Transcriptional Regulation of Different Rhizome Parts Reveal the Candidate Genes That Regulate Rhizome Development in Poa pratensis

A strong rhizome can enhance the ability of a plant to resist drought, low temperature, and other stresses, as it can help plants rapidly obtain water and nutrients. Poa pratensis var. anceps Gaud. cv. Qinghai (QH) is a variant of P. pratensis that is widely distributed in natural grasslands above 3000 m above sea level on the Qinghai–Tibet Plateau. It forms turf easily and has strong soil-fixing ability due to its well-developed rhizomes. Understanding the molecular mechanism of rhizome development in this species is essential for cultivating new varieties of rhizome-type pasture for ecological protection. To clarify the transcriptional regulatory changes in different parts of the rhizome, we analyzed three different rhizome parts (rhizome buds, rhizome nodes, and rhizome internodes) of QH and weak-rhizome wild P. pratensis material (SN) using RNA sequencing. A total of 3806 genes were specifically expressed in Q_B, 1104 genes were specifically expressed in Q_N, and 1181 genes were specifically expressed in Q_I. Analysis showed that MYB, B3, NAC, BBR-BPC, AP2 MIKC_MADS, BSE1, and C2H2 may be key transcription factors regulating rhizome development. These genes interacted with multiple functional genes related to carbohydrate, secondary metabolism, and signal transduction, thus ensuring the normal development of the rhizomes. In particular, SUS (sucrose synthase) [EC:2.4.1.13] is specifically expressed in Q_I, which may be an inducing factor for the production of new plants from Q_B and Q_N. Additionally, PYL, PP2C, and SNRK2, which are involved in the abscisic acid signaling pathway, were differentially expressed in Q_N. In addition, genes related to protein modification and degradation, such as CIPKs, MAPKs, E2, and E3 ubiquitin ligases, were also involved in rhizome development. This study laid a foundation for further functional genomics studies on rhizome development in P. pratensis .