Abstract: The seeds of Stylosanthes guianensis SW. ‘Reyan No.13’ were irradiated by ⁶⁰Co at 0, 325, 487 and 974 Gy. Phenotype and molecular variations of Stylosanthes M₁ generations were studied. Germination percentage, plant height, leaf length and stem diameter of M₁ seedlings were determined using SRAP-PCR. Results showed that biological character indices of treatments were significantly lower than that of control (CK). Irradiation inhibited plant growth. Growth indices of 974 Gy treatment, except leaf length, were significantly lower than CK and other two treatments. Eight effective primers selected from 24 primers combination were used for SRAP-PCR. SRAP analysis revealed that the 57 of 88 DNA fragments were amplified showing polymorphisms. The average percentage of polymorphic bands was 64.77%. The effects of ⁶⁰Coγ irradiation on DNA variation of seedlings were varied from different treatments. Numbers of polymorphic bands changed after irradiation. Coefficient of variation was in direct proportion to irradiation doses. Variation rates of 325 Gy, 487 Gy and 974 Gy treatments were 22.0%, 38.1% and 41.5%, respectively. The Nei’s genetic similarity coefficient of all treatments was ranged from 0.585 to 0.780 by software NTSYSpc 2.1 based on SRAP results and the average Nei's coefficient was 0.678. The Nei’s genetic similarity coefficient of 974 Gy treatment was 0.585 and variation degree was highest among all treatments, 487 Gy treatment was second and 325 Gy treatment was the lowest one. Based on present bands, four irradiated treatments were classified into two major groups by UPGMA cluster analysis. GroupⅠincluded CK, 325 Gy and 487 Gy treatment and groupⅡincluded 974 Gy. SRAP analysis determined variation of Stylosanthes after irradiation and the results of SRAP analysis were consistent with their biological indexes in some extent.

Key words: Stylosanthes SW., ⁶⁰Coγ-ray, Variation, SRAP

摘要： 采用不同剂量⁶⁰Coγ射线辐照处理(0,325,487,974 Gy)热研13号柱花草(Stylosanthes guianensis SW.‘Reyan No.13’)种子,统计M₁代植株的发芽率、株高、叶片长度和茎粗,进行SRAP分子标记分析,以期明确柱花草M₁代表型与分子水平的诱变效果。结果表明:辐射处理的各项生物性状指标均低于对照,随着辐照剂量的增加,柱花草生长所受抑制作用也增强,974 Gy处理下除叶长外其他生长指标均最低,显著低于另2个处理和对照(P<0.05);经SRAP分析显示,24对SRAP引物组合中共筛选出8对多态性好、条带清晰的引物组合,8对引物组合共扩增出88个条带,其中多态性条带57条,多态性比率达64.77%。柱花草的各辐照处理均与对照存在不同程度的多态性差异,相异系数随着辐照剂量的增加而增大。325 Gy,487 Gy和974 Gy处理的相异系数分别为22.0%,38.1%和41.5%;这些材料间的遗传相似系数(GS)变化范围为0.585~0.780,平均GS为0.678。974 Gy处理与对照的遗传相似系数为0.585,说明974 Gy处理与对照的遗传距离较远,变异程度最大,而487 Gy处理次之,325 Gy处理最小。通过UPGMA分子系统聚类法,可把4个辐照梯度处理分为2大类群:对照、325 Gy和487 Gy处理聚在第Ⅰ大类中,而974 Gy处理单独聚为第Ⅱ大类。SRAP分析结果与生物性状指标结果呈现一定程度的一致性,说明SRAP分析可以准确检测柱花草辐照材料的变异。

关键词: 柱花草, ⁶⁰Coγ射线, 诱变, SRAP