Production of Chimeral Thalli by Protoplast Fusion in Porphyra yezoensis and P.tenera

细胞融合是提高植物品质的上级技术。本研究尝试用细胞融合的方法从一种红藻紫菜中获得嵌合体。为了进行细胞融合，必须产生许多原生质体。从自然界中寻找能够降解藻类细胞壁的细菌，并从中筛选出3株能产生大量细胞壁降解酶（-1，4-甘露聚糖酶、-1，3-木聚糖酶和卟啉酶）的细菌。自发突变体的一个绿色菌体也从野生型的P. tenera获得。大量的原生质体来自野生型的菌体。用β-1，4-甘露聚糖酶、β-1，3-木聚糖酶和卟啉酶处理Yezoensis和P.tenera的绿色突变体。通过将这些原生质体暴露于聚乙二醇（PEG）来诱导它们融合。PEG处理的原生质体发育成不规则形状的愈伤组织，并由愈伤组织形成大量的小植株。这些小植株生长成由棕色和绿色部分以及棕色或绿色部分组成的扇形杂色嵌合体（嵌合体-I）。显微镜观察显示嵌合体-I的绿色区段变成棕色成熟细胞。嵌合体Ⅰ释放出的单孢子有的形成棕色和绿色的嵌合体，有的形成棕色或绿色的嵌合体。嵌合体-I的单孢子释放出果孢子，形成嵌合体叶状体。这些果孢子长成丝状体，产生壳孢子。38.4%的壳孢子长成由褐色和绿色组成的嵌合体.因此，嵌合体-I可能是条斑紫菜和柔嫩紫菜融合细胞发育而成的叶状体。

Cell fusion is the superior technique to improve the quality of plants. In this study was tried to produce chimeral thallus from a red sea algae, Porphyra, by cell fusion. For carrying out cell fusion it is necessary to produce a number of protoplasts. We searched bacteria capable of degrading the cell wall of algae from natural habitats, and isolated 3 strains of bacteria which could produce a lot of cell wall-degrading enzymes ( -1,4-mannanase, -1,3-xylanase, and porphyranase). A green thallus of the spontaneous mutant was also obtained from the wild type of P.tenera. A number of protoplasts from thalli of the wild type of . Yezoensis and the green type mutant of P.tenera by the treatment with -1,4-mannanase, -1,3-xylanase, and porphyranase. These protoplasts were induced to fuse by exposing them to polyethylene glycol (PEG). The PEG-treated protoplasts developed into calli of irregular shapes, and a large nummber of plantlets were formed from the calli. These plantlets grew into sectorially variegated chimeral thalli (chimera-I) composed of brown and green sectors, in addition to brown or green thalli. Microscopical observation revealed that green sector of chimera-I turned into brown mature cells. Some monospores released from chimera-I grew into chimeral thalli composed of brown and green, and others bedame brown or green thalli. A chimeral thallus developed from monospores of chimera-I released carpospores. These carpospores grew into conchocelis and produced conchospores. A 38.4 % of the conchospores grew into chimeral thalli composed of brown and green. Therefore, chimera-I was supposed to be a thallus developed from fusion cell of P.yezoensis and P.tenera.