Briones-Moreno, A. | Search bioRxiv

bioRxiv2022

DELLA proteins regulate spore germination and reproductive development in Physcomitrium patens.

O_LIProteins of the DELLA family integrate environmental signals to regulate growth and development throughout the plant kingdom. Plants expressing non-degradable DELLA proteins underpinned the development of high-yielding Green Revolution dwarf crop varieties in the 1960s. In vascular plants, DELLAs are regulated by gibberellins, diterpenoid plant hormones. How DELLA protein function has changed during land plant evolution is not fully understood. C_LIO_LIWe have examined the function and interactions of DELLA proteins in the moss Physcomitrium (Physcomitrella) patens, in the sister group of vascular plants (Bryophytes). C_LIO_LIPpDELLAs do not undergo the same regulation as flowering plant DELLAs. PpDELLAs are not degraded by diterpenes, do not interact with GID1 gibberellin receptor proteins and do not participate in responses to abiotic stress. PpDELLAs do share a function with vascular plant DELLAs during reproductive development. PpDELLAs also regulate spore germination. PpDELLAs interact with moss-specific photoreceptors although a function for PpDELLAs in light responses was not detected. PpDELLAs likely act as hubs for transcriptional regulation similarly to their homologues across the plant kingdom. C_LIO_LITaken together, these data demonstrate that PpDELLA proteins share some biological functions with DELLAs in flowering plants, but other DELLA functions and regulation evolved independently in both plant lineages. C_LI

plant biology↗

bioRxiv2018

Origin of gibberellin-dependent transcriptional regulation by molecular exploitation of a transactivation domain in DELLA proteins

DELLA proteins are land-plant specific transcriptional regulators known to interact through their C-terminal GRAS domain with over 150 transcription factors in Arabidopsis thaliana. Besides, DELLAs from vascular plants can interact through the N-terminal domain with the gibberellin receptor encoded by GID1, through which gibberellins promote DELLA degradation. However, this regulation is absent in non-vascular land plants, which lack active gibberellins or a proper GID1 receptor. Current knowledge indicates that DELLAs are important pieces of the signalling machinery of vascular plants, especially angiosperms, but nothing is known about DELLA function during early land plant evolution or if they exist at all in charophytan algae. We have now elucidated the evolutionary origin of DELLA proteins, showing that algal GRAS proteins are monophyletic and evolved independently from those of land plants, which explains why there are no DELLAs outside land plants. DELLA genes have been maintained throughout land plant evolution with only two major duplication events kept among plants. Furthermore, we show that the features needed for DELLA interaction with the receptor were already present in the ancestor of all land plants, and propose that these DELLA N-terminal motifs have been tightly conserved in non-vascular land plants for their function in transcriptional co-activation, which allowed subsequent exaptation for the interaction with the GID1 receptor when vascular plants developed gibberellin synthesis and the corresponding perception module.

evolutionary biology↗