圆紫菜(Pyropia suborbiculata)减数分裂时期的遗传分析与叶状体形态建成

本文以圆紫菜的绿色突变体(LT)和红色突变体(HT)进行杂交实验,证实了圆紫菜减数分裂发生的时期,并观察了圆紫菜的早期发育和形态建成过程。杂交F1叶状体中,出现了2种亲本色和2种重组色,它们分别为绿色(G,母本色)、红色(R,父本色)、野生色(W)和黄褐色(Y)。4种颜色在F1叶状体中形成了大量由2—4个色块组成的颜色嵌合体,色块出现了分离并呈线性排列。F1叶状体中嵌合体所占比例为82.9%,其中两嵌合最多,三嵌合次之,四嵌合最少。4种颜色在嵌合体的分离比为1G:0.97R:0.88W:0.69Y。上述结果证实圆紫菜的减数分裂发生在壳孢子萌发初期。减数分裂产生的四分子呈线形排列,随后继续发育成叶状体,叶状体发育至7—9个细胞时进行第一次纵向分裂,叶状体形态变宽。随后,圆紫菜梢部开始大量形成和放散单孢子,最终导致圆紫菜的形状为圆形或肾脏形。

GENETIC ANALYSIS ON THE PERIOD OF MEIOSIS AND MORPHOGENESIS IN GAMETOPHYTIC BLADES OF PYROPIA SUBORBICULATA (BANGIALES, RHODOPHYTA)

A cross experiment was carried out for two artificial pigment mutants to study the position of meiosis in P. suborbiculata. The early development and morphogenesis of P. suborbiculata blades were observed. Four types of unsectored blades and 84 types sectored blades in F₁ blades were found. Except for the two parents color types blades, a wild and a yellow-brown type blades were discovered. The sectored F₁ blades represented 82.9% of the total blades, and the chimera was composed mainly of two-sectored blades and three-sectored blades, accounting for 43.4% and 32.7%, respectively. Sectors of these four colors appeared in the sectored F₁ blades in the proportion of 870G:840R:766W:602Y, being approximately 1:0.95:0.88:0.69. The results indicate that the meiosis of P. suborbiculata occurs during the first two cell divisions of the germinating conchospores. The linear four cells that resulted from the meiosis continued to develop, and the first longitudinal division began at the blades division into 7-9 cells. Afterwards, a large number of monospores formed and were released in the top of the blade, which eventually led to round or kidney-shaped morphology of P. suborbiculata.