Plant hormones regulate a myriad of plant processes, from seed germination to reproduction, from complex organ development to microelement uptake. Much has been discovered on the factors regulating the activity of phytohormones, yet there are gaps in knowledge about their metabolism, signaling as well as transport. In this review we analyze the potential of the characterized phytohormonal transporters belonging to the ATP-Binding Cassette family (ABC proteins), thus to identify new candidate orthologs in model plants and species important for human health and food production. Previous attempts with phylogenetic analyses on transporters belonging to the ABC family suggested that sequence homology per se is not a powerful tool for functional characterization. However, we show here that sequence homology might indeed support functional conservation of characterized members of different classes of ABC proteins in several plant species, e.g., in the case of ABC class G transporters of strigolactones and ABC class B transporters of auxinic compounds. Also for the low-affinity, vacuolar abscisic acid (ABA) transporters belonging to the ABCC class we show that localization-, rather than functional-clustering occurs, possibly because of sequence conservation for targeting the tonoplast. The ABC proteins involved in pathogen defense are phylogenetically neighboring despite the different substrate identities, suggesting that sequence conservation might play a role in their activation/induction after pathogen attack. Last but not least, in case of the multiple lipid transporters belong to different ABC classes, we focused on ABC class D proteins, reported to transport/affect the synthesis of hormonal precursors. Based on these results, we propose that phylogenetic approaches followed by transport bioassays and in vivo investigations might accelerate the discovery of new hormonal transport routes and allow the designing of transgenic and genome editing approaches, aimed to improve our knowledge on plant development, plant–microbe symbioses, plant nutrient uptake and plant stress resistance.
Filling the Gap: Functional Clustering of ABC Proteins for the Investigation of Hormonal Transport in planta
L. Borghi,Joohyun Kang,Rita de Brito Francisco
Published 2019 in Frontiers in Plant Science
ABSTRACT
PUBLICATION RECORD
- Publication year
2019
- Venue
Frontiers in Plant Science
- Publication date
2019-04-17
- Fields of study
Biology, Medicine, Environmental Science
- Identifiers
- External record
- Source metadata
Semantic Scholar, PubMed
CITATION MAP
EXTRACTION MAP
CLAIMS
CONCEPTS
- abcc class
A subclass of ATP-binding cassette transporters discussed here in connection with vacuolar abscisic acid transport.
- abc class b transporters
A subclass of ATP-binding cassette transporters discussed here as carriers implicated in auxinic compound transport.
- abc class g transporters
A subclass of ATP-binding cassette transporters discussed here as carriers implicated in strigolactone transport.
- abscisic acid (aba)
A plant hormone discussed here as a substrate of low-affinity vacuolar ABCC transporters.
Aliases: ABA
- atp-binding cassette family
A large family of membrane transport proteins discussed here as the source of plant hormonal transporters and related defense proteins.
Aliases: ABC family, ABC proteins
- auxinic compounds
Auxin-related molecules discussed here as substrates transported by ABC class B proteins.
- pathogen defense
A plant defense context in which certain ABC proteins are discussed as participating in transport-related responses.
- strigolactones
Plant signaling molecules discussed here as substrates transported by ABC class G proteins.
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