The Influence Of Low Temperature Stress On The Growth And Biochemistry And The Clone Of LEA Gene From Phaeodactylum Tricornutum

P.tricornutum is an important Bacillariophyta and is widely distributed in the whole world. It is for the moment one of the good feed for the marine animals in the process of artificial culture. Due to the rapid development of marine economic sectors, the techniques used in the artificial culture of P.tricornutum are supposed to be advanced correspondingly. However, the changes in the external environment and the limitations of the current artificial culture together impede the normal growth of this plant. And among those numerous environmental factors which affect its growth, the influence of low temperature is one of the most serious ones. The Late-embryogenesis-abundant Protein is a class of low molecular protein which the plant seeds accumulate in the post-embryonic development and it expresses in the vegetative tissues which are dehydrated by low temperature, draught, high salt and so on. This kind of protein plays a very important role in the plants: it can effectively enhance the abilities of plants to resist cold, draught and salt; it can also help the osmoregulation and water transport; it protects the cell structure and is regarded as the molecular chaperones.Some physiological indexes of P.tricornutum including the contents of cell density,biomass,chlorophyll a,proline,MDA and soluble sugar were measured under different temperature of 3, 6, 9, 20℃in 3, 6, 9, 12, 15 days.The results showed that under different low temperature stress conditions,the cell density and biomass of P.tricornutum were all significantly lower than the control group;the content of chlorophyll increasesd in the first 3 days, and decreased obviously after 6 days;the contents of proline,MDA and soluble sugar significantly increased compared with the control group.The results provide some references to the mechanism study of low temperature resistance of P.tricornutum.A sequence fragment of Lea gene was cloned from P.tricornutum through RT-PCR technique and then the 3'-end which contains the function area of the Lea gene was cloned through the 3'RACE-PCR technique. The quantitative real-time PCR method was adopted to study the expression level of that gene in different low temperature conditions in P.tricornutum. The result showed that the Lea gene can express quickly, namely, the lower the temperature is, the more it expresses. The above foundings provided some theoretic basis for further revealing the molecular mechanism in the P.tricornutum which can resist the low temperature and for cultivating new varieties of P.tricornutum which are low temperature resistance.