小麦再生植株的变异研究 Ⅱ.再生植株当代(R_1代)的细胞学和形态学变异

再生植株具有高频率的染色体异常,其中有20.61％表现为染色体数量变异,最常见的为2n—1类型,其次为2n—2类型,也有2n 1、2n—3个体以及染色体数嵌合株。再生植株减数分裂各期均有染色体异常行为,可以见到的有落后染色体、染色体桥、断片、二分体延迟、微核,还有粗线期十字型配对等结构变异,以及五分体、六分体和畸型四分体等异常现象。微核率随培养时间延长而增加,可用作染色体伤害的一个指标。再生植株R_1代存在着许多形态学变异。性状变异与染色体数目变异没有明显关系。

Study on the Variation in Wheat Regenerated Plants II.Cytologic and Morphologic Variations of R1 Generation

1.Among 165 regenerated plants investigated in this study,20.61 percent of them showed chromosomal variation.The major type is 2n-l which has 55.88 percent in the variation,other variations such as 2n-2,2n-3 and 2n l also existed in the regenerated plants.We also observed the chromosome number-mosaic plants in the treatment of the 210-day culture.The variation frequency increased as the culture time increased.2.The meiotic aberration existed in all the regenerated plants investigated.The common types were high frequencies of poly-univalent in metaphase 1,lagging chromosome,bridges and micronuclei in tetrad,the other aberration was also observed in meiosis.3.There are no relations between the culture time and chromosomal aberration in Anaphase I-Telophase I and Anaphase II-Telophase II,but the aberration frequency of regenerated plants were significantly higher than that of the control.The micronuclei frequency in tetrad was increased as the culture time,and can be used as an index to measure chromosomal damage.4.A lot of morphologic character variations existed in the R1 generation of regenerated plants.The morphologic variation did not relate to the chromosomal variation.As time in culture increased,somaclones became later in heading,shorter in height and worse in many other agronomic traits.