Abstract
Simple SummaryIn this study, we provide comprehensive information on auxin transporter gene families in potato, including basic parameters, chromosomal distribution, phylogeny, co-expression network analysis, gene structure, tissue-specific expression patterns, subcellular localization, transcription analysis under exogenous hormone stimuli and abiotic stresses, and cis-regulatory element prediction. The responsiveness of auxin transporter family genes to auxin and polar auxin transport inhibitors implied their possible roles in auxin homoeostasis and redistribution. Additionally, the differential expression levels of auxin transporter family genes in response to abscisic acid and abiotic stresses suggested their specific adaptive mechanisms on tolerance to various environmental stimuli. Promoter cis-regulatory element description analyses indicated that a number of cis-regulatory elements within the promoters of auxin transporter genes in potato were targeted by relevant transcription factors to respond to diverse stresses. We are confident that our results provide a foundation for a better understanding of auxin transporters in potato, as we have demonstrated the biological significance of this family of genes in hormone signaling and adaption to environmental stresses.Auxin is the only plant hormone that exhibits transport polarity mediated by three families: auxin resistant (AUX) 1/like AUX1 (LAX) influx carriers, pin-formed (PIN) efflux carriers, and ATP-binding cassette B (ABCB) influx/efflux carriers. Extensive studies about the biological functions of auxin transporter genes have been reported in model plants. Information regarding these genes in potato remains scarce. Here, we conducted a comprehensive analysis of auxin transporter gene families in potato to examine genomic distributions, phylogeny, co-expression analysis, gene structure and subcellular localization, and expression profiling using bioinformatics tools and qRT-PCR analysis. From these analyses, 5 StLAXs, 10 StPINs, and 22 StABCBs were identified in the potato genome and distributed in 10 of 18 gene modules correlating to the development of various tissues. Transient expression experiments indicated that three representative auxin transporters showed plasma membrane localizations. The responsiveness to auxin and auxin transport inhibitors implied their possible roles in mediating intercellular auxin homoeostasis and redistribution. The differential expression under abscisic acid and abiotic stresses indicated their specific adaptive mechanisms regulating tolerance to environmental stimuli. A large number of auxin-responsive and stress-related cis-elements within their promoters could account for their responsiveness to diverse stresses. Our study aimed to understand the biological significance of potato auxin transporters in hormone signaling and tolerance to environmental stresses.
Highlights
Auxin is a plant hormone that possesses multiple functions that regulate the plant growth and development primarily at the cellular level and in response to diverse environmental stimuli as well [1,2,3,4,5]
From the reference genome retrieved from phytozome 12.1.6 for Arabidopsis thaliana, the 4 AtAUX/like AUX1 (LAX), 8 AtPINs, and 22 AtABCB protein sequences were used as queries to perform the BLAST searches against the available potato protein sequence data
22 StABCBs were identified from the potato genome, and they were named in accordance with their location order on the chromosomes, with the exception that the nomenclature of
Summary
Auxin is a plant hormone that possesses multiple functions that regulate the plant growth and development primarily at the cellular level and in response to diverse environmental stimuli as well [1,2,3,4,5]. The cell–cell polar transport of auxin is mediated by proteins localized in the plasma membrane (PM), and these proteins are members of three distinct gene families: the auxin resistant (AUX) 1/like AUX1 (LAX) influx carriers [7], the pin-formed (PIN). Unique polar transport of auxin forms auxin gradients that result in asymmetric distribution of PIN, AUX/LAX, and ABCB proteins across cells and tissues. Regulation of the uneven distribution of auxin within tissues and organs or throughout the entire plant body via auxin transporters provides an important strategy to execute the auxin functions in controlling various plant developmental processes and in response to stressful environments
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