Study on somaclonal variation and utilization for plant breeding

百脉根是一种广泛种植的远系杂交豆科饲料作物。71株，其中大部分是四倍体，再生愈伤组织来自一个单一的原生质体。对它们的形态和农艺性状进行了评价，并与种子生产群体进行了比较。大部分性状的方差在原生质体衍生（原克隆）群体小于种子生产群体。原克隆种群所有性状的平均值均显著向低值方向移动。然而，也观察到比最初用于原生质体分离的植物的值更高的新的表型变体。在原克隆中获得了比初始植物具有更少氢氰酸（其对牛具有毒性作用）的植物。一般情况下，原克隆的花粉育性显着低于种子生产的植物。这似乎部分是由于染色体异常的发生， ...更多信息 原生质体和/或愈伤组织培养过程中的一些结构，如再生体的中期I和后期I和II的单价体、落后染色体和片段染色体以及桥的形成所示。用Southern杂交技术对两株植物种子和五株原克隆植物的线粒体DNA进行了分析。在所有限制性内切酶和mtDNA探针的组合中，13%的种子来源的植物表现出不同的杂交片段模式。另一方面，大部分的原克隆植物的片段模式是相同的，从种子衍生的植物之一。在所有限制性内切酶和探针的组合中，只有2个（4%）出现了片段变异，但所有变异片段都与其中一个种子来源植物的片段完全相同。用Rubisco小亚基基因、苯丙氨酸解氨酶基因和核糖体RNA探针对核DNA进行了分析。从这个实验中发现，这些基因非常稳定，没有任何变异。少

Lotus corniculatus L. is a widely cultivated, outbreeding, leguminous forage crop. Seventy-one plants ; most of which were tetraploid, were regenerated from calli derived from a single protoplast. Their morphological and agronomic traits were evaluated and compared with those of the seed-produced population. The variances of most of the traits in the protoplast-derived(protoclonal)population were smaller than those of the seed-produced population. Mean values of all the traits of the protoclonal population shifted significantly towards lower values. However, new phenotypic variants with higher values than those of the plant initially used for protoplast isolation were also observed. Plants with less hydrocyanic acid(which has a toxic effect on cattle)than the initial plant were obtained in the protoclones. Generally, the pollen fertility of protoclones was significantly low compared with the seed-produced plants. This seems to be partly due to the occurrence of abnormalities in chromos … More ome structure during protoplast and/or callus culture, as suggested by the formation of univalents, lagging, and fragment chromosomes and bridges at metaphase I and anaphase I and II of the regenerants. The changes in chrome some structure, however, did not induce any malformed morphologies.The mtDNA of two plants derived seeds and five protoclonal plants were analyzed by Southern blotting. Seed-derived plants showed different hybridized fragment patterns in 13% of all the combinations of restriction enzymes and mtDNA probes. On the other hand, most of the fragment patterns of protoclonal plants were the same as those of one of plants derived from the seeds. Only 2(4%)of all the combinations of restriction enzymes and probes showed fragment variations.However, all of the varied fragments were identical to the fragments of one of the seed-derived plants. This fact indicates that variations may occur frequently at the same location of the mitocondrial genome or else the variations may occur in constant directions.The nuclear DNAs were also analyzed by using the probes of genes of small subunit of Rubisco, phenylalanine ammonia lyase and ribosomal RNA. From this experiment, it was found that these genes were very stable without any variations. Less