Pod-shattering characteristic differences between shattering-resistant and shattering-susceptible common vetch accessions are associated with lignin biosynthesis

The common vetch ( L.) is a self-pollinated annual forage legume that is widely distributed worldwide. It has wide adaptability and high nutritional value and is commonly used as an important protein source for livestock feed. However, pod shattering seriously limits the yield of common vetch. To clarify the mechanism of pod shattering in common vetch, the pod walls of three shattering-resistant (SR) accessions (B65, B135, and B392) and three shattering-susceptible (SS) accessions (L33, L170, and L461) were selected for transcriptome sequencing. A total of 17190 differentially expressed genes (DEGs) were identified in the pod wall of B135 and L461 common vetch at 5, 10, 15, 20, and 25 days after anthesis. KEGG analysis showed that “phenylpropanoid biosynthesis” was the most significantly enriched pathway, and 40 structural genes associated with lignin biosynthesis were identified and differentially expressed in B135 and L461 common vetch. We analysed the DEGs in the pod wall of three SR and three SS accessions at 15 days after anthesis, and most of the DEGs were consistent with the significant enrichment pathways identified in B135 and L461 common vetch. The total lignin content of SR accessions was significantly lower than the SS accessions. The present study lays a foundation for understanding the molecular regulatory mechanism of pod shattering related to lignin biosynthesis in common vetch and provides reference functional genes for breeders to further cultivate shattering-resistant common vetch varieties.