Poster: Temperature Responses
Abs #
183: Overexpression of mitochondrial small heat shock protein increased thermotolerance in transgenic tobacco
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Presenter: |
Shono, Mariko , mshono@affrc.go.jp |
Authors | Shono, Mariko (A) Sanmiya, Kazutsuka (A) Suzuki, Katsumi (A) Egawa, Yoshinobu (A) | | Affiliations: |
(A): Japan International Research Center for Agricultural Sciences
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Heat stress is one of the most significant constraints on crop production. Plants respond to heat stress by changing their metabolic pathways so as to acclimatize to high temperature. Accumulation of small heat shock protein in mitochondria (MT-sHSP) under heat stress has recently been reported in a number of plant species. We are aiming to analyze the function of MT-sHSP.
We cloned and sequenced a full-length cDNA (LeHSP23.8) encoding the precursor of the MT-sHSP from tomato (Lycopersicon esculentum Mill.). It responded to heat stress quickly and was induced within 5 min at 40C along with other classes of sHSP genes. In addition, MT-sHSP was confirmed to have a molecular chaperone activity in vitro. In spite of these findings, the role and importance of the protein in the heat-shock response is still unclear. To solve the problem, we introduced the tomato MT-sHSP gene with a sense and an antisense construct under control of CaMV 35S promoter into tobacco plants (Nicotiana tabacum L. cv. SR1) and examined the thermotolerance using the transgenic plants. The sense plants overexpressed MT-sHSP even under the normal growth temperature and antisense transformants accumulated less MT-sHSP compared with control plants at the heat stressed conditions. When the 4-week-old seedlings (T2 progeny) were exposed to sudden high temperature stress for 2 hr, sense plants exhibited thermotolerance and survived at 48C that control tobacco cannot survive at all. On the other hand, the antisense plants exhibited susceptible feature to the stress and died at 46C, the temperature control tobacco can survive. These results indicate that MT-sHSP plays a pivotal role in heat-shock response.
