Modulating Purothionin Accumulation and Signal Peptide Cleavage Fine‐Tunes Wheat Flour Gluten Properties to Improve Cookie‐Making Quality

In contrast to many wheat (Triticum aestivum)-based products that benefit from strong gluten development, cookies benefit from weaker gluten. However, the development of wheat varieties that produce flour optimal for cookie making remains limited. In this study, we identified the wheat mutant low gluten protein 2 (lgp2), with reduced gluten content and a weakened gluten network, that significantly improved several aspects of cookie-making performance. The lgp2 phenotype is caused by a missense mutation in LGP2 that affects the signal peptide cleavage site of the encoded protein. Map-based cloning reveals that LGP2 encodes alpha-2-purothionin, a member of the thionin family of small proteins with potential antimicrobial activity. The lgp2 mutation leads to endoplasmic reticulum stress, abnormal protein body formation, and disrupted gluten development. Additionally, alpha-2-purothionin interacts with key seed storage proteins, contributing to gluten formation. Knockdown and overexpression studies confirmed that LGP2 affects gluten quantity and quality. Based on these findings, we propose dual genetic strategies targeting signal peptide processing and modulating LGP2 expression to fine-tune gluten properties for improved cookie quality. The lgp2 allele offers great potential for breeding low-gluten wheat varieties tailored for the production of cookies and other specialty food products.