Abstract:

Two full-length cDNAs encoding aspartic proteinases(APs)were isolated respectively from the normal and mutant short catkin of the Castanea mollissima with RT-PCR and RACE amplification method. The sequence results showed that the full-length cDNA from normal was 1 822 bp, while that from mutant was 1 909 bp. They all contained a 1 539 bp open reading frame (ORF) which encoding a protein of 513 amino acids and had 83%, 80% and 75% amino acid sequence similarity with aspartic proteinases in Ricinus communis, Theobroma cacao and Vitis vinifera respectively. The two deduced proteins have six different amino acids, three of which are in the activity areas. Later they were confirmed to be existed both in normal and mutant short catkin,namely CmAPs1 and CmAPs2 (accession No.GQ984143 and GQ984144).The results of Realtime RT-PCR indicated that the expression of CmAPs1 and CmAPs2 gene in mutant catkins was both higher than that in the normal catkins in the primordia formation phase of catkin, floral cluster and flower. However, the expression of CmAPs1 and CmAPs2 gene in mutant catkins was so far lower than that in normal in the stage of perianth primordium formation (programmed cell death happened at the same time), it is speculated that CmAPs would be related to programmed cell death in the process of short catkin development.

Key words: chestnut (Castanea mollissima), catkin, programmed cell death, aspartic proteinases, real-time quantitative PCR