Identification of Cool-night Temperature Induced Reproductive Transition Related Genes from Phalaenopsis hybrida by Suppression Subtractive Hybridization
1 Guangdong Key Laboratory of Ornamental Plant Germplasm Innovation and Utilization, Environmental Horticulture Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China; 2 Crops Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China
Abstract：The development of floral buds is a biologic foundation for flower traits formation and regulation. Moreover, temperature is an important factor that affects the floral buds' differentiation and development of Phalaenopsis plants, even flowering. To gain genes related to cool-night temperature induced differentiation and development of spikes in Phalaenopsis hybrida cv. Brother Sister, we performed suppression subtractive hybridization, which allowed identification of flowering-related genes in spikes induced by cool-night temperature and the apical leaves in the vegetative growth phase. After PCR detection for each clone, 300 positive single clones were selected for sequencing. Totally, 207 non-redundant expressed sequence tags(ESTs)(GenBank accession Numbers: JK720764~JK720970) were obtained in the forward-subtracted library. These cDNAs covered a broad repertoire of flowering-related genes, provided helpful information for understanding molecular mechanism in transition from the vegetative to reproductive growth phase. Expression analysis by Real-time PCR of 23 genes from different functional categories validated the expression levels in vegetative apical leaves and spikes with different sizes induced by cool-night temperature. Expression patterns of these 23 genes showed diverse trends. However, they accumulated higher transcripts of these genes in spikes of some stage relative to apical leaves in vegetative phase. Compared with the expression levels in vegetative apical leaves, the transcripts of genes encoding flowering locus T(FT), APETALA1(AP1), jasmonate-O-methyltransferase(JMT) and NADH-ubiquinone oxidoreductase in different sizes spikes significantly increased. These findings indicated that the four genes might presumably play an important role in the process of cool-night temperature induced differentiation and development of spikes. This study supplies an important foundation for further exploration about the molecular mechanisms of cool-night temperature induction of flowering in Phalaenopsis orchids.
