For the first time, researchers have successfully demonstrated precision gene editing in miscanthus, a promising perennial crop for sustainable bioenergy production.
A team from the Center for Advanced Bioenergy and Bioproducts Innovation (CABBI) edited the genomes of three miscanthus species using CRISPR/Cas9, a much more specific and efficient way of developing new varieties than previous methods.
The results will accelerate efforts to harness the enormous potential of this highly productive but genetically complex grass as a source of biofuels, renewable bioproducts, and carbon sequestration. The study, published in Biotechnology for Biofuels and Bioproductswas led by three CABBI miscanthus researchers at the HudsonAlpha Biotechnology Institute in Alabama: faculty researcher Kankshita Swaminathan, research associate Anthony Trieu, and former postdoctoral researcher Mohammad Belaffif, and Nancy Reichert, professor of biological sciences at State University from Mississippi.
Swaminathan co-led an international team that sequenced the miscanthus genome in 2020. That work provided a roadmap for researchers exploring new ways to maximize plant productivity and decipher the genetic basis of its desirable characteristics. Miscanthus is extremely adaptable and easy to grow. It can thrive on marginal land, requires limited fertilization, has a high tolerance for drought and cold temperatures, and uses the most efficient C4 form of photosynthesis.
To date, efforts to genetically improve miscanthus have focused on transforming plants by introducing foreign genes into random places in their genomes, rather than targeting specific sites or modifying existing genes.
The CABBI team developed gene editing procedures using CRISPR/Cas9 that will allow researchers to selectively target existing genes within miscanthus plants to knock out or modify their function and introduce new genes at precise locations. That targeting ability presents a new avenue for genetic improvement of this important biomass crop.
The study demonstrated gene editing in three species of miscanthus: the highly productive Miscanthus x giganteusthat is grown commercially for bioenergy, and its parents, M. sacchariflorus Y M sinensis. Because those plants are paleo-polyploid, with duplicated sorghum-like ancient DNA and multiple sets of chromosomes, the design of the guide RNAs that locate genetic material for editing needed to target all copies of a gene, to take into account account for redundancy and ensure a complete “knockout.”
The CABBI researchers relied on similar gene editing in zea mays (maize), which identified the lemon white 1 (lw1) gene as a useful target for visual confirmation of genetic changes. That gene is involved in chlorophyll and carotenoid biosynthesis, which affects leaf color, and previous studies demonstrated that lw1 editing via CRISPR/Cas9 produced pale green/yellow, striped, or white leaf phenotypes.
Using sequence information from both miscanthus and sorghum, the researchers identified guide RNAs that could point to homeologs, or duplicate gene copies, of lw1 in miscanthus plant tissue. The leaves of the edited miscanthus plants displayed the same phenotypes found in maize, with green/pale yellow, striped, or white leaves instead of the typical green.
The work enhances CABBI’s mission to develop sustainable bioenergy production and engineer selected feedstocks (miscanthus, sorghum, and sugarcane) to produce new bioproducts, such as oils and specialty chemicals. Prior to this study, bioengineering work was limited to sorghum and sugarcane because methods for precise engineering in miscanthus had not been developed.
“Identifying transformable germplasm, developing reliable transformation methods, and demonstrating gene editing in miscanthus are crucial steps toward engineering pathways in miscanthus,” Swaminathan said. “The ability to precisely edit miscanthus to improve productivity, allow continued growth on marginal land, and produce specialty chemicals such as oils will help eliminate the ‘potential’ of its status as a viable bioenergy crop.
“This research helps us take a few more steps toward reducing our dependence on oil-based energy.”
To identify miscanthus lines that transformed well, the researchers selected germplasm from commercial suppliers and study collaborators. Most of the lines were provided by co-author Erik Sacks, Professor of Crop Science at the University of Illinois Urbana-Champaign, who has collected germplasm from around the world. Sacks and Swaminathan are deputy theme leads for CABBI’s feedstock production research.
“This research project was a highly collaborative, multi-institutional effort with researchers working across disciplines to achieve an important goal. It reinforced the ‘big picture’ approach to research within CABBI, as well as other BRCs,” Reichert said.
Other CABBI co-authors on the study included Steve Moose, professor of Crop Sciences at Illinois; Tom Clemente, Eugene W. Price Distinguished Professor of Biotechnology at the Center for Innovation in Plant Sciences at the University of Nebraska; Postdoctoral Researcher Pradeepa Hirannaiah, Technician Shilpa Manjunatha, Intern Rebekah Wood, and Workforce Development Specialist Yokshitha Bathula, all from HudsonAlpha; and research associate Rebecca Billingsley and graduate student Anjali Arpan from Mississippi State.
Anthony Trieu et al, Transformation and gene editing in the bioenergetic grass Miscanthus, Biotechnology for Biofuels and Bioproducts (2022). DOI: 10.1186/s13068-022-02241-8
Provided by the University of Illinois at Urbana-Champaign
Citation: Team Achieves First Precision Gene Editing in Miscanthus (Jan 20, 2023) Retrieved Jan 20, 2023 from https://phys.org/news/2023-01-team-precision-gene-miscanthus.html
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