Study on somaclonal variation and utilization for plant breeding

点击翻译按钮获取中文摘要

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