In vivo maternal haploid induction in tomato

• DOI: 10.1111/pbi.13755
• Publication Date: 2021-12-01T03:20:23Z
• Authors: Yu Zhong; Baojian Chen; Dong Wang; Xijian Zhu; Mengran Li; Jinzhe Zhang; Ming Chen; Min Wang; Tjitske Riksen; Jinchu Liu; Xiaolong Qi; Yuwen Wang; Dehe Cheng; Zongkai Liu; Jinlong Li; Chen Chen; Yanyan Jiao; Wenxin Liu; Sanwen Huang; Chenxu Liu; Kim Boutilier; Shaojiang Chen
• Keywords: Doubled haploidy

Tomato (Solanum lycopersicon) is the second largest vegetable crop and fruit (Costa Heuvelink, 2018). Progress in tomato breeding has been achieved by classical breeding, introgression of traits found related wild Solanum species exploiting heterosis F1 hybrid crosses (Lin et al., 2014). These approaches require development inbred lines to reduce or largely eliminate heterozygosity. Classically, multiple rounds selfing backcrossing are used generate (Gale, 1980), but homozygous can also be obtained a single generation using doubled haploid (DH) technology (Jacquier 2020). However, highly recalcitrant for induction (HI) (Seguí-Simarro, 2010). Significant breakthroughs DH production were made after identification zmpla1/mtl/nld zmdmp mutant genes that induce vivo maternal embryos maize extension this other monocot crops 2020 references therein). The utility dmp mutants HI dicots was demonstrated Arabidopsis (Zhong 2020), it not known whether approach applied dicot crops. Here we show efficient genotype-independent tomato. genome contains DMP gene (SlDMP; Solyc05g007920) expressed pollen flower buds We generated sldmp cv. Ailsa Craig CRISPR-Cas9 mutagenesis construct includes FAST-Red marker 2020, Figure 1a). Homozygous biallelic with insertions and/or deletions resulted translational frame shifts premature stop codons (Figure 1b). Compared type, significantly reduced number filled seeds 1c,d) increased percentage both aborted undeveloped ovules 1e), as previously reported determined haploids selfing. In absence segregating molecular markers, first identified putative plants based on their phenotype, is, smaller organs sterility 2019, Among 55 T1 seedlings, one plant 1f) showed typical phenotype 1g–j). This confirmed true flow cytometry 1k). Our data suggest mutation facilitates embryo Next, crossed four wild-type female (listed 1o) from different genetic backgrounds determine upon outcrossing. Ten derived these screened markers chromosome counting, 1l–o). To confirm origin, three seedlings whole-genome resequencing. Single-nucleotide polymorphism (SNP) analysis none carried paternally SNPs, suggesting induces 'clean' 1p). endosperm distinguish between diploid double fertilization (marker expression endosperm) only identify haploids, analysed DF199 × cross. Imbibed classified into red white seed groups colour under light. Under fluorescent light, weak RFP strong embryo, while 70% no 1q). Some florescent light recategorized red/RFP-expressing seeds. two checking root tip scored diploids, haploids. Ploidy 218 2303 100% accuracy selection 1r). diverse genotypes lines. rate (HIR) crossing 36 inducer ranged 0.5% 3.7%, an average HIR 1.9% 1s). HI. summarize, demonstrate major crop, tomato, facilitated marker. Given presence DMP-like ability likely inducers Extending system would represent advance over vitro production, especially members Solanaceae, Fabaceae Cucurbitaceae (Hooghvorst Nogués, thank Prof. Wencai Yang Huolin Shen providing seeds, Pu Wang greenhouse. work supported National Key Research Development Program China (2016YFD0101200), Agriculture System MOF MARA, Natural Science Foundation (91935303, 32001554, 31991185), Sanya Yazhou Bay Technology City (SKJC-2020-02-003) Postdoctoral (2020TQ0356). authors declare competing interests. Y.Z., B.C., C.L., K.B. S.C. conceived designed experiments. D.W., B.C. X.Z. performed most M.L., J.Z., M.C., M.W., T.R., J.L., X.Q., Y.W., D.C., Z.L., C.C. Y.J. some S.C., M.W. W.L. data. S.H., discussed prepared manuscript. All results provided feedback