The cultivation of the first filial generation of monoploid gametophyte clones of different Laminaria species (hybrid Laminaria) is an effective way of utilizing heterozygous vigor (heterosis). A female gametophyte cl...The cultivation of the first filial generation of monoploid gametophyte clones of different Laminaria species (hybrid Laminaria) is an effective way of utilizing heterozygous vigor (heterosis). A female gametophyte clone of L. japonica and a male gametophyte clone of L. longissima were hybridized, generating Dongfang No.2 hybrid Laminaria. The parentage of this hybrid Laminaria was determined using AFLP of total DNA, SNP of the ITS region of ribosomal RNA transcription unit and microsatellite DNA variation at two loci. In addition to 167 AFLP bands shared by Dongfang No.2, L. japonica and L. longissima, Dongfang No.2 hybrid Laminaria shared another 70 and 55 bands with L. japonica and L. longissima, respectively, which were obviously more than 11 bands shared by L. japonica and L. longissima. Dongfang No.2 held both ‘T’ and ‘C’ at position 847 of the ITS region, while ‘T’ at this position was specific for L. japonica and ‘C’ for L. longissima, respectively. Dongfang No.2 also held the microsatellite DNA alleles of two parents together at two microsatellite DNA marker loci. These observations clearly proved that Dongfang No.2 is a true hybrid of L. japonica and L. longissiuma. Unfortunately, the origin of the chloroplast of Dongfang No.2 was not determined based on the variation of RuBisCo spacer. More sequence variants of both ITS region and RuBisCo spacer were identified in Dongfang No.2 and most of them did not exist in either L. japonica or L. longissima. The unexpected variants may be due to the mutation of ga- metophyte clones occurring during their vegetative amplification.展开更多
In China, the total annual production of cultured Laminaria japonica reached half million tons in dry weight there few years. The routine sporeling culture technique conducted in the greenhouse took at least three and...In China, the total annual production of cultured Laminaria japonica reached half million tons in dry weight there few years. The routine sporeling culture technique conducted in the greenhouse took at least three and half months. In such a case, sometimes the sporelings died within a few days due to destructive diseases. In Order to overcome the mentioned problems, a new sporeling culture technique, the clone technique, is developed. The method includes three stead: (1) Gametophyte clone culture. The spores and the gametophytes are cloned in flasks under favorable environments. (2) Sporeling cul ture. Male and female clones are crushed and spread onto a frame to allow the gametophytes to attach to the substrata. The frames are cultured in tanks, and the sporophytes reach 1 cm in length within one and a half months. (3) Outgrowing of the plant. The frames are put in the open sea when seawater temperature decreased to 20℃. After one month, the sporelings are large enough to be transplanted. It is concluded that the clone technique has the following advantages: (1)Large amount of clones can be produced in a short period of time. (2) Clone seeding method makes it free from the biological rhythm, one can seed the plant anytime all the year round. (3) It takes only one and a half months to complete the process of sporeling cultivation in the greenhouse. At present, this technique is used in the breeding of new strains of Laminaria.展开更多
文摘The cultivation of the first filial generation of monoploid gametophyte clones of different Laminaria species (hybrid Laminaria) is an effective way of utilizing heterozygous vigor (heterosis). A female gametophyte clone of L. japonica and a male gametophyte clone of L. longissima were hybridized, generating Dongfang No.2 hybrid Laminaria. The parentage of this hybrid Laminaria was determined using AFLP of total DNA, SNP of the ITS region of ribosomal RNA transcription unit and microsatellite DNA variation at two loci. In addition to 167 AFLP bands shared by Dongfang No.2, L. japonica and L. longissima, Dongfang No.2 hybrid Laminaria shared another 70 and 55 bands with L. japonica and L. longissima, respectively, which were obviously more than 11 bands shared by L. japonica and L. longissima. Dongfang No.2 held both ‘T’ and ‘C’ at position 847 of the ITS region, while ‘T’ at this position was specific for L. japonica and ‘C’ for L. longissima, respectively. Dongfang No.2 also held the microsatellite DNA alleles of two parents together at two microsatellite DNA marker loci. These observations clearly proved that Dongfang No.2 is a true hybrid of L. japonica and L. longissiuma. Unfortunately, the origin of the chloroplast of Dongfang No.2 was not determined based on the variation of RuBisCo spacer. More sequence variants of both ITS region and RuBisCo spacer were identified in Dongfang No.2 and most of them did not exist in either L. japonica or L. longissima. The unexpected variants may be due to the mutation of ga- metophyte clones occurring during their vegetative amplification.
基金Key Project, the Ninth Five-Year Plan of China! 96-008-01-02-06Project of Bio-Engineering Center of China! SSTC 96-C01-05-01
文摘In China, the total annual production of cultured Laminaria japonica reached half million tons in dry weight there few years. The routine sporeling culture technique conducted in the greenhouse took at least three and half months. In such a case, sometimes the sporelings died within a few days due to destructive diseases. In Order to overcome the mentioned problems, a new sporeling culture technique, the clone technique, is developed. The method includes three stead: (1) Gametophyte clone culture. The spores and the gametophytes are cloned in flasks under favorable environments. (2) Sporeling cul ture. Male and female clones are crushed and spread onto a frame to allow the gametophytes to attach to the substrata. The frames are cultured in tanks, and the sporophytes reach 1 cm in length within one and a half months. (3) Outgrowing of the plant. The frames are put in the open sea when seawater temperature decreased to 20℃. After one month, the sporelings are large enough to be transplanted. It is concluded that the clone technique has the following advantages: (1)Large amount of clones can be produced in a short period of time. (2) Clone seeding method makes it free from the biological rhythm, one can seed the plant anytime all the year round. (3) It takes only one and a half months to complete the process of sporeling cultivation in the greenhouse. At present, this technique is used in the breeding of new strains of Laminaria.
