Impact of Selected Sugar Transporters on Plant Properties
2018/01/12 10:30 AM
Dr. Ekkehard Neuhaus (Professor (Chair), Department of Biology, Plant Physiology, University of Kaiserslautern, Germany)
Agriculture Bioeconomy of Taiwan
2018/01/15 10:30 AM
CRISPR Genome Editing in Outcrossing Species: from knockout to allelic series mutagenesis (and dose-dependent tradeoffs of lignin reduction)
2018/01/22 10:30 AM
Dr. Chung-Jui Tsai (Haynes Professor and Eminent Scholar, School of Forestry and Natural Resources, Department of Genetics, Department of Plant Biology, University of Georgia, USA)
The CRISPR genome editing technology is revolutionizing all facets of biology, from medicine to agriculture. It enables generation of transgenic null mutants with unprecedented precision and efficiency—a welcome breakthrough for outcrossing woody perennials with long generation cycles. In this talk, I will present case studies of CRISPR genome editing in the woody perennial Populus for targeted mutations of multigene family members as well as tandemly arrayed genes. An under-appreciated obstacle in genome editing of outcrossing species is the frequent occurrence of sequence polymorphisms that can render CRISPR genome editing ineffective. However, sequence polymorphism data are usually inaccessible from current genome portals, and are not considered in popular gRNA design algorithms. I will discuss variant-sensitive bioinformatics pipelines that we have developed to address the genome editing challenges of outcrossing, hybrid or polyploid species.
The ability to generate an allelic series of mutations enables us to investigate the plasticity of 4-coumarate:CoA ligase (4CL) gene function at higher resolution than possible using previous gene expression manipulation strategies. Null mutations of 4CL1, but not its genome duplicate 4CL5, led to significant lignin reduction, whereas mutations of both abolished lignin accrual and impacted plant viability outside of tissue culture. Interestingly, plants that sustained growth were all derived from incomplete editing of the four 4CL1/4CL5 alleles, either retaining one WT allele or containing an in-frame deletion. Those mutants exhibited a continuum of growth phenotypes according to the severity of lignin reduction, traceable to the number and origin (4CL1 vs. 4CL5) of functional alleles. Reduced vigor of lignin-deficient plants was in large part attributable to impaired xylem water transport.