Effects Of Low Temperature On Physiological Characteristics And Gene Expression Of Rice Roots

Chilling damage occurs mostly in high latitudes and in the southern regions where late spring cold occurs in China.As we all know,rice is a cold-sensitive crop.Although the physiological and molecular mechanisms of rice cold tolerance have achieved remarkable results,the anti-reverse regulation network is very complicated.The plants responded through a combination of above-ground parts and underground roots with a series of physiological changes under stress.In this study,extreme cold tolerance(C30,D55,S211)and extremely cold sensitive materials(C13,D20,S123)were used to observe the changes of root morphological structure at the seedling stage in rice under different low temperature treatments.Meanwhile,the contents of antioxidant enzyme system(SOD,POD,CAT)in roots were measured at different temperatures.The changes of antioxidant components in rice roots under low temperature conditions were analyzed,and under different temperatures the expression levels of rice stress-resistant genes were combined to initially explored the relationship between antioxidant system and stress-resistant genes.The results are as follows:(1)At low temperature stress,the activity of SOD in the roots of all materials increased.The SOD activity in the roots of materials at 14?,10? and 8? was significantly higher than that of the control.Among them,the SOD activity in the roots of C30,S211 and S123 was higher than that of the control at 10 ?,and reached a very significant level.(2)At low temperature stress,the POD activity in roots increased rapidly.At 14 ?,the POD activity in all roots was higher than that of the control,and reached a very significant level.(3)Under low temperature stress,the activity of CAT in the roots of experimental materials changed greatly.The CAT activity in the roots of C30 was higher than that of the control at 14 ?,10 ? and 8 ?,and both reached extremely significant levels.The CAT activity in roots of all materials was significantly higher than that of the control under different temperature stresses.(4)Under low temperature stress,the MDA content in the roots of the plants increased.At 14 ?,the MDA activity in all material roots was higher than that of the control,and C30 reached a significant level,while other materials reached extremely significant levels.(5)At low temperature stress,the proline content in the roots of the plants increased.At 8 ?,the content of proline in roots of all materials was higher than that of the control except S123,and C13 reached a significant level,and all other materials reached extremely significant levels.(6)Under low temperature stress,the soluble sugar content in the roots changed greatly,but the soluble sugar content in the roots of all the materials was significantly higher than the control at different temperatures.(7)At low temperature stress,the content of soluble protein in the roots of the plants increased,and all materials except C13 were significantly higher than the control at different temperatures.(8)Under low temperature stress,the ABA content in the roots of the plants changed greatly.At 14 degrees Celsius,there was no significant difference in ABA content between C13 and the control.Other materials were higher than the control and reached extremely significant levels.However,at 10? and 8?,the ABA content in the roots of C13 was significantly higher than the control,which reached a very significant level at 8?.The expression levels of Os PYL10,Os POX1,Os CATB and COLD1 in roots of extremely cold-tolerant and cold-sensitive materials were detected under different low temperature stress treatments.The results showed that the Os PYL10 expression of C30(cold-tolerant)was significantly higher than C13(cold sensitive)under cold treatment at 10 ?,and there was no significant change in other varieties with cold-tolerant and varieties without cold-tolerant.The expression of COLD1 in the roots in C30 was significantly higher than that in C13.The expression of COLD1 in the roots in S211 was significantly higher than that in C13.The expression of COLD1 in other roots did not change significantly.