Integrated Transcriptome and Metabolome Analysis Uncovers Dynamic Regulatory Mechanisms Underlying Inflorescence Development in Agropyron cristatum

Agropyron cristatum , a high-quality forage grass and a close relative of wheat (Triticum aestivum), exhibits an inflorescence development process critical for its seed yield and genetic improvement. However, the underlying molecular and hormonal regulatory networks remain poorly understood. In this study, we performed integrated tran-scriptomic sequencing (RNA-seq) and targeted phytohormone profiling on inflores-cences at three developmental stages (booting, heading, and flowering) in A. cristatum. Our metabolomic data revealed dynamic changes in gibberellin (GA), auxin (IAA), and cytokinin (CK) levels, highlighting their pivotal roles during inflorescence develop-ment. Transcriptomic analysis further identified key biosynthesis genes for these hor-mones, including CPS, KAO, KS, GA13ox, GA3ox, GA2ox, TDC, AO1, ALDH, YUCCA, amid, TAA1, miaA, and IPT. In addition, we detected differential expression of critical signaling components, such as GID1 and DELLA, AUX1/LAX, TIR1, ARF, GH3, and SAUR, and CRE1 and B-ARR. We also identified several key transcription factor fami-lies linked to flowering and meristem regulation, including AP2/ERF-ERF, MYB, TCP, HD-ZIP, WOX, LFY, and NF-YC. The current study provides a preliminary elucidation of the hormonal regulatory framework underlying inflorescence development in the Agropyron cristatum species complex, offering molecular insights into its inflorescence morphogenesis.