Wheat TaSPL13‐2B Improves Floret Fertility and Enhances Grain Number per Spikelet Through Jasmonic Acid Signalling Pathway

Floret fertility is a key determinant of grain number per spike and an important factor in cereal crop yield. However, the mechanisms by which phytohormone signalling and transcription factors coordinately regulate floret fertility and spikelet development are not well understood, especially in wheat. In this study, we identified the role of jasmonic acid (JA) in the regulation of floret fertility in wheat. TaSPL13-2B, a JA-responsive regulator, directly represses the gene expression of the key JA signalling factor TaJAZ1 to improve floret fertility and increase the number of florets and grains per spikelet. The TaSPL13-2B-regulated JA signalling module (TaJAZ1-TaMYC2) contributes to floret fertility by inducing the expression of TaMADS1, an E-class gene critical for floral organ identity and floret meristem activity, and increasing the content of jasmonoyl-isoleucine (JA-Ile) by upregulating the expression of genes involved in JA biosynthesis. We further demonstrated that TaSPL13-2B is a potential target for yield improvement through field trials. Our work provides mechanistic insights into floret fertility and demonstrates that improving floret fertility could be a promising strategy to increase yield.