Mutations of PsPALM1a and PsPALM1b associated with the afila phenotype in Pea

Semi-leafless represents an advantageous plant architecture in pea breeding due to its ability to enhance resistance to lodging and potentially to powdery mildew. The introduction of semi-leafless pea varieties is considered a seminal advancement in pea breeding over the past half-century. The afila (af) mutation leads to the replacement of lateral leaflets by highly branched tendrils; combined with the semi-dwarfing le mutation, it forms the semi-leafless cultivated variety. In this study, we identified that mutations in two tandemly-arrayed genes encoding Cys(2)His(2) zinc finger transcription factors, PsPALM1a and PsPALM1b, were closely associated with the afila phenotype. These two genes may be deleted in the af mutant. In situ hybridization showed that both genes exhibit specific expression in early leaflet primordia. Furthermore, suppression of PsPALM1a/PsPALM1b resulted in a high frequency of conversion of lateral leaflets into tendrils. In conclusion, our study provides genetic evidence demonstrating that mutations in PsPALM1a and PsPALM1b are responsible for the af locus, contributing to a better understanding of compound leaf formation in peas and offering new insights for breeding applications related to afila.