Research On Overexpression Of AtchyB In Eustoma Grandiflorum Shinn And Research On Agronomic Traits Of The Transgenic Maize

In nature, plants are often exposed to combinations of various stresses. Among themis high-light stress which can make potential harm to plants as long as the provokeddamage exceeds the capacity of defense and repair mechanism. Higher plants havedeveloped a number of defense strategies and mechanisms to avoid photo-oxidativedamage of the photosynthetic apparatus due to the formation of reactive oxygenspecies exposing to the excess light. Carotenoids are essential components of thephotosynthetic apparatus taking part in plant photoprotection. Plants can remove theexcess light through xanthophyll cycle which transforms the excess light energy toelectronic energy. What’s more some carotenoids like β-carotene, zeaxanthin,violaxanthin and neoxanthin play a chiefly role in the deactivation of3Chl*,1O2*andthe reduction of reactive oxygen species (ROS) formation to protect plants fromoxidative damage.Eustoma grandiflorum Shinn is a popular cut flower and ornamental plant, which,however, is susceptible to high-light stress UV, high temperature and so on. Its growthenvironment of soft light, warm temperature and suitable air humidity limited itsgrowing areas. To enhance its tolerance to high-light stress, we have increased thecapacity for their biosynthesis in Eustoma grandiflorum Shinn by overexpression ofβ-carotene hydroxylase gene (AtchyB) from Arabidopsis thaliana encoding β-carotenehydroxylase (BCH). This enzyme is involved in the conversion of β-carotene intozeaxanthin and plays an important role in the pathway of carotenoid biosynthesis. Theresults are as follows:1Optimization of the the transformation system of E. grandiflorum SIn this research, we optimized the transformation system of E. grandiflorum S. anddetermined the kanamycin concentration for screening.2High-light stress to the transgenic lines and the controlsUnder high-light stress, untransformed controls showed obvious growth retardation,while transformants were more tolerant. The net addition on biomass of thetransformants was more than that of the non-transformants under high-light exposure.3Determination of the crotenoid ontent and composition by HPLCNot only the total carotenoid content (1.046~3.141folds) of the transgenics was enhanced but also the zeaxanthin biosynthesis was more rapid and in larger quantitiesin transgenics (to3.344folds) than controls upon exposure to high-light stress.Additionally, a greater amount of Xanthophyll cycle pigments (1.46~2.44folds） inthe transgenics was also detected. What’s more, a new phenomenon that high-lightstress induced an apparent periodical accumulation of biomass and zeaxanthin intransformants was found. Our results indicate that the periodic enhancement ofzeaxanthin formation and the periodic enlargement of xanthophyll cycle poolcontribute to long-term high-light stress protection and prevent the plant from damage,which offers a supplement data for previous researches.