Comparative transcriptome analysis provides new insights into erect and prostrate growth in bermudagrass (Cynodon dactylon L.)

Bermudagrass (Cynodon dactylon L.) is a prominent warm-season turf and forage grass species with multiple applications. In most C. dactylon cultivars and accessions, erect-growing stems (shoot) and prostrate-growing stems (stolon) often coexist. These two types of stems are both formed through tillering but grow in two directions with different tiller angles. Elucidating the mechanism of tiller angle regulation in bermudagrass could provide important clues to breed cultivars with different plant architectural features for diverse usage. In this study, we compared the stem internode transcriptome of two bermudagrass wild accessions with extremely different tiller angles and stem growth directions. A total of 2088 and 12,141 unigenes were preferentially expressed in prostrate-growing wild accession C792 and erect-growing wild accession C793, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) Orthology-based Annotation System (KOBAS) analyses further indicated that light- and gravity-responsive genes were enriched in accession C792, whereas lignin synthesis-related genes were enriched in accession C793, which well explains the difference in lignification of vascular bundles and mechanical tissues in the two accessions. These results not only expand our understanding of the genetic control of tiller angle and stem growth direction in bermudagrass but also provide insight for future molecular breeding of C. dactylon and other turfgrass species with different plant architectures.