关键词: 丝瓜, 褐变, CAT1, 基因克隆, 实时荧光定量PCR

Abstract:

A length of 1 755 bp cDNA was isolated from Luffa cylindrical by using RACE and RT-PCR techniques，which contained a 1 479 bp open reading frame（ORF）that encoded 492 amino acids，with a predicted molecular weight of 56.98 kD and a hypothetical isoelectric point of 7.126. It shared over 92% identity with the homologous proteins from Cucumis sativus，Arabidopsis thaliana and Raphanus sativus，proving that it was highly conservative. This gene was named LcCAT1 and the GenBank accession was KP222260. Wolf Psort protection indicated that LcCAT1 protein was located in the peroxisome，and Motif Scan analysis showed that LcCAT1 protein had the characteristic amino acid sequences of catalase proximal heme-ligand and heme active sites in the position of 344–352 and 54–70 sites，respectively，which  suggested that LcCAT1 protein was a typical hydrogen peroxide enzyme（tCAT）.The Real time PCR revealed that LcCAT1 exhibited a tissue specific expression，and the expression level in Luffa cylindrical‘Fusi 3’leaves was the highest，which was almost five times than that in flowers，fruits，roots and stems. The levels of LcCAT1 were different among six luffa varieties，and the expression in Luffa cylindrical was higher than that in Luffa acutangula Roxb. What is more，the level of LcCAT1 in‘Fusi 3’was up-regulated during fresh-cut and post-harvest storage browning processes，which was consistent with the changes observed in peroxidase activity，suggesting that LcCAT1 gene may play a regulation role in luffa browning process.

Key words: Luffa cylindrical, browning, CAT1, gene cloning, real time PCR