[目的]研究不同剂量质子辐射(PR)的白马牙玉米M2代的生长发育、形态和基因组DNA水平上的变异情况.[方法]对白马牙玉米干种子进行5种不同剂量的辐射处理,研究M2代玉米生长状况,采用RAPD分子标记技术研究M2代损伤和变异.[结果]发芽率随着剂量的增加先升高后降低,20、30 Gy处理的发芽率均高于对照,20 Gy处理最高;空秆率随着剂量的增加呈先升高后降低再升高再降低的马鞍型曲线,其中20 Gy和50 Gy处理最低,40 Gy处理空秆率最高,达29.4%;光合速率PR组显著低于对照,随着剂量的增加呈马鞍形曲线;籽粒千粒重随着剂量的增加呈马鞍形曲线,10、20和40 Gy处理显著高于对照,50 Gy处理低于对照.综合考虑发芽率、空秆率、千粒重,对白马牙玉米M2代产量的有益变异多的辐射剂量依次为20、10和30 Gy.RAPD试验分析中16条随机引物扩增出142条条带,其中多态性条带71条,多态性比例达57.3%,各PR组变异率为20.2%~32.3%;各组在遗传相似度0.73附近处聚为2类,10 Gy组与50 Gy组聚为1类,表明其变异程度较大,其他组与对照聚为1类.[结论]该研究可为今后辐射诱变玉米产生有益变异和培育新品种提供辐射剂量的指导和参考,也为拓展玉米种质奠定一定的基础.%[Objective]The growth and development,morphology and variation of genomic DNA level in the M2 of maize were studied in different doses of proton radiation (PR).[Method]Maize seeds were irradiated by different doses of proton(10、20、30、40、50 Gy).We studied the growth status of M2 of maize,and studied the M2 damage and variation with RAPD molecular marker technology.[ Result] The germination rate increased firstly and then decreased with the increase of the dose.The germination rate of 20 Gy and 30 Gy groups were higher than the control,and the 20 Gy group's was the highest.The empty bar rate was a saddle shaped curve,the minimum was at 20 Gy and 50 Gy,the highest was at 40 Gy and up to 29.4%.The photosynthetic rate of the maize of irradiation groups was significantly lower than the control,it showed saddle shaped curve with the dose increasing.The thousand-grain weight also showed saddle shaped curve with the dose increasing,its values of the groups of 10 Gy, 20 Gy and 40 Gy were significantly higher than the control and the minimum was at 50 Gy.Comprehensive considering the germination rate,the empty bar rate and the thousand-grain weight,the radiation dose of producing useful variation of maize M2 generation was in the order 20 ,10 and 30 Gy.16 random primers were used on Random Amplified Polymorphic DNA,called RAPD experiment.All primers amplified 142 bands,71 poly-morphism bands.The polymorphism bands ratio reached 57.3%,and the variation rate of irradiation group was between 20.2% and 32.3%.The result of genetic similarity clustering analysis showed that those groups were clustered into two categories.One included the 10 Gy group and the 50 Gy group,and the variation was high.The other included the 20,30 and 40 Gy groups and the control.[Conclusion]These works can provide a guidance and reference of radiation dose for the radiation induced maize to produce beneficial mutations and cultivate new varieties,and may lay a certain foundation for expanding the maize germplasm.
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