Transcriptome analysis reveals the key roles of TaSMP1 and ABA signaling pathway in wheat seed dormancy and germination.

Main conclusion: This study analyzed dynamic transcriptome profiles to reveal differential expression patterns of ABA related and LEA protein family genes and verified that TaSMP1 affects seed germination by interacting with TaABI5. Seed dormancy is a crucial survival strategy for plants to cope with environmental stresses. High levels of seed dormancy result in uneven germination, while low levels of seed dormancy increase the risk of pre-harvest sprouting (PHS), which threatens crop yield and quality. Therefore, achieving the optimal balance between seed dormancy and germination is vital for maximum potential crop yield and quality. This study constructed dynamic transcriptome expression profiles of the germination process for the weakly dormant wheat variety Jing 411 (J411) and the strongly dormant landrace variety Hongsuibai (HSB), revealing the temporal expression of differentially expressed genes. Plant hormone-related genes played a crucial role in the early germination response, particularly the abscisic acid (ABA) signaling gene TaABI5 and the ABA catabolism gene TaCYP707A1. The late embryogenesis abundant (LEA) protein family genes exhibited differential expression patterns during the germination of seeds with varying levels of dormancy. The TaSMP1 gene, a member of the LEA protein family, was identified as a negative regulator of seed dormancy, interacting directly with the key transcription factor TaABI5 in the ABA signaling pathway and influencing the expression of the seed germination gene TaDOG1L1. This study provides essential insights into the molecular mechanisms balancing seed dormancy and germination, offering potential targets for enhancing wheat resistance to PHS.