[Identification of MADS-box gene family in Polygonatum cyrtonema and expression analysis in a natural sterile line].

Polygonatum, Chinese medicinal and edible plants, are renowned for various health benefits including replenishing Qi, nourishing Yin, moistening the lungs, invigorating the spleen, and benefiting the kidneys. MADS-box genes are widely present in plants and play roles as transcription factors in multiple growth and developmental processes. In this study, 74 MADS-box genes in Polygonatum cyrtonema were identified via bioinformatics methods. These genes were classified into 14 subfamilies, with members of the same subfamily clustering together on the phylogenetic tree and sharing conserved motifs and domains. They were unevenly distributed across 11 chromosomes. Additionally, in a naturally sterile P. cyrtonema mutant(QyS1), cytological observations revealed that the floral organs were homologously transformed into structures resembling filaments or perianths, leading to sterility. Correspondingly, transcriptome analysis identified that the expression levels of three AGAMOUS homologous genes, PcMADS46, PcMADS56, and PcMADS68, were significantly downregulated in the floral buds of QyS1 compared with those of the wild type, possibly leading to the sterility of QyS1. Through weighted co-expression network analysis, a regulatory model for the abnormal development of QyS1 floral organs was further proposed. That is, the expression levels of C-class genes in sterile lines decreased, leading to downregulation of downstream epigenetic inhibitory factors, upregulation of auxin signaling pathways and transporter genes, resulting in homologous transformation and infertility of stamen and carpel organs. This study identified and analyzed the MADS-box gene family and the sterility phenomenon in P. cyrtonema, providing theoretical insights and practical guidance for the germplasm resource conservation and breeding of P. cyrtonema.