Identification and Characterization of LBD Gene Family in Pseudoroegneria libanotica Reveals Functions of PseLBD1 and PseLBD12 in Response to Abiotic Stress.

The lateral organ boundaries domain (LBD) plays a vital role as a transcriptional coactivator within plants, serving as an indispensable function in growth, development, and stress response. In a previous study, we found that the LBD genes of Pseudoroegneria libanotica (a maternal donor for three-quarter of perennial Triticeae species with good stress resistance, holds great significance in exploring its response mechanisms to abiotic stress for the Triticeae tribe) might be involved in responding to drought stress. Therefore, we further identified the LBD gene family in this study. A total of 29 PseLBDs were identified. Among them, 24 were categorized into subclass I, while 5 fell into subclass II. The identification of cis-acting elements reveals the extensive involvement of PseLBDs in various biological processes in P. libanotica. Collinearity analysis indicates that 86% of PseLBDs were single-copy genes and have undergone a single whole-genome duplication event. Transcriptomic differential expression analysis of PseLBDs under drought stress reveals that the most likely candidates for responding to abiotic stress were PseLBD1 and PseLBD12. They have been demonstrated to respond to drought, salt, heavy metal, and heat stress in yeast. Furthermore, it is plausible that functional divergence might have occurred among their orthologous genes in wheat. This study not only establishes a foundation for a deeper understanding of the biological roles of PseLBDs in P. libanotica but also unveils novel potential genes for enhancing the genetic background of crops within Triticeae crops, such as wheat.