Transcriptome Analysis of the Seed Shattering Mechanism in Psathyrostachys juncea Using Full-Length Transcriptome Sequencing

Seed shattering (SS) functions are a survival mechanism in plants, enabling them to withstand adverse environmental conditions and ensure reproduction. However, this trait limits seed yield. <i>Psathyrostachys juncea</i>, a perennial forage grass with many favorable traits, is constrained by SS, limiting its broader application. To investigate the mechanisms underlying SS, second-generation Illumina sequencing and third-generation PacBio sequencing were conducted on abscission zone tissues of <i>P. juncea</i> at 7, 14, 21, and 28 days after heading. GO enrichment analysis identified several significant biological processes, including the "cell wall macromolecule catabolic process", "cell wall polysaccharide catabolic process", "hemicellulose catabolic process", and "xylan catabolic process", all involved in cell wall degradation. KEGG enrichment analysis showed that differentially expressed genes were predominantly enriched in pathways related to "starch and sucrose metabolism", "fructose and mannose metabolism", "phenylpropanoid biosynthesis", "pentose and glucuronate interconversions", and "galactose metabolism", each linked to both the synthesis and degradation of the cell wall. Further analysis of the "starch and sucrose metabolism" pathway revealed genes encoding fructokinase, hexokinase, β-glucosidase, sucrose phosphate synthase, sucrose synthase, and endoglucanase, all of which affected cellulose content. Reduced cellulose content can alter cell wall structure, leading to SS. These findings provide new insights into the regulation of SS in <i>P. juncea</i> and offer valuable references for other species within the Poaceae family.