| 1The key technique of tissue culture of asparagus UC308Asparagus officinalis L., as a nutrient-rich and important cash crop, has high medicinal value. As a dioecious plant, propagating asparagus with tissue culture can obtain a large number of plants without any change of its quality in a short time and reduce the high cost of seeds. In previous studies of asparagus tissue culture, people put too much emphasis on the specifical demands of different varieties, while, there is a lack of systematic study of the law on auxin which play an important role in the dedifferentiation and root induction. By propagating UC308, a new variety of asparagus through tissue culture, we try to establish its tissue culture system, and meanwhile, try to find the role of auxin played in the in the tissue culture, to narrow the scope of screening in the future research.The results show that the formation of asparagus calli depend exogenous auxin. More than0.5mg/L of NAA significantly increased the rate of calli induction; meanwhile, less than0.5mg/Lof NAA was favorable to the asparagus bud induction.The rooting rate was increased by subculturing explants for once, adjusting the time of rooting induction(15days more or less) and the existence of1.0mg/L PP333;2,4-D pretreatment accelerated the rooting but reduced the rate; the concentration of NAA lower than2.0mg/L in the regeneration of shoots hadn’t further influence on rooting. Comparing the four sorts of auxin, NAA, IAA, IBA and2,4-D during roots induction of asparagus, it showed that different kind of auxin had different effect on the rooting, and IBA was the best choice both in the quality and rate on rooting.In the anther culture of asparagus, exogenous auxin is necessary for embryoids and calli induction. Using high concentration of NAA (1mg/L or higher) can increase the rate of anther induction, while for2,4-D, high concentration (0.5mg/L) had a negative effect. Using N6Culture medium and incubating anthers at28℃in the early phase can also increase the induction rate. 2The analysis of phenotype of lls, a temperature sensitive mutant of ArabidopsisTemperature is an important environmental factor in plant morphogenesis. Due to the lack of research system, it isn’t clear about temperature receptors and its regulatory networks. The Arabidopsis mutant, Us (Long life Span), is a mutant obtained from a T-DNA insertional mutant library. It is a developmentally retarded and temperature sensitive mutant. Growing in normal temperature (24℃) and long day, it is characterized by its slow growth, dwarfed figure and increased branches, however, all these characters will be recovered when it grows in28℃. This shows that in lls, the mechanism which maintains the normal growth and development of plant within certain temperature range is broken. Study this mutant will make us be clearer about how plants cope with the change of temperature with its complex genes signal networks. Though studying the phenotype of this mutant in different development stages and under different temperature, we try to explain why the mutant has such phenotype and provide the morphological basis and more clues for the study of gene function and its regulatory networks.Results show that the SAM of mutant had more narrow size than the wild type and a clear delay of time to access to reproductive growth stage. This phenotype was recovered by high temperature. Comparing with the wide type, the number and structure of vascular bundles in mutant had no obvious change, while, their parenchyma cells in the vascular cylinder were much smaller which made the stem more slender; leaves of mutant were significantly less than the wild type which was due to smaller cell size; all these phenotypes were recovered or partly recovered under high temperature. This mutant was less sensitive to cytokinin, for its roots formed primary xylem when it grew with0.1μM BA. |
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