光质对尾叶桉愈伤组织O2·-代谢基因表达的影响OA

To study the effect of light quality on the expression of genes related to superoxide anion(O2·-)metabolism in Euca-lyptus urophylla callus,and to find a method for preventing browning of E.urophylla.The hypocotyls of sterile seedlings were inoculated into SPCa induction medium containing phenylurea(PBU),thidiazuron(TDZ),3-indoleacetic acid(IAA),and 6-benzylaminopurine(6-BA),with the concentrations of 0.86,2.57,0.57,and 0.57 μmol·L-1,respec-tively.They were first cultured in the dark for 14 days,and then different light qualities with the same light intensity(white light(W),blue light(B),red light(R),blue light∶red light=3∶1(3B1R),red light∶blue light=3∶1(3R1B))were used to induce callus formation.The results showed that after 56 days,the callus browning rate under red light(R)was the highest,reaching 43.21％,the browning rate under blue light(B)was the lowest,at 19.12％.The su-peroxide dismutase activity of callus induced by 3B1R was the highest,at 2 471.74 U·mg-1.The O2·-scavenging capacity of callus induced by blue light(B)was the strongest,at 4 556.61 μmol·min-1·g-1.The transcription levels of 7 rboh genes and 9 SOD genes were detected by qPCR.Under R induction,rboh3,rboh6,rboh7,SOD1,SOD2,SOD5,SOD6,SOD7,and SOD8 genes were significantly up-regulated.Under 3B1R induction,all 7 rboh genes were at low transcription levels,but the transcription of SOD3,SOD4,SOD5,SOD8,and SOD9 was significantly up-regulated.Under B induction,only the transcription levels of rboh9 and SOD2 were slightly higher.Light quality has a significant effect on O2·-metabo-lism in callus.Red light induces high expression of rboh to promote browning and causes high expression of SOD genes.Under blue light,the expression level of rboh is low,and the O2·-scavenging capacity is strong,which effectively reduces browning.