坛紫菜的单性生殖与遗传纯系分离

在随机抽检的天然野生坛紫菜叶状体群体中,发现99.9%的个体是雌雄异体,只有0.1%的个体是雌雄同体.以雌性叶状体和雄性叶状体为研究材料,用酶解法分别获得其单离体细胞进行再生培养,然后观察再生叶状体的生殖行为,发现再生的雌、雄叶状体均可进行单性生殖,产生遗传上纯合的丝状体.雌性叶状体生长2个月左右,叶片梢部的颜色逐渐变浅,细胞的星状色素体逐渐缩小变成圆盘状,叶片生长变慢.不久,单个细胞从叶片梢部边缘处释放出来,数小时后,它们开始萌发成丝状体.雄性叶状体生长1个多月,在梢部形成大量的精子囊,但在精子囊中间存在极少量的细胞,它们不发育成精子囊,其颜色反而变红,当四周的精子囊释放精子后,它们就发育成丝状体.由单雌或单雄生殖产生的丝状体,其生长发育正常,由它们释放的壳孢子发育成形态和颜色很一致的可育正常叶状体,其性别全为单性,即由单雌生殖产生的丝状体的后代叶状体全部为雌性,而由单雄生殖产生的丝状体的后代叶状体全部为雄性.

Parthenogenesis and isolation of genetic pure strains in Porphyra haitanensis (Bangiales, Rhodophyta)

The single somatic cells of the female and male gametophylic blades of Porphyra haitanensis Chang et Zheng were respectively isolated and then regenerated into blades to study their reproduction. It was found that in the regenerated blades, parthenogenesis occurred and the genetic pure conchocelis was produced. When the regenerated female blades were cultured for about 60 days, the upper parts of the hlades gradually became light in color as the primary brownish red stellate chloroplasts of cells became smaller, doughnut shaped and light brown yellow in color, meanwhile the growth of the blades became slower. When the culture conditions changed suddenly, a great many single cells released from the periphery of the upper parts of the blades. The fresh released cells were protoplasts and regenerated cell wall 3-5 h later, and then their colors gradually became brownish red and began to germinate into free-living conchocelis. After about 45 days in culture, a lot of spermatangia showing light red brown colors formed in the upper parts of the regenerated male blades, however, among the spermatangia, there were a few of cells showing brownish red color, which did not develop into spermatangia and finally germinated into free-living conchocelis after the spermatia had been released. The parthenoconchocelis grew and developed normally, and finally formed a lot of conchosporangia. Conchospores released from the partheno-conchocelis developed into normal gametophytic blades which showed the same color and morphology. All of the blades developed from the conchospores of the partheno-conchocelis produced by the female blade were female, while all of the blades developed from the conchospores of the partheno-conchocelis produced by the male blade were male.