Characterization of Auxin Transporter , and Gene Families in Pineapple and Evaluation of Expression Profiles During Reproductive Development and Under Abiotic Stresses

Polar auxin transport in plant is mediated by influx and efflux transporters, which are encoded by , and genes, respectively. The auxin transporter gene families have been characterized in several species from monocots and eudicots. However, a genome-wide overview of auxin transporter gene families in pineapple is not yet available. In this study, we identified a total of three genes, 12 genes, and seven genes in the pineapple genome, which were variably located on 15 chromosomes. The exon-intron structure of these genes and properties of deduced proteins were relatively conserved within the same family. Most protein motifs were widespread in the AUX, PIN or PILS proteins, whereas a few motifs were absent in only one or two proteins. Analysis of the expression profiles of these genes elucidated that several genes exhibited either preferential or tissue-specific expression patterns in vegetative and/or reproductive tissues. was specifically expressed in the early developmental ovules, while and were strongly expressed in stamens and ovules. , , , and were abundantly expressed in stamens. Furthermore, qRT-PCR results showed that several genes in these families were responsive to various abiotic stresses. Comparative analysis indicated that the genes with close evolutionary relationships among pineapple, rice and exhibited similar expression patterns. Overexpression of the in rescued the phenotype in , and resulted in increased lateral roots in WT. These results will provide new insights into auxin transporter genes of pineapple and facilitate our understanding of their roles in pineapple growth and development.