Abstract
BACKGROUND: Kentucky bluegrass (Poa pratensis L.) is a perennial cool-season turfgrass commonly utilized in lawns. However, turfgrass quality is affected by abiotic stress. Guided by previous reports demonstrating the critical involvement of MADS-box transcription factors in abiotic stress responses in monocot species such as rice (Oryza sativa) and sheepgrass (Leymis Chinesis), this study specifically focuses on the MADS-box gene family to investigate their potential roles in stress adaptaion mechanisms in Kentucky bluegrass. Although MADS-box genes are well-characterized as regulators of plant growth and development, there is currently limited information on their stress-related functions in this economically important turfgrass species. METHODOLOGY: This study examined the physiological and molecular responses of three Kentucky bluegrass varieties (K.B.G., Arcadia, and Jenny) to salt and drought stress. RESULTS: Following initial screening tests, Arcadia was more tolerant to drought and salt stress than Jenny and K.B.G. and, therefore, was selected for further analysis. 16 MADS-box genes from transcriptome analysis have been identified in Kentucky bluegrass. GO enrichment analysis revealed that these genes are primarily involved in transcriptional regulation, including RNA polymerase II-related functions and cis-regulatory region binding. To better understand the function of MADS-box genes under drought and salt stress in Arcadia, the expression levels of 16 MADS-box genes were investigated using quantitative real-time polymerase chain reaction (PCR). Furthermore, 12 of the 16 genes except AGL14, MADS1, MADS26, and MADS33 exhibited tissue-specific expression under drought stress, whereas AGL14, AGL66, MADS16, MADS26, MADS33, and MADS56 were significantly upregulated in all tissues under salt stress. The 2-kb upstream promoter regions of the MADS-box genes were bioinformatically analyzed to identify cis-acting regulatory elements, revealing the presence of multiple cis acting elements associated with development, phytohormone signaling, and stress responses. An in-depth comparative analysis of the varieties indicated that Arcadia exhibits greater resistance to drought and salt stress. The expression patterns of MADS-box genes suggest a potential association with drought and salt stress responses, implying that these genes may play a role in observed stress adaptation. CONCLUSION: This study identified 16 MADS-box genes in Kentucky bluegrass and revealed Tissue-specific expression patterns in Arcadia under drought and salt conditions. These candidate genes may contribute to stress tolerance, providing a foundation for further research and potential genetic improvement of Kentucky bluegrass for enhanced resistance to abiotic stresses.