| In the present study, melting peach fruit’HJML’[Prunus persica (L.) Batsch cv. Hujingmilu] were used to study the expression pattern of CBF/DREB1genes in response to different postharvest low temperature and humidity treatments. Main results are as follows:1. Six members of peach PpCBF gene family were cloned based on information from public EST and genomic database, and RACE technique.In addition to AP2/ERF DNA-binding domain, each PpCBF contains highly conserved regions on both sides of the AP2/ERF domain. Polygenetic analysis results showed that PpCBF3was grouped with AtDREB1a-d and belonged to one group, while the other five PpCBFs were grouped with AtDDFl-2.2. Transient chilling treatment with0℃,5℃,8℃and20℃for72h showed that PpCBF1, PpCBF5and PpCBF6were induced by low temperature. As for PpCBF5, transcription levels increased up to to4-fold after6h treatment with0℃and further increased to more than4000-fold at72h. The similar expression patterns were observed under5℃and8℃, in which transcription levels were induced by690and155-fold. Expression profiles of PpCBFl and PpCBF6were similar to that of PpCBF5under0℃,5℃,8℃and20℃. Transcription levels of PpCBFl and PpCBF6were induced up to575and6-fold higher. Expression levels of PpCBF2, PpCBF3and PpCBF4were relatively constant during treatment period.3. Low relative humidity (RH50%) treatment of72h resulted in14.13%weight loss, comparing with1.27%in controls. Water loss delayed the softening and juiciness increase in peach fruits. Except for PpCBF4, PpCBFs were induced by low relative humidity (RH50%) treatment, and peel tissue had higher transcripts than that in flesh tissue. The transcripts increased during24h for PpCBF1and PpCBF3,6h for PpCBF6in flesh and peel,48h for PpCBF2and PpCBF5, followed by decrease during low relative humidity treatment. PpCBF6tended to increase during72h in peel.4. During long-time cold storage, comparing with0℃, CI symptoms were earlier and severer in fruits storage under5℃, a chilling inducing temperature, manifested by higher electronic leak and disable to soften at shelf life. LTC treatment effectively delayed and alleviated fruit CI accidence, manifested by a normal softening process and higher ethylene production. The transcription level of PpCBFl, PpCBF5and PpCBF6expression under chilling inducing temperature were lower than that under0℃, the ratio were42.3%,74.5%and24.9%respectively.5. Three conserved motifs were found in1000bp upstream region of PpCBF genes. Two of the motifs were ICErl-like and ICEr2-like, which correspond to ICEr1and ICEr2, two essential motifs of AtCBF2for impart low temperature. Absence of ICEr1-like in PpCBF2,3or4upstream regions may cause insensitive of these genes to low temperature. |
