The molecular mechanisms underlying the polyploidization of a forage grass

What happens when a species carries more than two sets of homologous chromosomes? Eragrostis curvula, a perennial forage grass, serves as a model species for studying polyploidy, in which the nucleus contains more than two sets of chromosomes. This species includes cytotypes with varying ploidy levels and reproductive strategies. 

To understand how increased DNA content affects molecular and biological processes, researchers went beyond basic phenotypic analysis and used high-throughput RNA-seq to identify genes regulating these traits. The study revealed that more genes are expressed at higher ploidy levels, suggesting that genome duplication alters the plant’s regulatory network rather than simply adding copies with the same instructions. Several genes associated with stress responses, hormone signaling, epigenetic regulation, protein turnover, and cell wall remodeling were specifically modulated at higher ploidies. The study also identified candidate genes involved in lignin biosynthesis and cell wall structure, suggesting a possible trade-off: Higher stress tolerance may come at the cost of reduced forage digestibility. 

By identifying ploidy-sensitive genes involved in the ploidy transition, these findings provide valuable insights for breeding E. curvula varieties aimed at balancing resilience, biomass quality, and digestibility, supporting sustainable forage production.