In Silico Characterisation of the Late Embryogenesis Abundant (LEA) Protein Families and Their Role in Desiccation Tolerance in Ramonda serbica Panc

Ramonda serbica Panc. is an ancient resurrection plant able to survive a long desiccation period and recover metabolic functions upon watering. The accumulation of protective late embryogenesis abundant proteins (LEAPs) is a desiccation tolerance hallmark. To propose their role in R. serbica desiccation tolerance, we structurally characterised LEAPs and evaluated LEA gene expression levels in hydrated and desiccated leaves. By integrating de novo transcriptomics and homologues LEAP domains, 318 R. serbica LEAPs were identified and classified according to their conserved motifs and phylogeny. The in silico analysis revealed that hydrophilic LEA4 proteins exhibited an exceptionally high tendency to form amphipathic alpha-helices. The most abundant, atypical LEA2 group contained more hydrophobic proteins predicted to fold into the defined globular domains. Within the desiccation-upregulated LEA genes, the majority encoded highly disordered DEH1, LEA1, LEA4.2, and LEA4.3 proteins, while the greatest portion of downregulated genes encoded LEA2.3 and LEA2.5 proteins. While dehydrins might chelate metals and bind DNA under water deficit, other intrinsically disordered LEAPs might participate in forming intracellular proteinaceous condensates or adopt amphipathic alpha-helical conformation, enabling them to stabilise desiccation-sensitive proteins and membranes. This comprehensive LEAPs structural characterisation is essential to understanding their function and regulation during desiccation aiming at crop drought tolerance improvement.

Automated summary

Ramonda serbica Panc. is a plant capable of surviving long periods of desiccation and recovering metabolic functions upon watering. The accumulation of late embryogenesis abundant proteins (LEAPs) is important for desiccation tolerance. In this study, the LEAPs of R. serbica were structurally characterized and their gene expression levels evaluated in hydrated and desiccated leaves. The analysis revealed that hydrophilic LEA4 proteins have a high tendency to form amphipathic alpha-helices, while the abundant atypical LEA2 group contains more hydrophobic proteins that fold into defined globular domains. The majority of upregulated genes encoded highly disordered proteins, while downregulated genes encoded LEA2 proteins. These findings suggest that LEAPs may play a role in stabilizing desiccation-sensitive proteins and membranes.