陆地棉胚性愈伤组织的变异及高频胚胎发生

VARIATION AND HIGH FREQUENCY SOMATIC EMBRYOGENESIS OF EMBRYOGENIC CALLUS IN GOSSYPIUM HIRSUTUM

陆地棉（Ｇｏｓｓｙｐｉｕｍ ｈｉｒｓｕｔｕｍ Ｌ．）胚性愈伤组织在两年多的继代培养过程中，由淡绿或灰色疏松状转变成灰黄色致密团块状，胚胎发生能力经历了一个由低到高再到低的过程。培养两年半后，从中分离出３种不同的愈伤组织系。第一种可产生大量的胚状体；第二种可产生少量胚状体；而第三种失去了胚胎发生能力。第一种团块颗粒小，后两种团块颗粒大。通过选择培养第一种愈伤组织系，建立了３ 个陆地棉栽培品种的高频体细胞胚胎发生系。染色体观察显示：其变异频率随愈伤组织培养代数的增加而升高；３ 种不同的愈伤组织系中，二倍体细胞的频率大小依次为：第一种＞ 第二种＞ 第三种。此外，第一种含有较多的超二倍体细胞。

During two years subculture, the morphological characters of embryogenic callus from hypocotyl of Gossypium hirsutum L. had changed from loose and fragile with light green or grey in color to compact nodulated cluster with grey or yellow in color. The frequency of embryogenesis of the callus first rose from 20% to 90% and then fell to 60%. The high peak of embryogenesis was found in the early period after the formation of clusters. Three callus lines were derived from the embryogenic clusters cultured for more than two years. Line 1 was small and granular callus with green and yellow in color and was often covered with proembryoids. This kind of callus could produce a great number of embryoids. Line 2 and 3 were bigger and granular calli with grey or yellow in color. Line 2 could produce a small number of embryoids but line 3 could not. Through selecting line 1 subculture, the high frequency of embryogenesis clones were set up from three cultivars of G.hirsutum L. The rate of embryogenesis was over 90%, and after one more year′s subculture, the capability of embryogenesis still sustained. The chromosome variation of callus increased with the age of culture. The frequencies of diploid cells from callus line 1 to line 3 were in the order of from high to low. Moreover, the frequency of hyperdiploid cells in line 1 was higher than that of line 2 and 3. But the frequencies of hypodiploid cells in line 2 and 3 were higher than that of line 1.