Arabidopsis Thaliana CBF3Enhences The Tolerance Of Potato To High Temperature

Extreme high temperature is strongly detrimental to plant growth and development, In the long-term stress, plants may be damaged and even death, which is harmful to agricultural production. The use of biotechnology to improve thermo-tolerance of plants has an important role in theoretical and practical process. In the present study, we used ArCBF3-transgenic potato under the control of CaMV35S promoter and rd29A promoter respectively to investigate whether overexpression of AtCBF3can enhance the tolerance of potato to high temperature. The main results are as follows:(1) High temperature at40℃or above could significantly induce AtCBF3expression and reached maximum level at1h in leaves.(2) Heat stress lead to the decrease in the net photosynthetic rate (Pn) and stomatal conductance (Gs) of potato plant, especially Gs, which still decreased within24h after high temperature treatment.But the decrease is far greater in WT than in transgenic lines.(3) After plants exposed to40℃for4h, the O-J-I-P curves of transgenic and wild-type plants showed significantly difference, the chlorophyllfiuorescence parameter WK and VJ in WT were obviously higher than transgenic lines. Besides, analysis on multiple fluorescence found that under heat stress, DIo/RC, DIo/CSo, cpDo and Mo in WT were far higher than in transgenic lines, but PIABS was the opposite trend.(4) Transgenic lines enhanced the accumulation of D1protein and accelerated the repair of heat-enhanced photoinhibition to PSII under heat stress. Especially, under the normal condition, the accumulation level of D1protein in the transgenic35S::AtCBF3lines (S1) was much higher than those in WT and the transgenic rd29A::AtCBF3lines (R6), and under the post stress, it could be restored to normal levels faster in transgenic plants than in WT.(5) Compared with the WT, the accumulation of O2·" and H2O2was less in transgenic lines under heat stress and post stress. Moreover, the content of O2·-in transgenic plants could be restored to normal level faster than that in WT. In addition, transgenic plants could maintain relatively higher antioxidant enzyme activities than WT.(6) The expression patterns of these genes (StGLDH, StGMPase, StDHARl, StDHAR2, Staldolase, StsFBPase, StSPS and StADPase) were diverse. Under heat stress condition, StGMPase, StDHAR1and StDHAR2genes were down-regulated in WT, but were up-regulated dramatically in transgenic lines. Overall, the expression levels of eight genes were significantly higher in transgenic lines compared with the WT at heat stress, even at control or post stress.(7) Under the normal condition, the level of HSP70was similar between WT and transgenic lines. When exerted by heat stress, the level of HSP70increased in WT, but it dropped in transgenic lines. What more interesting was that during post-stress, the level of HSP70protein in R6was higher compared with WT and S1.(8) Exogenous CaCl2increased the expression of AtCBF3, while exogenous EGTA decreased the expression of AtCBF3.(9) Compared with wild type plants, transgenic potatoes of35S::AtCBF3suffered serious growth inhibition. It had obvious different between transgenic and wild type potato in leaf shape, size and the number of root. And morphology of transgenic lines is more conducive to the growth and development of plants.In conclusion, our results suggested that heat temperature induced the expression of AtCBF3and AtCBF3enhanced thermo-tolerance of potato plants. The enhanced tolerance might be associated with the AtCBF3-mediated enhanced expression of relational resisting adversity genes, such as genes involving in photosynthesis and antioxidant, but did not depend on the regulatory pathways which HSP70participated in. The expression of AtCBF3was induced by high temperature possibly through the regulatory processes that Ca2+participated in. In addition, the recovery situation of transgenic lines were faster and greater than that of WT, and ignoring morphology, two types of transgenic plants with different promoter were not obvious disparity in the thermo-tolerance.