Resistance Evaluation Of Transgenic Succari With TERF1 Gene

Citrus is an important subtropical fruits and is also one of important economic crops in the world. Citrus in the production process is often accompanied by drought, cold, disease and other adverse impact of stress which can lead to decrease fruit quality, yield reduction, pesticide application increased, and severe stress damage can even cause plant death to caused enormous environmental damage and economic loss.Succari(C. Sinensis)is a very popular sweet orange in china. It has a beautiful orange fruit shape and yellow-orange fleshed high sugar, low acid. Three transgenic TERF1 sugar Orange lines were used as experiment materials to test the ability of bearing drought, low temperature stress as well as bacterial infection. morphology observation, photosynthesis and various physiological, infection rate after inoculated with Citrus canker diseases statistics analysis have been used to evaluated the resistance under bio and abiotic stress. The results are as follows:(1) In normal growth, there is no significant difference in content of Pro,MDA and the activity of CAT, POD, SOD in plants between genetically modified sugar orange leaves. But under drought stress, the Pro in transgenic sugar orange leaves accumulated quickly and the amount increased with the stress increased. The control plant only accumulated Pro under moderate stress, meanwhile with Pro accumulation decreased under severe stress; under drought stress, transgenic sugar orange and control plants showed obvious changes in CAT, POD and SOD of leaves. With moderate stress, transgenic sugar orange and control plants had the CAT, SOD decreased with POD activities increased commonality. And with severe stress, CAT, POD, SOD in control plants dropped significantly, but transgenic sugar orange leaves remained at very high activity level. Among this transgenic sugar orange, line 3 (T3) maintained a high level of resistance to drought, and showed the highest resistance to stress.(2) Under the low temperature stress experiment, the leaf injury rate of transgenic sugar orange and control plants changed with gradient temperature variation as a "S" shape change. With the same stress treatment, leaf injury rate of three transgenic sugar orange lines was significantly lower than the control plants. After treated with -6℃for 30min, leaf injury rate of controlled plants began to rise sharply, which is consistent to the morphological observations. This results illustrated that the transgenic TERF1 sugar orange posses a stronger resistance to low temperature to the control plants.(3) By inoculation assay, the transgenic TERF1 sugar orange showed a certain resistance to citrus canker disease with a delayed disease occur time. The disease incidence of in vitro inoculated leaves of transgenic sugar orange was reduced about 55% and 3 to 5 days later to appeared the typical citrus canker symptoms then the control plants. The disease incidence of in vivo inoculated leaves was decreased at least 48% then the control plants.