Pedigreed mutant library as an efficient resource to discover targets for genome editing

Authors: Xin, Zhanguo; JIAO, YINPING - Texas Tech University; Burow, Gloria; Hayes, Chad; Chen, Junping; Ware, Doreen

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/12/2021
Publication Date: 10/12/2021
Citation: Xin, Z., Jiao, Y., Burow, G.B., Hayes, C.M., Chen, J., Ware, D. 2021. Pedigreed mutant library as an efficient resource to discover targets for genome editing. Meeting Abstract.

Interpretive Summary: Sorghum is a stress resilient crop with versatile uses and a model for tropical C4 grasses. However, it lacks critical resource for genome studies. ARS scientists at Lubbock, Texas developed a pedigreed sorghum mutant library for both genomic studies and for breeding. Many mutants with valuable agronomic traits have been isolated. Furthermore, a fast efficient bioinformatic pipe line has been developed to discover the mutations underlying the altered traits at affordable cost. This resource provides an efficient platform for selecting important traits for breeding and targets for genome editing.

Technical Abstract: Mutagenesis has been a classical and effective approach to dissect metabolic, developmental, and signal transduction pathways in both plants and animals due to the high density and random nature of induced mutations. A manageable number of lines can yield large number of mutations covering the entire genome. However, it suffers from the drawback of high density of background mutations, which requires many generations of backcross to clean up. This drawback can be overcome by precise and efficient genome-editing technologies. We have established Pedigreed Mutant Library in the sorghum inbred line BTx623 by mutagenizing the seeds with ethyl methane sulfonate (EMS). This library has 6,400 M4 seed pools and possesses a great diversity of mutant phenotypes. A large number of sorghum mutants with altered agronomic traits has been isolated from the mutant library. We have established an effective bioinformatic pipeline to identify the causal mutations through bulk-segregant-analysis (BSA) of the whole genome sequencing data of the pooled mutants selected from F2 populations. Once an F2 backcrossed population is established, the cost to identify the causal mutation is under $200 in NGS sequencing. In the last few years, we have identified over 50 causal mutations underlying the altered agronomic traits. These causal mutations can serve as targets for genome-editing in elite sorghum lines. The combination of high throughput gene discovery from mutant library with precise genome editing will truly revolutionize plant and animal breeding.