Molecular evolution and diversification of the GRF transcription factor family.

- Growth Regulating Factors (GRFs) comprise a transcription factor family with important functions in plant growth and development. They are characterized by the presence of QLQ and WRC domains, responsible for interaction with proteins and DNA, respectively. The QLQ domain is named due to the similarity to a protein interaction domain found in the SWI2/SNF2 chromatin remodeling complex. Despite the occurrence of the QLQ domain in both families, the divergence between them had not been further explored. Here, we show evidence for GRF origin and determined its diversification in angiosperm species. Phylogenetic analysis revealed 11 well-supported groups of GRFs in flowering plants. These groups were supported by gene structure, synteny, and protein domain composition. Synteny and phylogenetic analyses allowed us to propose different sets of probable orthologs in the groups. Besides, our results, together with functional data previously published, allowed us to suggest candidate genes for engineering agronomic traits. In addition, we propose that the QLQ domain of GRF genes evolved from the eukaryotic SNF2 QLQ domain, most likely by a duplication event in the common ancestor of the Charophytes and land plants. Altogether, our results are important for advancing the origin and evolution of the GRF family in Streptophyta.

Revising the PLAC8 gene family: from a central role in differentiation, proliferation, and apoptosis in mammals to a multifunctional role in plants.

PLAC8 is a cysteine-rich protein described as a central mediator of tumor evolution in mammals; as such, it represents a promising candidate for diagnostic and therapeutic targeting. The human PLAC8 gene is also involved in contact hypersensitivity response and presents a role in psoriatic skin. In plants, PLAC8 motif-containing proteins are involved in the determination of organ size and growth, response to infection, Ca2+ influx, Cd resistance, and zinc detoxification. In general, PLAC8 motif-containing proteins present the conserved CCXXXXCPC or CLXXXXCPC region. However, there is no devised nomenclature for the PLAC8 motif-containing proteins. Here, through the analysis of 445 sequences, we show that PLAC8 motif-containing proteins constitute a unique gene family, and we propose a unified nomenclature. This is the first report indicating the existence of different groups of PLAC8 proteins, which we have called types I, II, and III. Type I genes are found in mammals, fungi, plants, and algae, and types II and III are exclusive to plants. Our study describes for the first time PLAC8 type III proteins. Whether these sequences maintain their known functional role or possess distinct functions of types I and II genes remains unclear.

Programmed cell death (PCD) control in plants: New insights from the Arabidopsis thaliana deathosome.

Programmed cell death (PCD) is a genetically controlled process that leads to cell suicide in both eukaryotic and prokaryotic organisms. In plants PCD occurs during development, defence response and when exposed to adverse conditions. PCD acts controlling the number of cells by eliminating damaged, old, or unnecessary cells to maintain cellular homeostasis. Unlike in animals, the knowledge about PCD in plants is limited. The molecular network that controls plant PCD is poorly understood. Here we present a review of the current mechanisms involved with the genetic control of PCD in plants. We also present an updated version of the AtLSD1 deathosome, which was previously proposed as a network controlling HR-mediated cell death in Arabidopsis thaliana. Finally, we discuss the unclear points and open questions related to the AtLSD1 deathosome.

Fumarate reductase superfamily: A diverse group of enzymes whose evolution is correlated to the establishment of different metabolic pathways.

Fumarate and succinate are known to be present in prebiotic systems essential for the origin of life. The fumarate and succinate interconversion reactions have been conserved throughout evolution and are found in all living organisms. The fumarate and succinate interconversion is catalyzed by the enzymes succinate dehydrogenase (SDH) and fumarate reductase (FRD). In this work we show that SDH and FRD are part of a group of enzymes that we propose to designate "fumarate reductase superfamily". Our results demonstrate that these enzymes emerged from a common ancestor and were essential in the development of metabolic pathways involved in energy transduction.