| The developing condition of longan embryo is closely related to its taste quality, fruit set and production. It is not only of great theoretical importance for explaining regularity of longan embryo development , but also of important practical significance for selecting longan varieties, controlling fruit seeds, improving fruit quality and increasing longan production to study the changes of biomacromolecules, polyamines and specific proteins during longan embyo developing period.1. Changes of biomacromolecules in the process of the longan embryo developmentThe changes of nucleic acid , protein and starch content had an important effect on embryo developing condition in longan. On the basis of fresh weight, the experiment showed that maxium content of nucleic acid in ovules per gram could be reached around 10 to 17 days after anthesis , and decreased gradually until its minimal content could be reached around 45 days after anthesis , after that it began to level off. It was a two periods increasing form . DNA content would be gradually increased with the development of ovules.The changing trend of RNA content resembles that of DNA , but changes of DNA content came after RNA . It indicated that RNA changes followed DNA in the process of gene transcription. Change of protein was paralles with that of nucleic acid per ovule. Accumulation of protein basically paralles that of RNA, it showed that the changes of RNA and protein companied each other on the level of translation. Changing tend of starch content per ovules was slightly different from that of DNA, RNA and protein, the graph for the changes in starch content in ovules showed a broken line of four segments each with a different slop per gram , while the content of starch would increased gradually, especially, its later the process is greatly around 55 days after anthesis . Thus showed that the content in storing substance was greatly increased with the embryo development.2. Relationship between longan's embryo development and changes of polyaminesThe thesis also studied the relationship between longan embryo development and contents of polyamines . Experiments showed that the contents of polyamines in normal ovules were higher than those in abortive ones during the whole embryogenetic process. The highest levels were reached on 10 days after anthesis. Put among it accounted for about 65% of total contents of polyamines, after this, the contents of polyamines declined gradually. However, the contents of polyamines declined brightly from 31 to 38 days after anthesis . The contents of Spin in normal ovules were very higher than those in abnormal ovules, while Spd was higher in normal ovules than in abnormal vules except for 10 days after anthesis .The studies also showed that low ratios of (Spd+Spm)/Put and Spm/PAs might hindered embryo development. Polyamines contents hit the peak befor the contents of nucleic acid and protein reached maxium, which suggested that polyamines might affect embryo development by regulating the synthesis of biomacromolecules.3. Studies on longan's specific proteins in the embryo development stagesIEF-SDS-PAGE technique was applied to comparing and analyzing the changes of protein component during longan embryos differentiation and development.The results showed that major components of proteins were generally similar in different developing periods, however, some changes also took place . This experiment discovered 8 new specific proteins in different stages of the embryo development . They were 27.1kD pI7.5,17.5kD pI8.2 on 38 DAA; 11.4kD pI7.6, 13.2kD pI9.9 on 45 DAA; 22.6kD pI7.2, 18.6kD pI8.3, 23.5kD pI3.6,18.3 kD pI 10.1 on 52 DAA. The number of protein points were comparatively higher on 31 DAA gel map , which indicated that rich synthesis and accumulation of proteins appeared in the 31 DAA stage, these findings coincided with the results of the protein contents determination. The appearance or disappearance of the specific proteins might play an important role in longan embryo differentiation...
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