Abstract:To understand the protective effects of jasmonic acid(JA)on wheat exposed to ultraviolet B(UV-B)radiation stress,20-day-old wheat(Triticum aestivum L.,cv.Xinong 88)seedlings were pretreated with different concentrations of JA(1,2.5,5 and 10 mmol/L)before adding 7-day UV-B radiation(1.5 kJ·m-2·d-1).Physiology characteristics(such as pigment content,protective enzyme activities,lipid peroxidation level,and UV-B absorbance compounds content)and growth parameters among the control and JA treatment groups were ana-lyzed.The results suggested that there was the concentration effect of JA on plant physiology response.Low concentration JA(1 and 2.5 mmol/L)enhanced UV-B resistance of wheat seedlings significantly.Total chlorophyll content and antioxidant enzyme activity(SOD,POD and CAT)in leaves of wheat seedlings under UV-B radiation were enhanced under low JA concentrations.At the same time,exogenously applied JA increased free proline content,reduced lipid peroxidation level,and enhanced the anthocyanidin content of seedling leaves and root activity.These results show that JA can alleviate membrane lipid peroxidation and enhance defensive substance content by means of improving antioxidant enzyme activity,osmoregulatory compounds and protected pigment content in wheat seedling leaves.Consequently,wheat seedlings can counteract the damage caused by UV-B stress.