Cloning And Expression Analysis Of AP3-like Gene In Oncidium

The MADS-box genes such as AP3 gene family (AP3/PI family), plays an important role in floral initiation and reproductive processes.OAP3 with a MADS-box motif was cloned from Oncidium cultivar Milliongolds. The patterns of OAP3 gene expressions in Milliongolds were studied to find out its role and mechanism of regulation during organogenesis. The studies will help in utilizing the functions and regulatory element of OAP3 gene for developing new orchid populations through molecular breeding programs. The summary of the results is as follows:(1) The full length cDNA of OAP3 was synthesized using RT-PCR. The gene was 799 bp in length with an open reading frame (ORF) encoding 204 amino acids. The sequences were submitted to GenBank (Accession number GU644447).(2) OAP3 gene of Oncidium cultivar Milliongolds belongs to the paleo AP3 of AP3 - like gene families. Results of BLAST and amino acid sequence alignment showed 78% amino acid sequence homology with Phalaenopsis PeMADS5,62% with MADS16 of monocotyledons rice and LMADS1 of Lily. The sequence homologies were found higher than 50% when aligned with dicotyledonous plants Arahidopsis AP3 and Antirrhina majus DEF.(3) The molecular weight of OAP3 was determined as 23661.1 Dalton with 13.8%acidic and 18.3% alkaline amino acid. Of the total amino acids,33% were hydrophobic and 34.97% were polar. The isoelectric point (pI) f the gene was found at 9.49.(4) The qRT-PCR analysis showed enhanced transcript number of OAP3 mRNA with increasing the stage of flower bud development. The same observations have been recorded in all four floral organs as well as in vegetative leaves and shoots.