普通小麦体细胞无性系R2代变异发生特点

小麦Ｒ２代体细胞无性系变异存在４种发生方式，即合株性稳定谱异，全株分离变异，穗系嵌合稳定变异，穗系嵌合分离变异，其中稳定变异相当普遍、红占总变异的１／３。发生阶段较全株性变异于发生较迟的穗系嵌合变异。不同的变异性状有不同折发生方式。株型、穗型、芒型和叶色变异多为分离变异，熟期为稳定变异，株高，腊质等兼有稳定及分离变异，其中某性状是显性突变的结果，多数分离性状的分离均属简单分离，且箐少见到基因突变的

Characterization of Occurrence of R2 Somaclonal Variation in Common Wheat

Four kinds of occurrence patterns of somaclonal variation of several major traits were found in the R2 generation of common wheat, i.e. R2 family non-segregation or stable variation. R2 family segregating variation, R2 line chimeric stable variation and R2 line chimeric segregating variation. Among these the stable variations occurred more commonly in the R2 population, and amounting to one third of the total variation in this study. Frequency of R2 family variation, which probably had occurred from the single original cell of the callus at an early stage, was higher than that of R2 line chimeric variation, which might have occurred during the process of plantlet regeneration. Different traits had their own distinctive patterns of variation occurrence: plant type, spike type and leaf colour were subject to segregating variation: maturity was liable to stable variation, and plant stature and waxiness had both the pattern of stable variation and that of segregating variation. Part of the variations have proved to be resulted from gene(s) mutation in the dominant direction. Most of the segregating variations displayed simple segregation ratios. Chimerism in R2 segregating lines was rarely seen. The frequency of R2 variant individuals was estimated to be at least 10 times as much as that in the M2 population from radiation and chemical mutation.