Cloning And Expression Analysis Of α-mannosidase Gene During Fruit Softening Of Peach

α-mannosidase, a key enzyme in the process of N-glycan, was reported to play anvital role in controlling fruit softening and extending shelf life. This is of importantsignificance to make clear the physiological function and regulation mechanism of α-manduring peach fruits softening for further clarifying the softening mechanism. A full length ofα-mannosidase gene was cloned from mature peach fruit by RT-PCR and RACE methods,and its transcript level under different treatments (ethrel,1-MCP) on peach fruit werefurther detected by real-time qPCR. Furthermore, different storage properties of peachcultivars ‘Qin wang’ and ‘Bai li’were used to investigate the changes of fruit firmness, therate of ethylene release and the activity of α-mannosidase after harvest. The main resultswere as follows.1The obtained α-man gene, named Pp-α-man (Genebank accession number:JX310861), was3,491bp in length, with a single3,075bp opening reading frame thatpredicted to encode1,024amino acids.2In the N-terminal region of α-man gene, which contained a NXT/S glycosylated siteand belonged to glycosyl hydrolase38family. The first20amino acid is signal peptide, andbetween Ala（A）and Asp（D）is the signal peptide cleavage site. The29thanmino acid isglycosylation site. Binding sites and catalytic sites together constitute the active center ofα-mannosidase in conserved regions.3Real-time q-PCR showed that the expression of α-man in control fruits increased tothe first peak at2d after harvest. While in ethrel treatment, it reached to the maximum atthe first day, and the peak was significantly higher than that in the control. While in1-MCPtreatment, the peak time of α-man`s expression was delayed1day and the α-man`sexpression was suppressed through the whole softening progress, especially at later stage.4In the hardness of ‘Qin wang’ fruits, the activity of α-mannosidase increased tomaximum at5d after harvest, then decreased rapidly and significantly increased at the endof storage. While the ‘Bai li’ fruit, the α-mannosidase activity of ‘Bai li’ was clearly higherthan ‘Qin wang’, especially at the end stage. It consistented with the change of firmness.