Abstract:

Plant in vitro culture has a history of more than one hundred years, but it is still unable to be predicted and inferred. There are 4 kinds of elements for plant in vitro culture: genotype (genetic elements), explant-type (physiological elements), medium (chemical elements), culture-conditions (physical elements). In order to find out the effects of these elements and the mechanisms in plant in vitro culture, a series of “communication” experiments aimed at revealing the relationship between culture- elements and culture-results were conducted. Wheat was used as the main materials (Table 1). Callus induction, subculture and callus quality improvement and evaluation were carried out with mature and immature embryos of different varieties on different media (MS, LS, N6, C17 etc.) under different conditions (Table 2, 3). The effects of genotype, explant-type, medium, culture-conditions to plant tissue culture were studied systematically. The results showed that: Genotype only determined the quality but did not limit the induction of callus. Explants affected both the formation of callus and its quality at early stage. The difference of callus quality originated from explants was no less than that from genotypes. Despite of providing nutrients, medium also played a very important role in regulating the quality of callus. Generally, 2,4-D, NH₄⁺ usually accelerated cell division and the growth of callus but cytokinin, NO₃^- showed opposite effects. Light had the similar effects to cytokinins. Temperature variation played an influential role to callus too. These results were also improved with corn, rice, millet, cotton and so on. All the functions from these elements in in vitro culture can be considered or imagined as the effects at physiological and biochemical levels and they can be managed as coadjutant factors according to the needs of callus quality improvement. With this idea, plant in vitro culture comes to be more controllable. Through this study, a series of methods wildly used for wheat tissue culture was established.

Key words: Communication experiments, Tissue culture elements, Callus quality, Tissue culture of wheat