Enhancing grain-yield-related traits by CRISPR–Cas9 promoter editing of maize CLE genes

Current status and prospects of plant genome editing in Australia

“…The identification of target regions have been facilitated by rapid sequencing and assembly of plant genomes, exemplified by the recent release of wheat and barley pan-genomes (Bolger et al 2018;Jayakodi et al 2020). Although new epigenomic approaches to identify the functionally valuable fraction of the genome may expedite these efforts (Crisp et al 2019;Crisp et al 2020), to accurately annotate these genomes is seriously lagging behind (Bolger et al 2018), Hence, the identification of gene promoters and other cis-regulatory elements may provide useful editing targets to fine tune gene expression (Rodriguez-Leal et al 2017;Liu et al 2021). Likewise, many crop gene annotations are based on functional genetic evidence of orthologous genes from model species such as Arabidopsis.…”

Next Generation Cereal Crop Yield Enhancement: From Knowledge of Inflorescence Development to Practical Engineering by Genome Editing

“…Liu et al tested this strategy in maize, by CRISPR–Cas9 multiplex editing of the promoters of ZmCLE7 and ZmFCP1. This produced weak alleles that maintain normal ear length but with a quantitative increase in KRN and grain yield [ 17 ]. Potential regulatory regions for editing were predicted using chromatin state (assay for transposase accessible chromatin with sequencing and micrococcal nuclease digestion with sequencing) and conserved non-coding sequence (CNS) data [ 17 ].…”

“…This produced weak alleles that maintain normal ear length but with a quantitative increase in KRN and grain yield [ 17 ]. Potential regulatory regions for editing were predicted using chromatin state (assay for transposase accessible chromatin with sequencing and micrococcal nuclease digestion with sequencing) and conserved non-coding sequence (CNS) data [ 17 ]. Promoter-edited alleles with deletions in these regions had lower ZmCLE7 and ZmFCP1 expression, leading to an increase in IM size, kernel number and grain yield [ 17 ].…”

“…Recent studies suggest that we can create new beneficial alleles by genome editing to optimize the expression or function of these genes. Indeed, some of these new alleles may have a larger effect than natural alleles [ 16 , 17 , 18 , 19 , 20 ]. These findings suggest that applying the knowledge of crop inflorescence development can help to engineer crop yield improvement, and usher in a new era of breeding practice.…”

Next-generation crop engineering

“…MADS-box genes and genes in the CLAVATA-WUSCHEL circuit were selected, because they control important yield traits and are dose-sensitive. In the current issue of Nature Plants, David Jackson's group apply a similar strategy to maize by engineering three CLV genes 3 . Weak promoter-edited alleles and null alleles were generated, conferring quantitative variations of grain yields in the edited lines, some of which show impressive field performance.…”