Auxin response factors (ARF) are transcription factors that regulate auxin responses in plants. Although the genomewide analysis of this family has been performed in some species, little is known regarding ARF genes in apple (Malus domestica). In this study, 31 putative apple ARF genes have been identified and located within the apple genome. The phylogenetic analysis revealed that MdARFs could be divided into three subfamilies (groups I, II and III). The predicted MdARFs were distributed across 15 of 17 chromosomes with different densities. In addition, the analysis of exon–intron junctions and of the intron phase inside the predicted coding region of each candidate gene has revealed high levels of conservation within and between phylogenetic groups. Expression profile analyses of MdARF genes were performed in different tissues (root, stem, leaf, flower and fruit), and all the selected genes were expressed in at least one of the tissues that were tested, which indicated that MdARFs are involved in various aspects of physiological and developmental processes of apple. To our knowledge, this report is the first to provide a genomewide analysis of the apple ARF gene family. This study provides valuable information for understanding the classification and putative functions of the ARF signal in apple.

In plants, the transcription factor families have been implicated in many important biological processes. These processes include morphogenesis, signal transduction and environmental stress responses. Proteins containing the lateral organ bound-aries domain (LBD), which encodes a zinc finger-like domain are only found in plants. This finding indicates that this unique gene family regulates only plant-specific biological processes. LBD genes play crucial roles in the growth and development of plants such as Arabidopsis, Oryza sativa, Zea mays , poplar, apple and tomato. However, relatively little is known about the LBD genes in grape ( Vitis vinifera). In this study, we identified 40 LBD genes in the grape genome. A complete overview of the chromosomal locations, phylogenetic relationships, structures and expression profiles of this gene family during development in grape is presented here. Phylogenetic analysis showed that the LBD genes could be divided into classes I and II, together with LBDs from Arabidopsis. We mapped the 40 LBD genes on the grape chromosomes (chr1–chr19) and found that 37 of the predicted grape LBD genes were distributed in different densities across 12 chromosomes. Grape LBDs were found to share a similar intron/exon structure and gene length within the same class. The expression profiles of grape LBD genes at different developmental stages were analysed using microarray data. Results showed that 21 grape LBD genes may be involved in grape developmental processes, including preveraison, veraison and ripening. Finally, we analysed the expres-sion patterns of six LBD genes through quantitative real-time polymerase chain reation analysis. The six LBD genes showed differential expression patterns among the three representative grape tissues, and five of these genes were found to be involved in responses to mannitol, sodium chloride, heat stress and low temperature treatments. To our knowledge, this is the first study to analyse the LBD gene family in grape and provides valuable information for classification and functional investigation of this gene family.