Mutation breeding in the age of next-generation sequencing and genome editing

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

Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: 1/13/2022
Publication Date: 1/13/2022
Citation: Xin, Z., Jiao, Y., Burow, G.B., Hayes, C.M., Chen, J., Ware, D. 2022. Mutation breeding in the age of next-generation sequencing and genome editing. Plant and Animal Genome Conference.

Interpretive Summary: Sorghum is a stress resilient crop with versatile uses and a model for tropical C4 grasses. However, it lacks a 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: Mutation Breeding is a classical and effective approach to generate diversity and create novel traits. A manageable number of lines can yield large numbers of mutations covering the entire genome and produce a plethora of phenotypes. However, it suffers from high density of background mutations, which requires many generations to remove. This drawback can be overcome by the precise genome-editing technologies. We have established a 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. Over 1000 sorghum mutants with altered agronomic traits have been isolated from the mutant library. Furthermore, 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. On the other hand, we have sequenced 256 lines from the mutant library and generated >1.8 million EMS-induced mutations. Sequencing of an additional 1000 lines is underway. After completion, we expect to have over 10 million mutations. Every gene in sorghum genome will be covered by several deleterious mutations. The sorghum mutant library will be a useful resource for create new traits for breeding and promising targets for genome editing.