| In China, potatoes are grown in diverse regions and throughout the year. Nevertheless, freezing has become a key factor to result in serious yield reduction, especially for winter potato production in south China. In this paper, main potato cultivars in China were investigated for freezing tolerance. Gene expression induced by freezing was analysed. The main results are as follows:1.115potato cultivars were evaluated for their freezing tolerance using semi-lethal low-temperature (LT50). The results showed that LT50of cultivars tested ranged from1.0to-4.rC,85.3%of cultivars’LT50were above—3℃.LT50of Jin Shu No.2, Ke Xin No.2, Zheng Shu No.5and Zheng Shu No.6were below—3.5℃, which were top4varieties on freezing tolerance. By cluster analysis of LT50,115cultivars were divided into3categories, freezing sensitive, medium, and freezing tolerance, which accounted for29.6%、55.7%、14.7%, respectively.2. The freezing tolerance of cultivars evaluated in lab were verified by results exposed natural frost in the field. The LT50of the cultivars in lab before cold acclimation were high significantly related (p<0.01) to the results in exposed frost test.3. The change of LT50of cultivars before and after cold acclimation is very small, which indicated that potato cultivars possess little or no cold acclimation capacity.4. Expression level of DHNIO and CBF1gene in3cultivars and1wild species with different temperature treatments were analyed with quantitative PCR. We found that these two genes enhanced expression level under freezing stress, both improved cultivars and wild species. The differences of expression level of DHN10did not reach2times between the least and highest. After cold acclimation, the expression level of CBF1declined slightly in common cultivars, while that increased in wild specices. The results suggested that DHN10was not key gene for potato freezing tolerance, while CBF1played a important role whether in process of freezing tolerance or cold acclimation. |
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