摘要
美洲狼尾草和象草的种间杂种的体细胞染色体数为2n=21,为一个三倍体杂种,其中7条染色体来自美洲狼尾草,14条来自于象草。杂种的花粉母细胞减数分裂中期Ⅰ主要形成7个二价体和7个单价体的染色体构型,在后期Ⅰ,7个二价体以7Ⅰ:7Ⅰ均等地分向细胞二极,7个单价体则随机地分向细胞各部位,后期Ⅰ还有形成染色体桥、染色体落后等不正常现象;四分体期有三分体、五分体及四分体加上一小细胞等现象出现,并普遍有未被核膜包含的染色体和微核存在;有效花粉频率很低,并有一种小而圆的具双层壁且有一萌发孔的小花粉粒出现。从三倍体杂种产生的少量F_2及以后的世代中,选择仍具有一定优势的新选系是有效的。
The interspecific hybrid between Pennisetum americanum and P. purpureum which has high yield potential and high forage quality is cultivated in certain areas of South China and the Yangtze River region as a good green feed for domestic animals and fresh water fish. In order to elucidate the genetic background of the hybrid as the basis for wider use and further improvement of the hybrid, cytological observations of the pollen mother cells at different meiotic phases were done. The somatic chromosome number of the interspecific hybrid is 2n = 3x = 21, in which 7 come from P. americanum and 14 from P. purpureum. The PMCs usually form 7II + 7 I at meiotic metaophase I (Table l; Plate 1). Meiotic irregularities including chromosome bridges and laggards appeared at anaphase I (Table 2; Plate 4). Tetrads, triads, pentads and a special type of pentad composed of a tetrad and a small cell were observed ( Plate 3,5,6,7). Normal pollen grains occurred scarcely, and special small round pollen grains with a germinal pore and a double wall were found among the numerous abnormal pollen grains of the hybrid (Plate 8).
出处
《江苏农业学报》
CSCD
1990年第2期33-38,共6页
Jiangsu Journal of Agricultural Sciences
基金
国家自然科学基金资助项目
关键词
美洲狼尾草
象草
种间杂种
细胞学
Cytological observation
Pennisetum americanum Schum
Pennisetum purpureum K. Schum
Interspecific hybrid
