Rapid generation of tomato male-sterile lines with a marker use for hybrid seed production by CRISPR/Cas9 system

Owing to their superior agronomic performance, the hybrids of vegetable crops are currently applied extensively. However, effective hybrid production requires a laborious manual emasculation to ensure the purity of hybrid seeds in tomato because of the lack of an effective male sterility system. Here, we created two types of tomato nuclear male-sterile lines with different screening markers in a clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system. Co-knockouts of male sterile 10(35) (Ms10(35)) and glutathione S-transferase (GSTAA) created a male-sterile line marked by a green hypocotyl. The Ms10(35) biallelic mutation was introduced into the woolly tomato background, resulting in the linkage of male sterility and a non-woolly phenotype. Two types of male-sterile lines were easily selected at the seedling stage by hypocotyl color or trichome density and further showed high seed purity during hybrid seed production. Our work established the procedure for a rapid transfer of the male-sterile phenotype to the parents of hybrids without extra-modification by the CRISPR/Cas9 system that can be practically applied to hybrid seed production in tomato. This method will be the basis and example for sterile parent creation of multiple crops for hybrid production with the CRISPR/Cas9 system.

Automated summary

The creation of two types of tomato nuclear male-sterile lines with different screening markers in a CRISPR/Cas9 system has made hybrid seed production in tomatoes more efficient. This approach allows for easy selection of the male-sterile lines at the seedling stage and ensures high seed purity during hybrid seed production.