The ORFans’ tale: new insights in plant biology

Orphan genes (OGs) are taxonomically restricted, without significant sequence similarities to closely related species; they might have evolved from noncoding sequences via rearrangements or duplication and divergence. OGs from divergent species can interact with conserved regulators – such as sucrose non-fermenting 1 (SNF1)-related protein kinases (SnRKs), nuclear factor Y subunit C4 (NF-YC4) – and display the evolutionarily conserved functions. OGs have been shown to promote growth and development in the carbon metabolism of plants, possibly through the target of rapamycin (TOR)–SnRK1 signaling axis. OGs have been shown to compete with pathogenic effectors for their interaction with central regulators, and thereby participate in a growth–defense trade-off. OGs can retain their function when expressed as transgenes in other species, and can thus be used for biotechnological intervention against various environmental stresses.