Yang et al/Comparative transcriptome analysis of Phalaenopsis flowers Tab.3 Some genes related to floral differentiation and their expressions in petals and labella. Genes related to floral No.of up-regulated No.of DEGs in No.of up-regulated differentiation Total No.of DEGs No.of DEGs in petals DEGs in petals labella DEGs in labella MADS 16 16 MYB 12 9 3 12 9 ARF 10 10 w 10 7 NAC 6 6 6 bZIP 5 5 2 5 3 AP2 4 2 4 2 TCP 3 0 3 32 WRKY 3 2 YABBY 1 1 1 0 HD-ZIP 1 0 1 1 C3H 1 1 0 Tab.4 Some genes related to flower color and their expressions in petals and labella. No.of up- No.of up- Classification of Genes related to No.of DEGs in regulated DEGs in No.of DEGs in regulated DEGs in flower color genes flower color Total No.of DEGs petals petals labella labella Genes related CHI 3 3 0 to anthocyanin CHS 0 0 synthesis DFR 0 0 UFGT3 0 1 ANS(AS) 1 0 0 1 F3H 0 0 1 1 Genes related to PSY 1 1 0 carotenoid synthesis PAL 2 0 FLS 1 0 1 1 PDS 1 1 0 DXS 0 IPI 1 1 0 0 0 GGPS 1 1 0 Some other related MYB 12 12 9 genes bZIP 2 3 embryogenesis to senescence [19].Because more DEGs induced by bacterial and fungal infection [22];consequently, are up-regulated in labella,auxin may have a more complex the observed coexpression of WRKY genes and monoterpene role in labella patterning than in petals.We also found and sesquiterpene synthesis genes in labella and petals NAC transcription factors in both labella and petals,with a suggests that the function of these genes may be related to higher number of up-regulated DEGs identified in labella defense against biotic stress.The much higher expression in (5)than in petals(1).A previous study has shown that NAC labella than in petals also suggests a defensive role for WRKY transcription factors may be involved in pathogen infection transcription factors in the labella,a landing platform for responses in rice [20].The much higher expression observed pollinators.We also identified genes that affect floral organ in labella compared with petals may serve as a defensive development [23-25],namely YABBY,basic region/leucine weapon in the labella,which functions as a landing platform zipper motif(bZIP)transcription factor,and C3H-type zinc and nectar guide for pollinators.WRKY transcription factors finger protein genes.These developmental genes were found are key regulators of many plant processes,including biotic to have different expression levels between labella and petals, and abiotic stress response,senescence,seed dormancy, suggesting that they are associated with labella and petal and seed germination [21].We found WRKY transcription development but may have different functional mechanisms. factors in both labella and petals,with a greater number of up-regulated DEGs identified in labella(2 DEGs)than in Genes related to flower color petals(1 DEGs).WRKY1 regulates sesquiterpene synthase A single PeUFGT3 gene was detected in our study,and gene expression and the accumulation of sesquiterpene was found to be more highly expressed in red labella than The Author(s)2014 Published by Polish Botanical Soclety Acta Soc Bot Pol 83(3):191-199 197© The Author(s) 2014 Published by Polish Botanical Society Acta Soc Bot Pol 83(3):191–199 197 Yang et al. / Comparative transcriptome analysis of Phalaenopsis flowers embryogenesis to senescence [19]. Because more DEGs are up-regulated in labella, auxin may have a more complex role in labella patterning than in petals. We also found NAC transcription factors in both labella and petals, with a higher number of up-regulated DEGs identified in labella (5) than in petals (1). A previous study has shown that NAC transcription factors may be involved in pathogen infection responses in rice [20]. The much higher expression observed in labella compared with petals may serve as a defensive weapon in the labella, which functions as a landing platform and nectar guide for pollinators. WRKY transcription factors are key regulators of many plant processes, including biotic and abiotic stress response, senescence, seed dormancy, and seed germination [21]. We found WRKY transcription factors in both labella and petals, with a greater number of up-regulated DEGs identified in labella (2 DEGs) than in petals (1 DEGs). WRKY1 regulates sesquiterpene synthase gene expression and the accumulation of sesquiterpene induced by bacterial and fungal infection [22]; consequently, the observed coexpression of WRKY genes and monoterpene and sesquiterpene synthesis genes in labella and petals suggests that the function of these genes may be related to defense against biotic stress. The much higher expression in labella than in petals also suggests a defensive role for WRKY transcription factors in the labella, a landing platform for pollinators. We also identified genes that affect floral organ development [23–25], namely YABBY, basic region/leucine zipper motif (bZIP) transcription factor, and C3H-type zinc finger protein genes. These developmental genes were found to have different expression levels between labella and petals, suggesting that they are associated with labella and petal development but may have different functional mechanisms. Genes related to flower color A single PeUFGT3 gene was detected in our study, and was found to be more highly expressed in red labella than Genes related to floral differentiation Total No. of DEGs No. of DEGs in petals No. of up-regulated DEGs in petals No. of DEGs in labella No. of up-regulated DEGs in labella MADS 16 16 9 12 7 MYB 12 9 3 12 9 ARF 10 10 3 10 7 NAC 6 6 1 6 5 bZIP 5 5 2 5 3 AP2 4 4 2 4 2 TCP 3 3 0 3 3 WRKY 3 3 1 3 2 YABBY 1 1 1 1 0 HD-ZIP 1 1 0 1 1 C3H 1 1 1 1 0 Tab. 3 Some genes related to floral differentiation and their expressions in petals and labella. Classification of flower color genes Genes related to flower color Total No. of DEGs No. of DEGs in petals No. of up￾regulated DEGs in petals No. of DEGs in labella No. of up￾regulated DEGs in labella Genes related to anthocyanin synthesis CHI 3 3 3 3 0 CHS 1 0 0 1 1 DFR 1 0 0 1 1 UFGT3 1 1 0 1 1 ANS(AS) 1 0 0 1 1 F3’H 1 0 0 1 1 Genes related to carotenoid synthesis PSY 1 1 1 1 0 PAL 2 2 0 2 2 FLS 1 1 0 1 1 PDS 1 1 1 1 0 DXS 1 1 1 1 0 IPI 1 1 0 0 0 GGPS 1 1 1 1 0 Some other related genes MYB 12 9 3 12 9 bZIP 5 5 2 5 3 Tab. 4 Some genes related to flower color and their expressions in petals and labella