电子束辐照对小麦幼苗生长、生理特性及相关基因表达的影响

Effects of Electron Beam Irradiation on Wheat Growth Vigor,Photosynthetic Characteristics,and Photosynthesis and Antioxidant-related Genes’Expression

为了探讨电子束辐照对‘普冰151’小麦幼苗生理及相关基因表达的影响,采用150 Gy、250 Gy和350 Gy加速器电子束辐照处理小麦干种子,测定不同辐照剂量处理对小麦幼苗株高、根长等生长特性以及相关生理特性,分析光合和抗氧化酶相关基因的表达差异。结果表明:随着辐照剂量增加,小麦幼苗的苗高、根长、生物量均降低,与对照相比,250、350 Gy处理幼苗生长受到显著抑制(P<0.05);随着辐照剂量的升高,抗氧化酶活性均呈先升后降变化趋势,150、250 Gy处理显著提高SOD和CAT活性(P<0.05),低中剂量的辐照有促进保护酶活性增加的作用;不同辐照处理均显著降低了叶片叶绿素a含量和最大光能转换效率值(F_(v)/F_(m));随着辐照剂量的提高,叶片超氧阴离子(O_(2)^(-·))、MDA含量和质膜透性增加,说明辐照剂量增高引起活性氧代谢失调;与对照组相比,辐照处理下光合相关基因TaPEPC-5、TaPPDK-1、TaMDH-7、TaRuBisco-2、TaNADP-ME-1表达有所上调,可能与调动光合能力有关。150、250 Gy辐照处理明显提高了小麦叶片SOD、CAT活性以及TaSOD、TaPOD、TaCAT基因的表达水平,说明中高剂量有提高抗氧化的作用。

Food safety faces significant challenges due to the rapid growth of human population,the reducion of agriculture land area,and climate change.Irradiation mutagenesis methods,such as those usingγrays,laser,or ion beams,provide promising techniques for crop breeding.These methods are highly efficient,cost-effective,widely applicable and environmentally-friendly.In this study,electron beam irradiation was applied to wheat seeds to investigate its effects on plant growth vigor,physiology and photosynthetic and antioxidant-related gene expressions,and to determine the optimal dose of irradiation for wheat breading.The dry seeds of wheat variety‘Pubing 151’was exposed to three different doses of electron beam irradiation-150 Gy,250 Gy and 350 Gy by using a 10 MeV electron linac,with non-irradiated seeds as control.The effects of different irradiation doses on the growth characteristics of hydroponic wheat seedlings,such as plant height,root length,biomass,were analyzed.Chlorophyll fluorescence,,malondialdehyde(MDA)content,electrical conductivity,superoxide anion(O_(2)^(-·))content,superoxide dismutase(SOD)activity,the Catalase(CAT)activity and peroxidase(POD)activity were also measured.The results showed that the seedling height,root length,biomass of wheat seedlings decreased with the increasing irradiation dose,and the growth of wheat seedlings treated with 250 Gy,and 350 Gy was inhibited significantly compared with the control seedlings(P<0.05).The antioxidant enzyme activities were activated by low or middle strength irradiation.For instance,the activities of SOD and CAT in 150 Gy and 250 Gy treatments were significantly higher than the control and 350 Gy treatments(P<0.05),indicating that low and middle dose irradiation could increase the expression and activity of protective enzyme genes.The content of chlorophyll a and the maximum light energy conversion efficiency(F_(v)/F_(m))significantly decreased by irradiation treatments.The content of MDA and O_(2)^(-·),and the permeability of plasma membrane increased with the irradiation dose,indicating that electron beam irradiation caused the metabolic disorder related to active oxygen species.Compared with the control group,electron beam irradiation up-regulated the photosynthesis-related genes,such as TaPEPC-5,TaPPDK-1,TaMDH-7,TaRuBisco-2,TaNADP-ME-1.This up-regulation may be related to the compensatory photosynthetic ability and the protective activity of photosynthetic apparatus.In conclusion,electron beam irradiation significantly affects the growth vigor,physiological characteristics,and expression of photosynthesis and antioxidant-related genes in wheat.High-dose irradiation not only inhibits growth and photosynthesis activity but also causes metabolic disorder involving reactive oxygen species.Therefore,optimizing radiation dose is both theoretically and practically necessary for effective radiation mutagenesis breading.Among the three doses applied in this study,250 Gy is highly recommended for wheat mutagenesis breeding.