Establishment of an efficient haploid identification system by engineering anthocyanin accumulation in the wheat embryo

Efficient induction and rapid identification of haploid grains in tetraploid wheat by editing genes TtMTL and pyramiding anthocyanin markers

“…Recently, the identification of haploids has been simplified and visualized using eGPF proteins and DsRed signals specifically expressed in the embryo and endosperm ( Dong et al., 2018 ). Subsequently, a visually fast technique was reported to recognize haploid grains in common wheat by labeling embryos of the mtl-ABD mutant with embryo-specifically expressed anthocyanin, in which the diploid grains had purple embryos and the haploid grains had white ones ( Qi et al., 2023 ; Tang et al., 2023 ). We generated transgenic/edited plants of tetraploid wheat carrying two anthocyanin genes and an mtl-ab mutation by co-transformation.…”

“…Maize HI was labeled with embryo-specifically expressed ZmR2 and ZmC1 driven by the embryo-aleurone-specific bidirectional promoter ( Chen et al., 2022 ). Using a similar strategy, wheat haploid grains without anthocyanin markers induced by embryos specifically labeled with TaMTL -edited mutants with ZmC1 and ZmR were also conveniently visualized accurately ( Qi et al., 2023 ; Tang et al., 2023 ).…”

Editorial: Applications of fast breeding technologies in crop improvement and functional genomics study

“…CRISPR/Cas9 has been applied to rapidly modify important crop traits such as disease resistance, quality, maturity, grain weight, sterility, and pre-harvest sprouting tolerance ( Li et al., 2024 ). Particularly, new haploid inducer lines have been created in maize, rice, Arabidopsis , wheat, alfalfa, foxtail millet, tomato, Brassica oleracea , and soybean by editing MTL ( PLA1 / NLD ), DMP , and PLD3 genes via CRISPR/Cas9 to produce haploid grains directly ( Qi et al., 2023 ; Tang et al., 2023 ; Qu et al., 2024 ). Additionally, new types of molecular markers have been developed and used to trace agronomically important traits in breeding programs and locate target genes on chromosomes for gene cloning alongside generally employed makers such as simple sequence repeat (SSR), single-nucleotide polymorphism (SNP), and expressed sequence tags (EST) ( Rasheed et al., 2017 ; Hao et al., 2020 ).…”