Abstract: To explore the causes of germination during different cotton varieties to low temperature stress,used two type materials (strong chilling resistant of SCRC37,SCRC36,and chilling sensitive of Stoneville 2B,Stoneville 5A) to study the difference of physiological indexes and gene expression to low temperature stress during different germination stages. The results showed that the MDA content of sensitive varieties increased sharply,to 12℃ stress for 36 h. The content of MDA in Stoneville 2B,Stoneville 5A respectively increased by 48.17% and 50.65%,compared with SCRC 37,to 12℃ stress for 48 h. Therefore,It was suggested to be used as a selective index for seed germination of cotton to low temperature stress,which the change of MDA content to 12℃ stress for 36 h. The SOD activity and POD activity were maintained at a high level of SCRC 37 and SCRC 36 at all levels of treatment. To low temperature stress,the CAT activity of tolerant varieties was gradually surpassing that of chilling sensitive varieties. To 12℃ stress for 48 h,the content of free proline in SCRC37 from Stoneville 2B and Stoneville 5A,respectively was 33.32% and 23.27%. These results indicate that the physiological indexes were relatively stable in response to the differences of low temperature tolerance and germination of different varieties. The gene of CBF1, CBF2, CBF4, CBF6 were up-regulated more rapidly in strong chilling varieties,and the expression was reached peak when stressed to 12 h. These may be the reason why the strong chilling varieties are more sensitive and rapid in response to low temperature stress.

Key words: Cotton, Low temperature stress, Physiological indexes, Gene expression

CLC Number: 

• S562.01