Studies On Physiological And Biochemical Changes During Early Stage Of Cucumber In Vitro Gynogenesis

In vitro gynogenesis is one of the major methods for haploid production. There isfew report about physiological and biochemical changes of cucumber in vitro gynogenesis.An efficient and stable system for cucumber haploid production via in vitro gynogenesis wasestablished in Tianjin Keneil Cucumber Research Institute. On the basis of this system andpreviously morphological, physiological and biochemical studies on cucumber in vitrogynogenesis. Materials from both typical gynogenesis using M99 as induction medium andnon gynogenesis using W5 as induction medium were collected. The activities anddistribution of peroxidase and its isoenzymes, content of soluble protein and distribution of allprotein during early stage of cucumber in vitro gynogenesis and non gynogenesis wereinvestigated by biochemistry and histochemistry technology. Nucleic acid and amylose werealso studied by histochemistry. These researches aimed to give a probative value for celldifferentiation mechanism during the early stage of cucumber in vitro gynogenesis. The results showed that total peroxidase, NADH peroxidase, and glutathione peroxidaseactivities of explants in mediums M99 were all increased more and earlier than that in W5.While cytochrome peroxidase and ascorbate peroxidase of explants in mediums M99 were alwayslower than that in W5. The Indole-3-acetic acid oxidase activity of explants in medium M99increased markedly and remained high level, while that in W5 increased in the first 5 days anddecreased markedly after 5-day culture. Peroxidase localization in explants of medium M99 showed that total peroxidase wasfound mainly in cytoplasm of outer integument and nucellar tissue during 0-2 days of culture,peroxidases activity in parenchyma tissue of ovary increased gradually which showedgradient staining following culture days and peroxidases mainly localized in cell wall and theextracellular gaps. Whole ovule cells were completely stained. While in medium W5peroxidases mostly localized in ovule cells especially in integument during 2-4 days afterculture. Peroxidase located in cell wall and in the extracellular gaps of proligerous cells inintegument at day 4. Soluble proteins in explants of both M99 and W5 were all increased slightly in the first 4days of culture. But it decreased in explants of mediums M99, while it increased in that of W5after 4 days culture. Total protein in ovules increased, while that in parenchyma of mediumsM99 decreased. But total protein in both ovules and parenchyma of mediums W5 were allincreased. In explants of M99, DNA and RNA content increased in ovules, especially in nucellus.Small starch grains appeared in ovule cells, while no starch grains appeared in parenchyma.In explants of W5, DNA and RNA content increased in both ovules and parenchyma. DNAcontent in proligerous cells decreased after 6 days of culture. Amylose increased inparenchyma gradually and big starch grains appeared in proligerous cells.