Identification Of Key Genes Encoding Carotenoids Cleavage Dioxygenase In Malus Hupehensis Rehd

The cleavage of carotenoids played an important role in plant growth and development and the response to stresses. NCEDs and CCDs are the key enzymes in the process of carotenoids cleavage. In this present study, the expression pattern of MhNCED3and MhCCDl from Malus hupehensis, which is the apple rootstock, were detected under drought, high salinity, low temperature and CdSO4treatment. The transgenic Arabidopsis were obtained and the response to stresses was analyzed. The function of MhNCED3and MhCCD1were primary identified. The mail results were as follows:(1) MhNCED3in Malus hupehensis roots was induced by drought, chilling, high salinity and CdSO4leading to ABA accumulation;(2) Overexpression of MhNCED3in Arabidopsis increased ABA content in Arabidopsis seeds, delayed seeds germination and induced ABA-related genes expression;(3) Overexpression of MHNCED3enhanced water retention of Arabidopsis and enhanced the tolerance to osmotic stress.(4) Overexpression of MhNCED3enhanced the antioxidant capacity, decreased cell death rate, enhanced the tolerance to Cd2+stress;(5) The membrane lipid peroxidation of Malus hupehensis roots was higher in Cl-stress than in Na+after treated by NaCl, Na+solution and Cl-solution. ROS and NO was also higher in Cl-stress than in Na+stress. These results indicated that Malus hupehensis was Cl-sensitive plants(4) Exogenous ABA in Malus hupehensis induced the leaves Cl-content and the total Cl-content. MhNCED3was induced by Cl-stress and overexpress MhNCED3in Arabidopsis decreased Cl-content of leaves under Cl-stress.(5) NO and ROS in Malus hupehensis roots under Cl-treatment was generated more than that under Na+treatment. Application ABA decreased the Cl-content in Malus hupehensis leaves, overexpression of MhNCED3significantly decreased the Cl-content in Arabidopsis in Cl-stress;(6) MhNCED3expression was induced by NO production inhibiter and scavenger, overexpression of MhNCED3increased NO generation rate of Arabidopsis;(7) MhCCD1in Malus hupehensis roots was induced by AM fungi; Co-expression of MhCCD1in E. coli accumulated carotenoids cleaved carotenoids and make the bacteria color faded; (8) Overexpression of MhCCD1decreased carotenoids content, but interfering CCD1caused carotenoids accumulation; When treated with AM fungi, overexpression of MhCCDl decreased β-carotene and lutein content more than that before, and CCD1deficiency increase decrease amplitude.(9) Overexpression of MHNCED3in Arabidopsis increased the AtCCD1、AtCCD7and AtCCD8expression. Overxpression of MhCCDl in Arabidopsis also induced AtCCD7and AtCCD8expression but did not affect AtCCDl and AtNCED3.