, Michigan Technological University, Houghton, MI, United StatesDepartment of Horticultural Sciences, University of Florida, Gainesville, FL, United StatesKaveri Seed Company Limited, Secunderabad, IndiaRenewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, United StatesRenewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO, United StatesDepartment of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, United StatesComplex Carbohydrate Research Center, University of Georgia, Athens, GA, United StatesDepartment of Biological Sciences, Michigan Technological University, Houghton, MI, United StatesThe precise role of KNAT7 transcription factors (TFs) in regulating secondary cell wall (SCW) biosynthesis in poplars has remained unknown, while our understanding of KNAT7 functions in other plants is continuously evolving. To study the impact of genetic modifications of homologous and heterologous KNAT7 gene expression on SCW formation in transgenic poplars, we prepared poplar KNAT7 (PtKNAT7) overexpression (PtKNAT7-OE) and antisense suppression (PtKNAT7-AS) vector constructs for the generation of transgenic poplar lines via Agrobacterium-mediated transformation. Since the overexpression of homologous genes can sometimes result in co-suppression, we also overexpressed Arabidopsis KNAT7 (AtKNAT7-OE) in transgenic poplars. In all these constructs, the expression of KNAT7 transgenes was driven by developing xylem (DX)-specific promoter, DX15. Compared to wild-type (WT) controls, many SCW biosynthesis genes downstream of KNAT7 were highly expressed in poplar PtKNAT7-OE and AtKNAT7-OE lines. Yet, no significant increase in lignin content of woody biomass of these transgenic lines was observed. PtKNAT7-AS lines, however, showed reduced expression of many SCW biosynthesis genes downstream of KNAT7 accompanied by a reduction in lignin content of wood compared to WT controls. Syringyl to Guaiacyl lignin (S/G) ratios were significantly increased in all three KNAT7 knockdown and overexpression transgenic lines than WT controls. These transgenic lines were essentially indistinguishable from WT controls in terms of their growth phenotype. Saccharification efficiency of woody biomass was significantly increased in all transgenic lines than WT controls. Overall, our results demonstrated that developing xylem-specific alteration of KNAT7 expression affects the expression of SCW biosynthesis genes, impacting at least the lignification process and improving saccharification efficiency, hence providing one of the powerful tools for improving bioethanol production from woody biomass of bioenergy crops and trees.https://www.frontiersin.org/articles/10.3389/fpls.2021.762067/fullantisensedeveloping xylemoverexpressionsaccharificationsecondary cell wall biosynthesis |
| spellingShingle | Yogesh Kumar Ahlawat Yogesh Kumar Ahlawat Akula Nookaraju Anne E. Harman-Ware Crissa Doeppke Ajaya K. Biswal Ajaya K. Biswal Chandrashekhar P. Joshi Genetic Modification of KNAT7 Transcription Factor Expression Enhances Saccharification and Reduces Recalcitrance of Woody Biomass in Poplars Frontiers in Plant Science antisense developing xylem overexpression saccharification secondary cell wall biosynthesis |
| title | Genetic Modification of KNAT7 Transcription Factor Expression Enhances Saccharification and Reduces Recalcitrance of Woody Biomass in Poplars |
| title_full | Genetic Modification of KNAT7 Transcription Factor Expression Enhances Saccharification and Reduces Recalcitrance of Woody Biomass in Poplars |
| title_fullStr | Genetic Modification of KNAT7 Transcription Factor Expression Enhances Saccharification and Reduces Recalcitrance of Woody Biomass in Poplars |
| title_full_unstemmed | Genetic Modification of KNAT7 Transcription Factor Expression Enhances Saccharification and Reduces Recalcitrance of Woody Biomass in Poplars |
| title_short | Genetic Modification of KNAT7 Transcription Factor Expression Enhances Saccharification and Reduces Recalcitrance of Woody Biomass in Poplars |
| title_sort | genetic modification of knat7 transcription factor expression enhances saccharification and reduces recalcitrance of woody biomass in poplars |
| topic | antisense developing xylem overexpression saccharification secondary cell wall biosynthesis |
| url | https://www.frontiersin.org/articles/10.3389/fpls.2021.762067/full |
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