关键词: 越橘, 本氏烟, Lon2蛋白酶, 植物衰老

Abstract: Plant senescence always parallels peroxisome dysfunction，and Lon2 protease greatly involves in maintaining the function and structure of peroxisomes. However，little literature is available regarding Lon2 in plant senescence. In the present study，full length of Lon2 cDNA was cloned from blueberry（Vaccinium ssp.）and named VcLon2（KX611379），then the biological functions in plant senescence of VcLon2 were studied through Virus Induced Gene Silence（VIGS）and transgenetic techniques. Phenotypically，NbLon2-silenced Nicotiana benthamiana showed pygmyism with small and serious yellowing leaves，while VcLon2-overexpressed N. benthamiana plants grew well with bright green leaves. Moreover，chlorophyll content in NbLon2-silenced plants was about 50% of the control plants，and the H2O2 content as well as the membrane lipid peroxidation was more serious compared with the control. On the contrary，conversed change trend was observed in VcLon2- overexpressed plants. Furthermore，the transcription levels of catalase（CAT），a peroxisomal enzyme involved in the detoxification of ROS，showed no significant difference among different seedlings. However，CAT activity in NbLon2-silenced seedlings was reduced to 62.62% of the negative control，indicating that Lon2 plays an important role in structural and functional maintenance of peroxisomal protein. In addition，protein carbonylation degree in NbLon2-silenced plants were significantly higher than that in the control，and the expression level of SAG12 was 15 642.2 times the level in the control. It is suggested that Lon2 protease missing significantly accelerated degradation of photosynthetic pigment，destruction of membrane system and accumulation of carbonylated protein and Lon2 protease played an important role in delaying senescence in plants.

Key words: Vaccinium ssp., Nicotiana benthamiana, Lon2 protease, plant senescence