Comparative Research On Ultrastructure And Expressed Level Of Pigment Gene In Pigment Mutants Of Porphyra Haitanensis

Pigment mutation is a special phenomenon in the life-cycle of Porphyra. Recently, thepigment mutants of Porphyra have become the new research topic among algologists, becausepigment mutants were useful for genetic, physiology and breeding studies of cultivated porphyra.But previous reports were limited to the study of pigment mutants obtaining, genetic analysis,content and ratio of each pigment measuring and use for breeding, none study has been carriedon the forming mechanism of pigment mutants. So in the present study, comparisons ofultrastructure, pigment contents and expressed level of pigment genes were carried out amongsix pigment mutants (brown, breen, marron, dark brown, nacarat, and purple types) and one wildtype of Porphyra haitanensis. The results showed that:1. The main ultrastructural differences between the different color mutaants are the size,number of the chloroplasts and the structure of the thylakoids which contained in thechloroplasts. Whether contained pyrenoid in the chloroplasts and the number, length anddistribution of thylakoids which stretching into pyrenoid are also significantly different. Inaddition, there are many starch grains in the cell of wild, breen, purple thallus, but no in the cellof other color thallus.2. The contents of pigment proteins were significantly different in each pigment mutant.Thecontents of phycobiliproteins and chlorophyll a were higher in the early and bloom phase than inthe last phase. It was also found that the contents of pigment protein were different betweenthallus and conchocelis.3. Form the results of in vivo absorption spectroscopy in different portion (base portion,middle portion and sharp portion) and different phase (early phase, bloom phase and last phase)of each color thallus of P. haitanensis, we can found that there were five absorption peaks in thesame wave length, but the the locations and levels of these peaks are difference among all thepigment mutants.4. Quantitative real-time PCR was used to analysis the relative expressed levels of4pigment genes (Cpeα, Cpcα, Apcβ, Chl.a) in conchocelis and different growth phaseof thallus(early phase, bloom phase, last phase) of one wild line and6pigment mutant lines of P.haitanensis. The results showed that, in the thallus and conchocelis of all lines, the relativeexpressed levels of the4pigment genes were all in sequence: Apcβ>Cpcα>Chl.a>Cpeα. And the expressed level of Cpeα in thallus was unstable, which can significantly change in differentphase of all lines, but the expressed levels of Cpcα、Apcβ、Chl.a were stable in thallus fordifferent phase of all lines. Furthermore, the result of liner correlation and regression analysisindicated that the pigment gene expressed levels had no relation with the pigment proteincontents in all lines, in other words, the expressed levels of the4pigment genes had no relationwith the blade color of Porphyra.